The F-89H (Model N-138) was an adaptation of the missile-armed F-89D to carry the new Falcon air-to-air missile. It was a direct outgrowth of the abortive F-89G program, which had been a proposal to mate the Hughes MA-1 fire control system with the Hughes Falcon air-to-air missile. With the cancellation of the F-89G project, the Northrop company proposed a more straightforward upgrade of the F-89D with the Hughes E-9 fire control system (a simplified version of the MA-1). The USAF agreed to the project, and three F-89Ds (52-1830, 52-1939, and 53-249) were modified to test the weapons system changes. However, only one of these (serial number 52-1939) was redesignated YF-89H.
The wingtip pods of the F-89D were redesigned and enlarged with the forward third of each pod carrying six separate weapons compartments. Three of the compartments each held a single Hughes GAR-1 Falcon air-to-air missile, and the other three each carried a pack of seven 2.75-inch FFARs. So the total weapons load of the F-89H was six Falcons and 42 2.75-inch FFARs.
The Falcons were stored inside the wingtip pods until ready for firing. When ready for firing, the Falcons swung out on individual launchers through a pair of fairing doors on the pods.
The Hughes GAR-1 Falcon was the first guided AAM in the world to enter operational service. The first work on the Falcon had actually gotten started back in 1947. It had actually originally been assigned a designation in the fighter sequence: F-98. However, this was changed to GAR-1 in 1950. The Falcon weighed about 110 pounds at launch, and was powered by a Thiokol solid-propellant high-impulse rocket motor. The missile was fitted with four delta wings of extremely low aspect ratio, set at 90 degrees to each other, and each carrying a powered control surface at the rear. A 29-pound high-explosive warhead was carried, and the nose was fitted with a radar homing receiver. The GAR-1 used a semi-active radar homing technique, in which the launching aircraft's radar transmitter tracked the target and the missile homed in on radar waves reflected back from the target. Maximum speed of the Falcon missile was about Mach 2.8, and effective range was about 4 miles. In 1962, the designation of the GAR-1 Falcon was changed to AIM-4.
Later, an infrared homing version of the Falcon was developed. The infrared Falcon was known as GAR-2 (later changed to AIM-4B), and it became standard practice for the Scorpion to carry three radar homing and three infrared-homing Falcons. Were the Falcons to be fired in actual combat, the plan was usually to fire one Falcon of each type at the target in order to ensure a high probability of a kill.
The E-9 fire control system had a "universal computer" which enabled the crew to select the best mode of interception. The F-89H could use either a lead collision intercept mode (FFARs only) or a tail chase interception mode (Falcons and/or FFARs).
The USAF accepted the first production F-89H in September of 1955, but it was not until March of 1956 that the first F-89Hs became operational with the 445th Fighter Interceptor Squadron at Wurtsmith AFB in Michigan, almost two years later than originally scheduled. The delays were primarily caused by problems which developed with both the missile launching pods and with the E-9 fire control system. Just as in the case of the F-89D, there were problems with corrosion in the missile launching cavities which could result in an explosion or misfire if left uncorrected. The E-9 fire control system had a host of minor technical problems which needed to be worked out before maximum performance could be attained from the missile armament.
Because of the rapid advances being made in the supersonic interceptor program, particularly with the Convair F-102A Delta Dagger, the service life of the F-89H with the USAF was destined to be relatively brief. In November of 1957, the first F-89H was transferred to the Air National Guard, entering service with the 123rd FIS of the Oregon ANG at Portland. By September of 1959, all USAF F-89H interceptors had been passed along to the ANG.
Powerplants: Two Allison J33-A-35 turbojets, 5440 lb.st. dry, 7200 lb.st. with afterburner. Maximum speed: 636 mph at 10,600 feet, 523 mph at 46,500 feet. Initial climb rate 8360 feet per minute. Altitude of 46,500 feet could be attained in 18.1 minutes. Service ceiling 49,200 feet. Maximum range 1367 miles. Dimensions: wingspan 59 feet 8 inches, length 53 feet 10 inches, height 17 feet 6 inches, wing area 606 square feet. Weights 25,194 pounds empty, 37,190 pounds combat, 42,241 pounds gross, 46,789 pounds maximum takeoff. Armed with 42 2.75-inch folding fin unguided rockets and six Hughes GAR-1 Falcon semiactive-homing air-to-air missiles in wingtip pods. Underwing racks could carry 16 five-inch rockets or 3200 pounds of bombs.