Is a heat-sink nozzle and a regenerative cooled nozzle not the same think?
Quote from: Step55 on 10/21/2017 07:22 amIs a heat-sink nozzle and a regenerative cooled nozzle not the same think?I thought the regeneratively cooled nozzle specifically has the fine channels to route the liquid propellant through, to cool the nozzle. Meanwhile the heat sink nozzle would simply have heat sink drawing off the heat, without particularly involving the propellant.
Quote from: Space Ghost 1962 on 10/20/2017 12:27 amLooks like a good, stable burn. Few artifacts, and more than enough to begin a considerable test program. Impressive even at 50% power. It wouldn't surprise if this engine surpasses RD-191 before the end of this year, and reaches 3MN before the next year is out.I though they were targeting 2.45 MN as operational thrust. Is 122% a standard margin? Will they try to take it higher?
Looks like a good, stable burn. Few artifacts, and more than enough to begin a considerable test program. Impressive even at 50% power. It wouldn't surprise if this engine surpasses RD-191 before the end of this year, and reaches 3MN before the next year is out.
Quote from: edkyle99 on 10/20/2017 01:48 pm[...] it seems to me a good idea to wait to shelve it [the AR-1] until BE-4 has not only hit that full thrust mark, but racked up some serious firing time.I'm not a rocket designer, but if I was ULA I'd find 10 seconds at full thrust pretty convincing, much more so than full duration at any lesser power setting. Of course you need both, but at these power levels the engine should reach equilibrium pretty quickly. Running at less than full power is no guarantee the engine will survive higher, more stressful, settings. But if it runs for 10 seconds at full power, it should be more or less straightforward to make it run for 10 minutes.So if I was ULA, I'd ask BO to step power first, to find any design weaknesses, so I could make a quick decision. Then they can optimize for duration.
[...] it seems to me a good idea to wait to shelve it [the AR-1] until BE-4 has not only hit that full thrust mark, but racked up some serious firing time.
Yes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)
Quote from: Space Ghost 1962 on 10/21/2017 05:39 pmYes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)I suspect they probably were originally aiming for 2X Merlin 1D thrust levels.
Quote from: Patchouli on 10/21/2017 07:12 pmQuote from: Space Ghost 1962 on 10/21/2017 05:39 pmYes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)I suspect they probably were originally aiming for 2X Merlin 1D thrust levels.Why would Merlin thrust levels be relevant when setting BE-4 goals?
Quote from: envy887 on 10/20/2017 06:05 pmQuote from: Space Ghost 1962 on 10/20/2017 12:27 amLooks like a good, stable burn. Few artifacts, and more than enough to begin a considerable test program. Impressive even at 50% power. It wouldn't surprise if this engine surpasses RD-191 before the end of this year, and reaches 3MN before the next year is out.I though they were targeting 2.45 MN as operational thrust. Is 122% a standard margin? Will they try to take it higher?Yes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)
Does the portion of fuel passes through the regen-cooled nozzle also pass through the pre-burner?
Quote from: Space Ghost 1962 on 10/21/2017 05:39 pmQuote from: envy887 on 10/20/2017 06:05 pmQuote from: Space Ghost 1962 on 10/20/2017 12:27 amLooks like a good, stable burn. Few artifacts, and more than enough to begin a considerable test program. Impressive even at 50% power. It wouldn't surprise if this engine surpasses RD-191 before the end of this year, and reaches 3MN before the next year is out.I though they were targeting 2.45 MN as operational thrust. Is 122% a standard margin? Will they try to take it higher?Yes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)Blue was originally targeting 400 klbf (1800 kN). They upped it to 550 klbf (2450 kN) to sell it to ULA. Why would they need to fire it at 675 klbf (3000 kN)?Agree that it does seem oversized for 2450 kN and Blue is probably reserving performance.
Quote from: envy887 on 10/23/2017 06:49 pmQuote from: Space Ghost 1962 on 10/21/2017 05:39 pmQuote from: envy887 on 10/20/2017 06:05 pmQuote from: Space Ghost 1962 on 10/20/2017 12:27 amLooks like a good, stable burn. Few artifacts, and more than enough to begin a considerable test program. Impressive even at 50% power. It wouldn't surprise if this engine surpasses RD-191 before the end of this year, and reaches 3MN before the next year is out.I though they were targeting 2.45 MN as operational thrust. Is 122% a standard margin? Will they try to take it higher?Yes - ULA needed considerably more thrust (and margin) than Blue was originally after, thus a larger engine and fewer for NG as a result. Would also expect that they are expecting to gradually increase chamber pressure beyond afterward.(The engine seems "over scaled" for what they want/claim for it.)Blue was originally targeting 400 klbf (1800 kN). They upped it to 550 klbf (2450 kN) to sell it to ULA. Why would they need to fire it at 675 klbf (3000 kN)?Agree that it does seem oversized for 2450 kN and Blue is probably reserving performance.This engine does seem to have lots of upgrade potential just like the old Merlin. Upgrading to ~200bar in a future model would have thrust in the 3.7MN range...
Jeff Foust@jeff_foustGunderson: the first BE-4 test lasted as long as planned (although he didn’t say how long); team very excited. #vonbraun8:34 pm · 25 Oct 2017
QuoteJeff Foust@jeff_foustGunderson: the first BE-4 test lasted as long as planned (although he didn’t say how long); team very excited. #vonbraun8:34 pm · 25 Oct 2017https://mobile.twitter.com/jeff_foust/status/923271615307309056
Quote from: Star One on 10/25/2017 07:59 pmQuoteJeff Foust@jeff_foustGunderson: the first BE-4 test lasted as long as planned (although he didn’t say how long); team very excited. #vonbraun8:34 pm · 25 Oct 2017https://mobile.twitter.com/jeff_foust/status/923271615307309056What's the reference to #VonBraun - is this part of the nomenclature like Shepard, Glenn, Armstrong?What's it specifically referring to?
There were some good reasons for why it took so long with RS-68, but none of those are likely here. The two aren't comparable.From the artifacts present, suggest chamber pressure is the limiting factor in some form at the moment.
Quote from: Space Ghost 1962 on 10/21/2017 05:39 pmThere were some good reasons for why it took so long with RS-68, but none of those are likely here. The two aren't comparable.From the artifacts present, suggest chamber pressure is the limiting factor in some form at the moment.Wasn't RS68 the ablative cooled GG cycle LH2/LO2 for the Delta IV?I'd guess ablative reuse would have been an issue.Do you mean RS25, the SSME. There were 13 RUDs (of various levels of seriousness) getting it to flight. AFAIK It's still the only cryogenic SC (of any variant) to be developed in the US (before Blue and SX).
Quote from: john smith 19 on 11/03/2017 03:24 pmQuote from: Space Ghost 1962 on 10/21/2017 05:39 pmThere were some good reasons for why it took so long with RS-68, but none of those are likely here. The two aren't comparable.From the artifacts present, suggest chamber pressure is the limiting factor in some form at the moment.Wasn't RS68 the ablative cooled GG cycle LH2/LO2 for the Delta IV?I'd guess ablative reuse would have been an issue.Do you mean RS25, the SSME. There were 13 RUDs (of various levels of seriousness) getting it to flight. AFAIK It's still the only cryogenic SC (of any variant) to be developed in the US (before Blue and SX).RS-68B LRE Upgrade with regenerative cooling was shelved after i believe the Critical Design Review because Constellation program was terminated and there wasn't another rocket that needed it because it was easier to take certain components of RS-68 to make an RS-25E. This has been discussed many times and doesn't need to be repeated again.