Introduction

Once your rocket has landed on an alien planet, you need some transportation to get you around.

In the Andre Norton and A. M. Lightner novels, First-In scoutships would carry a light exploration aircraft called a "flitter." They have to be light because Every Gram Counts, and compact because storage space inside spacecraft is at a premium.

Such vehicles will commonly be equipped with survival kits and first-aid kits, in case they get stranded in a remote area.

Note that fitters are very different from landers and shuttlecraft. The latter is for transporting crew and cargo from an orbit-to-orbit spacecraft to the ground. For the same reason flitters are not dropships. The latter are just like shuttlecraft, except they are designed for when the ground is shooting weapons at you.

For bases on airless worlds, they would use rugged all terrain vehicles, often with tractor treads. Sometimes airless worlds would use rocket-propelled vehicles that would hop to their destination, like metal kangaroos. Some of these are large mobile labs.

Some ground vehicles deal with the jagged landscape problem by using ducted fan technology. These are called "hovercraft" "air-cushion vehicle", or "ground-effect machines". These exist in the real world, but on other planets they do require the presence of an atmosphere. A good example are the hover-tanks from David Drake's Hammer's Slammers series. Since they are levitating metric tons of armor plated vehicle, they require internal fusion reactors outputting unreasonable amounts of power.

More SFnal is the skimmer, which hovers a meter or so off the ground like a hovercraft, but uses handwavium technology e.g., antigravity. They work on all planets, atmosphere or no. An example is Luke Skywalker's Landspeeder.

If the handwavium hover tech is more extreme, the vehicle starts to blur the distinction between "ground vehicle" and "aircraft". In the Traveller RPG, they would use an antigravity car called an Air/raft. This was not only capable of flying, the blasted thing could actually reach low orbit. At this point you have to question why you are not using this technology on your spacecraft instead of a stupid rocket engine.

Ground Cars


groundcar

[first use unknown; dates at least back to 1940s]

General SFnal term for a conventional wheeled vehicle, used to imply that the normal "car" is a flitter or skimmer.

This term was used in Asimov's original Foundation novelette.

skimmer

[first use unknown]

General SFnal term for a ground vehicle with roughly the performance characteristics of a fast hovercraft, but with the implication that it uses some form of antigrav rather than ducted fans.

From An SF Glossary by Eric S. Raymond (2006)

Planet Buggy

A planet buggy is sort of a dune buggy for planetary and moon exploration. They are not pressurized, the astronaut ride exposed to ambient conditions. The only actual real-world example is the Apollo Lunar Roving Vehicle, though NASA and other space agencies have been trying to develop new ones.

MARSBUGGY

(ed note: this is from a nasty little story about two men trying to kill each other. But it does have Mars Buggies.)

      ONLY SHEER RUTHLESSNESS could have taken him out of town alive. The mob behind Carter hadn't tried to guard the Marsbuggies, since Carter would have needed too much time to take a buggy through the vehicular airlock. They could have caught him there, and they knew it. Some were guarding the personnel lock, hoping he'd try for that. He might have; for if he could have closed the one door in their faces and opened the next, the safeties would have protected him while he went through the third and fourth and outside. On the Marsbuggy he was trapped in the bubble.
     There was room to drive around in. Less than half the prefab houses had been erected so far. The rest of the bubbletown's floor was flat fused sand, empty but for scattered piles of foam-plastic walls and ceilings and floors. But they'd get him eventually. Already they were starting up another buggy.
     They never expected him to run his vehicle through the bubble wall.
     The Marsbuggy tilted, then righted itself. A blast of breathing-air roared out around him, picked up a cloud of fine sand, and hurled it explosively away into the thin, poisoned atmosphere. Carter grinned as he looked behind him. They would die now, all of them. He was the only one wearing a pressure suit. In an hour he could come back and repair the rip in the bubble. He'd have to dream up a fancy story to tell when the next ship came...
     Top speed for a Marsbuggy is about twenty-five miles per hour. The buggy rides on three wide balloon-tired wheels, each mounted at the end of a five-foot arm. What those wheels can't go over, the buggy can generally hop over on the compressed-air jet mounted underneath. The motor and the compressor are both powered by a Litton battery holding a tenth as much energy as the original Hiroshima bomb.
     Carter had been careful, as careful as he had had time for. He was carrying a full load of oxygen, twelve four-hour tanks in the air bin behind him, and an extra tank rested against his knees.
     His batteries were nearly full; he would be out of air long before his power ran low. When the other buggies gave up he could circle round and return to the bubble, in the time his extra tank would give him.
     His own buggy and the two behind him were the only such vehicles on Mars. At twenty-five miles per hour he fled, and at twenty-five miles per hour they followed. The closest was half a mile behind.
     The crater which was home dropped behind and was gone. Endless flat desert rose before the buggies, flowed under the oversized wheels and dropped behind. Gentle crescent dunes patterned the sand, but they were no barrier to a buggy.
     The hills were low and shallow. Even from yards away he might have been looking at the smooth flank of a sleeping beast—except that this beast was not breathing. Carter took a deep breath, noticing how stale the air had become despite the purifier unit, and turned on the compressed-air jet.
     The air of Mars is terribly thin, but it can be compressed; and a rocket will work anywhere, even a compressed-air rocket. Carter went up, leaning as far back in the cabin as he could to compensate for the loss of weight in the 0-tanks behind him, to put as little work as possible on gyroscopes meant to spin only in emergencies. He rose fast, and he tilted the buggy to send it skating along the thirty-degree slope of the hill. There were flat places along the slope, but not many. He should reach the first one easily...
     The compressor had almost stopped, which meant the tank was nearly full. But Carter would be a fool to take off before it was completely full. You got the greatest acceleration from an air jet during the first seconds of flight. The rest of the flight you got just enough pressure to keep you going.

From HOW THE HEROES DIE by by Larry Niven (1966)
GROUNDROVER

(ed note: in the first interstellar expedition to Epsilon Eridani, Mike Shaugnessy's aircraft goes down. Ricardo Nansen has to descend from the orbiting starship in a planetary lander on a rescue mission. But first he has to fly through a hurricane, which was ... challenging.)

      “ Land according to plan," he said. The order was scarcely necessary, except as a sound of triumph.
     Don't stop to celebrate, he thought. Not yet.
     The site had been chosen from space, the nearest spot that looked Safe without being close enough to endanger Shaughnessy should something go wrong. The boat slewed into vertical alignment, landing jacks extended, dust whirled up, impact thudded. The hull began to tilt. The jack on that side lengthened itself to compensate, and the boat stood stable.
     Nansen unharnessed and squirmed his way downward, aft, to the vehicle bay. He could have walked the rest of the distance, but Shaughnessy might need carrying. For a few minutes he was busy donning his equipment. He already wore the gloves, boots, and hooded coverall that protected him from ultraviolet. He slipped on his backpack, with its air tank and other gear, snugged goggles and breathmask over his face, opened the inner lock valve, and pushed the little groundrover through. The chamber expanded to accommodate them, barely. The valve closed, Nansen’s fingers directed the outer valve to move aside. A certain amount of interior air was lost in the local atmosphere. He gave the rover a shove to send it trundling down the ramp that had deployed. On the ground, he climbed to the control seat and drove.
     Strange, he thought, as often before, how half-familiar the scene was. The Solar System, where he had trained, held more foreignness than this, from red-brown Martian deserts under pale-red skies to the grandeur of Satum’s rings. Here he weighed about the same as on Earth, the horizon was about as far off, a sun that looked much like Sol stood in a blue heaven, the breeze was just comfortably warm, sand gritted under wheels and dust eddied lazily over their tracks. But the oxygen-poor air would choke him, and everywhere around stretched barrenness.
     The thought was equally old in him: Well, why should we ever have expected more? Life on Earth took three billion years to venture from the seas to the land. Our giant Moon, a cosmic freak, may well have hastened that by the tides it raised. Give this life here a few more geological ages. Yes, of course it was disappointing not to find woods and flowers and big, fine animals. But we knew the odds were against it. Meanwhile, what a dragon's hoard of scientific treasure we're winning.
     Steering by inertial compass, he topped a ridge and saw the fallen aircraft. Although it had dug itself half a meter into gravel, the composite body showed small damage. Impact had doubtless smashed most things inside. Nansen’s gaze strained. Shaughnessy—
     Yes, there, tiny across a kilometer but on his feet! Nansen's heart sprang. The rover rumbled downhill.
     Shaughnessy staggered to meet him. Nansen stopped and dismounted. They fell into one another's arms.
     “Are you all right?” Nansen gasped.
     “Barely, barely. It’s foul my air has gotten. Let me hook up." Shaughnessy plugged into the large tank on the vehicle.
     Weight penalty or no, Nansen thought, backpack units ought to include recyclers, the same as on spacesuits. Yet who could have foreseen? Every interstellar expedition was a leap into mystery. Oh, yes, you could send robots ahead, as had been done at first, but then you’d wait too long for less news than humans would bring.
     “Ah-h-h!” Shaughnessy sighed. “Like the breeze off a clover meadow. Or so it feels by our modest standards hereabouts. My father thanks you, my mother thanks you, my sister thanks you, my brother thanks you, and I thank you."
     The crew seldom spoke of kinfolk. When they retumed home, the crossing would take a few days of their time—and a quarter century would have passed on Earth. You didn't want to dwell on what time might have done meanwhile. Nansen forgave the tactlessness. He was too glad that his friend lived. Anxiety: “Are you well otherwise, Mike?"
     “I am. I did take a tumble on landing, which split my transceiver apart. We need a design more robust. Otherwise just bruises, not like my poor flyer. I'm afraid my fellow airmen will have fewer missions in future, Rico, for I'll be claiming my share of them.”

From STARFARERS by Poul Anderson (1998)

Mobile Bases

Unlike planet buggies, Mobile Bases are enclosed and usually are pressurized. Some are large enough to contain sleeping bunks and kitchens.

SAND FLEAS

      “I don’t suppose you know how to use these things yet,” said the pilot, producing two breathing masks. “But you’ve only got to wear them for a minute while you get over to the Fleas.” (The what? thought Gibson. Oh, of course, those little vehicles would be the famous Martian “Sand Fleas,” the planet’s universal transports.)
     Gibson climbed into Henderson’s Flea through the flexible plastic bag that was the vehicle’s simple but effective airlock, and the other joined him a minute later in the driving cab. It was a relief to discard the breathing mask; the few minutes he had spent in the open had been quite a strain.
     “Do these machines ever break down outside?” he asked as they climbed into the Flea.
     “Not very often. They’ve got a terrific safety factor and there’s really very little to go wrong. Of course, sometimes a careless driver gets stuck, but you can usually haul yourself out of anything with the winch.
     “How fast can these things go?” asked Gibson.
     “Oh, at least a hundred on a good road. But as there aren’t any good roads on Mars, we have to take it easy. I’m doing sixty now. On rough ground you’ll be lucky to average half that.”
     “And what about range?” said Gibson, obviously still a little nervous.
     “A good thousand kilometres on one charge, even allowing pretty generously for heating, cooking, and the rest. For really long trips we tow a trailer with spare power cells. The record’s about five thousand kilometres; I’ve done three before now, prospecting out in Argyre. When you’re doing that sort of thing, you arrange to get supplies dropped from the air.
     They reached the radio station half an hour after leaving the city. Feeling it was time to do some walking, they adjusted their masks and dismounted from the Flea, taking turns to go through the tiny collapsible airlock.
     “They’re quite a sociable crowd,” said the driver as he brought the vehicle to a halt. “It’s a pretty dull life up here and they’re always glad to see people. And there’ll be room inside the dome for us to stretch our legs and have dinner in comfort.”
     “Surely we can’t expect them to provide a meal for us,” protested Gibson, who had a dislike of incurring obligations he couldn’t readily discharge. The driver looked genuinely surprised; then he laughed heartily.
     “This isn’t Earth, you know. On Mars, everyone helps everyone else—we have to, or we’d never get anywhere. But I’ve brought our provisions along—all I want to use is their stove. If you’d ever tried to cook a meal inside a Sand Flea with four aboard you’d know why.

From THE SANDS OF MARS by Arthur C. Clarke (1951)
CATERPILLAR TRACTOR

Our expedition was a large one. We had two heavy freighters which had flown our supplies and equipment from the main lunar base in the Mare Serenitatis, five hundred miles away. There were also three small rockets which were intended for short-range transport over regions which our surface vehicles couldn’t cross. Luckily, most of the Mare Crisiurn is very flat. There are none of the great crevasses so common and so dangerous elsewhere, and very few craters or mountains of any size. As far as we could tell, our powerful caterpillar tractors would have no difficulty in taking us wherever we wished to go.


We had begun our journey early in the slow lunar dawn, and still had almost a week of Earth-time before nightfall. Half a dozen times a day we would leave our vehicle and go outside in the spacesuits to hunt for interesting minerals, or to place markers for the guidance of future travelers. It was an uneventful routine. There is nothing hazardous or even particularly exciting about lunar exploration. We could live comfortably for a month in our pressurized tractors, and if we ran into trouble we could always radio for help and sit tight until one of the spaceships came to our rescue.


We kept Earth-time aboard the tractor, and precisely at 22:00 hours the final radio message would be sent out to Base and we would close down for the day. Outside, the rocks would still be burning beneath the almost vertical sun, but to us it was night until we awoke again eight hours later. Then one of us would prepare breakfast, there would be a great buzzing of electric razors, and someone would switch on the short-wave radio from Earth. Indeed, when the smell of frying sausages began to fill the cabin, it was sometimes hard to believe that we were not back on our own world — everything was so normal and homely, apart from the feeling of decreased weight and the unnatural slowness with which objects fell.


Our driver was already outside in his spacesuit, inspecting our caterpillar treads. My assistant, Louis Garnett, was up forward in the control position, making some belated entries in yesterday’s log.


But I was curious to know what kind of rock could be shining so brightly up there, and I climbed into the observation turret and swung our four inch telescope round to the west.

From The Sentinel by Sir Arthur C. Clarke (1951)
MOBILE LAB

The mobile lab now rolling across the crater plain at fifty miles an hour looked rather like an outsized trailer mounted on eight flex-wheels. But it was very much more than this; it was a self-contained base in which twenty men could live and work for several weeks. Indeed, it was virtually a landgoing spaceship — and in an emergency it could even fly. If it came to a crevasse or canyon which was too large to detour, and too steep to enter, it could hop across the obstacle on its four underjets.

(ed note: in the movie version, the mobile lab was converted into the ballistic rocket Moon Bus. Presumably this is for dramatic reasons, since Clarke was of the opinion that ballistic vehicles were horribly inefficient as Lunar transports. At least compared to monorails and ground cars)


As he sat with Halvorsen and Michaels in the forward observation lounge, immediately beneath the driver’s position, Floyd found his thoughts turning again and again to the three-million-year-wide gulf that had just opened up before him.

A few hundred yards ahead, a signpost was coming up over the Moon’s strangely close horizon. At its base was a tent-shaped structure covered with shining silver foil, obviously for protection against the fierce heat of day. As the bus rolled by, Floyd was able to read in the brilliant earthlight:

EMERGENCY DEPOT No. 3
20 Kilos LOX
10 Kilos Water
20 Foodpaks Mk 4
1 Toolkit Type B
1 Suit Repair Outfit
! TELEPHONE !

“Please fasten your seat belts and secure all loose objects,” said the cabin speaker suddenly. “Forty degree slope approaching.”

Two marker posts with winking lights had appeared on the horizon, and the bus was steering between them.

Floyd had barely adjusted his straps when the vehicle slowly edged itself over the brink of a really terrifying incline, and began to descend a long, rubble-covered slope as steep as the roof of a house. The slanting earthlight, coming from behind them, now gave very little illumination, and the bus’s own floodlights had been switched on. Many years ago Floyd had stood on the lip of Vesuvius, staring into the crater; he could easily imagine that he was now driving down into it and the sensation was not a very pleasant one.

They were descending one of the inner terraces of Tycho, and it leveled out again some thousand feet below. As they crawled down the slope, Michaels pointed out across the great expanse of plain now spread out beneath them.

“There they are,” he exclaimed. Floyd nodded; he had already noticed the cluster of red and green lights several miles ahead, and kept his eyes fixed upon it as the bus edged its way delicately down the slope. The big vehicle was obviously under perfect control, but he did not breathe easily until it was once more on an even keel.

