The USN's effort to field a carrier-borne jet competitive with land-based types was a long one. While the USAF had the swept-wing F-86 operational well before Korea, the Navy was still integrating straight-wing jets into carrier operations, and it would not be until the mid-1950s that swept wings went to sea. Among the first of these was McDonnell's F3H Demon, contracted in September 1949. On paper, it appeared to be a much more formidable aircraft than the F2H Banshees then in service, and the F3H first flew in August 1951. However, it was soon realized that the Demon's Westinghouse J40 engine was severely underpowered.
The F3H was not the only aircraft program hurt by the failure of the J40, but wartime pressure led the USN to place an order for production F3H-1s. These were not completed in time for the Korean conflict, with many ending up being used as training hulks without ever having been flown. In the postwar period the aircraft was redesigned to use the somewhat better Allison J71, and the F3H-2s (from 1962 F-3Bs) served until 1964 before giving way to the F-4 Phantom II.
