simonh said:
Tom Kalbfus said:
...So the gravity drive works by altering the Universal Gravity constant around the vehicle causing its mass to repel gravitationally the Moon's surface....
If you were to change the gravitational constant in a field around avehicle, it would reduce the apparent mass of the vehicle for the purposes of calculating the pull of the moon on the vehicle. You would only be changing the value G in the equation. That makes things very simple, you just decide by what factor you want to change G. To cancel out gravitational pull alltogether you just change G to zero. To accelerate away from the moon at the rate you would normally accelerate towards it, you just change G to be a negative value with the same magnitude as it normally has psitive, so -6.674×10−11 N⋅m2/kg2 instead of 6.674×10−11 N⋅m2/kg2.
However your descriptions seems to be assuming that the attractive force of garvity would still be in action, at the same time that you are also manipulating G to cause a repulsive effect. The value of G can't be two different values at the same time in the same place though. Either the mass of the vehicle is being attracted by the moon, or it's being repulsed. Having both happen at the same time to the same mass due to the same force doesn't seem to me to make much sense, unless I'm totally and completely missunderstanding your explanation.
Okay, one more time.
1) The gravitational constant G is assumed to be not constant, it can be manipulated in much the same manner nuclear forces can be manipulated by a nuclear dampner thus preventing nuclear explosions through atomic fission
2) The value of G at the location of the grav vehicle is different from the value of G over most of the Moon, which assumes the value the Universe gives to it, but within the field surrounding the grav vehicle the value of G is the opposite sign and of a different amount that the rest of the Universe, the gravity field around the grav vehicle is repulsive, meaning that it pushes away all matter. The gravity field of the Moon still attracts all matter. Now at the boundary where the value of G changes, the gravity fields don't. That is if you are within the changed G field you feel a repulsive gravitational force coming from the grav vehicle, that is if you are holding your position with respect to the gravity field, you feel your weight pushing away from the vehicle, the closer you get to the vehicle, the heavier you feel, also your various body parts would also be repelling each other within this field, as your body and all other objects would possess repulsive gravity fields in proportion to their mass. If you go outside the G change field, you no longer feel this self repulsion of your body, but you still feel the repulsive gravity effects coming from the grav vehicle. The G value only affects the gravity field where it originates, at the mass of the object.
For simplicity sake lets assume the grav vehicle is in the shape of a sphere 10 meters in radius. Lets say at the surface of this sphere the antigravity is 4-g, the effects of the changed G value ends inside the vehicle, so everything at the skin of the vehicle and outwards is normal. A person grabbing onto handles at the surface of the grav vehicle would feel 4 times his weight pushing outward. if he lets go, he will fall away from the vehicle at 40 meters per second squared, by the time he reaches 20 meters from the center of the sphere, he is only falling away at 10 meters per second squared, by the time he reaches 40 meters away from the sphere, he is accelerating outwards at 2.5 meters per second squared and so on.
Now lets say there is a natural planet who's surface gravity is 1-g and who's radius is 6,400 km, at 12,800 km an object is accelerating toward the planet at 2.5 meters per second squared, then it reaches 6,400 km from the planet's center, it is falling at 10 meters per second squared, just before it hits the planet's surface.
Now lets suppose we have a grav vehicle 10 meters in radius generating a repulsive gravitational force of 4-g at its surface, and with its antigravity field on it falls towards the planet at 2.5 meters per second, that is because the planet is not within range of the vehicle's antigravity field, but the vehicle is within range of the planet's gravity field, the amount of push the vehicle gives the planet is negligible, but the attractive force of the planet on the gravity field is 0.25 g, so it falls. Now what happens if the planet is Earth is the grav vehicle enters the atmosphere, and atmospheric friction slows it down, the antigravity field pushes away the atmosphere, but not by enough to create a balloon like bouyancy, so it continue to fall with atmospheric friction slowing it down. as it approaches the planet's surface, we'll assume ocean, it hits the water and goes under, but in this case the water is denser that the grav vehicle so it floats to the top, and once it reaches the surface it rises above the ocean to a height of 10 meters, this is the distance at which the antigravity vehicle pushes on the ocean surface at the same rate as the Earth's gravity is pulling on the grav vehicle, so it continues to bob up and down until atmospheric friction causes it to settle at 10 meters where it hovers. if you push down on the sphere it will repel the ocean surface harder ad rise, if you raise it higher, then it will fall back towards the ocean and bob some more until it reaches its equilibrium distance. If you want to go higher, you can generate a repulsive force of 16 gs at the sphere's surface and it will rise to 20 meters above the ocean's surface, it also pushes away surrounding air in all directions creating a bubble of less dense air, if it does this enough, it will rise like a balloon until the density within the repulsive grav bubble equals the density of the thinner air surrounding it, much as an ordinary balloon would do. Passengers would need grav plating to counteract the effects of this antigravity field as it would also affect them!
