Ryan FR-4

The XFR-4 entered flight test in November 1944. Utilising the 19th FR-1 production airframe, this replaced the J31-GE-3 turbojet with a 1542kg Westinghouse J34-WE-22, discarded the wing root intakes of the FR-1 in favour of flush inlets in the sides of the forward fuselage, and had the aft fuselage extended by 20cm. It was found, however, that the thrust of the J34 was too great to permit efficient use of both engines and the XFR-4 programme was discontinued accordingly.