This GE-Rolls Royce competitor to the Pratt & Whitney F135 in the JSF has completed a round of tests in STOVL mode, which is generally considered the most demanding part of the engine envelope.

My guess would be the GE/RR want to get as far as possible as quickly as possible, because the Pentagon has repeatedly tried to kill the program, and it’s been Congress keeping it alive.

I have mixed emotions on the F-136. It’s clear that the F-100/F110 competition was a success in the F-15 and F-16, lowering cost and getting increased performance, but the F-110 was a derivative of the F-101 developed for the B-1 bomber, and as such the start up costs were much smaller.