Antigravity

Hence the yo-yo profile of non-air breathing shuttles. I suspect that if it produces a force against gravity that you should be able to manipulate this to produce a vector that is not completely normal to gravity and hence produces thrust parallel to the surface.

Bill Woods wrote: Oh, well they've already got that. Any ship with a wedge can generate far more kinetic energy than its fusion reactors produce.

Much as I love tHotQ, the parts where they are talking about the warheads on impeller driven missiles used for surface bombardment was kind of crazy.

Weird Harold wrote:

MaxxQ wrote:There's a difference between "countergrav" and "anti-gravity". Countergrav only negates the effects of gravity - it provides no lift against gravity as a true anti-gravity effect would, despite what any of the books say about CG belts.

You mean like:

More Than Honor
A Beautiful Friendship
Part VII wrote:Stephanie whooped in sheer exuberance as she rode the powerful updraft. Wind whipped her short, curly hair, and she leaned to one side, banking the glider as she sliced still higher. The countergrav unit on her back could have taken her higher yet—and done it more quickly—but it wouldn't have been anywhere near as much fun as this was!

Perhaps the countergrav units hang-glider pilots use are mis-named, but there is ample textev that personal countergrav units can provide at least limited amounts of lift -- negative weight, so to speak.

Yes, that is the one and only piece of text which suggests that counter-grav can push upwards. All other evidence suggests that this text is in error. We've discussed this on this forum several times.

The text can be rationalized as intending to mean that Stephanie could have used the countergrav pack to decrease her effective weight which would let the hang-glider take her higher faster.

SWM wrote:Yes, that is the one and only piece of text which suggests that counter-grav can push upwards. All other evidence suggests that this text is in error. We've discussed this on this forum several times.

Perhaps I just imagined this one:

Shadow of Saganami
Chapter Two wrote:She snapped down her locker's lid, set the combination, and brought the built-in counter-grav on-line. The locker rose smoothly, floating at the end of its tether, and she settled her beret perfectly on her head, turned, and marched out of her dormitory room forever.

Weird Harold wrote:

SWM wrote:Yes, that is the one and only piece of text which suggests that counter-grav can push upwards. All other evidence suggests that this text is in error. We've discussed this on this forum several times.

Perhaps I just imagined this one:

Shadow of Saganami
Chapter Two wrote:She snapped down her locker's lid, set the combination, and brought the built-in counter-grav on-line. The locker rose smoothly, floating at the end of its tether, and she settled her beret perfectly on her head, turned, and marched out of her dormitory room forever.

Or maybe this one:

Worlds of Honor, The Hard Way Home wrote:The lift towers for the advanced and intermediate slopes survived undamaged, as did three-quarters of the resort's other buildings and promenades. But almost seven hundred morning skiers found themselves squarely in the path of thundering death with no more than a few minutes warning. Some were lucky; they were on the fringes of the avalanche and managed to get clear of its outriders. Others had brought individual counter-grav belts with them as a means to avoid the lines at the lifts, and most of those managed to activate their belts and lift out of the way in time. Still others turned and skied as they never had before, racing madly to outrun destruction, and some of those managed to get clear, too. But over four hundred people were unable to escape, and the churning wall of snow and boulders smashed over them mercilessly.

Boldface is my emphasis.

I always thought of countergrav as "reversing the polarity" of gravity so that it would repel you from the gravitic center, the way two magnets of the same polarity repel each other. That would generate lift.

If the alternative is simply nullifying the effect of gravity on an object, perhaps by bending gravity around it, that would not generate lift.

As a practical matter, though, if I were designing a countergrav belt I would certainly try to develop a way to steer it. It might involve two technologies, one to dodge gravity and one to propel, but that seems much more useful than just the ability to experience free-fall on a planet's surface.

--snipping--

dscott8 wrote:As a practical matter, though, if I were designing a countergrav belt I would certainly try to develop a way to steer it. It might involve two technologies, one to dodge gravity and one to propel, but that seems much more useful than just the ability to experience free-fall on a planet's surface.

Interesting thoughts and I don't necessarily disagree, though my favorite MWW mentions of countergrav use it more like like the bubble of air under a hovercraft skirt. That is, it does nothing but lift so that a malfunction likely doesn't have a pull vector to it that could result in an out of control movement vs. simply letting you down towards the ground again. Then you use other controls to decide direction, speed, etc.

dscott8 wrote:I always thought of countergrav as "reversing the polarity" of gravity so that it would repel you from the gravitic center, the way two magnets of the same polarity repel each other. That would generate lift.

