The F-101A Voodoo was the first truly satisfactory long-range, all-weather interceptor to be operated by NORAD and its presence revolutionized the air defense of the United States. It seriously challenged the ascendancy of the bomber and for a period of five or six years provided serious opposition to the B-52 fleet at Red Sun. Eventually, it was eclipsed by the arrival of the RB-58 Hustler and the development of more advanced interceptors, notably the F-106 Delta Dart. Despite a high accident rate, the F-101 was popular with its crews and after the type was withdrawn from service, many were sold to private buyers and are popular “warbird” exhibits at airshows.
It had not gone unnoticed that the F-88C had the altitude and speed characteristics to form the basis of a good long-range interceptor, capable of handling B-52 type targets. Accordingly, McDonnell offered a two-seat interceptor version of the F-88C designated the F-88D. This was approved but because of the very different role of the aircraft, it was redesignated the F-101A Voodoo. At that time, the subsonic Northrop F-89 Scorpion was the backbone of USAF long-range all-weather interceptor squadrons, with the supersonic Convair F-102A Delta Dagger just beginning to undergo flight testing. The F-102A had always been considered by the USAF as only an interim interceptor, filling in the void until the far more advanced F-102B could be made available. However, the F-102A was at that time experiencing teething problems on its own and it appeared that its introduction into service might be appreciably delayed. In addition, the initiation of a hydrogen bomb by Chipan in August 1956 made it imperative that the Air Force find something other than the F-102A that would help fill in the gap between the subsonic F-89 Scorpion and the Mach-2+ F-102B.
The F-101A retained the center and rear fuselage sections and the wing and tail surfaces of the F-88C. However, it had a revised forward fuselage housing the MG-13 fire control system with automatic search and track mode, a two-seat tandem cockpit with pilot in front and radar operator in the rear, a retractable flight refuelling probe in front of the pilot's cockpit, and an all-missile armament. The internal fuel capacity was reduced to 2053 gallons to provide more room for electronic equipment and armament. Since the F-101A was heavier than its single-seat predecessor, it employed larger tires with a beefed-up undercarriage. Bulges had to be installed in the lower gear doors and in the undersides of the fuselage in order to accommodate the larger tires. Armament consisted of four Hughes GAR-1 semi-active radar homing or GAR-2 infrared-homing Falcon missiles carried on and launched from a rotary armament door covering the fuselage bay beneath and behind the rear cockpit. Two missiles were attached to recessed slots on each side of the door. After the first pair of missiles were launched, the door was flipped over, exposing the other pair.
McDonnell F-101A Voodoo
In the next two years, about 50 F-101As were accepted and subjected to extensive tests before being released for operational service. The first F-101As were delivered to the 60th Interceptor Squadron at Otis AFB in Massachusetts on January 5, 1958. F-101As ended up equipping 18 air defense squadrons (the 2nd, 13th, 15th, 18th, 29th, 49th, 59th, 60th, 62nd, 75th, 83rd, 84th, 87th, 98th, 322nd, 437th, 444th, and 445th Fighter Interceptor Squadrons). F-101Bs also served with the 4570th Test Squadron and the 4756th CCTS (later designated the 2nd Fighter Interceptor Training Squadron), both based at Tyndall AFB in Florida. These units carried out operational suitability tests and training for NORAD.
Specification of the F-101A:
Engines: Two Pratt & Whitney J57-P-55 turbojets, 11,990 lb.s.t. dry and 16,900 lb.s.t. with afterburner. Dimensions: wingspan 39 feet 8 inches, length 67 feet 5 inches, height 18 feet 0 inches, wing area 368 square feet. Performance: Maximum speed 1134 mph at 35,000 feet (Mach 1.72). Initial climb rate 49,200 feet/min. Service ceiling 58,400 feet, combat ceiling 51,000 feet. Normal range 1520 miles, maximum range 1930 miles. Weights: 28,970 pounds empty, 45,664 pounds gross, 40,853 pounds combat weight, 52,400 pounds maximum takeoff. Fuel: Maximum internal fuel load was 2053 US gallons, housed in five fuel cells in the upper fuselage and three in each wing.. A total of two 450 US gallon under-fuselage drop tanks could be carried, bringing maximum fuel load to 2953 US gallons. Armament: Armed with four Falcon AAMs (usually 2 GAR-1 (AIM-4) semiactive radar homers and 2 GAR-2 (AIM-4B) infrared homers) in an internal ventral weapons bay.
McDonnell F-101B Voodoo
The F-101B had a modified fire control systems and with provision for carrying a pair of Douglas MB-1 Genie unguided nuclear-armed rockets on the rotary weapons bay in place of the two Falcon missiles. The MG-13 fire control system was capable of hands-off Genie launches, including the automatic launch of the rocket, turning the aircraft into the escape maneuver, and detonating the nuclear warhead at the appropriate time. Since the Genies were bigger and created more drag, and also because they were more classified, they were normally carried internally until they were ready to be fired. Then the door would rotate and the rocket was fired. In addition, the F-101B was fitted with an infrared sensor in front of the pilot's cockpit in place of the retractable refuelling probe. Other modifications were made to the control system including a modified pitch control system for the automatic pilot in an attempt to address the "pitch-up" problem that had plagued the Voodoo throughout its service life. Included in the upgrades was an enhancement of the resistance of F-101B airframes to electromagnetic pulses, and an improved MG-13 fire control system was installed for use against low-flying targets. As an interim aircraft, the F-101 did not have a long service life and, by 1972, the type had been withdrawn from NORAD service.