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#140
by
WHAP
on 18 Oct, 2007 01:58
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tnphysics - 17/10/2007 6:49 PM
Why dosen't the Delta IV US use the RL-10C, which has more thrust?
This would help the heavy dramatically.
It does have less Isp.
A mentioned in the Atlas Q & A thread, there is no such engine.
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#141
by
tnphysics
on 18 Oct, 2007 02:15
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Could the MB-XX, which was tested, be incorporated into the Delta IV US?
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#142
by
WHAP
on 18 Oct, 2007 03:06
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Maybe - there would probably be a lot of integration work required (in addition to actually qualifying the engine). But, as with the Atlas thread and the RL10C, why? It would have to support some HUGE payloads, and those do not exist. There are a lot of "what if" scenarios out there, but unless any of them come up with money, no one will pursue them
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#143
by
Damon Hill
on 18 Oct, 2007 03:06
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tnphysics - 17/10/2007 7:15 PM
Could the MB-XX, which was tested, be incorporated into the Delta IV US?
MB-XX is still in development and a long way from flight status, it seems.
If development is finished, and someone wants to pay for it, yes. That was Boeing's long term thinking before ULA and the reason for the RL60 development program for Centaur, which has definitely been shelved after testing a prototype and starting to assemble a production prototype for testing.
Right now, the most advanced new small cryogenic engine that's anywhere close to flight status is Vinci:
http://cs.space.eads.net/sp/LauncherPropulsion/LaunchVehiclePropulsion.html#VinciFor a detailed description of Vinci and lots of internal details of an expander cycle
cryogenic engine, see this largish PDF file:
http://cs.space.eads.net/sp/PDF/vinci.pdfAny changes in design are going to be driven by need for additional performance, and the necessary funding being available to make those changes. It'd be nice if more advanced engines were available off the shelf but even then the upper stages might need significant changes just to swap in a single engine, let alone add multiple engines.
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#144
by
TrueGrit
on 18 Oct, 2007 04:34
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MB-XX family was supposed to be a “drop-in” replacement for the RL-10, and along with the AUS represented the next step in Delta evolution. It was all part of Boeing’s strategic planning… Where the launch vehicle and engine would be all under one house, just like the CBC. They were to team with Mitsubishi who would share the risks and costs to develop the MB-XX. And then strengthen the existing similarities with the H-II and Delta upper stages. This interestingly turns out to be way the 787 is being done, with major suppliers who share the risks and costs in exchange for more power and profit potential. In the end the MB-XX would filter down to replacing the RL-10 on all Delta upper stages… Of course all work in the direction and development money dried up with the commercial satellite market collapse.
MB-XX testing reached demonstrator level, having tested “battleship” subassemblies (pumps, injector, and chamber). But I don’t believe ever tested an integrated engine, and is therefore years and hundreds of millions dollars away from production. Of course any discussions of the MB-XX are moot now that Pratt owns Rocketdyne… No corporate will to replace the RL-10. Although MB-XX isn’t completely dead as the lessons learned are living on in the J-2X and RS-68 update programs. And who knows… If the RL10 is upgraded as part of the lunar lander program may end up with significant MB-XX like design changes.
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#145
by
meiza
on 18 Oct, 2007 14:33
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Damon Hill - 18/10/2007 4:06 AM
For a detailed description of Vinci and lots of internal details of an expander cycle
cryogenic engine, see this largish PDF file:
http://cs.space.eads.net/sp/PDF/vinci.pdf
Any changes in design are going to be driven by need for additional performance, and the necessary funding being available to make those changes. It'd be nice if more advanced engines were available off the shelf but even then the upper stages might need significant changes just to swap in a single engine, let alone add multiple engines.
Quite high pressure, 60 bars on an expander. RL-10A-4 is under 40 bars, if astronautix is to be believed... Guess the Germans and French want to one-up.
Also the stowable ceramic nozzle... I hope all goes well with this ambitious design, I wouldn't be that surprised if there was a failure during the early flights.
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#146
by
edkyle99
on 18 Oct, 2007 15:00
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Pratt & Whitney Rocketdyne's web site no longer catalogs RL60, and of course MB-XX is not there either. Instead, the company "offers" RD-0146, which is roughly speaking a Russian RL10 equivalent.
Why PWR would offer to "shorthaul" itself this way is a bit mystifying. The only explanation that makes sense to me is that PWR would rather not have to build RL10 at all.
- Ed Kyle
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#147
by
hyper_snyper
on 18 Oct, 2007 19:02
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Before launch, LH2 boiloff on the shuttle is piped away from the pad to be burned safely.
How does Delta IV differ in terms of what do to with LH2 boiloff? For that matter how does any vehicle with any sort of hydrogen stage deal with boiloff before launch?
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#148
by
TrueGrit
on 18 Oct, 2007 23:03
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It's a range requirement to capture and burn-off, or dilute to 1/4-th flamability limit all hydrogen (gaseous or liquid). GO2 is allowed to free vent, and liquid oxygen is dumped into a dedicated pond (depression). Interestingly the RL-10 powered DC-X free vented hydrogen... But that was White Sands, and each range site has there own rules abou these things.
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#149
by
kevin-rf
on 19 Oct, 2007 00:25
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Besides the DC-X how many LH fueled vehicles have flown out of White Sands?
