Stoney3K wrote:93143 wrote:It's possible that if this technology works, but falls short of its hoped-for potential, it could be useful as a space drive but not as a launch engine. But if that happens, it will also be useless for hovering...
Not really, even a good hover engine has plenty of uses, think ground-based hover vehicles (cars, trucks, skateboards!) and replacement of helicopters.
No, you didn't understand me. If you can make a Mach-effect thruster that's good enough for hovering, it's much much easier to make it a bit bigger and use it for everything else as well than it is to add a whole other drive system (vastly inferior in every way) to do the rest. So if it's good for hovering, it should be good for launch, but just because it's good for launch doesn't necessarily mean it's good enough for hovering while something else does the launch. The capability gap is not small; the "something else" will be orders of magnitude less good in at least one way (propellant consumption), and probably another one (thrust energy efficiency). Now consider that there's a huge weight penalty for having two drives instead of one...
[EDIT: As others have noted, even if you can't quite do 1 gee with the Mach effect engine, you can use wings to get aloft under fractional gee acceleration and go to orbit (and beyond) that way. It's still better than conventional propulsion.]
Suppose the craft is Polywell-powered and, therefore, has a pretty big power supply up it's engine room to power the Mach drive.
Where conventional launch vehicles *need* to propel their payload to orbital velocity from the start (otherwise it'll fall down again), why not make a Mach drive that pushes down with a steady 1,0g (hover) or just a little bit more, to slowly gain altitude? Even jet engines can make that grade these days (e.g. Harrier and JSF) so that's not even a technological challenge.
Sure, you're not in orbit yet, but you're in space. Once you're up there, normal engines (chemical or ion, I prefer the latter since you've got a Polywell on the back!) can speed up the craft in near-vacuum a lot more efficient than in the atmosphere.
Or gradually change the direction of thrust of the Mach drive once you start increasing orbital velocity (from 'hover' to 'forward'), any way you like it.
That's exactly it! If you've got a Mach drive good enough to hover, it's silly to use anything else to go sideways. Just use the Mach drive (or if you really want, add another one pointing sideways; there's more than one way to skin a cat).
Or you could make your power supply about ten thousand times bigger and do it your way, sacrificing the advantages of propellantless operation in the process.
And, although this thing is a thruster and doesn't create a gravity field, it IS an A/G device since it can provide a force which counteracts gravity (with no apparent reactive mass). Useful in all apparent cases.
Yes. I was just trying to head off a potential misunderstanding. Looks like it was unnecessary.
With regarding to landing stability: Any decent pilot will tell you that landing something (aircraft or rotorcraft) on a non-level surface is plain stupid. Counteracting crosswinds is easy if you have a good RCS thruster system. :)
Tell that to the next bush pilot you meet. Or maybe Neil Armstrong. Having a vehicle capable of landing on a non-level surface is better for any number of reasons, not least of which is that for exploration purposes (or emergency response purposes) you can't guarantee a level surface to land on. The steeper the slope you can land on, the better. There are arguments in favour of a sphere, but certainly nothing taller.
As for wind gusts, your RCS (presumably composed of Mach-effect units, because they're immeasurably superior to rocket clusters in pretty much every way) doesn't do you any good if you've already landed and powered down. Why would you deliberately design something that needs power to not fall over in a hurricane if you don't have to?
Your next post seems to be attacking a really dumb idea I never advocated; that of using an on/off engine to drop the vehicle hard down on the struts. That's not what I meant by stability.
