Author Topic: Yet another 'What if' SDLV design ...  (Read 13874 times)

Offline Danny Dot

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Re: Yet another 'What if' SDLV design ...
« Reply #40 on: 04/07/2010 05:08 AM »

1) Since the SSME's burn oxygen and hydrogen at a 6.0:1 ratio, this does not leave sufficient hydrogen for downstream combustion with oxygen alone, so you have to inject both hydrogen and oxygen into the downstream flows.

snip

Burning down stream of the throat is like really, really inefficient dude.  That is the point of the throat, nozzle design in the first place. 

Danny Deger
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Offline Lampyridae

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Re: Yet another 'What if' SDLV design ...
« Reply #41 on: 04/07/2010 09:44 AM »

1) Since the SSME's burn oxygen and hydrogen at a 6.0:1 ratio, this does not leave sufficient hydrogen for downstream combustion with oxygen alone, so you have to inject both hydrogen and oxygen into the downstream flows.

snip

Burning down stream of the throat is like really, really inefficient dude.  That is the point of the throat, nozzle design in the first place. 

Danny Deger

Yeah, the main idea is to "pinch" exhaust flow, not make some kind of afterburner... in effect, it's just like shrinking the effective diameter of the nozzle by sacrificing a small amount of propellant in those downstream injectors.
« Last Edit: 04/07/2010 09:44 AM by Lampyridae »
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Offline JohnFornaro

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Re: Yet another 'What if' SDLV design ...
« Reply #42 on: 04/07/2010 02:14 PM »
...
I suspect, however, that a sizable chunk of the SSME operations cost was NASA overhead.  $230 million should, for example, be enough to pay for more than 1,500 employees.  Were 1,500 Rocketdyne (later PWR) employees actually working SSME?  I doubt it, but I'm not certain.  In a differently-structured, lower-overhead program, SSME might be affordable without reducing testing much....

1500?  This seems excessive.  Why, in the history of mankind then, do so many produce so little, for so few to use?

Perhaps more to the point, why can't this be changed?  Ok, the bell, that is, the nozzle, right?  What else?
Sometimes I just flat out don't get it.

Offline nooneofconsequence

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Re: Yet another 'What if' SDLV design ...
« Reply #43 on: 04/07/2010 10:19 PM »
TAN: http://selenianboondocks.com/2007/11/thrust-augmented-nozzles/

This is overkill for a SSME RLV and a major research project.

On the plus side - you wouldn't have to buy much of an advantage to drop the solids. And SSME is a regeneratively cooled engine that could have such a specialized nozzle, has the requisite flight history, and test stands that could accommodate it.

On the negative, you might find it hard to discover how to 1) get stable performance w/o understanding the codes for combustion here (staged combustion might not be so easy do to this with), 2) prove a reliable and cost effectively reusable powerplant w/o growth of complexity/weight.

So at a minimum you'd shed non cryogenic drop tanks in place of SRBs.

Still don't know if SSME is just destined as an expendable booster engine. Or will we go back to kerolox for that?
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Offline Kitspacer

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Re: Yet another 'What if' SDLV design ...
« Reply #44 on: 04/09/2010 12:20 AM »
1) Since the SSME's burn oxygen and hydrogen at a 6.0:1 ratio, this does not leave sufficient hydrogen for downstream combustion with oxygen alone, so you have to inject both hydrogen and oxygen into the downstream flows.

Simple question: RP-1 kerosene is a hydrocarbon fuel, so I am assuming that it contains both hydrogen and oxygen.  I assume that the thrust plume from the SSME must be hot enough to crack RP-1 into its atomic constituents.  If this is the case, does RP-1 have the necessary extra hydrogen and oxygen to supply the extra required?

Just trying to take the idea seriously...  :)

Unfortunately because a hydrolox eng' comb'chmbr temperature is about 2000deg.F less than the Kerolox equiv' that doesn't hold "hydrox"! ;)

Offline Kitspacer

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Re: Yet another 'What if' SDLV design ...
« Reply #45 on: 04/09/2010 12:28 AM »
One of the design concepts used an unmodified Shuttle RSRM. The orbiter mounted with the two attach points. On the side like Shuttle.

This orbiter is different than the shuttle in that most of the mass is LOX/LH in internal tanks. Think of it as if the Shuttle was its own ET.

More than sufficient damping for TO given Ares I-X flight test data.

Not the same issues. New issue with roll control requiring an unusual guidance and control approach with significant control authority.

Works very much like Shuttle in most other respects.

No issues with ice/TPS damage. Or SRB debris field on SRB linear charge destruct (rips opposite orbiter).

Granted an Orbiter is a lot smaller than a fully fuelled ET, but even so it would use all the payload space just with hydrolox fuel: less for kerolox but would it generate sufficient deltaV to achieve LEO. I'd have thought not.

Offline mrryndrsn

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Re: Yet another 'What if' SDLV design ...
« Reply #46 on: 04/22/2010 06:48 PM »
1) Since the SSME's burn oxygen and hydrogen at a 6.0:1 ratio, this does not leave sufficient hydrogen for downstream combustion with oxygen alone, so you have to inject both hydrogen and oxygen into the downstream flows.

Simple question: RP-1 kerosene is a hydrocarbon fuel, so I am assuming that it contains both hydrogen and oxygen.  I assume that the thrust plume from the SSME must be hot enough to crack RP-1 into its atomic constituents.  If this is the case, does RP-1 have the necessary extra hydrogen and oxygen to supply the extra required?

Just trying to take the idea seriously...  :)

Unfortunately because a hydrolox eng' comb'chmbr temperature is about 2000deg.F less than the Kerolox equiv' that doesn't hold "hydrox"! ;)
There's less than 300 deg F difference between the SSME and the RD-180. SSME is about 6000 deg F (=3589 Kelvin) and RD-180 is about 3700 deg Kelvin.

Murray Anderson

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