Main Engine Cut OffBlue Origin Confirms BE-3U Uses Expander Cycle
In a tweet firmly buried by the news cycle—on a Friday afternoon in August, while everyone else was talking about the Parker Solar Probe launch—Blue Origin showed off a video of a BE-3U firing, gave an update on their testing, and confirmed it will use a different cycle than the BE-3:
Recent footage of BE-3U demonstration engine hot fire. Two BE-3Us will power upper stage of #NewGlenn & deliver our customers to orbit. We’ve completed over 700 seconds of test time & confirmed performance assumptions used for final BE-3U expander cycle design
The switch to expander cycle is a big deal. Because of the BE-3U’s thrust level, it’ll be an open/bleed cycle. That does decrease efficiency a bit, but its specific impulse will be very much in the ballpark of the RL10 and Vinci.