From 2001 A SPACE ODYSSEY by Sir Arthur C. Clarke (1969)
CATERPILLARS

There are only two methods of long-range transport on the Moon. The high-speed monorails link the main settlements with a fast, comfortable service running on a regular schedule. But the rail system is very limited, and likely to remain so because of its cost. For unrestricted ranging over the lunar surface, one must fall back on the powerful turbine-driven tractors known as "Caterpillars" or, more briefly, "Cats." They are, virtually, small spaceships mounted on fat little tires that enable them to go anywhere within reason even over the appallingly jagged surface of the Moon. On smooth terrain they can easily do a hundred kilometers an hour, but normally they are lucky to manage half that speed. The weak gravity, and the caterpillar treads they can lower if necessary, enable them to climb fantastic slopes. In emergencies, they have been known to haul themselves up vertical cliffs with their built-in winches. One can live in the larger models for weeks at a time without undue hardship, and all the detailed exploration of the Moon has been carried out by prospectors using these tough little vehicles.


He eased the vehicle forward, gingerly skirting a vast talus slope where splintered rock had been accumulating for millennia. Such slopes were extremely dangerous, for the slightest disturbance could often set them moving in slow, irresistible avalanches that would overwhelm everything before them. For all his apparent recklessness, Jamieson took no real risks, and always gave such traps a very wide berth. A less experienced driver would have gaily galloped along the foot of the slide without moment's thought — and ninety-nine times out of a hundred would have got away with it. Jamieson had seen what happened on the hundredth time. Once the wave of dusty rubble had engulfed a tractor, there was no escape, since any attempt at rescue would only start fresh slides.

Wheeler began to feel distinctly unhappy on the way down he outer ramparts of Plato. This was odd, for they were much less steep than the inner walls, and he had expected a smoother journey. He had not allowed for the fact that Jamieson would take advantage of the easier conditions to crowd on speed, with the result that Ferdinand was indulging in a peculiar rocking motion. Presently Wheeler disappeared to the rear of the well-appointed tractor, and was not seen by his pilot for some time. When he returned he remarked rather crossly, "No one ever told me you could actually be seasick on the Moon."

The view was now rather disappointing, as it usually is when one descends to the lunar lowlands. The horizon is so near — only two or three kilometers away — that it gives a sense of confinement and restraint. It is almost as if the small circle of rock surrounding one is all that exists. The illusion can be so strong that men have been known to drive more slowly than necessary, as if subconsciously afraid they might fall off the edge of that uncannily near horizon.


They stopped for a meal about ten kilometers east of the Straight Range, and investigated more of the boxes which the Observatory kitchen had given them. One corner of the tractor was fitted out as a tiny galley, but they didn't intend to do any real cooking except in an emergency. Neither Wheeler nor Jamieson was a sufficiently good cook to enjoy the preparation of meals and this, after all, was a holiday.


From the Straight Range they swung southeast, and presently the great headland of Promontory Laplace appeared on the skyline. As they rounded it, they came across a disconcerting sight — the battered wreck of a tractor, and beside it a rough cairn surmounted by a metal cross. The tractor seemed to have been destroyed by an explosion in its fuel tanks, and was an obsolete model of a type that Wheeler had never seen before. He was not surprised when Jamieson told him it had been there for almost a century; it would still look exactly the same a million years from now.


It is seldom realized that driving on the moon by day is far less pleasant, and even less safe, than driving by night. The merciless glare demands the use of heavy sun filters, and the pools of inky shadow which are always present except on those rare occasions when the sun is vertically overhead can be very dangerous. Often they conceal crevasses which a speeding tractor may be unable to avoid. Driving by Earthlight, on the other hand, involves no such strain. The light is so much softer, the contrasts less extreme.

To make matters worse for Jamieson, he was driving due south — almost directly into the sun. There were times when conditions were so bad that he had to zigzag wildly to avoid the glare from patches of exposed rock ahead. It was not so difficult when they were traveling over dusty regions, but these became fewer and fewer as the ground rose toward the inner ramparts of the mountain wall.


The ground was extremely broken and treacherous here, but drivers who had gone this way before had left markers for the guidance of any who might come after them. Jamieson was using his headlights a good deal now, as he was often working through shadow. On the whole he preferred this to direct sunlight, for he could see the ground ahead much more easily with the steerable beams from the projectors on top of the cab. Wheeler soon took over their operation, and found it fascinating to watch the ovals of light skittering across the rocks. The complete invisibility of the beams themselves, here in the almost perfect vacuum, gave a magical effect to the scene. The light seemed to coming from nowhere, and to have no connection at all with tractor.

From EARTHLIGHT by Sir Arthur C. Clarke (1951)
THE CREEP

The whole area was as bare as his hand. Except for the pitted, scarred, slagged-down spots which showed so clearly what driving blasts would do to such inconceivably cold rock and metal, Palainport was in no way distinguishable from any other unimproved portion of the planet’s utterly bleak surface.

There were no signals; he had been told of no landing conventions. Apparently it was everyone for himself. Wherefore Samms’ tremendous landing lights blazed out, and with their aid he came safely to ground. He put on his armor and strode to the airlock; then changed his mind and went to the cargo-port instead. He had intended to walk, but in view of the rugged and deserted field and the completely unknown terrain between the field and the town, he decided to ride the “creep” instead.

This vehicle, while slow, could go — literally — anywhere. It had a cigar-shaped body of magnalloy; it had big, soft, tough tires; it had cleated tracks; it had air- and water- propellers; it had folding wings; it had driving, braking, and steering jets. It could traverse the deserts of Mars, the oceans and swamps of Venus, the crevassed glaciers of Earth, the jagged, frigid surface of an iron asteroid, and the cratered, fluffy topography of the moon; if not with equal speed, at least with equal safety.

From FIRST LENSMAN by E. E. "Doc" Smith (1950)
IRON MAIDEN

And so it was that three of us set forth in the iron maiden — a sort of amphibious tank designed and built on Penaflor, and supposedly the last word in transport for alien worlds. Penaflor has an unnaturally high regard for the efficacy of armour plating, which testifies to a military bent in its attitude. I'd never been in such a monstrosity before, so I was suspicious of its utility. But it was a lot faster than walking, and the only other alternative was to take the Swan up again and stooge around in atmosphere searching for the wreck.


Things began to get difficult when we reached what looked like a gigantic flat plain. We had a fairly humpy ride down to it, and from up above it looked like an endless mottled carpet, with colours flowing and fusing like an oil-slide. Close to us, we could see the leaves and the tendrils and the flowers changing too, dwindling away or bursting forth, shrivelling and exploding, caught in helpless, purposeless gaiety by their relentless dancing master. But further away we could see nothing of shape — only colour and preternatural flatness. The plain stretched clear to the horizon on three sides of us. Far away to our right, the sun was beginning to sink. Its inconstant light flared and faded, its diameter changed and blurred. Prominences were clearly visible in dazzling white and harsh, electric yellow.

Johnny eased us down the slope — where I saw bare rock protruding from the living sheath for the first time — and onto the plain. Where we promptly stopped.

     'The wheel won't grip,' he said. 'I'm going down. Sinking.'
     'You're not sinking, you're floating,' I told him. 'This is the sea.'
     'Covered with plants?'
     'Why not? Even on nice, normal worlds there are Sargasso Seas. Surface weed, extending skin, clustering plant islands. Thousands of square miles, on a lot of worlds. This isn't unusual.'
     He switched on the turbines, and the screws began to shove us laboriously through the tangle.

The way delArco chose — had to choose, for there was no other — was sheer and bumpy. But the iron maiden was built to take it. Once or twice, I worried lest we slip backward, but she was a tenacious beast, and climbed the cliff with dogged insistence.

From THE HALCYON DRIFT by Brian Stableford (1972)



North American Rockwell Prime Mover

This is from Lunar base synthesis study. Volume 3 - Shelter design Final report, North American Rockwell's study on constructing a lunar base. The "Prime Mover" is a lunar tractor that can perform various vital tasks in the construction and maintenance of a lunar base. It can assist with unloading space tugs, assembling modules into a lunar base, covering said modules with lunar regolith for radiation shielding, creating and maintaining landing fields and roads, transporting lunar expeditions, and a host of other functions.

It has 90-degree approach and 60-degree exit angles, a short turning radius, 10k ampere-hours of battery power, over 17 cubic meters of free volume, and weight just over 1,800 kilograms.

Mars One Rover

This is the planetary rover for the Mars One mission. It is from the fictional book THE MARS ONE CREW MANUAL by Kerry Mark Joëls

The main mission uses a chemical rocket engine. In an attempt to improve performance for the crew's benefit, the mission payload is sent ahead in an uncrewed rocket. The mission payload is basically the Mars Rover.

Mars Rover was launched in its aerocapture vehicle on May 6, 1996 (245-0210 JD), swung by Venus on June 14, 1996 (245-0249.2 JD), and arrived at Mars January 11, 1997 (245-0460 JD), 40 days (39 sols) ahead of you. After descent and landing, the Mars Rover (MR, or Rover) was remotely guided on a traverse to within one-half kilometer of your expected landing site. The 3,330-kilogram Rover, which will be used for the long traverse (19.5 sols), is made of two basic modules. The forward module is a sphere with a diameter of 3 meters. The second module is a tank like affair 2.1 meters in diameter. These modules are nested together and sit on four 1.53-meter diameter wheels. The wheelbase is 3.7 meters and tool and sample boxes are mounted between the wheels on both sides. Overall length is 6.1 meters. Ground clearance is 0.65 meters which should permit safe-passage over much of the rock-strewn terrain.

Rover has four electric motors. Electric power is provided by a fuel cell which also produces fresh water, and by a series of silver-zinc 36 volt batteries. The Rover has a range of 48 kilometers per battery charge. The fuel cell trickle charges the batteries at night.

Rover is capable of about 16 kph maximum and 11.2 kph cruise. It can negotiate slopes of up to 25 degrees.

The top of the second module is surrounded by 2.4-meter long radiators for the fuel cell. On top there is a low-gain antenna and mounting brackets for portable video cameras. Two intelligent robot arms are attached to the sides of the spherical module. These arms are integrated with the main landing computer and can be used for contingency sample gathering, general sample gathering, and trenching tor manual sample gathering. The arms, coupled with the computer, will have their own active collection program, and can be controlled remotely from orbit as well.

Lithium hydroxide (LiOH) canisters are used to remove carbon dioxide from the air, and a portable water purification unit will allow you to recycle liquid waste. Solid wastes will be stored in an airtight compartment. Fecal collection bags will be used tor solid waste and a urine collection device tor liquids. Biocide wipes will be used for cleanliness. There will be no showers until you are back at the main ship.

The suits, portable life-support system backpacks (PLSS), and an umbilical arrangement are stored inside. The Rover has no airlock. When you open the hatch for EVAs, both crewmen must be suited up, even if only one is working outside. The 1.5-meter diameter hatch is the only way in and out of the Rover. An umbilical can be ted out the open hatch and permits a 6.1-meter radius of movement without needing a PLSS backpack. This will permit very short stops to pick up special samples or make quick observations.

Inside Rover is a driving station, a large storage closet section (on the starboard side), a narrow 0.45-meter aisle in the second module with storage compartments, and above them, two narrow berths with hammocks. Suits may be hung near the hatch or placed in the berths, depending on your activities. The inside is fairly cramped, but you will be spending about six hours per day outside and eight hours sleeping.

From THE MARS ONE CREW MANUAL by Kerry Mark Joëls (1985)

Lost In Space Chariot

The Chariot

The chariot was an amphibious tracked vehicle the crew used when they were on a planet. Since most body panels were clear—including the roof and its dome-shaped gun hatch—the chariot had retractable mylar curtains for privacy. Both a roof rack for luggage and roof mounted solar cells were accessible by exterior fixed ladders on either side of the vehicle. The roof also had a swivel-mounted, interior controllable spotlight near each front corner. The chariot had six bucket seats (three rows of two seats) for passengers. The interior featured a seismograph, a radar scanner with infrared capability, a radio transceiver, a public address system, and a rifle rack that held four laser rifles vertically against the inside of the left rear body panel.

Exotic Propulsion

2001 A SPACE ODYSSEY

Several very odd vehicles were rolling up to the Aries-lB spaceship — cranes, hoists, servicing trucks — some automatic, some operated by a driver in a small pressure cabin. Most of them moved on balloon tires, for this smooth, level plain posed no transportation difficulties; but one tanker rolled on the peculiar flex-wheels which had proved one of the best all-purpose ways of getting around on the Moon. A series of flat plates arranged in a circle, each plate independently mounted and sprung, the flex-wheel had many of the advantages of the caterpillar track from which it had evolved. It would adapt its shape and diameter to the terrain over which it was moving, and, unlike a caterpillar track, would continue to function even if a few sections were missing.

From 2001 A SPACE ODYSSEY by Sir Arthur C. Clarke (1969)

Walkers

WAR OF THE WORLDS - TRIPOD GAIT
"A [lightning] flash, and it came out vividly, heeling over one way with two feet in the air, to vanish and reappear almost instantly as it seemed, with the next flash, a hundred yards nearer. Can you imagine a milking stool tilted and bowled violently along the ground? That was the impression those instant flashes gave. But instead of a milking stool imagine it a great body of machinery on a tripod stand."

A rotating gait could be made to work but it would very tricky. I've always assumed this description was a literary device rather than an attempt to specify the actual gait. I assume that the hood sensors and effectors always point forwards.

It seems to me that only three gaits are possible - let's call them the 123, the 2(13) and the (123) gaits.


The 123 gait has the three legs 120deg out of phase:

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WalkGait

It's the gait that's closest to a horse walking. At any instant only one leg is off the ground.

You could lengthen each of the "on the ground" segments of the 123 gait so that sometimes three feet are on the ground. And you could shorten each of the "on the ground" segments so that sometimes only one foot is on the ground; that would be trotting. But you would never change the phase relation of the legs. That's like a bipedal gait. Humans have only one gait; the proportion of the time each foot is on the ground changes between walk, trot, run but the phase relation is always 180deg. Horses have several with different phase relations for walk, trot, canter and gallop.

When walking, the legs swing in straight line so the footsteps show three separate parallel lines. A tripod does not walk like a human whose footsteps are in a single line as it is difficult for the centre leg to zig-zag between the outer two. The body weaves from side to side so as to keep the centre of gravity over the point of maximum support. The speed of walking is tuned to match the period of both the pendulum of the legs and the inverted pendulum of the body above the feet.


The 2(13) gait is like a "one-legged-man on crutches" (In the Traveller RPG, the alien Pentapods use this gait):

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Bound Gait

This gait requires dynamic balancing while the centre leg is the only support. It's closest to bounding. When a greyhound or cheetah bounds, the front legs do not hit the ground at exactly the same time.


In the (123) gait, all the legs move together and act like a pogo stick:

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Gallop Gait

This gait is the closest to a horse galloping.

JANSEN'S LINKAGE

The Jansen's linkage is a planar leg mechanism designed by the kinetic sculptor Theo Jansen to simulate a smooth walking motion. Jansen has used his mechanism in a variety of kinetic sculptures which are known as Strandbeesten (dutch for "beach beasts"). Jansen's linkage bears artistic as well as mechanical merit for its simulation of organic walking motion using a simple rotary input. These leg mechanisms have applications in mobile robotics and in gait analysis.

The central 'crank' link moves in circles as it is actuated by a rotary actuator such as an electric motor. All other links and pin joints are unactuated and move because of the motion imparted by the crank. Their positions and orientations are uniquely defined by specifying the crank angle and hence the mechanism has only one degree of freedom (1-DoF). The kinematics and dynamics of the Jansen mechanism have been exhaustively modeled using circle intersection method and bond graphs (Newton-Euler mechanics). These models can be used to rate the actuator torque and in design of the hardware and controller for such a system.

From the Wikipedia entry for JANSEN'S LINKAG
WALKING INVISIBLE WEAPONS CARRIER

      For the first time in his life, he saw something only a few hundred people of his time had seen in an undelayed picture; he saw the ship. It was two hundred miles away from his present location, and two hundred fifty miles high.
     Fifty years ago, the alien ship landed butt-down in the northwest quadrant of the central plain of the United States. Stern-first, she had put one of her four landing jacks straight down to bedrock through the town of Scott’s Bluff, Nebraska, and the diagonally opposite leg seventy-five miles away near Julesburg, Colorado. Her shadow swept fifty thousand square miles.