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#150
by
Skyrocket
on 19 Oct, 2007 07:25
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kevin-rf - 19/10/2007 2:25 AM
Besides the DC-X how many LH fueled vehicles have flown out of White Sands?
no other vehicles (counting the DC-XA as DC-X)
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#151
by
tnphysics
on 22 Oct, 2007 11:55
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Wouldn't the Delta IV Heavy's payload to the ISS be about 32 metric tons with both an RS-68 upgrade and propellant crossfeed?
The RS-68 upgrade alone gives about 27 metric tons to the ISS.
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#152
by
edkyle99
on 22 Oct, 2007 15:52
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tnphysics - 22/10/2007 6:55 AM
Wouldn't the Delta IV Heavy's payload to the ISS be about 32 metric tons with both an RS-68 upgrade and propellant crossfeed?
The RS-68 upgrade alone gives about 27 metric tons to the ISS.
Dan Collins, Boeing's VP of Delta Programs back when Delta still was a Boeing product, presented a paper on Delta IV growth options during the 2004 Space Congress. Here is a link.
http://www.spacecongress.org/2004/Panel-4/2Collins.pdfLockheed Martin and ATK also provided presentations.
http://www.spacecongress.org/sessions.htmNothing there about propellant cross feed, which doesn't sound to me like something that would provide a large benefit at any rate.
According to the paper, Delta IV can get to 30 tonnes with an RS-68 upgrade combined with a new upper stage. Atlas V would also need a reconfigured upper stage to make 30 tonnes.
- Ed Kyle
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#153
by
meiza
on 22 Oct, 2007 15:58
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There is a delta growth path presentation from Boeing somewhere that has the multiple options with both benefit and risk listed. Cross feed is one of them... I think it was from 2004 or 2005 and related to the VSE somehow. It had options to the future for 8 meter cores I think...
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#154
by
rsp1202
on 22 Oct, 2007 16:13
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#155
by
edkyle99
on 22 Oct, 2007 16:56
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meiza - 22/10/2007 10:58 AM
There is a delta growth path presentation from Boeing somewhere that has the multiple options with both benefit and risk listed. Cross feed is one of them... I think it was from 2004 or 2005 and related to the VSE somehow. It had options to the future for 8 meter cores I think...
I stand corrected. There was one mention of propellant crossfeed for one of the projected growth options in that presentation, but it was combined with propellant densification, which probably accounted for a majority of the payload growth.
- Ed Kyle
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#156
by
hyper_snyper
on 22 Oct, 2007 17:09
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edkyle99 - 22/10/2007 12:56 PM
meiza - 22/10/2007 10:58 AM
There is a delta growth path presentation from Boeing somewhere that has the multiple options with both benefit and risk listed. Cross feed is one of them... I think it was from 2004 or 2005 and related to the VSE somehow. It had options to the future for 8 meter cores I think...
I stand corrected. There was one mention of propellant crossfeed for one of the projected growth options in that presentation, but it was combined with propellant densification, which probably accounted for a majority of the payload growth.
- Ed Kyle
What is propellant densification?
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#157
by
kevin-rf
on 22 Oct, 2007 19:04
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hyper_snyper - 22/10/2007 1:09 PM
edkyle99 - 22/10/2007 12:56 PM
meiza - 22/10/2007 10:58 AM
There is a delta growth path presentation from Boeing somewhere that has the multiple options with both benefit and risk listed. Cross feed is one of them... I think it was from 2004 or 2005 and related to the VSE somehow. It had options to the future for 8 meter cores I think...
I stand corrected. There was one mention of propellant crossfeed for one of the projected growth options in that presentation, but it was combined with propellant densification, which probably accounted for a majority of the payload growth.
- Ed Kyle
What is propellant densification?
Chilling the LH to a lower slush like state. That way you can fit more in the same volume. I would have thought you would take an ISP hit doing that with the RS-68. Does it not have an issue with the LH entering at to low a temp to begin with? I wonder what that does to the LOM numbers on the LH turbine. Solids in the flow and all.
It was also a trick proposed for NASP.
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#158
by
TrueGrit
on 22 Oct, 2007 22:33
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Densification has been an idea floating around for some time now, but is at a high technical risk level... There are multiple modifications required to the ground storage/transfer system and vehicle tank system. And would require a new engine development and certification program to test the engine at the ultra low propellant temps (meaning test stand mods too). The general feeling is that it isn't worth the cost...
Crossfeed is something both Atlas and Delta have studied in depth... It is a very large performance improvement. The idea being that you don't deplete the Core Booster propellant when the Strapons are burning. This maximizes the stagging effect of the three-body booster system. By not using any Core propellant until the Strapons drop away you make sure the impulse provided by the proepllant isn't wasting lifting Strapon dry weight. It is actually somewhat more prefered than adding solids by some in the community. Difficulties are in getting the propellant transfer switching on the Core and umbilical seperation system to work under very high lfowrates ~1600lbm of LOx. There's some expereience doing this at engine test stands and thru the Shuttle program to anchor designs to.
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#159
by
tnphysics
on 10 Nov, 2007 01:59
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Why is the LH2 tank below the LOX tank, as opposed to the more structurally efficient method of putting the LOX tank on the bottom?
Also the stowable ceramic nozzle... I hope all goes well with this ambitious design, I wouldn't be that surprised if there was a failure during the early flights.