Originally Posted by
B Fraser
They lost a lot of F1 engines on the test stand (56 ???) due to issues including combustion instability at the injector plate. The RS25 engines have always achieved orbit, albeit by a very narrow margin at times.
The F1 engines were a huge step in technology and size relative to anything that existed previously (as in an order of magnitude in thrust). It was also designed when computers were in their infancy and slide-rules were state-of-the-art. And they eventually figured it out - no F1 engines failed during a launch (although 'pogo' remained an issue).