     So Runner kept his eyes firmly fixed on the device he was showing.
     Keeping his eyes where they were was not as easy as it might have been. The speckled, bulbous distortion in front of him was what Headquarters, several hundred miles away under The Great Salt Lake, was pleased to refer to as an Invisible Weapons Carrier. It was hard to see — because it was designed to be hard to see.
     But Malachi Runner was going to have to take this thing up across several hundred miles of terrain, and he was standing too close to it not to see it. The Invisible Weapons Carrier was, in fact, a half-tone of reality. It was large enough inside to contain a man and a fusion bomb, together with the power supply for its engine and its light amplifiers. It bristled with a stiff mat of flexible-plastic light-conducting rods, whose stub ends, clustered together in a tight mosaic pointing outward in every conceivable direction, contrived to bend light around its bulk. It was presently conducting, toward Runner, a picture of the carved rock directly behind it.
     The rock, here in this chamber cut under the eastern face of the Medicine Bow Mountains, was reasonably featureless; and the light-amplifiers carefully controlled the intensity of the picture. So the illusion was marred by only two things: the improbable angle of the pictured floor it was also showing him, and the fact that for every rod conducting light from the wall, another rod was conducting light from Runner’s direction, so that to his eyes the ends of half the rods were dead black.
     “Invisibility,” Compton said scornfully from behind and to one side of Runner. Or, rather, he whispered and an amplifier took up the strain in raising his voice to a normal level. “But it’s not bad camouflage. You might make it, Colonel.”

     And in the morning he set out. He crawled into the weapons carrier, and was lifted up to a hidden opening that had been made for it during the night. He started the engine and, lying flat on his stomach in the tiny cockpit, peering through the cat’s-eye viewports, he slid out onto the surface of the mountain and so became the first of his generation to advance into this territory that did not any more belong to Man.

     The interior of the weapons carrier was padded to protect him from the inevitable jounces and collisions. So it was hot. And the controls were crude; the carrier moved from one foot to another, like a turtle, and there were levers for each of his hands and feet to control. He sweated and panted for breath.
     No other machine could possibly have climbed down the face of that mountain and then begun its heaving, staggering progress toward the spaceship’s nearest leg. It could not afford to leave tracks. And it would, when it had covered the long miles of open country that separated it from its first destination, have to begin another inching, creeping journey of fifty-five miles, diagonally up the broadening, extensible pillar of the leg.
     It stumbled forward on pseudopods — enormous hollow pads of tough, transparent plastic, molded full of stress-channels that curled them to fit the terrain, when they were stiffened in turn by compressed colorless fluid. Shifting its weight from one of these to another, the carrier duck-walked from one shadow to another as Runner, writhing with muscle cramps, guided it at approximately the pace of a drunken man.

     Gingerly, he extended a pseudopod. It touched the metal of the ship, through which the stabilizing field ran. There was an unknown danger here, but it hadn’t seemed likely to Intelligence that the field would affect non-metallic substances.
     It didn’t. The pseudopod touched the metal of the ship, and nothing uptoward happened. He drew it back, and cycled an entirely new fluid through the pseudopods. Hairline excretory channels opened on their soles, blown clean by the pressure. The pads flattened and increased in area. He moved forward toward the pylon again, and this time he began to climb it, held by air pressure on the pads and the surface tension on their wet soles. He began, then, at the end of a week’s journey, to climb upon the ship no other aggression of Man’s had ever reached. By the time he was a thousand feet up, he dared look only through the foreports.

     He was past laughter of any kind now — but exultation sustained him even when, near the very peak of his climb, he came to the rat guard.
     He had studied this problem with a model. No one had tried to tell him what it might be like to solve it at this altitude, with the wind and mist upon him.
     The rat guard was a collar of metal, cone-shaped and inverted downward, circling the leg. The leg here was several miles in diameter; the rat guard was a canopy several yards thick and several hundred feet wide from its joining at the leg to its lip. It was designed to prevent exactly what was happening — the attempted entry of a pest.
     Runner extended the carrier’s pseudopods as far and wide as they would go. He pumped more coagulant into the fluid that leaked almost imperceptibly out of their soles, and began to make his way, head-downward, along the descending slope of the rat guard’s outer face. The carrier swayed and stretched at the plastic membranes. He neutralized the coagulant in each foot in turn, slid it forward, fastened it again, and proceeded. After three hours he was at the lip, and dangling by the carrier’s forelegs until he had succeeded in billowing one of the rear pads onto the lip as well.
     And when he had, by this patient trial and error, scrambled successfully onto the rat guard’s welcome upward face, he found that he was not past laughing after all. He shouted it; the carrier’s interior frothed with it, and even the itching in his ears was lost. Then he began to move upward again.

     He wanted only to find a good place to attach his bomb, set the fuse and go. Before the leg, its muscles cut, collapsed upon the aliens’ hope of ever returning to whatever peace they dreamed of.
     When he climbed out of the carrier, as he had to, to attach the bomb, he heard one noise that was not wind-thrum or the throb of internal machinery. It was a persistent, nerve-torn ululation, faint but clear, deep inside the ship and with a chilling quality of endurance.
     He hurried back down the leg; he had only four days to get clear — that is, to have a hope of getting clear — and he hurried too much. At the rat guard’s lip, he had to hang by his heels and cast the fore pads under. He thought he had a grip, but he had only half a one. The carrier slipped, jerked and hung dangling by one pad. It began to slide back down the short distance to the lip of the guard, rippling and twisting as parts of its sole lost contact and other parts had to take up the sudden drag.
     He poured coagulant into the pad, and stopped the awful series of sticks and slips. He slapped the other pads up into place and levered forward, forgetting how firmly that one pad had been set in his panic. He felt resistance, and then remembered, but by then the pull of the other three pads had torn the carrier forward and there was a long rip through which stress fluid and coagulant dripped in a turgid stream.
     He came down the last ten miles of the leg like a runaway toboggan on a poorly surfaced slide, the almost flaccid pads turning brown and burnt, their plastic soft as jelly. He left behind him a long, slowly evaporating smear of fluid and, since no one had thought to put individual shut-offs in the cross-valving system between the pads, he came down with no hope of ever using the carrier to get back to the mountains.

From FOR LOVE by Algis Budrys (1962)

Hoppers

LUCKY STARR AND THE OCEANS OF VENUS

     "It's important. I've got to get out of here."
     "Then you'll have to walk," said the policeman.
     Lucky gritted his teeth with vexation. There was no way of getting through the crowd on foot or on wheels. It had to be by air and it had to be now.
     "Isn't there anything available I can use? Anything?" He was scarcely speaking to the policeman, more to his own impatient self, angry at having been so simply duped by the enemy.
     But the policeman answered wryly, "Unless you want to use a hopper."
     "A hopper? Where?" Lucky's eyes blazed.
     "I was just joking," said the policeman.
     "But I'm not. Where's the hopper?"
     There were several in the basement of the building they had left. They were disassembled. Four men were impressed to help and the best-looking machine was assembled in the open. The nearest of the crowd watched curiously, and a few shouted Jocularly, "Jump it, hopper!"
     It was the old cry of the hopper races. Five years ago it had been a fad that had swept the solar system: races over broken, barrier-strewn courses. While the craze lasted, Venus was most enthusiastic. Probably half the houses in Aphrodite had had hoppers in the basement.
     Lucky checked the micropile. It was active. He started the motor arid set the gyroscope spinning. The hopper straightened immediately and stood stiffly up­right on its single leg.
     Hoppers are probably the most grotesque forms of transportation ever invented. They consist of a curved body, just large enough to hold a man at the controls. There was a four-bladed rotor above and a single metal leg, rubber-tipped, below. It looked like some giant wading bird gone to sleep with one leg folded under its body.
     Lucky touched the leap knob and the hopper's leg retracted. Its body sank till it was scarcely seven feet from the ground while the leg moved up into the hollow tube that pierced the hopper just behind the control panel. The leg was released at the moment of maximum retraction with a loud click, and the hopper sprang thirty feet into the air.
     The rotating blades above the hopper kept it hovering for long seconds at the top of its jump. For those seconds, Lucky could get a view of the people now immediately below him. The crowd extended outward for half a mile, and that meant several hops. Lucky's lips tightened. Precious minutes would vanish.
     The hopper was coming down now, its long leg extended. The crowd beneath the descending hopper tried to scatter, but they didn't have to. Four jets of compressed air blew men aside just sufficiently, and the leg hurtled down harmlessly to the ground.
     The foot hit concrete and retracted. For a flash Lucky could see the startled faces of the people about him, and then the hopper was moving up again.
     Lucky had to admit the excitement of hopper racing. As a youngster, he'd participated in several. The expert "hop rider" could twist his curious mount in unbelievable patterns, finding leg room where none seemed to exist. Here, in the domed cities of Venus, the races must have been tame compared to the bone-breakers in the vast, open arenas of rocky, broken ground on Earth.

From LUCKY STARR AND THE OCEANS OF VENUS by Paul French (Isaac Asimov) (1954)

  • [1] Pressurized cabin
  • [2] Non-pressurized storage area
  • [2] Door into non-pressurized storage area
  • [4] Leg
  • [5] Foot
  • [6] Gyroscope
  • [7-8] Gyroscope frames (with pinions on tips)
  • [9-10] Gyroscope guide rails (with racks)
  • [11-14] Gyroscope frame servos (drives pinions)
  • [15] Upper frame
  • [16] Roof platform
  • [17] Roof platform railing
  • [18] Roof platform crane
  • [19] Solar power plant
  • [20] Heat radiator for cabin air
  • [21] Heat radiator for equipment
  • [22] Driver's front window
  • [23] Driver's foot window
  • [24] Optical range finder to calculate jumps
  • [25] Crew windows
  • [26] Periscope windows to look upwards
  • [27] Periscope window mirror
  • [28] Top floor (Storage room)
  • [29] Jump gas tank
  • [30] Jump cylinder
  • [31-32] Reinforcing girders for emergency brake
  • [33] Water tank
  • [34] Middle floor (Crew room)
  • [35] Driver's seat
  • [36] Driver's control stick
  • [37] Jump calculator
  • [38] Driver's emergency brake
  • [39] Driver's jump pedal
  • [40] Airlock
  • [43] Washroom
  • [44] Shower
  • [45] Toilet
  • [46] Wash basin
  • [47] Toilet exhaust door
  • [48] Roller for washroom rubber sheet/door
  • [49] Driver control panel
  • [50] Lower floor (Engine room)
  • [51] Horizontal gyro
  • [52] Trap door for engine access
  • [53] Reinforcing ribs
  • [61] Gyroscope coolant line to heat radiator 21
  • [72] Pendulum
  • [107] Jumping piston
  • [108] Leg cylinder gas compression pump
  • [109] Jumping piston rubber bumper
  • [110] Top stop for 109
  • [111-112] reinforcing rods
  • [118-121] Counterweight channels
  • [124-125] Counterweights
  • [126-127] Counterweight springs
  • [135] Emergency brake harpoon/anchor
  • [136] Emergency cable
  • [137] Emergency pulley
  • [138] Solar power plant mast
  • [142] Mirror
  • [144] Pipes

Unicycles

Subterrene

Dust Boats

Arthur C. Clarke postulated that on Luna, there could be pools of lunar dust that act like they were fluid, even though they are more dry than the Sahara desert. These have never been actually observed, but are not totally impossible. If they do exist, it might be possible to create something analogous to a boat to sail on these dusty seas.

What Clarke didn't foresee was that lunar dust is so abrasive that it makes sandpaper look like satin silk. It is more or less composed of zillions of microscopic razor blades. So the belly of any lunar boat had better be tough.


      To be the skipper of the only boat on the Moon was a distinction that Pat Harris enjoyed. As the passengers filed aboard Selene, jockeying for window seats, he wondered what sort of trip it would be this time. In the rear-view mirror he could see Miss Wilkins, very smart in her blue Lunar Tourist Commission uniform, putting on her usual welcome act.
     But to all of them, the Sea of Thirst was a novelty. Beyond Selene’s observation windows, its gray, dusty surface marched onward unbroken until it reached the stars.
     It was a sea of dust, not of water, and therefore it was alien to all the experience of men; therefore, also, it fascinated and attracted them. Fine as talcum powder, drier in this vacuum than the parched sands of the Sahara, it flowed as easily and effortlessly as any liquid. A heavy object dropped into it would disappear instantly, without a splash, leaving no scar to mark its passage. Nothing could move upon its treacherous surface except the small, two-man dustskis—and Selene herself, an improbable combination of sledge and bus, not unlike the Sno-cats that had opened up the Antarctic a lifetime ago. Selene’s official designation was Dust-Cruiser, Mark I, though to the best of Pat’s knowledge, a Mark II did not exist even on the drawing board. She was called “ship,” “boat,” or “moon bus,” according to taste; Pat preferred “boat,” for it prevented confusion. When he used that word, no one would mistake him for the skipper of a spaceship—and spaceship captains were, of course, two a penny.


     Pat scarcely heard the familiar introduction; he was busy with his count-down. Selene was virtually a grounded spaceship; she had to be, since she was traveling in a vacuum, and must protect her frail cargo from the hostile world beyond her walls. Though she never left the surface of the Moon, and was propelled by electric motors instead of rockets, she carried all the basic equipment of a full-fledged ship of space— and all of it had to be checked before departure.
     Oxygen—O.K. Power—O.K. Radio—O.K. (“Hello, Rainbow Base, Selene testing. Are you receiving my beacon?”) Inertial navigator—zeroed. Air-lock safety—On. Cabin-leak detector—O.K. Internal lights—O.K. Gangway—disconnected. And so on for more than fifty items, every one of which would automatically call attention to itself in case of trouble. But Pat Harris, like all spacemen hankering after old age, never relied on autowamings if he could carry out the check himself.
     At last he was ready. The almost silent motors started to spin, but the blades were still feathered, and Selene barely quivered at her moorings. Then he eased the port fan into fine pitch, and she began to curve slowly to the right. When she was clear of the embarkation building, he straightened her out and pushed the throttle forward.
     She handled very well, when one considered the complete novelty of her design. There had been no millennia of trial and error here, stretching back to the first neolithic man who ever launched a log out into a stream. Selene was the very first of her line, created in the brains of a few engineers who had sat down at a table and asked themselves: “How do we build a vehicle that will skim over a sea of dust?”
     Some of them, harking back to Ole Man River, had wanted to make her a stern-wheeler, but the more efficient submerged fans had carried the day. As they drilled through the dust, driving her before them, they produced a wake like that of a high-speed mole, but it vanished within seconds, leaving the Sea unmarked by any sign of the boat’s passage.
     Selene surged forward. For the first time, there was a real sensation of speed. The boat’s wake became longer and more disturbed as the spinning fans bit fiercely into the dust. Now the dust itself was being tossed up on either side in great ghostly plumes; from a distance, Selene would have looked like a snowplow driving its way across a winter landscape, beneath a frosty moon. But those gray, slowly collapsing parabolas were not snow, and the lamp that lit their trajectory was the planet Earth.
     The passengers relaxed, enjoying the smooth, almost silent ride. Every one of them had traveled hundreds of times faster than this, on the journey to the Moon. But in space one was never conscious of speed, and this swift glide across the dust was far more exciting. When Pat swung Selene into a tight turn, so that she orbited in a circle, the boat almost overtook the falling veils of powder her fans had hurled into the sky. It seemed altogether wrong that this impalpable dust should rise and fall in such clean-cut curves, utterly unaffected by air resistance. On Earth it would have drifted for hours—perhaps for days.

     Most of the Moon, they read, was covered by a thin layer of dust, usually no more than a few millimeters deep. Some of this was debris from the stars—the remains of meteorites that had fallen upon the Moon’s unprotected face for at least five billion years. Some had flaked from the lunar rocks as they expanded and contracted in the fierce temperature extremes between day and night. Whatever its source, it was so finely divided that it would flow like a liquid, even under this feeble gravity.
     Over the ages, it had drifted down from the mountains into the lowlands, to form pools and lakes. The first explorers had expected this, and had usually been prepared for it. But the Sea of Thirst was a surprise; no one had anticipated finding a dustbowl more than a hundred kilometers across.
     As the lunar “seas” went, it was very small; indeed, the astronomers had never officially recognized its title, pointing out that it was only a small portion of the Sinus Roris—the Bay of Dew. And how, they protested, could part of a bay be an entire sea? But the name, invented by a copywriter of the Lunar Tourist Commission, had stuck despite their objections. It was at least as appropriate as the names of the other so-called seas—Sea of Clouds, Sea of Rains, Sea of Tranquillity. Not to mention Sea of Nectar.
     The brochure also contained some reassuring information, designed to quell the fears of the most nervous traveler, and to prove that the Tourist Commission had thought of everything. “All possible precautions have been taken for your safety,” it stated. “Selene carries an oxygen reserve sufficient to last for more than a week, and all essential equipment is duplicated. An automatic radio beacon signals your position at regular intervals, and in the extremely improbable event of a complete power failure, a dustski from Port Roris would tow you home with little delay. Above all, there is no need to worry about rough weather. No matter how bad a sailor you may be, you can’t get seasick on the Moon. There are never any storms on the Sea of Thirst; it is always a flat calm.”

