* US Air force developing concepts for replacing the Lockheed F-22 after 2030, which includes updating existing designs with new technology.
* Re-engining the F-35 with an adaptive cycle, 45,000lb-thrust engine.

The U.S. hasn't designed a clean-sheet fighter in twenty years, and Penetrating Counter Air (PCA) will differ from the F-22 and F-35 in some ways to deal with new strategic realities. PCA will emphasize range to fly escort missions for B-2 and B-21 bombers over Russia and against China in the Asia-Pacific.

The Air Force hopes for the best of both worlds with so-called "three-stream propulsion," which uses a third air stream to make the engine more efficient or provide more thrust.

PCA will also be stealthy, and likely lose vertical tail fins that are standard on all aircraft, from the P-51 Mustang to the F-22 Raptor.

Funds are being requested to create a new super missile – Air Dominance Air-to-Air Weapon to replace the 30 year old AIM-120 AMRAAM.

Future engines are the key

The Air Force Research Laboratory has been working with GE and Pratt and Whitney on adaptive, "three-stream" engine technology for several years, under a science and technology program called Adaptive Engine Technology Development (AETD).