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#80
by
Prober
on 04 Nov, 2014 14:55
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#81
by
russianhalo117
on 04 Nov, 2014 15:01
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Doubt there is much difference in shape between 181 and 191.
There are differences in engine mount and fuel oxidizer piping are completely different.
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#82
by
CardBoardBoxProcessor
on 04 Nov, 2014 15:23
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Yes the RD-193 and RD-181 are very different. I was saying I doubt the RD-191 and RD-181 are much different.
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#83
by
Lars-J
on 04 Nov, 2014 16:23
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I was saying I doubt the RD-191 and RD-181 are much different.
Really? I thought the 18X series had two combustion chambers, whereas the 19X/15X series has one combustion chamber. Or am I mistaken?
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#84
by
arachnitect
on 04 Nov, 2014 19:17
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At one point didn't we have a big "Antares Engines" thread?
Did that get merged into something else or am I misremembering? There was stuff in there about the RD series engines, theoretical solid boosters, etc. A whole bunch of stuff.
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#85
by
russianhalo117
on 04 Nov, 2014 19:34
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#86
by
Coastal Ron
on 04 Nov, 2014 19:37
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Of course I'd be surprised if SpaceX wanted to be an engine supplier, especially to a competitor, but to me it would be a better choice that being dependent yet again on Putin's Russia.
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#87
by
Lars-J
on 04 Nov, 2014 19:41
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Of course I'd be surprised if SpaceX wanted to be an engine supplier, especially to a competitor, but to me it would be a better choice that being dependent yet again on Putin's Russia.
Falcon 5, back from the dead!
An amusing thought, but very unlikely.
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#88
by
GClark
on 04 Nov, 2014 19:44
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I was saying I doubt the RD-191 and RD-181 are much different.
Really? I thought the 18X series had two combustion chambers, whereas the 19X/15X series has one combustion chamber. Or am I mistaken?
It has been my opinion (not that it's worth much) since Dec '12 when NPO EM first mentioned RD-181 that they are using -18x as a series designation for engines intended for the U.S. market.
That slide I linked to up-thread clearly shows RD-180 for Atlas V and RD-181 for Antares.
The only deviation from that was them pushing the notional RD-175(?) for SLS(!).
It is also possible given the differing plumbing that RD-181 is designed around the attachments unique to the Antares/AJ-26 combination.
Truth in advertising: I am not an Aerospace Engineer/Rocket Scientist.
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#89
by
baldusi
on 04 Nov, 2014 20:21
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Different O/F, different isp, different cycle (you have to deal with the gas generator output), different TVC, different diameters... etc. Save for the thrust nothing similar.
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#90
by
yg1968
on 04 Nov, 2014 20:25
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#91
by
TrevorMonty
on 04 Nov, 2014 20:52
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Of course I'd be surprised if SpaceX wanted to be an engine supplier, especially to a competitor, but to me it would be a better choice that being dependent yet again on Putin's Russia.
NASA wouldn't like it as both ISS suppliers would dependent on same engine. A failure of either LV would instantly ground the other LV until engine was eliminated or longer if engine was at fault.
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#92
by
FinalFrontier
on 04 Nov, 2014 21:06
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Will be very interested to see how this turns out. I am expecting them to switch to either RD193 or another Russian motor but who knows. I wish/hope they would switch to a domestic U.S. motor of some type, either something BE is developing or (spacex? unlikely though) or switch to flying out on Atlas V for CRS until a domestic US engine was ready. But they won't. IMO though anything is better than continuing with the NK33.
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#93
by
Coastal Ron
on 04 Nov, 2014 21:34
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Different O/F, different isp, different cycle (you have to deal with the gas generator output), different TVC, different diameters... etc. Save for the thrust nothing similar.
Same oxidizer and fuel - LOX/RP-1 - otherwise I wouldn't have mentioned it as a possibility.
NASA wouldn't like it as both ISS suppliers would dependent on same engine. A failure of either LV would instantly ground the other LV until engine was eliminated or longer if engine was at fault.
SpaceX has flown 130 Merlin engines with only one flight failure, so I'd say at this point the design is pretty mature. And yes, mature designs do have issues, but they get fixed pretty quick. That said I would agree that where possible NASA wants diversity for a good reason, but for me I'd rather be dependent on a SpaceX design than an engine from Putin's Russia.
But as I said in my original post, I don't think it will happen.
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#94
by
Kryten
on 04 Nov, 2014 21:58
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maybe someone can focus on the history and see if this engine has a flight history?
None, yet. It's been specifically designed to replace NK-33 on Soyuz 2.1v, but I haven't seen any indication of when that's actually supposed to happen.