If the alternative is simply nullifying the effect of gravity on an object, perhaps by bending gravity around it, that would not generate lift.

As a practical matter, though, if I were designing a countergrav belt I would certainly try to develop a way to steer it. It might involve two technologies, one to dodge gravity and one to propel, but that seems much more useful than just the ability to experience free-fall on a planet's surface.

Closer to what I envisioned. IMO, a counter gravity would involve a countering to the effects of gravity. Hence, the name. An equal and opposite lift against the easily deduced variable of gravity by some mechanism, electromagnetic or some other method.

Antigravity, intuitively, would involve a negating of the effects of gravity. Perhaps by bending gravity waves around an object to achieve immunity to gravity. Essentially creating an outerspace bubble in inner space. In the manner akin to bending light waves around an object to make it invisible.

Something from the real world, tho slightly off subject. The purpose of AG or CG is to make reaching heights easier. For space travel, rockets are very inefficient

Someone has just gotten a patent for a space tower that might actually work - Pneumatic. Details I don't have, but consider a tower with maybe 200 PSI at the bottom, vertical segments to transfer material weight to the air pressure, radial segments to induce counter-bowing against external forces, such as wind, and a platform on top. Vessels are lifted to the platform by further pneumatic forces, perhaps in an internal tube. If, at the top, you still have 30 PSI, this would allow a platform averaging about 90 inches thick steel.

Something like this seems to be their design. It likely wouldn't reach even low orbital heights, but would lift above most of the atmosphere without needing fuel (and oxidizer ) to lift fuel to lift fuel, etc. For this segment of the journey, efficiency would be much higher.

They are already using balloons to lift very small rockets high before firing them into low orbit.

Energy wise, reaching low orbit is the most expensive part of space travel. We don't have AG or CG, but this, unless something prevents it from being practical, would improve the most expensive part of the journey. There would still need to be enough fuel to reach orbital velocity. However, gaseous fuel and oxidizer, perhaps condensed at the platform into liquids, could be used and would be easy to lift to the platform. Hydrogen or methane would even supply a little lift to the tower.

Sigh, handwavium is SO much easier

DDHvi wrote:Something from the real world, tho slightly off subject. The purpose of AG or CG is to make reaching heights easier. For space travel, rockets are very inefficient

Someone has just gotten a patent for a space tower that might actually work - Pneumatic. Details I don't have, but consider a tower with maybe 200 PSI at the bottom, vertical segments to transfer material weight to the air pressure, radial segments to induce counter-bowing against external forces, such as wind, and a platform on top. Vessels are lifted to the platform by further pneumatic forces, perhaps in an internal tube. If, at the top, you still have 30 PSI, this would allow a platform averaging about 90 inches thick steel.

Something like this seems to be their design. It likely wouldn't reach even low orbital heights, but would lift above most of the atmosphere without needing fuel (and oxidizer ) to lift fuel to lift fuel, etc. For this segment of the journey, efficiency would be much higher.

They are already using balloons to lift very small rockets high before firing them into low orbit.

Energy wise, reaching low orbit is the most expensive part of space travel. We don't have AG or CG, but this, unless something prevents it from being practical, would improve the most expensive part of the journey. There would still need to be enough fuel to reach orbital velocity. However, gaseous fuel and oxidizer, perhaps condensed at the platform into liquids, could be used and would be easy to lift to the platform. Hydrogen or methane would even supply a little lift to the tower.

Sigh, handwavium is SO much easier

The tower in the Patent is ~ 20 KM tall, which would reduce the fuel use of LEO orbital launches by ~30%.

http://www.gizmag.com/canadian-firm-patents-inflatable-space-elevator/38773/

Elevators are designed to climb the sides in a helix, and the top is planned to be large enough to land an aircraft.
This appears to be simultaneously easier and harder to accomplish than a "traditional" space elevator.

Of the "space Elevator" concepts, the one which I believe is the "most" feasible from an engineering standpoint is the Ion Fountain - where a super collider is opened upwards to form a steam of ions pointing heavenward, and a rocket would "ride the stream" for a period before engaging their engines fully. Unfortunately, this requires a supercollider on the scale of the formerly planned Texas Collider, and multiple nuclear plants feeding it 24/7.