December 3, 2017
Considerations for (far) future engineers… In the Stars Wars movies vehicles are shown to have some kind of anti-gravity mechanism to ‘float’ above the surface of the planet. I realize that there is no known physics that allows for that. But my question is, if such a mechanism existed, what properties must this force have to allow for vehicles to float above the planet? To my mind there are two possibilities. One is a long range anti-gravity, where the vehicle acts against the mass of the entire planet. The second is a short range force analogous to magnets that maglev vehicles use to float above a track.
The long range force would not work well near the planet’s surface because the vehicle would bounce around like a balloon in the wind, unless the vehicle uses ailerons to deflect air, which the vehicles in the movies don’t appear to have. And a vehicle could not react to the local changes in terrain because a hill has negligable gravity. Another issue would be the problem that hovercraft have, namely no lateral constraints against sliding left or right or down a slope.
The second option, a local force, has a better chance of working near a planet’s surface. The vehicle would need to have an ability to adjust the upward force at every moment to smooth the motion. The control systems must ignore a small rock, but react to a overall change in elevation. And it would need the ability to create lateral forces to prevent the hovercraft problem. One thing to consider with short range force is flying over water, the water below the vehicle would be displaced by the downward reaction force that balances the upward force that holds the vehicle up, so the vehicle must be less dense than water, or if not, it must travel at high speed over water.
The problem with a short range force is that it can’t give the high flying spacecraft their anti-gravity. No spacecraft in Star Wars entering a planet’s atmosphere has a problem with braking to slow it down. So maybe the spacecraft would need both a short range and a long range force.