The XP-60B project got a new lease of life after the R-2800-10 engine was installed on it with a conventional four-blade propeller and a nearly entirely similar XP-60C design without any significant changes.
The aircraft was renamed the YP-60E, the first flight was only taken on May 26, 1943, after the problems with the engines were fixed.
In April 1943 testing at Patterson Field airfield began with the testing of the 3 Curtiss models to see which type the USAAF would consider choosing as a fighter.
In January 1944, the prototype was transferred to Eglin Field Airfield, where the official test program was launched by test pilots.
The fighter was too unstable in flight, and pulled the aircraft to the left in unexpected dives.
The test pilots considered the aircraft too heavy for operational flight.
Eventually, Curtiss had to admit that the program had failed.
In turn, the Army insisted that the two prototypes were still completed in accordance with the previously signed contract.
These prototype aircraft were needed by USAAF rather for experimental purposes, as their mass production was not planned.
However, only one YP-60A fighter was completed, and the second was brought to the level of the last modification and was designated YP-60E.
Curtiss installed the 18-cylinder R-2800-18 engine with a four-blade propeller, as well as redesigned the cockpit canopy and vertical trimming’s, likening them to similar elements of the fighter P-47D-25.
Curtiss pilots performed only two flights on the YP-60E, the first of which took place on July 15, 1944, and then the aircraft was transferred to Wright Field Air Force Base for testing.