Re: Scram Success

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

Date: Tue, 23 Nov 2004 01:41:43 GMT

Tkalbfus1 wrote:
>
> >This is one of the silliest ideas I've seen in this thread. The scramjet
> >won't reach space at a high velocity because the engines won't work in
> >vacuum.
>
> Why does it have to? Couldn't it reach the necessary velocity to reach space
> while still in the atmosphere? Once the scramjet shuts down, it will still
> retain some of this velocity won't it? Isaac Newton once said that an object in
> motion will tend to stay in motion unless a force acts upon it. the two forces
> in question are air resistance and gravity. Are you saying that those two
> forces will act to bring the ship to a complete halt once the scramjet shuts
> down, and that the ship will plummet straight down to the ground afterwards?

   No, but it means that you would have to get to somewhat *higher* than
orbial velocity while in useable atmosphere, in order to cover the final
drag losses while you're coasting.

> Could you not take atmospheric drag and gravity into account and yet conclude
> that they still won't slow the ship down enough to prevent it from reaching
> space?

   Yes, but see above. You've got to run yet faster/hotter in the upper
atmosphere.

   Going the last few thousand feet per second on a rocket is probably
easier, and you've got to have it for orbit trim and retro propulsion,
anyway....
  

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

Relevant Pages

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