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#95
by
Lourens
on 04 Nov, 2014 22:01
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Different O/F, different isp, different cycle (you have to deal with the gas generator output), different TVC, different diameters... etc. Save for the thrust nothing similar.
Same oxidizer and fuel - LOX/RP-1 - otherwise I wouldn't have mentioned it as a possibility.
I think he means Oxidiser/Fuel
ratio, i.e. the AJ-26 runs oxidiser-rich, while the Merlin 1D runs fuel-rich. As a result, they'd have to move the bulkhead so as to carry more fuel and less oxidiser.
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#96
by
Lobo
on 04 Nov, 2014 22:04
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If they were going to move Cygnus to another launcher I'd think F9 would be the logical choice. It would be cheaper than Atlas, Cygnus is designed for horizontal integration already,and OSC payloads have already flown on F9. OSC and SpaceX really aren't in competition with each other (at this time) as they both have COTS contracts and OSC is not competing for commercial crew nor even commercial payloads (yet). Dragon and Cygnus capabilities don't really overlap.
And I'm sure Elon would jump at the chance to be NASA's sole commercial cargo launcher.
This would defeat the whole purpose of keeping two separate systems for redundancy. And we right now see how wise that actually was. Imagine what would happen if F9 would become the only LV for COTS and then fail.
Launching Cygnus on Falcon9 certainly beats not launching Cygnus at all. It may not be a long term solution but it would be a solution.
Besides, a long time stand down of Falcon 9 is not impossible but with their launch record and their proven ability to identify and rectify problems fast a long time stand down is now very unlikely.
@This.
If Cygnus were to launch on Falcon, it's not like ULA would close shop and Atlas and Delta would go away leaving only Falcon. ULA and the EELV's will always be there and could be used if there was an issue with Falcon. And vice versa.
However, ULA is more expensive for a few reasons. High overhead is one, but meeting USAF/DoD standards is another. Cygnus doesn't need anything more than F9/SpaceX already have. Their processing and pad flow are similar. Horizontal HIB, MTE, etc. Cygnus doesn't -need- ULA's features and capabilities whoc USAF/DoD do, and pay extra for.
Besides, I don't think OSC/ATK is going to get out of the launch business, but they may need an interim option to keep Cygnus flying to the ISS while they re-engine Antares, if the AJ26 was determined to be the cause of the failure and they decide to not launch Antares using that engine again. Even if the problem was not related to the AJ26, the pad will take time to fix, and they pay just decide to go ahead with the new engine in the mean time and do the re-engine work and pad repairs in parallel. So they'd need about a 2-year interim option. That could be SpaceX or ULA...but SpaceX would likely have a lower cost of OSC/ATK and Cygnus doesn't need more than a "budget" launch service like F9 or Antares.
Besdies, if F9 were to have a failure and for some reason, and be grounded for a length of time (somewhat unlikely given how everything is built in-house so everything could be directly investigated and evaluated and they'll soon have a 2nd pad at the Cape in case one were to suffer Wallops-like launch failure damage) then NASA would have other problems as neither of their COTS providers would be able to launch. There'd probably be something quickly worked out with ULA to get at least Cygnus flying on Atlas or Delta. I don't know that Dragon's downmass capabilities are quite as critical, so in such a scenario the larger volume of Cygnus would probably get the first to get an emergency transfer. And it's already designed to launch inside a PLF like a traditional satelite I think. Not sure what adaptation would be required to get Dragon launching on Atlas or Delta.
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#97
by
Lobo
on 04 Nov, 2014 22:08
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Don't know if someone already mentioned this, but in looking at the specs for the AJ-26 and Merlin 1D it looks like you could replace two AJ-26 with five Merlin 1D. It's an almost exact match, with a little more sea level thrust and a little less vacuum thrust.
Of course I'd be surprised if SpaceX wanted to be an engine supplier, especially to a competitor, but to me it would be a better choice that being dependent yet again on Putin's Russia.
Why not just launch on F9 then and save the development?
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#98
by
TrevorMonty
on 04 Nov, 2014 23:46
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SpaceX already has pad facilities for support ISS payloads so launching Cygnus on F9 has some pluses. Not sure how ULA a setup for this if Cygnus was to fly on a Atlas. I suspect Jim would have some knowledge on this.
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#99
by
Jim
on 05 Nov, 2014 00:59
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SpaceX already has pad facilities for support ISS payloads so launching Cygnus on F9 has some pluses. Not sure how ULA a setup for this if Cygnus was to fly on a Atlas. I suspect Jim would have some knowledge on this.
The payloads are loaded the payload processing facility.
An amusing thought, but very unlikely.