All real booster engines are overexpanded at sea level, many have the exit pressure at about 0.6 atm. This improves overall performance during flight.
Quote from: Chasm on 01/09/2018 03:45 amYes, what is the BE-3E. Previously we only heard about the BE-3U being worked on.They are the same engine. (or it is a very close cousin, like the RL-10 variants)
Yes, what is the BE-3E. Previously we only heard about the BE-3U being worked on.
Sorry if I missed this in the discussion earlier...Anyone know what the BE-4 nominal mixture ratio s supposed to be, compared to the Aerojet AR-1 (2.2?)?Wouldn't that have a definite impact on tank sizing? If so, how can ULA be designing it's Vulcan booster stage, tanks and all, if it hasn't committed 100% to one engine?
Quote from: silverthorne on 01/22/2018 04:46 pm...Wouldn't that have a definite impact on tank sizing? If so, how can ULA be designing it's Vulcan booster stage, tanks and all, if it hasn't committed 100% to one engine?Easy. Double design, double CDR.
...Wouldn't that have a definite impact on tank sizing? If so, how can ULA be designing it's Vulcan booster stage, tanks and all, if it hasn't committed 100% to one engine?
Quote from: woods170 on 01/22/2018 04:50 pmQuote from: silverthorne on 01/22/2018 04:46 pm...Wouldn't that have a definite impact on tank sizing? If so, how can ULA be designing it's Vulcan booster stage, tanks and all, if it hasn't committed 100% to one engine?Easy. Double design, double CDR.Which is why I'm confused that ULA doesn't seem to be in a rush to down select.
Quote from: mme on 01/22/2018 05:15 pm...Which is why I'm confused that ULA doesn't seem to be in a rush to down select.Who says they haven't downselected? They don't have to announce it right away.
...Which is why I'm confused that ULA doesn't seem to be in a rush to down select.
Jeff Foust@jeff_foustTshudy: no downselect yet on Vulcan engine, but anticipate it “this year.”10:58 AM - 18 Jan 2018
Maybe E for expendable, just like the upper stage it will be used on? Which would imply that Blue would be considering reuse for their own upper stage.
Quote from: Nilof on 01/10/2018 11:59 pmMaybe E for expendable, just like the upper stage it will be used on? Which would imply that Blue would be considering reuse for their own upper stage.Or it may stand for "Exploration" as it is being considered for the Exploration Upper Stage. That may involve design specifications to accommodate longer loiter times than the BE-3U is designed for. I have seen recent images released by Bigelow on Instagram that suggest that they are considering the EUS as a propulsion block for their modular spacecraft designs.
Anyone know what the BE-4 nominal mixture ratio s supposed to be, compared to the Aerojet AR-1 (2.2?)?
From what I understand from friends I have at ULA, they are working towards a single CDR.
Or it may stand for "Exploration" as it is being considered for the Exploration Upper Stage. That may involve design specifications to accommodate longer loiter times than the BE-3U is designed for. I have seen recent images released by Bigelow on Instagram that suggest that they are considering the EUS as a propulsion block for their modular spacecraft designs.
Quote from: silverthorne on 01/22/2018 04:55 pmFrom what I understand from friends I have at ULA, they are working towards a single CDR.No, that is wrong. Tony Bruno reported via Twitter that CDR had begun. That was well over a month ago.
Jeff Foust @jeff_foustJim Centore, Blue Origin: making good progress on BE-4 engine testing. Getting to longer duration [but unspecified] burn times, and multiple runs on the same engine. Continuing testing for the next several months.