In 1952 McDonnell Aircraft executives, fearing that the grossly underpowered Westinghouse J40 engine might be the stake through the heart of the F3H Demon program, asked for and received permission from an initially reluctant Bureau of Aeronautics to consider other turbojet engines for the aircraft. BuAir hesitated at first because the J40 had been designated as the powerplant in many of the aircraft programs on the drawing board. But the handwriting was on the wall and BuAir authorized McDonnell to conduct a feasibility study of fitting the F3H with the Allison J71 afterburning turbojet.
This new version of the F3H with the J71 engine was designated the F3H-2N. In August of 1953 BuAir inspected a mockup of this version and in November of 1953 they amended the McDonnell contract to fit the 32nd and 34th F3H-1N aircraft with Allison J71 prototypes. Another amendment followed which called for the 61st and all subsequent Demons to be fitted with the J71.
The Allison engine was heavier than the Westinghouse J40 and this increased weight plus the increase accrued in the process of making the Demon an all-weather fighter forced changes in the F3H airframe specifications. Wing area was increased by 77 square feet by lengthening the wing chord by 40 inches at the root and moving the trailing edge back.
On April 23, 1955, the first F3H-2N prototype (BuNo 133520) lifted off the runway at Lambert Field and the first production F3H-2N flew in June of 1955. McDonnell delivered 140 production F3H aircraft powered by the Allison J71-A2 engine to the Navy. The A2 engine provided 10,000 lbs. of thrust at full military power and 14,400 lbs. in afterburner. The A-2 was later replaced by A-2A or A-2B versions of the engine.
Another version of the F3H, the F3H-2M, was concurrently produced with the F3H-2N. The "M" version, "M" for missile, was equipped with the APG-51B radar that was configured for the guidance of the semi-active homing Sparrow III (AIM-7C) missile. Although four Sparrows could be carried, their combined weight seriously compromised aircraft performance and a full load of Sparrows was rarely carried by fleet aircraft. 80 F3H-2M were delivered to the Navy by McDonnell.
There was proposal to build a photographic reconnaissance version designated the F3H-2P which carried cameras in place of the radar and missiles. This proposal was the lingering shadow of the ill-fated J40 powered F3H-1P project and never materialized into aircraft production.
In addition to Sparrow III capability, the F3H-2 was configured to carry the AIM-9B Sidewinder heat seeking missile as well as up to 6000 pounds of air-to-ground ordnance. Other external store configurations included an external fuel tank, an inflight refueling pod, and a towed target (Del Mar) system. Demon pilots just loved carrying the external fuel tank. Early in 1955 an air-to-air refueling probe was added to the starboard side of the fuselage just under the canopy rail.
The last F3H-2 Demon was delivered to the Navy on April 8, 1960. The total number of production aircraft built and delivered by McDonnell was 519. In March of 1956 the VF-14 Tophatters at NAS Cecil Field Florida received the F3H-2N and flew the aircraft from USS Forrestal (CVA-59) during a January to July, 1957 Mediterranean deployment. The Navy eventually equipped 22 squadrons with the Demon.
The last squadron to fly the Demon was VF-161 at NAS Miramar California. Cdr. Wayne Welty, the Commanding Officer, flew the last Demon from Miramar to NAF Litchfield park on 21 September, 1964.
Other pages on this site will document some of the unique elements of the Demon's history such as the J71 engine flame-out problems in heavy weather.