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Nozzles

Posted by: SymbolicFrank - Tue Apr 14, 2009 6:44 pm
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Nozzles 
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Post    Posted on: Mon Apr 20, 2009 7:00 pm
Actually, for an SSTO density is as important as, maybe more than, the Isp. Density affects the dry mass of the vehicle, as a less dense fuel requires bigger tanks.


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Post    Posted on: Tue Apr 21, 2009 6:25 pm
Andy Hill wrote:
SymbolicFrank wrote:
As a different idea: how about an ablative nozzle, that slowly expands? But that gives problems when you want to brake when coming down.


Are you talking about a nozzle that burns away making a larger volume for the exhaust gases to expand into at higher altitudes? This would improve overall Isp as it would better match the expanding exhaust gases and not have to have a "one size suits all" approach during assent.

If you are talking about a mechanically expanding nozzle, I think something along those lines was tried on an upper stage using an RL-10 engine, although I'm not sure about the details.

Yes, I was talking about the first one.


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Post    Posted on: Tue Apr 21, 2009 6:28 pm
Terraformer wrote:
Actually, for an SSTO density is as important as, maybe more than, the Isp. Density affects the dry mass of the vehicle, as a less dense fuel requires bigger tanks.

Yes, while "simple", liquid fuel would offer less ISP, it makes the vehicle smaller and lighter. But it requires additional pressurizing.


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Post    Posted on: Tue Apr 21, 2009 6:32 pm
I came across this: a solid-state jet engine (no turbines or other moving parts), that seems to work continuously (ie. no pulse engine). It might be usable as an all-round engine: add a resizable inlet for high-speed operation and close it for rocket propulsion.

Does anyone have an idea how it might work?


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Post    Posted on: Tue May 05, 2009 3:13 pm
There's a ramjet solution that has an intake that closes when the atmosphere thins, and uses onboard Lox instead. Or rather it transitions through from ramjet ox to Lox. Well, solution might be going a bit far, but you get the gist. Don't know if that'd be enough for full orbit though. In fact, I'd be fairly certain that it'd not have the beans for the job. If i remember correctly, it was being touted for use in atmo skipping quick intercontinental flights.

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