McDonnell's detail design of a strategic penetration fighter intended to escort bombers of the recently established-21 March 1946-Strategic Air Command. The Air Force ordered two prototypes of McDonnell's original Voodoo under the designation XF-88. The first XF-88 flew on 20 October 1948, some 6 months after the contracted delivery date. This initial slippage, the contractor claimed, was the result of changes in the prototype's structural design. The change from straight wing to a 35-degree wing-swept back, along with the danger of compressor stalls at high speed, caused McDonnell engineers to alter the shape of the ducts through which air entered the turbine engines. The second XF-88, with short afterburners boosting the thrust of its J--43-WE-22 engines, did not fly until 2 years later.
The Air Force cancelled the XF-88 contract a few months after the second prototype's first flight. The decision was due primarily to the shortage of funds that had been forewarned by President Truman in mid-1948 and to the United States endorsement of defense plans brought back from Europe by Secretary of Defense James V. Forrestal in the fall of the same year. These plans, urging greater use of the atomic bomb, meant that more atomic power had to be packed into SAC's forces. Hence, most of the Air Force money was spent on the B-36, one of the bombers that the F-88 had been designed to escort. Although the F-88 had failed to perform satisfactorily in its intended roles of escort fighter and ground support plane, many desirable qualities were attributed to its prototypes. Nevertheless, there were other reasons for cancelling production. A significant number of Republic's F-84Es, under contract since late 1948, had already entered USAF inventory and could satisfy immediate requirements for a penetration fighter. Moreover, a new model series of the proven North American Sabre, the F-86D-flown in December 1949-was expected to meet the urgent requirements for a better interceptor.
The Air Force, pending development of a new fighter, planned to replace the F-84E with the F-84F, the production of which had been decided. SAC, however, did not support these plans and wanted a long range fighter capable of escorting the transoceanic B-36s. On 12 January SAC outlined the minimum characteristics of the interim aircraft needed for the period 1952-1953. Headquarters USAF agreed to evaluate several contractor offers which might more nearly satisfy SAC.
The general operational equirements of 6 February 1951, published as Skeleton GOR 101, was subsequently expanded as GOR 101-2 to cover the aircraft's next model series. Both GORs were cancelled in November 1958, when the Air Force decided to terminate the F-101 production--the F-lO1B interceptor, excepted. New requirements, if any, would be met by modifying existing F-101s.
Included in the contractor's offers in response to GOR 101 were Lockheed's F-90 and F-04, an improved configuration of the McDonnell F-88, North American's F-93, Northrop's improved F-89, and three Republic . submissions the F 91, the already purchased F-84F, and another version of the F-84F that would be equipped with a turboprop engine. McDonnell's new F-88 was chosen, but the Air Force did not commit itself to go to production until several months later.
The October production decision was the result of Korean War experiences. Existing fighters had proved unsatisfactory as escorts for B-29s. Between June 1950 and September 1951, American pilots flew a mix of fighters and downed 13 Russian-built MIGs for every plane lost, a ratio reflecting superior flying skill rather than better equipment. The Air Force thus found itself facing two problems: development of a satisfactory escort fighter and replacement of the F-84s and F-86s used in Korea. In October 1951, it released fiscal year 1952 funds, previously allocated to the F-84F and F-86F aircraft, to get McDonnell's new F-88 into production without further delay. Moreover, instead of procuring the Voodoo solely as an interim fighter while an "ultimate" long range fighter was being developed, the Air Force decided that the latter would be obtained by improving early Voodoo productions. The first production aircraft would have the same airframe as the "ultimate" series, but the first aircraft would only incorporate "available" production-type equipment, systems components, and engines. Then, as more advanced equipment became available, the airframes would be modified to receive them.
The Cook-Craigie production policy (26 November 1951), outlined for the Convair F-102, was extended to the new Voodoo. This meant that the initial production run of the basic aircraft would be kept to the minimum needed for comprehensive testing. While these aircraft were being assembled, preparations would be made for full scale production of a version that would incorporate the changes judged necessary because of the test program. The test airplanes already produced would then be reworked on the production line into the approved configuration. The leading objectives were to eliminate the faults in a basic design before many aircraft had been built and to get operationally effective weapon systems into tactical use as quickly as possible.
The improved Voodoo bore the designation F-101. The Air Force Council directed the new designation because of the significant differences between the F-88 and the new configuration proposed by McDonnell in May 1951.
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