     “I’ll turn off the cabin lights,” said the stewardess, “so you can get a better view.”
     As the dim red background illumination vanished, each traveler felt he was alone in the lunar night. Even the reflected radiance of Earth on those high peaks was disappearing as the cruiser raced farther into shadow. Within minutes, only the stars were left—cold, steady points of light in a blackness so complete that the mind rebelled against it.
     It was hard to recognize the familiar constellations among this multitude of stars. The eye became entangled in patterns never seen from Earth, and lost itself in a glittering maze of clusters and nebulae. In all that resplendent panorama, there was only one unmistakable landmark—the dazzling beacon of Venus, far outshining all other heavenly bodies, heralding the approach of dawn.
     It was several minutes before the travelers realized that not all the wonder lay in the sky. Behind the speeding cruiser stretched a long, phosphorescent wake, as if a magic finger had traced a line of light across the Moon’s dark and dusty face. Selene was drawing a comet tail behind her, as surely as any ship plowing its way through the tropical oceans of Earth.
     Yet there were no microorganisms here, lighting this dead sea with their tiny lamps. Only countless grains of dust, sparking one against the other as the static discharges caused by Selene’s swift passage neutralized themselves. Even when one knew the explanation, it was still beautiful to watch—to look back into the night and to see this luminous, electric ribbon continually renewed, continually dying away, as if the Milky Way itself were reflected in the lunar surface.

     For a million years the bubble had been growing, like a vast abscess, below the root of the mountains. Throughout the entire history of Man, gas from the Moon’s not yet wholly dead interior had been forcing itself along lines of weakness, accumulating in cavities hundreds of meters below the surface. On nearby Earth, the ice ages had marched past, one by one, while the buried caverns grew and merged and at last coalesced. Now the abscess was about to burst.
     Captain Harris had left the controls on autopilot and was talking to the front row of passengers when the first tremor shook the boat. For a fraction of a second he wondered if a fan blade had hit some submerged obstacle; then, quite literally, the bottom fell out of his world.
     It fell slowly, as all things must upon the Moon. Ahead of Selene, in a circle many acres in extent, the smooth plain puckered like a navel. The Sea was alive and moving, stirred by the forces that had waked it from its age-long sleep. The center of the disturbance deepened into a funnel, as if a giant whirlpool were forming in the dust. Every stage of that nightmare transformation was pitilessly illuminated by the earthlight, until the crater was so deep that its far wall was completely lost in shadow, and it seemed as if Selene were racing into a curving crescent of utter blackness—an arc of annihilation.
     The truth was almost as bad. By the time that Pat had reached the controls, the boat was sliding and skittering far down that impossible slope. Its own momentum and the accelerating flow of the dust beneath it were carrying it headlong into the depths. There was nothing he could do but attempt to keep on an even keel, and to hope that their speed would carry them up the far side of the crater before it collapsed upon them.
     The straining motors were making some headway, but not enough. The falling dust was gaining speed—and, what was worse, it was rising outside the walls of the cruiser. Now it had reached the lower edge of the windows; now it was creeping up the panes; and at last it had covered them completely. Pat cut the motors before they tore themselves to pieces, and as he did so, the rising tide blotted out the last glimpse of the crescent Earth. In darkness and in silence, they were sinking into the Moon.


     At that very moment, though neither party knew the fact, one of the searching dustskis was passing overhead. Built for speed, efficiency, and cheapness, not for the comfort of tourists, it bore little resemblance to the sunken Selene. It was, in fact, no more than an open sledge with seats for pilot and one passenger—each wearing a space suit—and with a canopy overhead to give protection from the sun. A simple control panel, motor, and twin fans at the rear, storage racks for tools and equipment—that completed the inventory. A ski going about its normal work usually towed at least one carrier sledge behind it, sometimes two or three, but this one was traveling light. It had zigzagged back and forth across several hundred square kilometers of the Sea, and had found absolutely nothing.

From by ()
JENNIFER PETKUS ANALYSIS

While reading I wondered, and not for the first time, what the Selene from Clarke’s book would look like. If you haven’t read the novel, the Selene is a tourist boat on the Sea of Thirst, a vast body of moon dust that flowed into a depression in the Sinus Roris or Bay of Dew, in the northwest corner of the Moon (that is of the side facing the Earth), which is turn is part of the northern edge of Oceanus Procellarum. I believe the Sea of Thirst and the Mountains of Inaccessibility are entirely fictional, but they’re not beyond imagining. Certainly the central idea of a vast sea of moon dust isn’t disproven—just no such body of dust has ever been directly observed and measured by astronauts, lunar rovers or satellites.

Moon dust, of course, does exist and the Apollo astronauts directly experienced it on the Moon, touching, smelling and tasting it. Lunar regolith is an extremely dry composition of mostly silicon dioxide glass created by the countless impact of micrometeorites, with some iron, calcium and magnesium. It’s extremely abrasive because of the absence of most weathering (wind, water) on the Moon and is electrostatic-ally charged by UV rays during the day and the solar wind at night.

Unfortunately no one on Earth (except for the actual astronauts to walk on the Moon) have ever experienced the real properties of Moondust. The dust was so pervasive and abrasive that it threatened the integrity of spacesuits and destroyed the sealed containers of dust and rock that were brought back to Earth. Scientists could never observe exactly how it behaves on the Moon. Here’s how Clarke describes it:

“Our great problem, of course, is the dust. If you’ve never seen it, you can’t imagine what it’s like. Any ideas you may have about sand or other materials on Earth won’t apply here; this stuff is more like a liquid. Here’s a sample of it.”

Lawrence picked up a tall vertical cylinder, the lower third of which was filled with an amorphous gray substance. He titled it, and the stuff began to flow. It moved more quickly than syrup, more slowly than water, and it took a few seconds for its surface to become horizontal again after it had been disturbed. No one could ever have guessed, by looking at it, that it was not a fluid.

“This cylinder is sealed,” explained Lawrence, “with a vacuum inside, so the dust is showing its normal behavior. In air, it’s quite different; it’s much stickier, and behaves rather like very fine sand or talcum powder. I’d better warn you—it’s impossible to make a synthetic sample that has the properties of the real thing. It takes a few billion years of desiccation to produce the genuine article.”

Now I don’t know that actual moon dust would behave quite so much like a liquid. I imagine the fact that it is so abrasive would prevent it from flowing, but again, we won’t know until we return to the Moon. What’s amazing is that Clarke wrote his description in 1961, more than eight years before the first Moon landing and it’s still quite accurate. Clarke also predicted the problem of television cameras depicting stars during the lunar day, the less than spectacular topography of lunar mountains and the mundane technicalities of CO2 scrubbers, heat exchangers and tourism on the Moon. Only a very few details seem dated, most notably the idea that people would be allowed to smoke in the closed environment of the tourist boat.

(Another puzzle—how the dust might have collected in the Sea of Thirst—could partially be explained by the fact that the Moon does have dust trapped in the “atmosphere.” A probe confirmed what astronauts had reported—a haze around the Moon. I suppose the dust kicked up electostatic forces could have been deposited in the Sea of Thirst.)

Like any good adventure tale, the story proceeds in an orderly fashion. Twenty tourists and a crew of two aboard the Selene are trapped when a trapped pocket of gas in the Moon’s crust opens directly under the boat. Normally it would be almost impossible for the boat to sink, but the moon dust draining into the void pulls the Selene down like an ant falling into an antlion’s lair. The collapsing dust then submerges the boat to a depth of 15 meters.

The dust acts as an electrostatic blanket that blocks the boat’s emergency transponder. When the Selene misses a scheduled check-in, the story becomes the struggle to remain sane in the boat and the race to find it before it’s week worth of oxygen is depleted. I’ve always greatly enjoyed the ways the crew and passengers of the Selene entertain themselves while awaiting discovery and rescue. The only reading material are two paperbacks: an academic analysis of the Western Shane, originally published in 1949 by Jack Schaefer (most people know it from the 1953 Alan Ladd film); and The Orange and the Apple, a fictional contemporary to the time of Clarke’s novel that is a romance between Sir Isaac Newton and Nell Gwyn. Clarke says it was written by a teenage girl. Of course Clarke wrote Moondust before the advent of personal electronics and social media. Today enough people might have entertainment stored on phones and tablets, but of course they might still be cut off from internet access. I much prefer the image of the passengers reading the books aloud rather than twenty two people reading alone from their phones.

The story seamlessly advances from the discovery of the exact location of the boat, plans of how to rescue the passengers, unforeseen disasters and last-minute engineering. It’s clearly a forerunner of Andy Weir’s The Martian, although I don’t know if it was a direct inspiration. What I love about Clarke’s story is that it essentially depicts well-meaning, mostly intelligent people working to solve a problem, rather like Weir’s story. Most of the characters in Moondust rise above their limitations, rather than sink below them.

Now Clarke only gives enough information about the Selene to tell the story, but I’ve always imagined quite a broad vessel, no doubt influenced by the cover of the 1974 Signet edition I own. The boat is several times described as a bus and also resembling a SnoCat familiar from arctic expeditions or ski resorts, so it’s definitely not streamlined. Considering the abrasive quality of moon dust, I doubt it would make sense to have the entire undersurface of the boat making contact with the surface of the sea. The friction caused by the dust would slow the boat and erode the hull.

The boat is powered by variable pitch fan blades that churn the dust and expel it, moving the boat forward like a jet ski. Clarke mentions the blades are made of rubber and are designed to break free if they hit a subsurface obstruction, so clearly they’re not internal as on jet ski. Probably the Moon bus from the movie 2001 makes a good starting point for the design of the Selene. I would just have the Selene float on outriggers or have a catamaran-like hull.

Other details Clarke includes is that the Selene is double-hulled, the hull is made of fiberglass and the outside is covered in a reflective material like Mylar. The airlock is in the rear of the ship and doubles as a small galley. References are made to heat exchangers, batteries, a restroom and liquid oxygen tanks—the standard sort of thing we would expect in any space vehicle. The top speed of the boat is 120 kph (about 75 mph).

If one were to make a diorama, it might be nice to have a backdrop with the Mountains of Inaccessibility and a crescent Earth overhead. Part of the scene should be in shadow, however, because Clarke describes the boat sending perfect parabolas of dust behind in (it wouldn’t float in the absence of wind) and the wake of the boat leaving a phosphorescent trail of discharged particles.

Of course if you want to make a diorama of the rescue, you wouldn’t see the Selene at all. Instead it would be a little cluster of rafts on top of which would be inflatable habitats, with space-suited figures and dust skis (two-man Skidoo type conveyances), and maybe a crane lowering the caisson used to rescue the passengers and crew.

From A FALL OF MOON DUST by Jennifer Petkus (2017)
ESCAPING LUNAR DUST

(ed note: Jamieson and Wheeler are on the moon inside a lunar mobile base named Ferdinand. They are fleeing a lunar fort which will be the focus of a nuclear attack any minute now. Alas they plunge into a pool of lunar dust)

      IT WOULD NEVER HAVE HAPPENED had Jamieson been thinking more of driving and less of politics—though, in the circumstances, he could hardly be blamed. The ground ahead looked level and firm—exactly the same as the kilometers they had already safely traversed.
     It was level, but it was no firmer than water. Jamieson knew what had happened the moment that Ferdinand's engine started to race, and the tractor's nose disappeared in a great cloud of dust. The whole vehicle tilted forward, began to rock madly to and fro, and then lost speed despite all that Jamieson could do. Like a ship foundering in a heavy sea, it started to sink. To Wheeler's horrified eyes, they seemed to be going under in swirling clouds of spray. Within seconds, the sunlight around them had vanished. Jamieson had stopped the motor; in a silence broken only by the murmur of the air circulators, they were sinking below the surface of the Moon.
     The cabin lights came on as Jamieson found the switch. For a moment, both men were too stunned to do anything but sit and stare helplessly at each other. Then Wheeler walked, not very steadily, to the nearest observation window. He could see absolutely nothing: no night was ever as dark as this. A smooth velvet curtain might have been brushing the other side of the thick quartz, for all the light that could penetrate it.

     Suddenly, with a gentle but distinct bump, Ferdinand reached the bottom.
     "Thank God for that," breathed Jamieson. "It's not very deep." "What good does that do us?" asked Wheeler, hardly daring to believe there was any hope. He had heard too many horrifying of these treacherous dust bowls, and the men and tractors they had engulfed.

     The lunar dust bowls are, fortunately, less common than might be imagined from some travelers' tales, for they can occur only under rather special conditions, which even now are not fully understood. To make one, it is necessary to start with a shallow crater pit in the right kind of rock, and then wait a few hundred million years while the temperature changes between night and day slowly pulverize the surface layers. As this age-long process continues, so a finer and finer grade of dust is produced, until at last it begins to flow like a liquid and accumulates at the bottom of the crater. In almost all respects, indeed, it is a liquid: it is so incredibly fine that if collected in a bucket, it will slop around like a rather mobile oil. At night one can watch convection currents circulating in it, as the upper layers cool and descend, and the warmer dust at the bottom rises to the top. This effect makes dust bowls easy to locate, since infra-red detectors can "see" their abnormal heat radiation at distances of several kilometers. However, during the daytime this method is useless owing to the masking effect of the sun.

     "There's no need to get alarmed," said Jamieson, though he looked none too happy. "I think we can get out of this. It must be a very small bowl, or it would have been spotted before. This area's supposed to have been thoroughly marked."
     "It's big enough to have swallowed us."
     "Yes, but don't forget what this stuff's like. As long as we can keep the motors running, we have a chance of pushing our way out—like a submarine-tank making its way up on to shore. The thing that bothers me is whether we should go ahead, or try and back out."
     "If we go ahead, we might get in deeper."
     "Not necessarily. As I said, it must be a pretty small bowl and our momentum may have carried us more than halfway across it. Which way would you say the floor is tilted now?"
     "The front seems to be a bit higher than the rear."
     "That's what I thought. I'm going ahead—we can get more power that way, too."
     Very gently, Jamieson engaged the clutch in the lowest possible gear. The tractor shook and protested, then lurched forward a few centimeters, then halted again.
     "I was afraid of that," said Jamieson. "I can't keep up a steady progress. We'll have to go in jerks. Pray for the engine—not to mention the transmission.
     They jolted their way forward in agonizingly slow surges, and Jamieson cut the engine completely.
     "Why did you do that?" Wheeler asked anxiously. "We ought to be getting somewhere."
     "Yes, but we're also getting too hot. This dust is an almost perfect heat insulator. We'll have to wait a minute until we cool off."

     "Do you hear that noise?" said Jamieson suddenly. He switched off the air-circulator, so that complete silence fell inside the cab.
     There was the faintest of sounds coming through the walls. It was a sort of whispering rustle, and Wheeler could not imagine what it was.
     "The dust's starting to rise. It's highly unstable, you know, and even a small amount of heat is enough to start convection currents. I expect we're making quite a little geyser up at the top—it will help anyone to find us if they come and look."
     That was some consolation, at any rate. They had air and food for many days—all tractors carried a large emergency reserve—and the Observatory knew their approximate position. But before long the Observatory might have trouble of its own, and would be unable to bother about them…
     Jamieson re-started the motor, and the sturdy vehicle started butt its way forward again through the dry quicksand that enveloped them. It was impossible to tell how much progress they were making, and Wheeler dared not imagine what would happen if the motors failed. The caterpillar treads were grinding at the rock beneath them, and the whole tractor shook and groaned under the intolerable load.
     It was almost an hour before they were certain they were getting somewhere. The floor of the tractor was definitely tilting upward, but there was no way of telling how far below the quasi-liquid surface they were still submerged. They might emerge at any moment into the blessed light of day—or they might have a hundred meters still to traverse at this snail-like pace.
     Jamieson was stopping for longer and longer intervals, which might reduce the strain on the engine but did nothing to reduce that on the passengers. During one of these pauses Wheeler asked him outright what they should do if they could get no further.

     "We've only two possibilities," Jamieson answered. "We can stay here and hope to be rescued—which won't be as bad as it sounds, since our tracks will make it obvious where we are. The other alternative is to go out."
     "What! That's impossible!"
     "Not at all. I know a case where it's been done. It would be rather like escaping from a sunken submarine."
     "It's a horrible thought—trying to swim through this stuff."
     "I was once caught in a snowdrift when I was a kid, so I can guess what it would be like. The great danger would be losing your direction and floundering around in circles until you were exhausted. Let's hope we don't have to try the experiment."
     It was a long time, Wheeler decided, since he had heard a bigger understatement than that.

