Re: Scram Success

From: Joann Evans (bondage_at_frontiernet.net)
Date: 11/23/04 

Date: Tue, 23 Nov 2004 01:21:23 GMT

Tkalbfus1 wrote:
>
> > It also would've cost far more than Scaled Composites could ever have
> >dreamed of spending, and hypersonic seperation and staging is not a
> >trivial thing at all.
>
> You don't separate in the atmosphere, you separate above it. The second stage
> is carried inside the scramjet carrier so there is no airstream to consider
> when the second stage is separating from the scram.
>
> > Dropping things off your plane (including another plane) at subsonic
> >speeds is old, comfortable technology. Doing so at the highest altitude,
> >not necesairily the highest speed, to reduce drag on SS1 and for its
> >nozzle to be most efficent (its expansion needed to be only a compromise
> >between launch altitude and vacuum, not sea-level and vacuum) was the
> >key...
>
> Well what's the highest altitude that a scramjet can receive lift from the
> atmosphere? If it can go Mach 10 at that altitude, what then happens if it
> pulls into a climb and soars into space?

   Why necessairiy Mach 10?

   Remember, scramjets don't *accelerate* nearly as well as they
*cruise* in a limited design range. (Which is one of the reasons that
designing one that can go all the way to robit is difficult.) Rockets
don't care nearly as much. If you want something to essentially pop-up
above the effective atmosphere, there are easier ways to do it. And even
some of those are part rocket. ('Black Horse' and 'Cosmos Mariner' and
whatever Kelly Aerospace calls its design, are some private proposals to
to that.)

> Or perhaps the separation ought to
> occur at the highest cruising altitude. The atmosphere is bound to be very thin
> at this altitude.

   No, I think you were closer to the truth the first time. If you must
seperate at hypersonic velocities (a phrase that has questionable
meaning in a vacuum), best to do it outside the meaningful atmosphere,
if you can. If you're 'crusing,' then it goes back to the messy
aerodynamics I referred to. 

-- 
   You know what to remove, to reply....

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