re: Do the numbers

Space/Science » in reply to Do the numbers, Tom. Then forget it.

re: Do the numbers

Tom Brosz — 5/30/2004 6:22:58 AM (archived)

Carrying a rocket to high altitude (either in a balloon or a plane) before you launch it buys you two big things.

First, you get past a lot of the atmosphere, and its associated drag penalty.

Second, and more important, you can use a much higher expansion ratio on your engine which buys you some extra specific impulse.

This can result in significant performance gains, although I don't have exact percentages handy.

This isn't really germane to the airship-into-space argument, but I thought I should clarify that.

The whole thread (31 posts)

Airships to orbit - Tom Brosz - 5/27/2004 3:07:34 AM
- re: I don't understand why anyone would build all that hardware if they didn't do the numbers - Success_Machine - 5/31/2004 4:10:21 PM
  - There's no way you'll get an L/D of 50 - Gary - 5/31/2004 8:27:13 PM
    - re: I believe it does get an L/D of 50, when forced to go hypersonic speed - Success_Machine - 6/1/2004 11:06:48 AM
- There are exactly TWO practical ways of launching a payload into orbit. - David F Mayer - 5/30/2004 5:22:24 AM
  - Actually...... - Gary - 5/31/2004 8:31:49 PM
    - A scramjet won't get you into orbit (they flame out at Mach 10). - David F Mayer - 6/1/2004 1:03:18 AM
      - Scramjet 101 - Gary - 6/1/2004 4:35:26 AM
        
        re: Scramjet 101 - David F Mayer - 6/2/2004 12:32:24 AM
        
        Use a detonation wave analogy to understand this - Gary - 6/2/2004 3:27:55 AM
        
        You wrote: "You'll find that the detonation velocity for hydrogen-air at STP is 1968 m/sec" - David F Mayer - 6/2/2004 7:06:04 AM
        
        Yes, air for combustion is pre-heated by the bow shock - Gary - 6/2/2004 4:25:13 PM
        
        re: The only design for a scramjet that works in theory - Success_Machine - 6/2/2004 1:09:56 PM
        
        re: Controlled Flame Speed Limited to Mach 5 - Success_Machine - 6/2/2004 2:34:40 AM
- Do the numbers, Tom. Then forget it. - David F Mayer - 5/30/2004 5:09:45 AM
  - re: Do the numbers - Tom Brosz - 5/30/2004 6:22:58 AM
    - Look at the VOLUME of a balloon of ANY type required to lift a reasonable spacecraft to 30,000 meters. - David F Mayer - 5/30/2004 1:35:00 PM
  - I was only referring to using a balloon to lift a rocket here. (n/t) - DFM - 5/30/2004 5:19:50 AM
- re: Airships to orbit - Nathan Koren - 5/28/2004 3:12:12 AM
- It was me... - Adam - 5/27/2004 11:33:12 AM
- Low thrust to orbit for an airship has got to be bogus - Gary - 5/27/2004 5:52:06 AM
  - "Something is not right here." You are correct. The concept is bullshit! (n/t) - David F Mayer - 5/30/2004 5:17:07 AM
  - Color me skeptical - Larry J - 5/27/2004 6:12:43 PM
    - power sources... - Adam - 6/1/2004 11:19:27 PM
      - Still very skeptical - Larry J - 6/2/2004 2:33:32 PM
    - re: Skipping Over the Atmosphere on a Surfboard - Success_Machine - 5/27/2004 9:04:04 PM
  - re: Low thrust to orbit for an airship has got to be bogus - Adam - 5/27/2004 11:31:06 AM
    - Use VASIMR - phil - 5/27/2004 12:42:19 PM
      - For a large balloon, at any altitude, the air resistance even at low speed is comparable to its weight. I STILL say the idea is bullshit. (n/t) - David F Mayer - 5/30/2004 1:37:21 PM
- re: Airships to orbit - Raoul - 5/27/2004 5:35:39 AM
  - Visible Horizon... - Adam - 5/27/2004 11:30:18 AM

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