     The driving cab emerged above the dust level about an hour later, and no men could ever have greeted the sun with such joy. But they had not yet reached safety; though Ferdinand could make better speed as the resistance slackened, there might still be unsuspected depths ahead of them.
     Wheeler watched with fascinated repulsion as the horrible stuff eddied past the tractor. At times it was quite impossible to believe that they were not forcing their way through a liquid, and only the slowness with which they moved spoiled the illusion. He wondered if it was worth suggesting that in future Caterpillars have better streamlining to improve their chances in emergencies like this. Who would ever have dreamed, back on Earth, that that sort of thing might be necessary?
     Even so, they might have made it. But they had just started their on way again, and were crawling over the top of a quite gentle ridge, when there was a scream of tearing metal and Ferdinand tried to spin round in a circle. Jamieson cut the motor instantly and they came to rest broadside-on to their direction of motion.
     And that," said Jamieson softly, "is most definitely that. I don't think we're in a position to grumble. If the starboard transmission had sheared while we were still in that dust bowl—"

From EARTHLIGHT by Arthur C. Clarke (1955)

Ground Handwavium

For the equation to calculate the power needed for handwavium antigravity vehicles, go here.

Grav Armor

Suddenly, Grav Armor is a game where armies are transported by spaceships, then campaign across a dozen worlds, each world presenting its own problems. Armored vehicles can fly faster than jet fighters — how else can they traverse planetary distances and campaign effectively?


One of the game's most interesting aspects is the gravitics propulsion. Grav Armor postulates two-dimensional gravitic effect plates, which can produce a directed gravitational field, much like ripples travelling across water (except a ripple is one-dimensional, by comparison). Gravity is a two-body equation: It works as a relationship of masses (in this case, the mass of the vehicle versus the mass of the planet). By affecting the gravitational relationship between vehicle and planet, you not only let the vehicle float, you can also push it in any direction. The same fields, within the vehicle, compensate for inertia whenever the vehicle makes a tight turn. With such a system, there is no reason why the vehicle can't make a 90 degree turn on a dime while doing well over Mach One. However, if the vehicle is close to the ground at the time, dirt and rock may go flying in the opposite direction, since the planet doesn't have any inertial compensators, and the quick turn of the vehicle has suddenly altered some very powerful forces. But since when have tankers worried about chewing up the countryside?

These devices allow for the ultimate in NOE (nape of the earth) travel. Vehicles zoom along a few feet off the ground, taking advantage of every fold in the terrain, while the recon drones act as their "eyes" in all directions. If the vehicle lacks self-guiding missile weapons, it simply "pops up" the minimum distance to fire over intervening terrain, pauses for a millisecond or so, then pops down again — it's all computer-controlled, and so fast it's almost impossible to see with the naked eye.

From Grav Armor by Arnold Hendrick (1982). Available here

Flitters

Introduction

Flitter n. a small usually short-range, aircraft or spaceship.

  • 1941 July, Edward Elmer Smith, “The Vortex Blaster”, Comet Stories, volume 1, number 5, page 10:
    Then all three went out to the flitter. A tiny speedster, really; a torpedo bearing stubby wings and the ludicrous tail-surfaces, the multifarious driving-, braking-, side-, top-, and under-jets so characteristic of the tricky, cranky, but ultra-maneuverable breed.
  • 1944 March, George Oliver Smith, “Circle of Confusion”, Astounding Science Fiction, volume 33, number 1, page 54:
    Small flitters were powered and made ready, and everything that carried manual controls was inspected and cleared for action.
  • 1955, Alice Mary "Andre" Norton (as Andrew North), Sargasso of Space, page 53:
    The small flitters carried by the Queen for exploration work held with comfort a two-man crew—with crowding, three.
From Brave New Words: The Oxford Dictionary of Science Fiction by Jeff Prucher (2007)

antigrav

[contraction of "antigravity"; first use unknown]

General SFnal term for a hypothetical technology of local gravity nullification or control allowing objects (especially vehicles) to levitate or fly without wings, ducted-fans or other aerodynamics. There are variants including contragrav and agrav, understood to be equivalent.

Antigrav is functionally similar to a reactionless drive, but unlike the latter it is often assumed to be limited to operating near a planetary surface or other large mass. It is generally (but not always) assumed that antigravity is a major consequence of forcefield technology, which is applied in many other ways.

flitter

[first use unknown]

General SFnal term for a personal flying vehicle, typically not winged but rather using some form of antigrav or exotic aerodynamics such as ducted-fan and Coandă-effect technology. Unlike a skimmer, a flitter is capable of free flight.

ornithopter

[revived in SF by Frank Herbert's Dune (1967), but occurs in Cordwainer Smith's earlier Instrumentality of Mankind stories c.1960]

A flying machine that uses flapping wings. This term is well known to historians of flight; Leonardo Da Vinci drew pictures of ornithopters in his famous sketchbooks, and several early-20th-century attempts at powered flight were ornithopter variants. Unfortunately for their inventors, flapping wings are only effective given the high power-to-weight ratio of avian muscle. We cannot yet attain this in the real world, but SF is free to assume it in the future.

(ed note: in Dune, often abbreviated as 'thoptor)

From An SF Glossary by Eric S. Raymond (2006)

The small flitters carried by the Queen for exploration work held with comfort a two-man crew—with crowding, three. Both of the planes had been carefully checked by the engineering section that afternoon while Dane had been busied with unloading the expedition supplies. And there was no doubt that the next morning would see the first of the scouting parties out on duty.

There were no lights to break the sombre dark of Limbo’s night. And the men of the Queen lost interest in the uniformly blank visa-screens which kept them in touch with the outside. It was after the evening meal that they drew for membership on the flitter teams. As usual the threefold organization of the shop determined the drawing; one man of the engineers, one of the control deck, and one of Van Rycke’s elastic department (cargo) being grouped together.


Dane strapped on his helmet with its short wave installation, fastened about his waist an explorer’s belt with its coil of tough, though slender rope, its beam light, and compact envelope of tools. Though they did not expect to be long from the Queen, into the underseat storage place on the flitter went concentrated supplies, a small medical kit, and their full canteens, as well as a packet of trade “contact” goods. Not that they would have any use for that in Dane’s estimation.

Ali took the controls of the tiny ship while Dane and Tau shared a cramped seat behind him. The engineer-apprentice pushed a button on the board and the curved windbreak slid up and over, enclosing them. They lifted smoothly from the side of the Queen, to level off at the height of her nose, swinging north for the route Jellico and Van Rycke had charted them.

From The Sargasso of Space by Andrew North (Andre Norton) (1955)
EXILES OF THE STARS

What was left to us now was to make secure our own safety. Somewhere hidden among these roughly splintered hills (for this land was all sharp peaks and valleys so deep and narrow that they might have been cut into the planet by the sword of an angry giant) there was a Patrol beacon. To reach that and broadcast for help was our only hope.

Within the shell of the Lydis was a small two-man flitter, meant to be used for exploration. This was brought out, assembled for service. Over the broken terrain such a trip in search of a beacon which might lie half the world away was a chancy undertaking. And though all the crew were ready to volunteer, it was decided that they should draw lots for the search party.

This they did, each man drawing from a bowl into which they had dropped small cubes bearing their rank symbols. And chance so marked down our astrogator Manus Hunold and second engineer Griss Sharvan.

They took from the stores, making packs of emergency rations and other needs. And the flitter was checked and rechecked, taken up on two trial flights, before Captain Foss was assured it would do.

From EXILES OF THE STARS by Andre Norton (1971)
Time for the Stars

(ed note: The good starship Lewis & Clark (L-C or "Elsie") is a torchship, and lands in the water. Otherwise its mass-converter powered torch drive would have the ship landing in a huge crater of freshly-created boiling lava. The mass coverter can use water or any other non-corrosive fluid as fuel. A "monkey island" is a nautical term referring to an open platform at the top most accessible height or an open deck directly above the navigating bridge, pilothouse, or chart house. In the Lewis & Clark, the navigating bridge is right at the top of the starship. )

There was a "monkey island" deck temporarily rigged up there, outside the airlock; it was a good place to watch the boats being loaded at the cargo ports lower down.

The airlock was only large enough for people; anything bigger had to go through the cargo ports. It was possible to rig the cargo ports as airlocks and we had done so on Inferno around Beta Hydri, but when the air was okay we just used them as doors. They were at the cargo deck, underneath the mess deck and over the auxiliary machinery spaces; our three boats and the two helicopters were carried just inside on that deck. The boats could be swung out on gooseneck davits from where they nested but the helicopters had to be hooked onto boat falls (a tackle used to hoist or lower a ship's boat from or to the davits), swung out, then a second set of falls hooked to them from the monkey island above, by which a helicopter could be scooted up the Elsie's curved side and onto the temporary top deck, where her jet rotors would be attached.

Mr. Regato cursed the arrangement every time we used it, "Mechanical buffoonery!" was his name for it. "I've never seen a ship's architect who wasn't happy as soon as he had a pretty picture. He never stops to think that some poor fool is going to have to use his pretty picture."

As may be, the arrangement did let the helis be unloaded with a minimum of special machinery to get out of order—which, I understand, was a prime purpose in refitting the ships for the Project. But that day the helicopters were outside and ready, one of them at camp and the other tied down near me on the monkey island.

From Time for the Stars by Robert Heinlein (1956)

Rocket Pack

A rocket pack or rocket belt is a one-person flying device. They have been a science fiction staple since 1920. Which is why one of the standard complaints about the slow pace of technological advancement is "I Want My Jet Pack"

They are not to be confused with those pathetically weak Manned Maneuvering Units sometimes found on spacesuits, for use in microgravity. MMUs have a thrust comparable to a spray-can of underarm deodorant. Rocket packs have enough thrust to allow one to fly under at least a full gravity, maybe more.

Powered Armor often has "jump jets" to augment their leaping ability (as in Robert Heinlein's Starship Troopers) or full flight ability (as with Iron Man).


Typically rocket packs take the form of a back-pack full of engines and fuel, with one or more rocket nozzles protruding from the bottom or on booms on either side. As a general rule you want the nozzles to be located above the user's center of gravity, or flight instability will be a problem. Meaning that when the nozzles start thrusting, your center of gravity wants to move below the level of the nozzles. You will flip over so your head is facing the ground and auger into an instant shallow grave.

Occasionally one will find the nozzles mounted on the hips or on boots. Extreme designs will have the engines, fuel, and nozzles crammed into tiny units on the hips or in the boots, with no back-pack. While this is stylish, it is unclear how to fit all of this into such a compact package. This also has the "center of gravity above the nozzle" problem.

To be practical the design must feature a pair of widely separated rocket nozzles, say a bit further apart than the shoulders. Otherwise the rocket exhaust will incinerate your gluteus maximus. Failing that, the least you can do is angle the nozzles left or right so the flames miss your body. This reduces the effective thrust by an amount proportional to the cosine of the angle off-center, but at least it will spare you the agony of a burning rump-roast with each flight.

TV Tropes calls this the "Toasted Buns" problem. This does not happen with powered armor, there is no toasted buns problem when your buns are protected by armor that can shrug off a laser bolt.

When Yves Rossy flies his jet wingpack he wears a heat-resistant suit similar to that of a firefighter or racing driver to protect him from the hot jet exhaust. And this is in addition to the carbon fibre heat shield extending the jet nozzle around the exhaust tail.

A rocket pack carries its own oxidizer, so it can operate on an airless world. A jet pack or turbojet pack relies upon ambient atmospheric oxygen (or other oxidizer) to operate, so it only works on a world with the proper atmosphere (but it can carry about twice as much fuel). In real world devices, the main drawback is the drastically limited flight time. Conventional rocket packs use the decomposition reaction of hydrogen peroxide, and carry enough fuel for about 30 seconds of flight. The specific impulse is pathetic as well. Actual chemical rocket fuel would double the specific impulse, but would also severely increase the thermal flame damage inflicted on the hapless user.

Jet packs use traditional kerosene-based jet fuel. They typically have enough fuel for a whole 10 minutes of thrust (more than a rocket pack because they don't have to carry oxidizer).

It is hard to see how the flight time can be increased unless more energetic fuel is used, and I don't mean chemical. Metastable hydrogen or helium at a minimum, but we are probably talking nuclear energy here. Just imagine what an atomic exhaust will do to your backside. Not to mention what the radiation will do to your gonads.


Another drawback is that people typically fly with rocket packs at an altitude too low to use a parachute (below 30 meters) but too high to survive the fall (above 9 meters). This is assuming that the planet has an parachute-friendly atmosphere to begin with. Perhaps rocket pack users can wear suits covered in rapidly inflatable air bags, like NASA used on Mars Pathfinder. This will look comical, but at least you'd be alive enough to be embarrassed.

Jet and rocket packs are typically controlled via two throttles mounted on the tips of two metal arms at about elbow level. In The Rocketeer the controls were mounted on the gloves. Right glove wrist movement controls yaw and pitch via thrust vectoring. Left glove has rocket throttle. In addition the Rocketeer had a large fin mounted on the helmet which acted like a rudder. This was controlled by turning the head, which severely limited your rubbernecking.

Goggles or a motorcycle face-mask are recommended, otherwise you'll have splattered bugs all over your face. How can you tell a happy rocket-packer? By all the bugs on their teeth.

Trope-a-Day: Jet Pack

Jet Pack: They exist. Mostly used in conjunction with combat exoskeletons or their civilian industrial counterparts, to avoid the, uh, Toasted Buns problem, and also the need for a fairly elaborate harness to avoid a painful and undignified jet-wedgie. (While obviously avoidable with a larger framework that keeps the jets further outboard, that’s about as clunky to maneuver in as a whole exoskeleton anyway.)

The exception to the above rule are the ones commonly used to aid maneuvering in microgravity, which are rather smaller and even implantable into the body, for that matter – but that’s because they use simpler, less-high-thrust-because-no-gravity technologies like cold-gas nitrogen jets and ducted fans, and so will not hurt you.

And, of course, without any of this you can always Spider-Man it up (swinging from building to building by slinging "webs" from your web shooters) with your vector-control effectors, tractor beams obeying Newton’s Third Law, and all.

Wings

These are more for a romantic scifi atmosphere to a story than they are practical. Just try not to think too much about Icarus

Hang gliders and paragliders more or less work in the real world, given that their range is very limited and you need a cliff for take-off. But they do not need any fuel or muscle power. An important limitation is about the only way to gain altitude is by entering a thermal. Otherwise you can only climb by using fuel or muscle power.

Actual muscle-powered flapping wings are probably impractical under 1 gee or more planetary gravity. Flapping wings are generally encountered in science fiction stories set in the 1/6th gravity of a Lunar colony. The lunar colonists are pros, and have to steer clear of the stupid flailing Terran tourists who can't resist trying to fly. Even then, for human flight on Luna the air-pressure in the flight chamber will have to be higher than on Terra.

If you can spare payload mass for a small gasoline or electric powered motor you can make a powered hang glider or ultralight aircraft. Powered hang gliders are gliders ridden by a pilot with a motor strapped to their backs. Ultralights actually have framework cockpit with the pilot sitting in something looking like a lawn chair. Typically such craft only carry a bare miniumum of flight instrument due to payload constraints. Sometimes the instruments are strapped to the pilot's forearm instead of being mounted on the airframe. There will be a variometer (to sense thermals) and an altimeter. If there is spare payload mass they might also bring an airspeed indicator, a radio, and maps/GPS unit.


A muscle powered non-flapping aircraft made an appearance in Arthur C. Clarke's Rendezvous with Rama. These exist in the real world, but typically have wingspans around 30 meters (which is also their weight in kilograms). The first plane to win the Kremer Prize was called the Gossamer Condor, and they were not kidding about the "gossamer" part.


Aircraft that fly by actually flapping their wings are called "ornithopters", you may have encountered the term in Frank Herbert's Dune novels.

While not in common use in the real world, in theory ornithopters have advantages in maneuverability and lower energy costs, as well as the possibility of vertical take off and landing. Like a helicopter the wings have to be designed to provide both lift and thrust. The advantage is without the need for separate lifting and thrusting airfoils, the over-all drag is reduced. The flapping wing can be set at a zero angle of attack on the upstroke, reducing drag.

There are disadvantages of course. Most of the advantages appear only if the aircraft is of small size and has a low maximum flying speed. Making the wings durable is also a problem, they undergo a lot more stress than the rotor on a helicopter with all that flapping and deforming.

Some researchers hope to replace ornithopter motors and gears with synthetic animal flight muscles. These are called entomopters. In Frank Herbert's Dune novels, ornithopters use tissue harvested from an alien animal called a heart scallop.

Ornithopter surveillance drones are much easier to disguise as a bird than are quadcopters. This is important if you do not want to tip off the object of your surveillance that they are being watched.

THE STORMS OF WINDHAVEN

(ed note: the wings here are pretty much hang gliders)

He began with the Song of the Star Sailors.

It was the oldest ballad, the first of those that they could rightly call their own. Barrion sang it simply, with easy loving familiarity, and Maris softened to the sound of his deep voice. How often she had heard Coll, late at night, plucking at his own instrument and singing the same song. His voice had been changing then; it made him furious. Every third stanza would be interrupted by a hideous cracked note and a minute of swearing. Maris used to lie in bed and giggle helplessly at the noises from down the hall.

