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F-101A "Voodoo"

McDonnell accepted on 15 January the initial F-101A letter contract offered by the Air Force on condition that the final contract would be of the fixed price, incentive type. The Air Force accepted McDonnell's terms and signed such a contract on 11 June 1952. Cost increases, judged excessive by the Air Force, led to a renegotiation of the contract. It was finally concluded in November 1956 as a modified fixed price incentive contract, in which the cost ran about 5 percent more than the target cost. McDonnell made neither the 10 percent maximum profit, nor the 8 percent target profit permitted by the original F-101 contract. The contractor's profit reached 6.85 percent of the total cost, or about as much as a cost plus fixed fee contract would have allowed. Other F-101 contracts followed almost the same buying pattern. As with the original model, the manufacturer began production under a temporary letter contract which was later replaced by a more formal, negotiated agreement. The Air Force endorsed the LC procedure only to make sure that the contractor's work would not be delayed by time consuming negotiations.

McDonnell proposed building and testing the first 33 F-101As as 6.33 g (One g is the measure or value of the gravitational pull of the earth or of a force required to accelerate or decelerate at the rate of 32.16 feet per second per second any free moving body.) airplanes; then making necessary modifications on the next 30 airplanes to bring them up to the 7.33 g strength requirements specified by GOR 101. The Air Force agreed in principle, but negotiations over design details for making the Voodoo a strategic fighter one that could not only escort bombers but also could act as an atomic bomber and at all times be able to engage in air to air combat were to consume almost another 2 years.

The mockup inspection occurred on 21 July 1952. The Air Force Board approved close to 90 requests for alteration, half of which concerned items required by contract and, therefore, mandatory on the first airplane. This first inspection was supplemented in the following 12 months by several others, including that of an atomic weapons mockup held on 17 and 18 March 1953.

The Air Force decided that release of FY 54 funds allocated to the F-101 would be held in abeyance until the end of the Category II flight tests, then expected to be sometime in March 1955. This suspension of funds resulted in a postponement of mass production. The armistice in Korea enabled the Air Force to move more deliberately in committing itself to a particular design. This less frenzied approach was dubbed the "fly before you buy policy," a catchphrase that accurately reflected the shift of emphasis from a crash production to a peacetime, more economical research and development program.

The aircraft was delivered as programmed in early 1952.

The aircraft was flown on 29 September 1954 at Edwards AFB through the programmed flight test profile with encouraging results and attained Mach 1.07 in dive. Three other F 101As were accepted by the Air Force before the end of the year. They immediately began to undergo Category I flight tests.

The Air Force lifted its production hold order on 28 October 1954 and gave McDonnell an early 1957 operational deadline.

Category II flight tests, started in January 1955, confirmed deficiencies first identified during the Category I flight tests of late 1954. Foremost in the problems encountered, and which proved to be much more difficult to overcome than anticipated, were the compressor stalls of the two Pratt & Whitney J57-P-13 turbojet engines (that had replaced the less powerful J-43-WE-22 engines of the F-88 prototypes and the aircraft's tendency to "pitch up." Despite ensuing corrective efforts, by mid 1956 the continued testing of 29 F-101As thus far accepted by the Air Force showed a number of still unsolved structural, propulsion, aerodynamic, and armament problems.

McDonnell's failure to fix the aircraft's malfunctions led the Air Force once again to halt production in May 1956. The hold order was of short duration, but the F-101A production and that of the aircraft's reconnaissance version remained limited to a total of eight airplanes per month through the end of October 1956.

