Re: World building: implications of counter gravity

Sorry if this is duplicated; not sure if it came through the first time.

One thing I failed to point out was that simply 'turning off gravity'
would cause a limited 'lift' from inertia, the false 'centripetal'
force. The fact that a planet is spinning means that a body tends to
move away unless gravity holds it 'down'.
Some time in the last few years, Frank Chadwick suggested it as a form
of liftwood propulsion. Liftwood allows the craft to 'rise', and then
shutting off the liftwood panels would cause the craft to 'fall',
allowing it to use a form of gliding to move. The 'rise' is actually so
slow that winds would be far more a cause of moving than the
up-and-down, so he was being a bit silly trying to use the violation of
conservation of momentum for horizontal movement, especially on the even
smaller Mars, but I didn't try to dissuade him.
 
I think elsewhere, I even mentioned my take was that sail craft could
remain at the turbulent boundary between different wind flows and use
the differential for directed movement. 

Still, it IS a 'rise' from the surface. All the quotes are from the
handwavium involved.
Doug 

    On Wednesday, November 8, 2017, 9:21:29 AM CST, Doug Evans via Gzg
<gzg@firedrake.org> wrote:  
 
  Don't recall from the actual book, but from the movie First Men on the
Moon, the Cavorite did use a 'directional' gravity attraction, blocking
the Earth's and using the moon's. Did ignore the whole inverse square
thingy, but I can be picky.
Might help avoid using it AS a thrust, though.
As for slingshot, as there's as much gravity on both approach and
withdrawal from a body, so that you can use to increase or brake,
depending on moving with or against the body as you pass.
Cutting the gravity on either leg would be HUGE. I think. Can't do the
math. Can't even do the math as to whether 'as much gravity on both' is
true as you are accelerating as you approach, and decelerating after
you've passed. After half a century, calculus is a bit rusty.
Combining a launch system, say a canon or XL-5's trolley, with gravity
blocking would get something off the ground without lot of reaction
material.
Does that help?
Course, the whole Hyperloop talk has re-energized an idea I had for
reusing a long distance tube system for launches...

Doug