Now she listened to the words, as Barrion sang sweetly of the star sailors and their great ship, with its silver sails that stretched a hundred miles to catch the wild starwinds. The whole story was there. The mysterious storm, the crippled ship, the coffins where they died awhile; then, driven off course, they came here, to a world of endless ocean and raging storms, a world where the only land was a thousand scattered rocky islands, and the winds blew constantly. The song told of the landing, in a ship not meant to land, of the death of thousands in their coffins, and the way the sail—barely heavier than air—had floated atop the sea, turning the waters silver all around the Shotans. Barrion sang of the star sailors' magic, and their dream of repairing the ship, and the slow agonizing dying of that dream. He lingered, melancholy, over the fading powers of their magic machines, the fading that ended in darkness. Finally came the battle, just off Big Shotan, when the Old Captain and his loyalists went down defending the precious metal sails against their children. Then, with the last magic, the sons and daughters of the star sailors, the first children of Windhaven, cut the sails into pieces, light, flexible, immensely strong. And, with whatever metal they could salvage from the ship, they forged the wings.

For the scattered people of Windhaven needed communication. Without fuel, without metal, faced by oceans full of storms and predators, given nothing free but the powerful winds: the choice was easy.

The last chords faded from the air. The poor sailors, Maris thought, as always. The Old Captain and his crew, they were flyers too, though their wings were star-wings. But their way of flying had to die so a new way could be born.

(ed note: thus arose the class of The Flyers. Since they can make no more wings, they have periodic contests where those who currently own a wing defend their fitness against a wingless challenger. The winner gets the wing.)

From THE STORMS OF WINDHAVEN by George R. R. Martin (1975)
THE MENACE FROM EARTH

     Most of the stuff written about Bats’ Cave gives a wrong impression. It’s the air storage tank for the city, just like all the colonies have — the place where the scavenger pumps, deep down, deliver the air until it’s needed. We just happen to be lucky enough to have one big enough to fly in. But it never was built, or anything like that; it’s just a big volcanic bubble, two miles across, and if it had broken through, way back when, it would have been a crater.

     I left my shoes and skirt in the locker room and slipped my tail surfaces on my feet, then zipped into my wings and got someone to tighten the shoulder straps. My wings aren’t readymade condors; they are Storer-Gulls, custom-made for my weight distribution and dimensions. I’ve cost Daddy a pretty penny in wings, outgrowing them so often, but these latest I bought myself with guide fees.
     They’re lovely — titanalloy struts as light and strong as bird bones, tension-compensated wrist-pinion and shoulder joints, natural action in the alula slots, and automatic flap action in stalling. The wing skeleton is dressed in styrene feather-foils with individual quilling of scapulars and primaries. They almost fly themselves.
     I folded my wings and went into the lock. While it was cycling I opened my left wing and thumbed the alula control — I had noticed a tendency to sideslip the last time I was airborne. But the alula opened properly and I decided I must have been overcontrolling, easy to do with Storer-Gulls; they’re extremely maneuverable. Then the door showed green and I folded the wing and hurried out, while glancing at the barometer. Seventeen pounds — two more than Earth sea-level and nearly twice what we use in the city; even an ostrich could fly in that. I perked up and felt sorry for all groundhogs, tied down by six times proper weight, who never, never, never could fly.
     Not even I could, on Earth. My wing loading is less than a pound per square foot, as wings and all I weigh less than twenty pounds. Earthside that would be over a hundred pounds and I could flap forever and never get off the ground.
     I felt so good that I forgot about Jeff and his weakness. I spread my wings, ran a few steps, warped for lift and grabbed air — lifted my feet and was airborne.
     I sculled gently and let myself glide towards the air intake at the middle of the floor — the Baby’s Ladder, we call it, because you can ride the updraft clear to the roof, half a mile above, and never move a wing. When I felt it I leaned right, spoiling with right primaries, corrected, and settled in a counterclockwise soaring glide and let it carry me toward the roof.
     A couple of hundred feet up, I looked around. The cave was almost empty, not more than two hundred in the air and half that number perched or on the ground — room enough for didoes. So as soon as I was up five hundred feet I leaned out of the updraft and began to beat. Gliding is no effort but flying is as hard work as you care to make it. In gliding I support a mere ten pounds on each arm — shucks, on Earth you work harder than that lying in bed. The lift that keeps you in the air doesn’t take any work; you get it free from the shape of your wings just as long as there is air pouring past them.
     Even without an updraft all a level glide takes is gentle sculling with your finger tips to maintain air speed; a feeble old lady could do it. The lift comes from differential air pressures but you don’t have to understand it; you just scull a little and the air supports you, as if you were lying in an utterly perfect bed. Sculling keeps you moving forward just like sculling a rowboat… or so I’m told; I’ve never been in a rowboat. I had a chance to in Nebraska but I’m not that foolhardy.
     But when you’re really flying, you scull with forearms as well as hands and add power with your shoulder muscles. Instead of only the outer quills of your primaries changing pitch (as in gliding), now your primaries and secondaries clear back to the joint warp sharply on each downbeat and recovery; they no longer lift, they force you forward — while your weight is carried by your scapulars, up under your armpits.
     So you fly faster, or climb, or both, through controlling the angle of attack with your feet — with the tail surfaces you wear on your feet, I mean.
     Oh dear, this sounds complicated and isn’t — you just do it. You fly exactly as a bird flies. Baby birds can learn it and they aren’t very bright. Anyhow, it’s easy as breathing after you learn… and more fun than you can imagine!
     I climbed to the roof with powerful beats, increasing my angle of attack and slotting my alulae for lift without burble — climbing at an angle that would stall most fliers. I’m little but it’s all muscle and I’ve been flying since I was six. Once up there I glided and looked around. Down at the floor near the south wall tourists were trying glide wings — if you call those things “wings.” Along the west wall the visitors’ gallery was loaded with goggling tourists. I wondered if Jeff and his Circe character were there and decided to go down and find out.
     So I went into a steep dive and swooped toward the gallery, leveled off and flew very fast along it. I didn’t spot Jeff and his groundhoggess but I wasn’t watching where I was going and overtook another flier, almost collided. I glimpsed him just in time to stall and drop under, and fell fifty feet before I got control. Neither of us was in danger as the gallery is two hundred feet up, but I looked silly and it was my own fault; I had violated a safety rule.
     There aren’t many rules but they are necessary; the first is that orange wings always have the right of way — they’re beginners. This flier did not have orange wings but I was overtaking. The flier underneath — or being overtaken — or nearer to wall — or turning counterclockwise, in that order, has the right of way.
     I felt foolish and wondered who had seen me, so I went all the way back up, made sure I had clear air, then stooped like a hawk toward the gallery, spilling wings, lifting tail, and letting myself fall like a rock.
     I completed my stoop in front of the gallery, lowering and spreading my tail so hard I could feel leg muscles knot and grabbing air with both wings, alulae slotted. I pulled level in an extremely fast glide along the gallery. I could see their eyes pop and thought smugly, “There! That’ll show ‘em!”

     Mary flew in ahead of me, braked and stalled dead to a perfect landing. I skidded a little but Mary stuck out a wing and steadied me. It isn’t easy to come into a perch, especially when you have to approach level. Two years ago a boy who had just graduated from orange wings tried it … knocked off his left alula and primaries on a strut — went fluttering and spinning down two thousand feet and crashed. He could have saved himself — you can come in safely with a badly damaged wing if you spill air with the other and accept the steeper glide, then stall as you land. But this poor kid didn’t know how; he broke his neck, dead as Icarus. I haven’t used that perch since

     So I taught Ariel Brentwood to “fly.” Look, those so-called wings they let tourists wear have fifty square feet of lift surface, no controls except warp in the primaries, a built-in dihedral to make them stable as a table, and a few meaningless degrees of hinging to let the wearer think that he is “flying” by waving his arms. The tail is rigid, and canted so that if you stall (almost impossible) you land on your feet. All a tourist does is run a few yards, lift up his feet (he can’t avoid it) and slide down a blanket of air. Then he can tell his grandchildren how he flew, really flew, “just like a bird.”
     An ape could learn to “fly” that much.
     I put myself to the humiliation of strapping on a set of the silly things and had Ariel watch while I swung into the Baby’s Ladder and let it carry me up a hundred feet to show her that you really and truly could “fly” with them. Then I thankfully got rid of them, strapped her into a larger set, and put on my beautiful Storer-Gulls

     She was feeling out the tail controls. “The big toes spread them?”
     “Yes. But don’t do it. Just keep your feet together and toes pointed

     We went back to the tourist slope and I let her glide, cautioning her to hold both alulae open with her thumbs for more lift at slow speeds, while barely sculling with her fingers.

From THE MENACE FROM EARTH by Robert Heinlein (1957)
EXIT EARTH

Russ Corey stood on the brink of a cliff ledge eighty feet above the rock floor of the great cavern. Eighty feet straight down and if he miscalculated so much as an instant he'd smash himself to spattering gore. He looked straight before him, across the cavern to the opposite walls glistening with condensation, reflecting the blue-yellow radiance of the artificial sun overhead. A sudden babble of argument and concern drifted up to him from far below. He lowered his gaze to look past his feet at the small human figures staring upward at him. Bird's-eye puppetry. The brief thought amused him.


Then he forgot the issue. Slowly he raised his arms until they stretched fully outward to each side of his body. He breathed deeply and steadily oi the thick air, feeling its rich heaviness as his chest rose and fell in perfectly timed movement. He flexed his fingers to test his arm muscles, then brought together the fingers and thumb of each hand. He arched his back slightly and his powerful leg muscles tensed as he rose slightly on the balls of his feet, balanced like a great upright cat.

He took a deep breath, and held It, lips pressed tightly. Again he looked straight ahead, through air to the glistening rock wails. Feathery white and brown flashed for a moment as his falcon wheeled before him, inviting him with a single plaintive screech to fly. Russ Corey smiled easily this time and then he sprang up and forward, hurling his body from the edge of the cliff to the certain death waiting far below.

He snapped his arms down and hard against his sides as his body fell in perfect balance toward the lethal rock. His hearing at such moments was incredibly, exquisitely sensitive and he heard the sudden intake of breath from those looking up as he plunged headfirst. God, he loved this moment! His entire future could now be measured in the briefest of seconds. He still must pass the test. He heard the shrill cry from below, not so far away this time.

"For God's sake—!" Another sound, the screech of the falcon, closer, diving with him. Only thirty feet left now. He snapped out his arms again, the great feathery wings arched perfectly in position, catching the rushing air with a gusting sigh. As quickly as his arms moved his feet snapped apart to angle the tai! pinions into maximum lift. With a sigh of a hundred hushed violins, the song of the wind, he transformed his death plunge into a marvelous sweeping curve. His head came up, the pressure on his arms grew to a terrible intensity, and he knew if a single tendon failed it would spell his doom.

Russ Corey did not fail and neither did his body. Every muscle and tendon and nerve straining to the perfection of the moment, performing as he commanded, his body raced over the rock floor of the cavern, his chest bare inches above the surface. Now he had all the speed and lift he wanted and he twisted his arms and angled his feet to alter the curvature of the wings, to change their camber, to twist the tail pinions into another command of lift. His body ascended another few inches above the rocky surface, then several feet, and suddenly the center of lift moved along his feathered arms and he flashed upward. With a sudden cry of joy, a shout instead of words, he again twisted his arms and beat them fiercely in great curving movement. Feathers rolled and twisted and flexed and spiraled the air about him and back along his body and he flew with the falcon; bird and man in a single flashing lunge, and the man grinned as he and his feathered brother soared within the great lunar cavern.

Russ Corey swooped and plunged, banked steeply and moved his arms closer to or farther from his body to change his lift, arcing downward, crashing against the air with fierce flapping energy, savoring the incredible feeling that had haunted men from the first time they looked into the skies and comprehended, finally, that their feathered cousins truly flew from the lifting force of air.


Russ Corey thought now of distant Mars as his own personal dream, but every time he had the opportunity he came here to Cavern Fourteen. As he was here this very moment, birdman extraordinary. He had personally strawbossed Number Fourteen. Extra sealant for the walls and the flooring and the overhead. Doors of thick metal, double chambered for doubled strength. Oxygen and nitrogen pumped and squeezed into the chamber until he achieved pressure six times greater than on the surface of their birth world. He grew vines and created gardens and the plants cleansed the air and made it sweet, and the delicate flowers that grew best trader flimsy gravity flourished and bathed them in gentle fragrance. Flight Bowl was his joy.

With the air pressure at ninety pounds a square inch, thickly fluid and heavy, the lifting capability of a wing moving through such viscous atmosphere became almost magical. But there were other marvelous advantages unattainable on Earth. The lunar gravity was but one-sixth that of the birthworld. There Russ Corey weighed one hundred eighty pounds. Russ Corey on his adopted world weighed only thirty earth pounds. And he was as strong as ever, despite the ghostly diminution of his weight. Inserting that strength and the science of synthetic feathers into the soupy air in Flight Bowl enabled Corey to become what had forever eluded man until this moment: a creature of true, self-sustaining flight.

Corey beat his winged arms steadily, climbing until he felt the warmth of the "artificial sun" gleaming near the cavern roof. He made a circle of the upper reaches and held his arms steady, angling the wing camber to spill lift, bringing him into a wide descending spiral toward the floor. He would make his approach into the face of strong air currents churned by a great shrouded fan so that he would land "into the wind" as birds did from instinct.

"Down below!" he shouted in his curving descent. "Birdman landing!"

He caught a glimpse of Vicki Correnti in a bright red feathery ensemble, waving to him. "All clear, Russ! Come on in!" He continued his circling descent, judging his approach with practiced eye and memory, and then he brought down his legs and moved his body from horizontal to near vertical, his powerful arms churning a storm of downbeating air from the glassine feathers. With a final thrust of energy he angled his arm wings to create the sudden ground/air cushion to bring his feet lightly to the rocky surface.

Vicki came to him immediately, her hands curling away the velcro strips binding his feathery covering to his body. A flight attendant took their feather gear to be hung on racks in the drying room. Nature accommodated birds with wet feathers. Not so with upstart men. Attempting flight with wet synthetic feathers guaranteed a crumpling fall from any height.

Vicki brushed her lips against his cheek. She was always beautiful, but more so at such a moment when everything she did was action and movement. Short, curly black hair, startling white skin, and wine-red lips bobbed before him. "That was beautiful, Russ. Just beautiful. It's the best I've ever seen you."

He nodded to acknowledge her praise. She was the best manflier he'd ever seen, and accolades regarding flight came rarely from her. He should have known better. "Your start, however—"

His eyes flicked upward. "You mean from the ledge?"

"Yes You're an unmitigated idiot also, Russ Corey. A Grade-A, homogenized blithering numbskull. If the pressure was one pound less than ninety—" She took a deep breath, "Damn you, that would be a very stupid way to go."

"Yeah. Like Icarus. Next you'll tell me," he gestured to the dazzling globe suspended high above them, "that I flew too close to the sun like our Greek hero of mythology. Singed my feathers, I guess."

From EXIT EARTH by Martin Caidin (1987)
RENDEZVOUS WITH RAMA

     'You know, Commander, that I was in the Lunar Olympics last year.'
     'Of course. Sorry you didn't win.'
     'It was bad equipment; I know what went wrong. I have friends on Mars who've been working on it, in secret. We want to give everyone a surprise.'
     'Mars? But I didn't know . . .'
     'Not many people do—the sport's still new there; it's only been tried in the Xante Sportsdome. But the best aerodynamicists in the solar system are on Mars; if you can fly in that atmosphere, you can fly anywhere.'
     'Now, my idea was that if the Martians could build a good machine, with all their know-how, it would really perform on the Moon—where gravity is only half as strong.'
     'That seems plausible, but how does it help us?'
     Norton was beginning to guess, but he wanted to give Jimmy plenty of rope.
     'Well, I formed a syndicate with some friends in Lowell City. They've built a fully aerobatic flyer with some refinements that no one has ever seen before. In lunar gravity, under the Olympic dome, it should create a sensation.'
     'And win you the gold medal.'
     'I hope so.'
     'Let me see if I follow your train of thought correctly. A sky-bike that could enter the Lunar Olympics, at a sixth of a gravity, would be even more sensational inside Rama, with no gravity at all. You could fly it right along the axis, from the North Pole to the South—and back again.'
     'Yes—easily. The one-way trip would take three hours, non-stop. But of course you could rest whenever you wanted to, as long as you kept near the axis.'
     'It's a brilliant idea, and I congratulate you. What a pity sky-bikes aren't part of regular Space Survey equipment.'
     Jimmy seemed to have some difficulty in finding words. He opened his mouth several times, but nothing happened. 'All right, Jimmy. As a matter of morbid interest, and purely off the record, how did you smuggle the thing aboard?'
     'Er—"Recreational Stores".'
     'Well, you weren't lying. And what about the weight?'
     'It's only twenty kilograms.'
     'Only! Still, that's not as bad as I thought. In fact, I'm astonished you can build a bike for that weight.'
     'Some have been only fifteen, but they were too fragile and usually folded up when they made a turn. There's no danger of Dragonfly doing that. As I said, she's fully aerobatic.'
     'Dragonfly—nice name. So tell me just how you plan to use her; then I can decide whether a promotion or a court martial is in order. Or both.'

