On Mon, 12 Aug 2002 [EMAIL PROTECTED] wrote:
> I believe it simply starts the initial shock wave away from the blunt
> nose cone. Since the angle of this shock wave is dependent on the Mach
> number, it would make sense that the length of this spike would increase
> with the max. Mach encountered.
As far as I know, the existing systems don't get that fancy, they're
fixed-length... but that's based on rather thin information; I could
easily be wrong.
If you want a *really* high-tech solution, Leik Myrabo has shown that you
can get much of the effect of a physical spike by using focused laser or
microwave energy to create a spark ahead of the nose. Now *that* you
could reasonably move in and out to match velocity, and in fact you could
probably move it laterally for aerodynamic steering. But this is right up
at the level of "barely proven to work at all", far beyond the region of
confident engineering design.
> Now, this won't help you a bit on reentry, unless you turn the seats
> around and return nose first. This also assumes that the spike is
> effective at reducing drag at Mach 20+ speeds, so that you can
> retract the spike and increase drag substantially.
Also note that on reentry, a nice pointy low-drag nose is exactly what you
do not want! You want a blunt surface, the blunter the better, to put as
much energy as possible into the shock wave and the air, and as little as
possible into the surface by friction. (Things like the shuttle not only
aren't very pointy at the nose, but in fact they reenter more or less
belly-first.) And the more drag the better, to shed velocity as quickly
as possible, before you have time to fall into thicker air.
Henry Spencer
[EMAIL PROTECTED]
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