Here is a report on the new F-35B aircraft for the US Marine Corps. The aircraft line (F-35A/B/C) is a tri-service aircraft (and also for eight international customers). The international partners are contributing $4 billion dollars to the Research and Development costs. Plus they will purchase a large number of aircraft, thus keeping production costs down (the famous "Learning Curve").
A write-up on the program, from Wikipedia, can be found here.
My reason for writing is the question of the "Second Engine". Is it another Ear Mark boondoggle or is it a wise hedge? I will state my bias up front. When I was commanding the 86th Fighter Wing (Ramstein AB, FRG) we were the first unit to field the F-16 with the GE second source jet engine. It was a marked improvement in performance over the Pratt Whitney engined jets. That said, a later model of the PW engine matched the GE engine. The story of this engine competition is written up in The Air Force and the Great Engine War.
The second engine for the F-35 was a pet project for Senator Ted Kennedy. Maybe it was for the jobs in Lynn—Pork. From my perspective it was about pushing the technology and having options. It is also about the benefits of competition. Competition extracts better performance. See the F-16 engine competition.
Whatever the late Senator Kennedy's reason for backing the second engine, it was a good idea.
The second engine may be what allows the F-35B to achieve a positive production decision and operational success.
Regards — Cliff