     Dragonfly was certainly a good name. The long, tapering wings were almost invisible, except when the light struck them from certain angles and was refracted into rainbow hues. It was as if a soap bubble had been wrapped round a delicate tracery of aerofoil sections; the envelope enclosing the little flyer was an organic film only a few molecules thick, yet strong enough to control and direct the movements of a fifty-kph air flow. The pilot—who was also the power plant and the guidance system—sat on a tiny seat at the centre of gravity, in a semi-reclining position to reduce air resistance. Control was by a single stick which could be moved backwards and forwards, right and left; the only 'instrument' was a piece of weighted ribbon attached to the leading edge, to show the direction of the relative wind.
     Once the flyer had been assembled at the Hub, Jimmy Pak would allow no one to touch it. Clumsy handling could snap one of the single-fibre structural members, and those glittering wings were an almost irresistible attraction to prying fingers. It was hard to believe that there was really something there . . .
     As he watched Jimmy climb into the contraption, Commander Norton began to have second thoughts. If one of those wire-sized struts snapped when Dragonfly was on the other side of the Cylindrical Sea, Jimmy would have no way of getting back—even if he was able to make a safe landing. They were also breaking one of the most sacrosanct rules of space exploration; a man was going alone into unknown territory, beyond all possibility of help. The only consolation was that he would be in full view and communication all the time; they would know exactly what had happened to him, if he did meet with disaster.

     Jimmy nodded absentmindedly as he tested the controls. The whole rudder-elevator assembly, which formed a single unit on an outrigger five metres behind the rudimentary cockpit, began to twist around; then the flap-shaped ailerons, halfway along the wing, moved alternately up and down.

     Very slowly, Jimmy started to move the foot-pedals. The flimsy, broad fan of the airscrew—like the wing, a delicate skeleton covered with shimmering film—began to turn. By the time it had made a few revolutions, it had disappeared completely and Dragonfly was on her way.

From RENDEZVOUS WITH RAMA by Arthur C. Clarke (1973)
INFERNO

(ed note: In the novel, the protagonist dies and wakes up in Inferno. Which just so happens to be as described in Dante's Inferno. The protagonist frantically tries to remember his Dante since it is now a road map. He figures the best way to escape is by making a glider out of locally available materials: saplings, vines, and cotton robes)

     I looked at the saws and lusted. With a saw and nothing else we could build a glider. Other things would be useful, but they were easier to make than a saw would be. I had to have one.

     Now I had a saw that I could use to cut frames and ribs and stringers, if I could find anything to cut.

     First things first. I used a log to flatten out an area larger than the glider would be, then cut a long springy sapling for a ruler. After a while I had a whole collection of saplings of various lengths and thicknesses.
     You draw the rough outlines, then spring the batten — in this case one of the saplings — across the important points. That makes a smooth fair curve. It was the way the Wright Brothers designed airplanes, and it was the way the Douglas Gooney Bird was designed. It wasn’t until World War II, long after the age of flight was underway, that airplanes were designed on drafting tables. Before that they were done on the loft floors, the same way that boats were designed for centuries.
     Did you ever try to set up ribs and make them keep their shape by tying them with vines? When the ribs are whatever you can cut off swamp willows? As a lesson in patience the job has few equals…
     Eventually it looked liked a glider. The wings weren’t precisely symmetrical, and the control surfaces pivoted on wooden bearings with dowels shaped by flint knives and thrust into holes enlarged by flint drill bits; the fabric was sewn with vine tendrils shoved through holes poked with a thorn; but it looked like a glider.
     I remembered the Cargo Cults of the South Seas.
     The islanders had been sorry to see the airplanes go after World War II ended. Native magicians had made mockups of airplanes and landing fields. It was sympathetic magic intended to bring back the real airplanes and the great days of cargo and trade. I told Benito about the Cargo Cults, amusing him greatly, and only later realized what had brought them to mind.
     What I was building would never look like more than a crude imitation of an airplane. But it would fly!
     I spent as much time making tools as I did working on the sailplane. A bow drill: take one bow, as for shooting arrows; get a good curve in it, and instead of an arrow, take a piece of sapling. Wrap the bowstring around the piece of sapling. Attach the drill bit to one end. You need a hard block in which the top of the sapling chunk will rotate freely because you’ve worn a depression in it. Hold that block in one hand, put the drill point where you want it, and draw the bow back and forth with the other hand. The sapling turns. The point turns. In about a week you can drill a hole.
     I’d heard that boatbuilders in Asia preferred their bow drills to American electrics. They must have been crazy.

     We pulled the glider up the slope and carried it until the land fell away as a steep cliff. The swamp bubbled like sludge, with sickly lights glowing among the odd-shaped bushes and trees.
     “If we crash down there, we’ll never get out,” I said “Can you fly this thing?”
     “I have flown them.” Benito laughed, with real humor.
     “What?”
     “I have done this before. We launched the glider from a much higher cliff. An Austrian soldier came to get me out of a sticky situation.” He settled himself at the controls.
     Something familiar about that story… but Benito was looking out at the swamp, and I didn’t ask him. He looked awfully big and heavy to be a glider pilot, and I had to remember that we didn’t weigh what we should. I strained against the fuselage and shoved outward.

     I heaved against the plane, and then there was no room for thought. The plane dropped like a rock, with me hanging onto the tail, crawling forward to get into the rear seat. Benito knew how to fly, all right. He let us dive, just missing the cliff, until we had built up speed; then he leveled out, taking us above the swamp and toward the red-hot city.

     “No question about that.” We headed out over the swamp again, feeling the rising air that was just strong enough to keep us level. If we didn’t find an updraft we’d crash in the swamp.
     The trouble was, we were looking for something invisible. You can’t see a wind, you can only see what it does. I was looking for heat turbulence, or formations that might break a horizontal airstream and send it upwards; anything.

From INFERNO by Larry Niven and Jerry Pournelle (1975)

Flycycles

Ringworld

     The lockers held an ominous plethora of exploration gear. There was nothing Louis could have pointed to, saying, "That's a weapon." But there were things which could be used as weapons. There were also four flycycles, four flying backpacks (lift belt plus catalytic ramjet), food testers, phials of dietary additives, medkits, air sensors and filters. Someone was sure as tanj convinced that this ship would be landing somewhere.

     He went out on one of the flycycles: a dumbbell-shaped thruster-powered vehicle with an armchair seat in the constriction.

     "How about water?" Louis was asking. "I couldn't see any lakes. Do we have to haul our own water?"
     "No." Nessus opened the aft section of his own flycycle to show them the water tank and the cooler-extractor which would condense water from the air.
     The flycycles were miracles of compact design. Aside from their highly individualistic saddles, they were built all alike: a pair of four foot spheres joined by the constriction that held the saddle. Half the rear section was luggage space, and there was harness for stringing additional gear. Four flat feet, extended now for landing, would recess against the two spheres during flight.
     The puppeteer's flycycle had a reclining saddle, a belly-bed with three grooves for his three legs. Nessus would he immobile on his belly, controlling the vehicle with his mouths.
     The 'cycles intended for Louis and Teela held padded contour chairs with neck rests and power controls for attitude. Like Nessus's and Speaker's, these saddles rested in the constriction in the 'cycle's dumbbell shape, and were split to accommodate leg supports. Speaker's saddle was much larger and broader, and without a neck rest. There was rigging for tools on both sides of his saddle.

     Nessus had shown them how to use the slave circuits. Now each of the other 'cycles was programmed to imitate whatever Louis's did. Louis was steering for them all. In a contoured seat like a masseur couch without the masseur attachments, he guided his 'cycle with pedals and a joystick.

     The rest facilities were simple, comfortable, and easy to use. But undignified!
     He tried pushing his hand into the sonic fold. The fold was a force field, a network of force vectors intended to guide air currents around the space occupied by the flycycle. It was not intended to behave like a glass wall. To Louis's hand it felt like a hard wind, a wind that pushed straight toward him from every direction. He was in a protected bubble of moving wind.
     The sonic fold seemed idiot-proof.
     He tested that by pulling a facial tissue from a slot and dropping it. The tissue fluttered underneath the 'cycle, and then it rested on the air, vibrating madly. Louis was willing to believe that if he fell out of his seat, which would not be easy, he would be caught by the sonic fold and would be able to climb back up again.
     It figured. Puppeteers ...
     The water tube gave him distilled water. The food slot gave him flat reddish-brown bricks. Six times he dialed a brick, took a bite, and dropped the brick into the intake hopper. Each brick tasted different, and they all tasted good.
     At least he would not get bored with eating. Not soon, anyway.
     But if they could not find plants and water to shovel into the intake hopper, the food slot would eventually stop delivering bricks.

From Ringworld by Larry Niven (1970)

Flying Platforms

Flying Sled

Rocheworld Dragonfly

In Robert Forward's The Flight of the Dragonfly the first interstellar expedition travels to Barnard's Star via laser lightsail starship to explore the Rocheworld twin planets.

Since the twin planets have atmospheres (actually they are close enough that they share a common one), some sort of flitter for exploration is indicated. Therefore the lander carries a nuclear powered aircraft called a Surface Excursion Module (SEM).


      Later Shirley called the crew together. "It's time to lower the Dragonfly to the surface and put its wings on. I want to get through the lowering phase before Barnard sets behind Eau."
     "Do be careful!" said Arielle.
     "We won't hurt your pet," said Shirley. She walked around to the front of the lander and stood at the base of the landing strut that had been modified to act both as a leg for the lander and as a lowering rail for the aerospace plane. Shirley watched a point near the tail of the plane.

     "Release hold-down lugs, Jack," she said, then nodded in satisfaction as the clawlike devices swung clear. The aerospace plane shivered slightly as the hold on it was loosened, but it was still hanging vertically from its nose hook. Shirley stepped quickly to one side and looked up the belly of the plane to the top.
     "Lower top winch!" she called, and slowly the nose of the airplane tilted away from the lander, the tail staying in place at the top of the lowering rail. Shirley could now see the cockpit windows and the large triangular gap in the side of the lander as the plane pulled away from the side of the ship. The rotation continued until the airplane was leaning away from the lander at an angle of about thirty degrees.
     "Now both winches!" said Shirley. Jack started the bottom winch, and letting out both the nose cable and the tail cable at the same speed, it lowered the aerospace plane slowly down the lowering rail, still at the thirty degree angle. As the plane moved down the rail, the rudder finally cleared the side of the lander. About two meters from the end of the rail, the tail winch stopped, while the upper nose winch continued to pay out cable. Slowly the huge plane rotated about the pivot point near the tail, and as it approached the horizontal orientation there was a noticeable tilt to the lander as it reacted to the weight of the plane.
     "Lower landing skids!" said Shirley, and slots appeared in the belly of the aerospace plane and three skids came out. They reached to a half-meter of the surface.
     "Lower her down!" said Shirley, bending down to watch underneath. Slowly the plane was lowered to the surface.
     "Done!" she yelled, then raced to detach the lowering cables from the front and rear of the aerospace plane. The winches retrieved their cables, their job done.

     Dawn was breaking over the distant arc of Eau when Shirley awoke and assembled her press gang. Red was left on board the lander not only in case they had to leave in a hurry, but also so she could continue to monitor the seismic and radar signals still coming from the volcano hidden over the arched western horizon of the inner pole. Everyone else became common laborers as they assisted Shirley and the Christmas Branch to assemble the outer wing panels of the Magic Dragonfly.
     The panels were hollow graphite fiber composite structures designed without internal bracing so that the wing panels nested inside each other. The nested wing sections then fit neatly inside the lower portion of the lander on either side of the rudder of the Dragonfly. Using the upper winch that had let the aerospace plane down to the surface, Shirley and Jack carefully pulled each segment out one at a time and lowered them down to a waiting team of spacesuited humans.
     "Stand back," warned Shirley from her vantage point up in the wing storage hold. "Let Jack winch the panel all the way down to the surface before you get near. I have epoxy that will fix the dings in the wing section, but Katrina left her people-epoxy back home and we can't fix you if you get a ding."

     Slowly each section was lowered to the ground, then George would unfasten the winch cable, and the crew of eight would lift the five by six meter section of wing and take it over and place it on the ground on either side of the stub-winged Magic Dragonfly.
     After the wing panels were unloaded and arranged, Shirley and Jack lowered a bundle of small struts and two long telescoping poles. Before she came down, Shirley unfastened the lower winch and brought it with her over to the plane.
     "OK, Jack," she puffed as she clambered up to the top of the aerospace plane with the heavy winch and attached it to a waiting fixture. "Have the Christmas Branch (the utility robot) install the struts in the first section."
     She motioned to the suited figures scattered about her below on the ground.
     "This will be just like we practiced it on Titan," she said. She tossed down the end of the cable from the winch. "Set up the tripod over the section the Christmas Branch is working on, then when it's done installing the inner braces, hook it up to the central lifting lug and get out of the way." Shirley looked up at the sky. They had been working hard since daybreak, and Barnard was already overhead. They were behind schedule. Slightly exasperated, she allowed a note of irritation to creep into her voice.
     "And hurry up! We've only got an hour and a half of daylight left. If we're not done by then, we'll have to work by floodlight to keep up with the mission schedule."

     The tripod was assembled and the first section was raised into place, the Christmas Branch riding up on the inside.
     "We're about ten centimeters off," said Shirley. The Christmas Branch extended its body between the hanging section and the wing stub. then contracted to draw the two sections closer together. Shirley straddled the narrowing gap and using a long pointed pry-bar between two aligning lugs, she pulled the wing section forward until the edges were lined up.
     "Hold it!" said Jack as the two were about to meet. A large spider-imp (part of the Christmas Branch) scurried around the narrow gap, removing the thin plastic protective cover from the sealing material. Shirley could feel internal fasteners clicking into place beneath her feet, then the pressure on her pry-bar lessened as the fasteners were rotated to pull the two wing sections together.
     The outer wing sections, being much lighter, were on well before dark, and Jill was able to pump them down, check for leaks, then refill them with fuel from the main tanks of the Eagle while the tired construction crew reboarded the lander for a last dinner together.

One leg of the Surface Lander and Ascent Module (SLAM) is part of the "Jacob's Ladder", while another leg acts as the lowering rail for the Surface Excursion Module (SEM) (aircraft). The wings of the Surface Excursion Module are chopped off in mid-span just after the VTOL fans. The remainder of each wing is stacked as interleaved sections on either side of the tail section of the SEM. Once it has its wings attached, the SEM is a completely independent vehicle with its own propulsion and life support system.


Surface Excursion Module

The Surface Excursion Module (SEM) is a specially designed spacecraft capable of flying as a plane in a planetary atmosphere or as a rocket for short hops through empty space. An exterior view of the aerospace plane is shown in Figure 10. The exploration crew christened the aerospace plane the Magic Dragonfly because of its long wings, eye-like scanner ports at the front, and its ability to hover. The Dragonfly was ideal for the conditions on Rocheworld. For flying long distances in the rarefied non-oxidizing atmosphere, the propulsion comes from heating of the atmosphere with a nuclear reactor operating a jet-bypass turbine.

For short hops outside the atmosphere, the engine draws upon a tank of monopropellant that not only provides reaction mass for the nuclear reactor to work on, but also makes its own contribution to the rocket plenum pressure and temperature.

Dragonfly uses a nuclear power plant for its primary propulsion. Rocheworld had two large lobes to explore that were equivalent in land area to the North American continent. Although the humans would use the excellent mapping and exploration instruments on-board the plane to supplement their own limited senses, even these have distance limitations, and a long criss-cross journey over both lobes was needed to determine the true nature of the double-planet.

A naked nuclear reactor is a significant radiation hazard, but the one in the aerospace plane was well designed. Its outer core was covered with a thick layer of thermoelectric generators that turn the heat coming through the casing into the electrical power needed to operate the computers and scientific instruments aboard the plane. A number of metric tons of shielding protected the crew quarters from radiation, but the real protection was in the system design that had the entire power and propulsion complex at the rear of the plane, far from the crew quarters. Since the source of the plane's power (and heat) was in the aft end, it was logical to use the horizontal and vertical stabilizer surfaces in the tail section as heat exchangers. Because most of the weight (the reactor, shielding, and fuel) was at the rear of the plane, the center of mass and the placement of the wings were back from the wing position on a normal airplane of its size.