In September 1955 McDonnell had informed the Air Force that F-101A production had proceeded much faster than the test program so that the two were out of phase. Contrary to past expectations, it would be impossible to get a 7.33 g F-101 from the production line prior to production of the 116th airframe. The 115 6.33 g airframes built, including those of the aircraft already accepted by the Air Force, could still be brought up to the 7.33 8 load specification of GOR 101, but they would have to be torn down and practically rebuilt. Furthermore, so much redesign work would be necessary that most of the 7.33 g airplane parts would not be interchangeable with the parts of the former 6.33 g aircraft. After investigating every possible modification, including cost and time required, the Air Force decided in June 1956 that it would accept the 6.33 g aircraft. When accepted, this type of aircraft would not be able to engage in aerial maneuvers at a gross weight in excess of 37,000 pounds. The immediate concern, however, was to get an aircraft that would meet even these reduced operational requirements.

Three months after the June decision to accept the 6.33 g aircraft, Headquarters USAF approved designation of the 7.33 g F-101 as the C model series. Except for one aircraft used in development of the F-101's interceptor version, all 6.33 g aircraft received the A suffix assigned to the initial F-101s and to their reconnaissance counterparts.

Since the end of May 1956 McDonnell had been running a modification rather than a production line, incorporating more than 300 Air Force approved design changes and some 2,000 engineering improvements of its own in the aircraft that were in production. Although the first of these modified aircraft would not be ready for delivery before the end of November, it looked as if the contractor was finally getting a fix for pitch up, the most serious deficiency of the aircraft and the one that took longest to correct.

Satisfied with the active inhibitor (pitch up device) installed by McDonnell, the Air Force decided that production for the combat inventory could proceed and completely rescinded the May production restrictions. The decision marked the conclusion of a 3 month review of the entire F-101 program, including funding, schedules, requirements for the aircraft, and any alternatives available to the Air Force.

The Air Force final endorsement of the F 101 was accompanied by several changes. The peak production rate projected for the Voodoo interceptor and the F 101A program was reduced, with the last 96 F 101As scheduled to be converted to the reconnaissance configuration. This conversion was associated with an accompanying decision to delete the RF 104 and RF 105 from the Air Force budget. Reduction of the F 101A program also reflected the impact of SAC's 1954 cancellation of its original requirements, the forthcoming reassignment of the aircraft, the 7.33 g F 101Cs included, to the Tactical Air Command, and TAC's mild enthusiasm toward its new acquisitions. Initially developed as a strategic penetration fighter, intended to escort SAC bombers and therefore designed to operate from permanent installations, the F 101A, as well as the F 101C, would be difficult to adapt to TAC's doctrine of dispersal because their weights and takeoff/landing needs would not permit them to deploy to or from temporary or hastily prepared runways. Too, the F 101A and .F 101C were only nuclear fighter bombers, incapable of delivering conventional bombs.

The first acceptance (production aircraft) came on 2 May 1957. This was the 41st F-101A built, but the first one accepted for the operational inventory.

The aircraft became operational at Bergstrom with the 27th Fighter Bomber Wing, a SAC unit which, like the aircraft, was to be transferred to TAC on 1 July 1957. The whole complement of F-101As were used ultimately to equip three squadrons of TAC's 81st Tactical Fighter Wing.

Other Configurations of the F-101A included the RF-101A, F-101C, RF-101C, RF-101G, and RF-101H.

End of Production came on October 1957 With the delivery of the last seven aircraft.

A total Of 77 were accepted, only 50 reached the combat forces. The others, referred to as "preproductions," were allocated to the experimental and test inventory.

Fifteen F101As were accepted in FY 55, 14 in FY 56,13 in FY 57, and 35 in the first 4 months of FY 58.

Flyaway Cost Per Production Aircraft was $2,906,373.00--airframe, $2,364,143; engines (installed), $429,016; electronics, $25,249; ordnance, $15,300; armament, $72,665.

Average Maintenance Cost Per Flying Hour was $362.00

Phaseout occured from 1966-1970. The F-101A began leaving the USAF inventory in 1966, when 27 of the aircraft were transferred to the Air National Guard. By mid 1970, several major flying accidents, the cannibalization of a dozen aircraft, and a number of conversions accounted for the rest of the F-101As.

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Page last modified: 07-07-2011 02:29:58 ZULU