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Landing Gear

vegascat

SOC-13
How do you handle landing gear? All the landing gear I have seen are retractable into bays in the hull bottom. I have seen Wheels, tank treads, and a majority shown as flat plates. Docking clamps are in the design guides for most of the systems.
As the craft get heavier, the number and size of wheels grow. Look at a Russian Antonov cargo carrier. I see wheels as having an upper limit, and rubber tires have difficulties with vacuum.
Tank treads would be useful for heavier craft. The upper limit would start eating into cargo capacity.
Just about every Sci-Fi ship in the movies or TV are shown with flat landing plates. They are seen on all Star Wars, BSG, Babalon-5, Serenity-Firefly, and most traveller ship depictions. The exception are Japanese shows with rubber Tires. I see the solution as making those flat landing plates as strong gravatic plates. Give them enough power to float the weight of the loaded ship 6 inches above the ground, and most problems would disappear.
Gravatic landing plates would allow for tail sitting ships, aerial landing at speed on pavement or unimproved surfaces. Once landed, the ship could be easily moved by star port handling tractors with no friction, just mass and wind resistance to overcome. Turn the landing gear off and you are solidly planted. Turn the gear on for easy movement.
The only difficulty would by water landings. Movement over water would not be a problem, but standing still would and the water would displace under the pads.
Dead stick landings would be a nasty difficulty as the gravatic landing pads with no power would be ripped off on contact with a solid surface. The repair difficulties would be good for game master humor, but piss off the players. Jacking the ship up on surfaces soft enough not to damage the ship hull severely to effect repairs would be a hazardous undertaking. The rolls to reattach and repair the gravatic pads would be nasty. The lesson being, if you loose power close to a planet, don’t land unless you have no choice.
 
How do you handle landing gear? All the landing gear I have seen are retractable into bays in the hull bottom. I have seen Wheels, tank treads, and a majority shown as flat plates. Docking clamps are in the design guides for most of the systems.

Wheels et al are only necessary if you plan on moving the ship unpowered on the ground, vs clicking the grav-neutrelizing buoyancy switch and towing your "ship as balloon" with a tractor.
 
How do you handle landing gear? All the landing gear I have seen are retractable into bays in the hull bottom. I have seen Wheels, tank treads, and a majority shown as flat plates.

Mine are just part of the hull that extents a foot or so downward or enough to maintain stability once on the ground. Circular in shape. No significant ship volume used. Airframe will have wheels that partially lower for runway usage.
 
Reflatable tyres.

Considering there's a fusion plant onboard, you could drop skirts and have a hovercraft.

Wouldn't wander too closely during operation.
 
Hover-skirts for landing gear? Not something I would want to use on a vacuum world. When the power plant shuts down or you cut the lift fans to allow cargo transfer, the hull pressure may cause nasty problems.
 
I simply land on a reinforced ship bottom, somewhat like a nautical vessel does when they are in dry dock, except I do not assume the presence of wooden supports, but simply sit on the ship bottom. Given the mass of even a small ship, unless you use very large landing plates, you are going to have problems with any form of tire.

Now, the star ports may have some form of resilient covering on the primary landing pads to ease the pressure on the ship and pad. A frontier installation may simply have a large wooden baulk covered surface for use as a landing pad.
 
I'd have thought the issue would be not the supports but the surface on which the ship lands. If a 100 ton jet landing can break 30cm reinforced concrete runways, a 2000 ton (Approx 200dTon) freighter is going to do nasty things to anything but a seriously strong landing pad.
 
I'd have thought the issue would be not the supports but the surface on which the ship lands. If a 100 ton jet landing can break 30cm reinforced concrete runways, a 2000 ton (Approx 200dTon) freighter is going to do nasty things to anything but a seriously strong landing pad.

Jets land at high speed and come down HARD as a result. A space ship can land at 0.1 mph if needed.
 
It is a matter of weight distribution. The greater the area of landing surface, the lower the effective ground pressure. Tires concentrate the ground pressure onto a limited area, hence the need for massively reinforced runways. Tanks distribute their weight through the tank treads, with a lower ground pressure giving it higher maneuverability. Piper has his large ships using landing pads, that sink into the ground enough so as to leave long term marks.

You want to estimate the mass of the ship, then figure out the surface area of whatever you are using for landing, and see if you come in under about 100 pounds per square foot, you can use moderately thick concrete runways.
 
You want to estimate the mass of the ship, then figure out the surface area of whatever you are using for landing, and see if you come in under about 100 pounds per square foot, you can use moderately thick concrete runways.

My van is 4,400 lbs. Sits on 4 tires with about 1 square foot of ground contact each = ~440 lbs. square foot. My 3" thick driveway has no problem with that. 100 lbs. /square foot can be handled by a 2" thick slab with reinforcing rods
 
My van is 4,400 lbs. Sits on 4 tires with about 1 square foot of ground contact each = ~440 lbs. square foot. My 3" thick driveway has no problem with that. 100 lbs. /square foot can be handled by a 2" thick slab with reinforcing rods

Remember that your driveway is resting on a ground bed that is also absorbing the weight. The ground bed under the concrete needs to be firm as well.
 
Landing pressures are much, much higher as the vessel hits the ground moving. A B17 would hit at 85lbs per square inch or 12240lbs/sq foot with suspension and shock absorbers. That broke 8" of reinforced concrete in less than 12 months.
 
I'd have thought the issue would be not the supports but the surface on which the ship lands. If a 100 ton jet landing can break 30cm reinforced concrete runways, a 2000 ton (Approx 200dTon) freighter is going to do nasty things to anything but a seriously strong landing pad.

I did the math once, the landing skids don't have to be that big to spread out the ground pressure to "reasonable" levels. Smaller than you think.

Look at modern Main Battle Tanks -- super heavy, but their ground pressure is actually quite low.

Also consider modern dump trucks.

If you look, at least here in California, the dump trucks and garbage trucks carry an extra axle and set of wheels that are lowered when the truck is loaded. They're not even double axles, just 2 wheels. A typical truck has 10 wheels. 2 front, 8 in the year. Lower that axle and they go up to 12 wheels. 20% bonus to offset the large weight. Saves wear on the roads, saves gas and tires on the truck.
 
How do you handle landing gear?

I just learned how to do this:

https://gyazo.com/195a033791b8cb22742f819aa0933613

Gravitic pads integrated into the landing gear is a great idea. You can have a connection for shore power to plug into the pads, maybe wired in such a way that you only got to connect to one and all pads with gravitic plate energize. Don't have to be full power lifters, just enough to get the ship up and steady.

The main lifters would be integrated into the hull. While the landing gear are designed to hold the weight of the ship, I think it would be safer to mount the lifters more solidly with the frame or hull of the ship.
 
Look at modern Main Battle Tanks -- super heavy, but their ground pressure is actually quite low.

In 1982, in the Falklands Islands, British troops with FV101 Scorpion light tanks were looking to flank Argentine positions, and came across a marshy area in their path. The local guide they had (a UK-citizen sheep farmer) told them that the marsh was impassible, as a man with a pack would sink to the knees - too deep to walk, - so their tanks would just bog down.

The Scorpions crossed the marsh easily, as their ground pressure was less than that of an adult male human without pack!
 
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