Dragonfly was more insect than plane. Although it could travel through space without any atmosphere, and could fly through the atmosphere at nearly sonic speeds, the attribute that made it indispensable in the surface exploration work, were the large electrically powered vertical talk-off and landing (VTOL) fans built into its wings. These fans take over at low speeds from the more efficient jet, and can safely lower Dragonfly to the surface.

The details of the human-inhabited portion of the Magic Dragonfly are shown in Figure 11. At the front of the aerospace plane is the cockpit with the radar dome in front of it. Just behind the cockpit is the science instrument section including port and starboard automatic scanner platforms carrying a number of imaging sensors covering a wide portion of the electromagnetic spectrum. Next were the operating consoles for the science instruments and the computer, where most of the work was done. Further back was the galley and food storage lockers. This constituted the working quarters where the crew spent most of their waking hours. The corridor was blocked at this point by a privacy curtain which led to the crew quarters. Since the crew would be together for so long, the need for nearly private quarters were imperative, so each crew member had a private bunk with a large personal storage volume attached. Aft of the bunks was the shower and toilet, then another privacy curtain.

At the rear of the aerospace plane was the airlock, suit storage, air conditioning equipment, and a "work wall" that was the province of the Christmas "Branch", a major subtree of the Christmas Bush that went along with the aerospace plane on its excursions. Not designed for use by a human, the work wall was a compact, floor-to-ceiling rack containing a multitude of housekeeping, analyzing, and synthesizing equipment that the Christmas Branch used to aid the astronauts in their research and to keep them and the Magic Dragonfly functioning. Behind the work wall was the power conditioning equipment, the liquified air supply, and a large tank of monopropellant. All this mass helped the lead shield in front of the nuclear reactor keep the radiation levels down in the inhabited portions of the aerospace plane.

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Winged Aircraft

Rockwell XFV-12

Phalanx MP-18 Dragon

Leif Ericson Scoutship

Convair Model 49

Flying Saucers

NAA Space Bomber

The NAA Manned Bombardment and Control Vehicle was a 1963 study done by North American Aviation to design a USAF space bomber study. The lenticular shape probably came from Alan Kehlet, a NASA aerodynamicist.

This does not strictly belong in the "flitter" section since it is more of a re-entry vehicle, but it was filed here because it looks like a flying saucer.

The old design exploded into popular culture with the publication of a breathless and error-ridden article entitled AMERICA'S NUCLEAR FLYING SAUCER A trail of secret documents reveals the startling truth about the U.S. Air Force's flying disc aircraft in the November 2000 issue of Popular Mechanics magazine. The article is almost, but not quite, totally worthless, but the illustrations are grand. No, it was not nuclear powered, it was not based on German World War II designs, and had absolutely no connection to Project Silverbug or Project Py Wacket.

For the real data, refer to the Astronautix article.


The vehicle was 12.2 meters in diameter, and carried four thermonuclear weapons each carrying the name of a major Soviet city or industrial complex. The vehicle would remain in a 560 kilometer orbit for six weeks at a time, waiting for the signal from the President's nuclear football to start global thermonuclear war.

The Manned Bombardment and Control Vehicle had control over several orbital unmanned weapons clusters containing multiple thermonuclear warheads (docs hint there are four warheads per cluster). Each warhead was carried by a reentry vehicle with a delta V of 300 m/s (plus delta wings), enough to attack targets up to 2,000 kilometers left or right of the orbital ground track. The manned vehicle could also reenter in order to deliver its payload of four nukes personally.


While waiting, the crew would use a small interorbital shuttle to visit each weapon cluster at six week intervals, topping off the weapon's fuel tanks and doing maintenance as needed. The interorbial shuttle carries 860 kg of hypergolic nitrogen tetroxide+hydrazine fuel. The shuttle engine produces a thrust of 900 Newtons.

Each weapon in the cluster was 7 meters long, 0.5 meters in diameter, wingspan of 1.4 meters, total mass 913 kg including 90 kg of propellants, thrust of 9,000 Newtons. Delta V of 300 m/s. Every six weeks it would need to be topped off with 22 kg of propellant per weapon cluster. The weapons in the cluster are connected to a central propellant tank so they are constantly being topped off.


The manned vehicle was 12.2 meters in diameter and had a gross launch mass of 20,500 kg. It was disc shaped to increase the internal volume but also to increase the leading-edge radii to reduce the aerodynamic heating during reentry. Surface area of about 144 m2. It contains an interorbital shuttle for servicing weapon clusters. The crew compartment can be jettisoned for emergency escape if the booster rocket explodes on lift-off. The useful load was 12,514 kilograms, including 3,650 kg for the four internal thermonuclear weapons. For maneuvering and refueling missiles it carries 4,252 kg of hypergolic nitrogen tetroxide+hydrazine fuel.

The manned vehicle had four internal compartments: crew escape capsule, living quarters, work area, and thermonuclear armaments bay. The work room contains the controls and monitors for the orbital weapon clusters. All of the compartments are pressurized except for the armaments bay.


The escape capsule is also the control cabin, about 5.2 meters long and 1.8 meters wide. It has emergency life support and power enough to get the crew to safety in the unhappy event of the booster rocket exploding. The escape capsule solid-fuel abort rocket has 400,000 N of thrust burning for 10 seconds. It accelerates the capsule at 8.5 g. This is fast enough to outrun the deadly 0.3 bar overpressure explosion wave seeking to crush the capsule like a used beer can. The 10 seconds is to get the escape capsule high enough so that the parachutes can prevent it from auguring into a shallow grave for the crew.

The armaments bay is unpressurized. It has two nuclear weapons stored port, two starboard, and the interorbital shuttle in the center. The weapons are stored with the nose facing to the rear. Once the vehicle reaches orbit, the shuttle is used to remove the weapons and attach them to the belly of the vehicle in their ready position. In case of an emergency return to base, the nuclear weapons would be ejected and left in orbit for later recovery.


During the boost phase power is supplied by a silver-oxide battery (90 kg): peak load of 12 kW for 10 minutes or average load of 7 kW for 2 hours.

During the orbital phase 7 kW of power is supplied by a solar turboelectric system (360 kg). A 8.2 meter diameter solar collector gathers energy, paired with a 260° C heat radiator on the backside. A binary Rankine-cycle system converted the heat into mechanical energy, which an alternator converted into electricity. The working fluid would be either mercury or steam. An integral lithium hydride battery stores energy for use during the dark periods of the orbit. The collector incorporates a RCS and a sun-seeking circuit to keep the collector aimed properly.


Again, for more details, refer to the Astronautix article.

Code Name: Pye Wacket

This section has been moved here

MHD Lift Fan

This is a magnetohydrodynamic flying vehicle designed in 1962 by Dr. Richard Rosa (who created the first successful MHD generator in 1959). The goal was to make a vertical take off and landing (VTOL) aircraft that was also capable of flying horizontally at high speed (unlike helicopters and the Harrier jump jet). The design had promise, it would be very maneuverable. But since it utilized plasmas it would probably glow in the dark.

The fundamental idea was to use electromagnetic forces to move air, rather than using wings, propellers, rotors, or turbines.

In the diagram above, the heart of the design is the superconducting magnetic field coil. It surrounds an annular (ring-shaped) duct, with the top of the duct marked "intake" and the bottom marked "exhaust". There are cathodes on the inner surface of the annular duct and anodes plating the outer surface.

In operation, an electric arc is struck between the cathode and the anode. This turns the air inside the annular duct into plasma. The interaction between the electric current of the arc and the magnetic field of the coil creates the J × B force. This force makes the air plasma rotate inside the annular duct.

The rotating air wants to expand radially outward from its spin axis. The fact that the annular duct has side walls that slant instead of being straight up and down forces the air to move along the slant, in a downward direction.

The bottom line is that the air plasma jets out of the bottom, with no material turbines required. Fresh air is sucked in from the top. It is basically the magnetohydrodynamic equivalent of a centrifugal pump. It bears some similarity to the Magnetoplasmadynamic rocket, except it is using the atmosphere for propellant.

The advantage is that since it is not using physical turbine blades the MHD jet can operate equally well at low or high speed. It is very difficult to make turbines that can do this.

For take-off or hovering, you want a jet that ingests large amounts of air but expels it at low speed (this is why a helicopter blade has such a large diameter but spins relatively slowly). For rapid flight you want a jet that ingests small amounts of air but expels it a high speed (this is why a jet engine has such a small diameter turbine but spins relatively rapidly).

Since the MHD jet is using force fields instead of physical blades, it can in theory be reconfigured by changing the shape of the fields.

Dean Ing Scoutship

Among the most fascinating military craft are those designed for scouting forays: surveillance, pinpoint bombing sorties, troop support, and courier duty being only a few of their duties. The Germans briefly rescued Mussolini with a slow but superb scout craft, the Fieseler Storch. Our SR-71 does its scouting at Mach 3, while the close-support A-10 can loiter at a tiny fraction of that speed. Now in development in the U.S., Britain, and Germany is a family of remotely piloted scout craft that may be the next generation of scout ships, combining the best features of the Storch and the SR-71.

The general shape of the scout ship is that of a football flattened on the bottom, permitting high-speed atmospheric travel and crabwise evasive action while providing a broad base for the exhaust gases of its internal ACV fans. The ship is MHD powered, drawing inlet air from around the underlip of the shell just outboard of the ACV skirt. The skirt petals determine the direction of deflected exhaust for omnidirectional maneuvers, though auxiliary jets may do the job better than skirt petals.

The scout uses thick graphite composite skin and sports small optical viewing ports for complete peripheral video rather than having a single viewing bubble up front. The multiple videos offer redundancy in case of damage; they permit a stiffer structure; and they allow the occupant, if any, maximum protection by remoting him from the ports.

The question of piloting is moot at the moment. Grumman, Shorts, and Dornier are all developing pilotless observation craft for long-range operations, but a scout craft of the future would probably have a life-support option for at least one occupant. The design has an ovoid hatch near its trailing edge. For manned missions, an occupant pod slides into the well-protected middle of the ship, and could pop out again for emergency ejection. For unmanned missions the occupant pod might be replaced by extra fuel, supplies, or weapons. Some version of this design might inherit the missions of the battle tank, but with much-improved speed and maneuverability.

Well, we've specified high maneuverability and a graphite composite skin. Given supersonic speed and automated evasion programs, it might be the one hope of outrunning an orbital laser weapon!

Of course the scout doesn't exceed the speed of light. What it might do, though, is survive a brief zap long enough to begin a set of evasive actions. Let's say the enemy has an orbital laser platform (OLP) fairly near in space, not directly overhead but in line-of-sight, four hundred miles from the scout which is cruising innocently along at low altitude at a speed of Mach 1. The laser is adjusted perfectly and fires.

What does it hit? A thick polished carapace of graphite composite, its skin filaments aligned to conduct the laser's heat away from the pencil-wide target point. Sensors in the scout's skin instantly set the craft to dodging in a complex pattern, at lateral accelerations of about 10 g's. At this point the occupant is going to wish he had stayed home, but he should be able to survive these maneuvers.

Meanwhile the OLP optics or radar sense the change of the scout's course—but this takes a little time, roughly two millisec, because the OLP is four hundred miles away. Reaiming the laser might take only ten millisec, though it might take considerably longer. Then the OLP fires again, the new laser burst taking another two millisec to reach the target.

But that's fourteen thousandths of a second! And the scout is moving roughly one foot per millisec, and is now angling to one side. Its change of direction is made at well over three hundred feet per sec, over four feet of angular shift before the second ('corrected') laser shot arrives. The scout's generally elliptical shell is about twenty feet in length by about ten in width. Chances are good that the next laser shot would miss entirely, and in any case it would probably not hit the same spot, by now a glowing scar an inch or so deep on the scout's shell.

Discounting luck on either side, the survival of the jittering scout ship might depend on whether it could dodge under a cloud or into a steep valley. It might, however, foil the laser even in open country by redirecting a portion of its exhaust in a column directly toward the enemy OLP. The destructive effect of a laser beam depends on high concentration of energy against a small area. If the laser beam spreads, that concentration is lost; and beam spread is just what you must expect if the laser beam must travel very far through fog, cloud, or plasma. If the scout ship could hide under a tall, chemically seeded column of its own exhaust for a few moments, it would have a second line of defense. And we must not forget that the laser's own heat energy, impinging on the target, creates more local plasma which helps to further spread and attenuate the laser beam.

One method of assuring the OLP more hits on a scout ship would be to gang several lasers, covering all the possible moves that the scout might make. The next question would be whether all that fire-power was worth the trouble. The combination of high-temperature composites, MHD power, small size, and maneuverability might make a scout ship the same problem to an OLP that a rabbit is to a hawk. All the same, the hawk has the initial advantage. The rabbit is right to tremble.

An unmanned scout ship, capable of much higher rates of angular acceleration, would be still more vexing to an OLP. If the OLP were known to have a limited supply of stored energy, a squadron of unmanned scouts could turn a tide of battle by exhausting the OLP in futile potshots. It remains to be seen whether the jittering scout craft will be able to dodge, intercept, or just plain outrun a locally-fired weapon held by some hidden infantryman. But given a compact reactor or an antimatter drive, the scout ship could become a submersible. In that event the scout craft could escape enemy fire by plunging into any ocean, lake, or river that's handy. The broad utility of such a craft might make obsolete most other designs.

Coanda-effect

The Coandă-effect is a clever way of thinking outside of the box. Conventional aircraft use Bernoulli's principle to generate lift by moving a wing through stationary air. Henri Coandă had the brilliant idea that this would also work if you had a stationary wing and blew moving air over it. This would allow Coandă aircraft to perform vertical take off.

For maneuverability purposes, the wing is bent into a circle, creating the classic flying-saucer profile. It was used for Project Y, Project Silver Bug and the Avrocar.

The main drawback of the circular wing designs is the increased maneuverability is at the expense of stability. Flying one is akin to walking on black ice wearing boots made of banana peels coated in axle grease.

The Coandă-effect has been successfully used on straight winged aircraft such as the Boeing YC-14, the Antonov An-72 'Coaler', the Shin Meiwa US-1A flying boat, the McDonnell Douglas YC-15, and the Boeing C-17 Globemaster III.

Project Y

Project Silver Bug

Project 1794

Project 1794 Design Alfa

Project 1794 Design Bravo

Project 1794 Design Charlie

Project 1794 Design Delta

VZ-9 Avrocar

Flying Submarine

A flying submarine not quite impossible, but it will probably have the disadvantages of both aircraft and submarine and the advantages of neither. There is also the question of why anyone would want such a silly thing (unless you happened to be James Bond). What sort of mission is it optimized for anyway? Other than just being real cool?


     It's an aeroplane! It's a submarine! It's a floor wax! It's a dessert topping! There's nothing that spells progress in large, friendly letters like trying to combine two totally incompatible technologies.
     Submarines are supposed to be thick hulled to keep out pressure and aeroplanes are supposed to be thin hulled to make them light enough to fly, so let's make one machine that splits the difference and does the job of both—badly.
     It's the greatest idea since the armour-plated pillow!

Air Handwavium

Antigravity is currently handwavium, physics currently does not allow the possiblity of antigravity vehicles. But they are too cool for school, most science fiction fans love them.

For the equation to calculate the power needed for handwavium antigravity vehicles, go here.

Air/Raft

Air/Raft

Also known as a flier, the air/raft relies on solid-state anti-grav modules for lift and propulsion. Four independent, individually replaceable modules insure a maximum of safety, in that each provides one-quarter of the vehicle's total lift. A standard air/raft masses about 4 tons, and can carry a payload of about 4 tons, including the pilot and 3 passengers. Cruising speed is usually 100 kph, with unlimited range and endurance. The normal air/raft is open-topped and subject to the effects of weather and climate.

The major drawbacks to the air/raft are its low load capacity, its relatively slow speed, and its susceptibility to weather (both the negative effects of bad weather on passengers and the slowing effects of high winds and buffeting).

Most air/rafts are capable of reaching orbit (occupants must wear vacc suits) but the trip will take several (6 to 8) hours. Also, most can be overloaded with passengers (a maximum of 8 can fit with minimal comfort) so long as the tonnage maximum is not exceeded.

From Classic Traveller Adventure 3: Twilight's Peak (1980)

It's worth noting, that in the Traveller universe, after antigravity becomes available, the distinction between ground and air troop carriers pretty much disappears. In fact, at the Imperial tech level, the distinction between tank/APC/speeder is "Is this chassis optimized for heavy weapons, passengers, or speed?"?

Eric Tolle (2015)

Spacemobile

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