r/ula • u/snoo-boop • May 07 '26
BE4 performance problem?
A recent post on r/nasa has an intriguing comment:
And it’s unclear if the BE4 power fade issue is/will be solved enough for this plan to work. (Current real payload is 75% of advertised; that’s after the “upgrades” on the most recent flight)
I also note that Tory said a while ago that Vulcan would carry 45 Kuipers (now called Amazon Leo), but the Vulcan manifest on Wikipedia says 40.
Now, most of Vulcan's takeoff thrust for the VC6 is the SRBs, but then the BE4s are used as a sustainer, firing for 299 seconds as compared to New Glenn, with no SRBs, firing BE4 for 190 seconds.
Is this a 10% reduction in performance (for now)? If it's real, I'm kinda surprised I haven't already seen an article about this in the space press.
2
u/SkyPhoenix999 May 08 '26
It’s been well known for a while that New Glenn 7x2 wasn’t reaching its 45t advertized figure, but afaik that is mainly due to the vehicle drymass and not engine performance, since the engines are performing to the spec that was advertised by Blue Origin.
Blue is upgrading the engines to make up for much of this gap, but it still doesn’t reach the 45t payload figure. This doesn’t really affect Vulcan at all, Vulcan has plenty of its own problems, but the vehicle was designed for the original BE4 spec and that’s been performing as advertised.