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Air Breathing Combined Cycle Engine

Posted by: Pete - Wed Apr 14, 2004 11:17 pm
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Air Breathing Combined Cycle Engine 
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Post Air Breathing Combined Cycle Engine   Posted on: Wed Apr 14, 2004 11:17 pm
I did some reading yesterday regarding what is required to get something into orbit.

It seems to me that the shuttle and supporting rocket system was a simple answer to a series of questions. We need to get to a speed of 30,000 (roughly) kph. What's the most suitable currently available propellant? How much of the propellant do we need to reach this speed and return? What size/type of rocket do we need to contain it? Obviously this is hugely over simplifying, please don't burn me unnecessarily :)

The issue I want to raise is that I think things need to be done differently in the future. I plan to release a full plan of my thinking in a few months but initially I wanted to get some feedback from all the engineers on this forum.

Instead of building a huge system to contain available propellant, I believe we need to look for the most optimal engine. Scram jet? Pulse jet? Or maybe Air Breathing Combined Cycle?

This article talks about the engine under development for NASA
http://www.spacedaily.com/news/rocketscience-02j.html

They're talking about having an engine to test by the end of the decade? Could we feasibly advance development by prototyping on a small scale? Is this technology even the answer I'm looking for?

I'd appreciate your views.


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Post    Posted on: Thu Apr 15, 2004 1:30 am
SSTO is the BIG DREAM. It is an achievable goal but so far not a useful one.

An SSTO will never put 100T into orbit in one boost.

To be useful an engine needs to reach an ISP of about 460+.

the SSME's only get about 450 and they use hydrogen/lox. It looks like an Aerospike H2/Lox engine will be required for any sort of heavy lifting.

However one of the up and coming X Prize teams has a design to replace their engine with a methane/lox Expander Cycle engine and have an SSTO or SS+assist within two years. Such a design will not really be to good for heavy lifiting but will get people up and down with the greatest of ease.

Personally I think that "hybrid" designs are solutions for problems that only exist due to badly laid out plans.

A more Substantial link on the subject:

http://www.spacefuture.com/pr/archive/single_stage_to_orbit_vertical_takeoff_and_landing_concept_technology_challenges.shtml

And a really good read:

http://www.hobbyspace.com/AAdmin/archive/SpecialTopics/RocketCom/titlePage.html

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Post    Posted on: Thu Apr 15, 2004 10:45 am
Did anybody see that BBC thing about the Nazis trying to bomb New York? Apparently some scientists advocated 12 V-2/a4 type engines propelling a bomber to high speed on a track before its own engines took over to achieve orbit. They then planned to release a weapon to strike the city (possibly irradiated sand to burst at altitude) and re-enter back in German airspace to land on a runway. It seemed a little fanciful but the images they showed of the craft looked a lot like the later Soviet Spiral 50/50.

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Post    Posted on: Thu Apr 15, 2004 12:07 pm
Its quack...

If Von braun was on it then it would have been moving towards staging.

the A-10 was started in 1940 as a transatlantic, but was dropped in '43 to concentrate on the A-4.

Handy link:

http://www.astronautix.com/lvfam/v2.htm

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Post    Posted on: Thu Apr 15, 2004 2:53 pm
Yes, I agree that the war criminal von Braun would go for staging. I believe it was a proposal by one of two rival design teams of the day. Nothing was too whacky for the Germans. Look at that vertical take off Nadar/Viper they made to take off with no runway to launch nose mounted rockets into the bomber stream. It was recovered by falling apart and parachuting down in sections where it was usually dented a bit. Sounds like team Armadillo when you think about it! :lol: Thanks for the link, nice for quick reference.

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Post    Posted on: Sun May 17, 2009 6:26 am
I don't if I already asked it during the years - but what about making use of the water vapor in the atmosphere? Might it be taken in, broken into the elements and then used by air breathing engines?

Might that be of assistance?



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Post    Posted on: Sun May 17, 2009 1:23 pm
No. The energy required to turn water into H2/O2 is (due to inefficiences) greater than the amount of energy you get from combusting them. Better to use the energy directly.

However, synthesising your oxidiser from the atmosphere is something the Avatar spacecraft is supposed to be doing (actually, it liquifies atmospheric Oxygen).

TSTO is our best current bet, until we can upgrade the first stage to go full orbital. I like using a high efficiency hypersonic airship for the first stage, then a rocket (H2O2/Propane) for the upper stage.


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