Re: Mojave airport is not a spaceport

From: Earl Colby Pottinger (earlcp_at_idirect.com)
Date: 06/23/04 

Date: Wed, 23 Jun 2004 15:53:33 -0500

Andrew Nowicki <andrew@nospam.com> :

> John Carmack wrote:
> JC> Look at:
> JC> http://media.armadilloaerospace.com/2004_06_15/perfectBoostedHop.mpg
>
> JC> An actual pressure fed rocket with almost no moving parts doing a
> JC> powered landing. It is my considered opinion that this is The Right
> JC> Way To Do It. Build a big, simple booster that lofts a high
> JC> performance upper stage all the way out of the atmosphere, then
> JC> returns to land on the same pad it took off from. At first flance it
> JC> sounds like an inefficient staging strategy, since the upper stage
> JC> requires nearly SSTO dV, but removing the requirment of boosting
> JC> through the atmosphere (optimize only for vaccuum boost and reentry)
> JC> does still simplify the problem quite a bit, and the operational and
> JC> testing aspects are great.
>
> A winged rocket does not need as strong propellant tank as
> the splashdown rocket, but it costs more to fabricate and
> it may crash during landing.

But you are the only one demanding a splashdown. The rest of us see landing
the booster right back at it launching point as a good thing. Cuts
turn-around time, prevents salt water damage, prevents thermal shock. So why
insist on a water landing where you need the tow the craft back, clean it up,
and check for damages that would never happen by landing back at it's start
point.

> I am glad you understand some advantages of the pressure-fed
> rockets, but I do not understand why you insist on the two stage
> design.

Maybe because unlike you he is building real rockets and flying them. That
means he is risking his money and life on the designs. He has decided on a
design that will works over a guess.

> I do not know what is the specific impulse of your
> hydrogen peroxide pressure-fed rocket, but I doubt it is greater
> than 150 seconds.

Right, as usual you are guessing instead of learning. Please real *ALL* of
John's site before mouthing off on how he should build his designs, or for a
quick rundown check out my website before making guesses about other people's
designs.

> It would be a perfect first stage because it
> is very safe and reusable. The best design for the second stage
> is my engine cluster. So far it exists only on paper, but it
> looks very good: mass ratio in the range of 4 to 8 and specific
> impulse in the range of 300 to 330 seconds. It is not just
> another dumb booster, but a novel, reusable, and inexpensive
> design. It is not protected by any patents, so anyone can use
> it without any restrictions. Its description is posted at:
> http://www.islandone.org/LEOBiblio/SPBI101.HTM#engine_cluster

Do I see ego :) Have you built a prototype yet, even a simple model to test
your ideas? No! But you want to tell JC a person making his own working
engines what he should use! Please grow up

By the way I just checked out the page you listed. That was not a design,
that is a simple drawing, where are the control valves and thier support
equipment? What starts the engines, or where are catalyst packs? What is
the sizing of the flow lines? What type of injectors are being used? The
list goes on and on.
 
> _________________________________________________________________________

> johnhare wrote:
> j> I may be in disagreement with you about the nearly SSTO performance
> j> requirement. MR for SSTO seems to be about 16 (Lox/Kero) from the
> j> ground, and 10 from the vacuum altitude you deliver to. Going from
> j> 6.25% dry mass including payload to 10% dry mass including payload
> j> is a major gain in margins. Even without the mass savings on lighter
> j> engine and tank mass percentage, 37.5% of the upper stage dry mass
> j> becomes available to increase payload. I was convinced several years
> j> ago by Len Cormiers' Space Van booster concepts.
>
> SSTO development costs billions of dollars. Pressure-fed
> rockets are cheaper by orders of magnitude and they are
> reusable, reliable, and strong enough to survive reentry
> and splashdown.

There you go with your splashdown again, no-one else wants to do it if they
can afford not, so why keep insisting on it.
                         Earl Colby Pottinger 

-- 
I make public email sent to me!  Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC.  What happened to
the time? http://webhome.idirect.com/~earlcp

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