10 successful 100-second AR-22 engine firings in 240 hours! The @AerojetRdyne, @NASA, @BoeingSpace & DARPA team just proved the propulsion system is ready for our Experimental #Spaceplane program’s goal to launch on demand with rapid turnaround. pic.twitter.com/yd8nx3aI6I
— DARPA (@DARPA) July 6, 2018
The engine is being tested for Boeing’s Phantom Express, which is a DARPA-funded project focused on developing a low-cost, reusable satellite launch vehicle capable of launching 10 times in 10 days.