The McDonnell F3H Demon is a subsonic swept-wing United States Navy carrier-based jet fighter aircraft. The successor to the F2H Banshee, the Demon was originally designed to use the Westinghouse J40 engine, but had to be redesigned to accept the Allison J71 after the J40 suffered severe problems and was ultimately abandoned.[​1] Though it lacked sufficient power for supersonic performance, it complemented daylight dogfighters such as the Vought F8U Crusader and Grumman F11F Tiger as an all-weather, missile-armed interceptor[​2] until 1964.