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F-111 Aardvark

History

Boeing won all four stages of the competition, but McNamara overruled the source selection board. After extensive study of the recommendations of a joint Air Force-Navy evaluation board, McNamara decreed on 24 November 1962, that the General Dynamics and Grumman Team would build the TFX.

In 1963, political turmoil surfaced as a special Senate subcommittee chaired by Senator McClellan of Arkansas held hearings on the award of the TFX Program. The decision, based on cost-effectiveness and efficiency considerations, irritated the chief of naval operations and the Air Force chief of staff, both of whom preferred separate new fighters for their services and Boeing as the contractor. Under the new management policies of Defense Secretary Robert McNamara and the "flexible response" military strategy of Joint Chiefs of Staff chairman Gen Maxwell D. Taylor, Air Force Chielf of Staff Curtis E. LeMay found himself at constant odds. In his four years as chief, LeMay argued strenuously for new air weapons like the Skybolt missile and B-70 bomber, and against the swingwing "fighter" plane, the General Dynamics TFX. He lost all these battles.

As a result of a poorly thought-out development specification, both the Navy and Air Force had become committed, much against their will, to the civilian-inspired TFX program. The program was designed to save $1 billion in development costs by using a common airframe to fulfill the Navy's fleet air-defense fighter requirement and the Air Force's long range nuclear and conventional tactical fighter requirement. In retrospect, this was impossible to achieve, especially since planners placed priority upon the Air Force requirement, and then tried to tailor this heavy landplane to the constraints of carrier-based naval operations.

On December 19, 1962, representatives of General Dynamics and Grumman visited NASA Langley for discussions of the supersonic performance of the F-111. The manufacturers were informed that the supersonic trim drag of the aircraft could be significantly reduced and maneuverability increased by selecting a more favorable outboard wing-pivot location. Unfortunately, the manufacturers did not act on this recommendation, and it was subsequently widely recognized that the F-111 wing pivots were too far inboard. (It should be noted that the F-14 designers, aware of this shortcoming, designed the F-14 with a more outboard pivot location.) The F-111 subsequently exhibited very high levels of trim drag at supersonic speeds during its operational lifetime.

The first F-111A flew in December 1964, and the first F-111B flew in May 1965. The most positive result from early flight evaluations was the very satisfactory behavior of the variable-sweep wing system. However, the aircraft were judged to be sluggish and underpowered. Furthermore, the engines exhibited violent stalling and surging characteristics.

As concern over the aerodynamic performance of the F-111 increased in 1964, it was also suggested that the wing with the longer span of the Navy aircraft be used on the Air Force aircraft. During 1965 Grumman discussed methods of improving the acceleration and maneuverability of the Navy F-111B. Modifications considered by Grumman included modified wing and pivot location, a straightened tailpipe, and an improved interengine fairing. In addition, Grumman examined a modified horizontal tail, alternate missile arrangements, and an aft-fuselage modification. Although these modifications never came to fruition for the F-111B, the discussions had a large impact on the later design of the F-14 by Grumman, which became an outstanding Navy aircraft.

Unfortunately, the naval F-111B configuration was too long to met the requirements for aircraft carrier elevator spotting (compatibility of the aircraft dimensions with the elevator on the aircraft carrier that transports aircraft to and from the flight deck and the lower hangar area).

The early F-111A exhibited numerous engine problems, including compressor surge and stalls. NASA was a participant in finding solutions to these problems, as its pilots and engineers flew test flights of the aircraft to determine inlet pressure fluctuations (dynamics) that led to these events. Eventually, as a result of NASA, Air Force, and General Dynamics studies, the engine problems were solved by a major inlet redesign.

Because of high cost overruns, trouble in meeting performance objectives, flight test crashes, and difficulties in adapting the plane to Navy use, the TFX's future became more and more uncertain. In 1968, the Navy TFX program was canceled due to the test aircraft's poor performance and incompatibility with carrier operations. After 1968, the Air Force was left with a TFX design that was compromised by McNamara's original commonality requirement. Ultimately, the Air Force fielded the TFX as different variants of the F-111 at five times the planned unit cost per airframe. The aircraft never developed all the performance capabilities proposed in the original program. The problems with the TFX can be directly attributed to the restrictions and requirements imposed by the common development program. Some of McNamara's critics in the services and Congress labeled the TFX a failure, but versions of the F-111 remained in Air Force service two decades after McNamara decided to produce them.

By far the most sophisticated design of its time, the F-111 pushed the state of the art and, in doing so, it opened up a Pandora's box of surprises. For example, integrating all of those new little black boxes, in a "fly-fix-fly" fashion, proved to be an extremely laborious and, more important, time-consuming process. And this was only one of many problems encountered in the program.

Secretary McNamara's reach exceeded his grasp. The contrast between his success with the F-4 (an operational Navy fighter that McNamara persuaded the Air Force to buy by refusing to authorize purchase of any more F-105's) and his failure with the F-111 is instructive. In the first, he could get what he judged best for the nation by saying: no. In the second. his affirmative decision amounted to an order, the accomplishment of which depended on actions over a period of many years by individuals and organizations, semi-independent of his control, with objectives different from his. By stopping Air Force purchase of F-105's, and offering the Air Force F-4's if they liked, McNamara had leverage. In telling the Air Force and Navy to develop an aircraft jointly (the thought of which they abhorred) for a limited war mission (which TAC regarded as secondary), McNamara asked for too much. The principal power of a Secretary of Defme (and Secretaries in other departments) is the power to say no.



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