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.
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.
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.
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.
-  Pressurized cabin
-  Non-pressurized storage area
-  Door into non-pressurized storage area
-  Leg
-  Foot
-  Gyroscope
- [7-8] Gyroscope frames (with pinions on tips)
- [9-10] Gyroscope guide rails (with racks)
- [11-14] Gyroscope frame servos (drives pinions)
-  Upper frame
-  Roof platform
-  Roof platform railing
-  Roof platform crane
-  Solar power plant
-  Heat radiator for cabin air
-  Heat radiator for equipment
-  Driver's front window
-  Driver's foot window
-  Optical range finder to calculate jumps
-  Crew windows
-  Periscope windows to look upwards
-  Periscope window mirror
-  Top floor (Storage room)
-  Jump gas tank
-  Jump cylinder
- [31-32] Reinforcing girders for emergency brake
-  Water tank
-  Middle floor (Crew room)
-  Driver's seat
-  Driver's control stick
-  Jump calculator
-  Driver's emergency brake
-  Driver's jump pedal
-  Airlock
-  Washroom
-  Shower
-  Toilet
-  Wash basin
-  Toilet exhaust door
-  Roller for washroom rubber sheet/door
-  Driver control panel
-  Lower floor (Engine room)
-  Horizontal gyro
-  Trap door for engine access
-  Reinforcing ribs
-  Gyroscope coolant line to heat radiator 21
-  Pendulum
-  Jumping piston
-  Leg cylinder gas compression pump
-  Jumping piston rubber bumper
-  Top stop for 109
- [111-112] reinforcing rods
- [118-121] Counterweight channels
- [124-125] Counterweights
- [126-127] Counterweight springs
-  Emergency brake harpoon/anchor
-  Emergency cable
-  Emergency pulley
-  Solar power plant mast
-  Mirror
-  Pipes
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.
In traditional science fiction (i.e., the Andre Norton space novels) two types of starships carried flitters: scout ships looking for human habitable planets and Free Traders exploring alien inhabited planets looking for trade goods.
What they used the flitters for was [a] to widen their radius of exploration and [b] search-and-rescue (SAR) operations for explorers who got into trouble.
In both cases, while aircraft have windows allowing the pilot a view directly ahead (so they don't collide with a mountain-top or something), both exploration and SAR need to allow a good view of the ground. Military and police helicopters had similar needs, their solution is the "chin bubble." These are windows near the pilot's feet allowing them to see things underneath the helicopter.
Chin bubbles are also a big help if the pilot is landing in unknown terrain; so they can spot bolders, sink-holes, and other landing hazards.
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.
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.
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. They also appear in Cordwainer Smith's Instrumentality of Mankind stories
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.
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).
The Sikorsky X-Wing is a combination helicopter/aircraft. The blades are designed so they generate lift regardless of which of the two edges is leading. That is, a conventional aircraft traveling backward would quickly discover that in such a situation the wings would generate zero lift and the plane would plummet to its doom. The special blades on the X-Wing make lift going backward and forward.
Why? This means the blades can spin in place like a helicopter for vertical take-off, or be locked in place to act like a conventional fixed-wing aircraft in horizontal flight. With conventional blades, when locked in place only the right-hand "wing" would generate lift, the left-hand would make zero lift, and the X-Wing would auger into the ground.
The secret was blowers on both edges of the blade. They used the Coandă-effect to dynamically alter the shape of the blade. Which ever edge had the blower activated would act like the trailing edge of a wing, the non-blower edge would act like the leading edge. This means the leading and trailing edge of a given blade could be swapped by flipping a switch.
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.
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.
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.
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 1794 Design Alfa
Project 1794 Design Bravo
Project 1794 Design Charlie
Project 1794 Design Delta
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?