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XF-88 "Voodoo"

After World War II, attempts to create an American fighter aircraft to escort their bombers ended in nothing. A number of different proposals were considered to increase the range of fighter. A few experiments were conducted on bombers towing the jet fighters P-80 and P-84, but it was a little tricky and difficult to implement in practice. The fighter XF-85 "Goblin" was created in the late 1940s, but achieved little success due to the complexity of the mooring bomber. Then there were such long-established fighters like the P-81 with a combined power plant, and the XP-83 with plenty of fuel on board. But they were built only as prototypes.

The XF-88 was designed to fill a USAF requirement for a "Penetration Fighter", a new class of aircraft for long-range escort of USAF bombers. First flight was on 29 October 1948. This was McDonnell's detail design of a strategic penetration fighter intended to escort bombers of the recently established - 21 March 1946 - Strategic Air Command. Designed as a penetration fighter to operate deep within enemy territory against aircraft and ground targets, the new jet fighter, the McDonnell XF-88, was tested by the U. S. Air Force. The plane had swept-back wings and tail surfaces, weighs approximately 15,000 pounds.

The Air Force in 1946 stated tactical and technical requirements for along-range fighter with a turbojet engine, which could be used to escort Convair (Convair) B-36 bombers. The company McDonnell signed a contract to build two prototypes of the aircraft McDonnell XF-88 February 1947. Under the name "Model 36" the layout of the aircraft included engines installed in the fuselage and air inlets in the wing root, hoping to release a large amount of space under fuselage fuel tanks.

Initially, the project unit was V-shaped. Air Force interest in the project company, and on May 7, 1946 sent a confirmation of the continuation of the work. In the summer, a prototyping Commission, after examining the layout of the fighter, made comments which were taken into account. The front edge of the air intake was changed, before it installed fairing, to prevent ingress of the boundary layer from the fuselage, and the V-tail was replaced by the usual swept.

Following the modifications the US Air Force February 14, 1947 ordered McDonnell to build two prototypes under the designation XP-88. Eighteen months later the prototype, changed by the time designation in the XF-88 Voodoo, was built. The aircraft was delivered to the base at Muroc where October 20, 1948 it made the first flight under the control of Robert Edholma. This was 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.

Flight tests revealed minor problems. The motors installed on the machine were clearly not enough because the S-shaped inlet duct. The contractor partially solved this problem by setting a spring-loaded flap channel. Due to the lack of speed of the aircraft, there was increased roll chord ailerons and wing stiffness. The flight buffeting led to restricted deviations of the air brakes. The resulting improvements have improved the handling of the aircraft, but because of the large take-off weight flight performance proved unsatisfactory. Shows the maximum airspeed was lower than the mass of the F-86 "Sabre", and the range was insufficient. Involves the installation of additional fuel tanks on the wing tips sharply deteriorated manuverability of the aircraft.

These flight data for the fighter clearly did not meet the Air Force requirements. The company "Westinghouse" could not modify the engines, so the company "McDonnell" had to do it itself. In the second experimental XF-88A aircraft uprated engines XJ34-WE-15 of the company "Westinghouse" were installed. To increase the range of flight in a wing equipped with additional fuel tanks, which increased the fuel capacity to 3160 kg. Flight data improved, but not by much. As a result, fuel consumption has increased substantially, but the plane could develop in a dive speed of more than M = 1.

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.

To determine the order for long-range escort fighter, the Air Force held a contest fighters of different firms. The competition involved three aircraft: XF-88A company "McDonnell"; XF-90 the company "Lockheed" and XF-93A company "North American." The Air Force gave preference to the fighter of the company "North American", which received the order. Due to lack of funds to finance the work and change the priority in the construction of interceptors and strategic bombers order on the F-88 was canceled.

Work on the XF-88 fighter Voodoo was continued by "McDonnell". In the summer of 1950, the Air Force conducted a comparative flight test involving the same three firms. This time the winner was the fighter XF-88A, but it did not receive the order because of the outbreak of the Korean War.

The F-88 was a monoplane with low / mid-swept wing and swept tail, elongated (extended) fuselage and two turbojet engines Westinghouse (Westinghouse) XJ34-WE-13 thrust of 1361 kg (3000 lb). The second prototype XF-88A was equipped with turbojet engines reheat XJ34-WE-22.

The twin-engine fighter McDonnell XF-88 was equipped with axial turbojets Westinghouse J-34 1360 kg thrust. Air intakes were in the wing root. The engines were placed at the bottom in the rear fuselage. This unusual arrangement of the engines in the fuselage freed space for considerable reserves of fuel, which is required for the first jet engines. Although the prototype was unarmed, it was possible to install six 20-mm cannon in the forward fuselage XF-88 had swept wing and stabilizer at 35. This wing was installed instead of the anticipated direct wing.

Prototyping Commission was held in August 1946 at Lambert Field. The structure was further amended before 14 February 1947 a contract was signed the AS-14582. The contract provided for the release of two experimental XF-88. Work on them began immediately after signing the contract.

At the end the first XF-88 (46-525) was transferred to the Air Force test center on the Muroc dry lake. The first flight was successfully accomplished 20 October 1948. However, the project fell on hard days, not only because of the lag in the six months to the first flight. Even more unpleasant was that the characteristics obtained in Phase I trials were much lower than expected, although the handling was good, and the necessary range has been reached. The main problem was the low engine thrust to raise the maximum speed of the second Voodoo (46-526) installed engines XJ-34-WE-22 with afterburner of thrust to 1633 kg.

Under the new designation XF-88A - a second prototype made its first flight in 1950. Increased fuel consumption reduced range. However, the testing continued until June 1950, when they were formally completed.

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.

The introduction of jet engines into the Air Force after World War II reveals that the military invested in a number of prototypes, or even in numbers of different types of operational models, before the technology is proven in operations. Aircraft powered by these engines can be divided into three categories. The first category consists of experimental aircraft built to test a new design or concept, such as the Bell X1 series aircraft designed to break the sound barrier. The second category includes aircraft built as part of a development program, such as the XF88 McDonnell penetration fighter of 1946. Though such aircraft were never produced for actual service use, tests on them helped jet propulsion technology mature. The third category consists of operationally fielded aircraft, such as the F101.

The F-101 Voodoo was an improved version of the XF-88 aircraft to escort bombers. Strategic Air Command aircraft expected to get support from long range. But despite all efforts, the F-101 could not achieve this. When it became clear that wishful thinking, it was decided that the satisfactory evaluation tests will be made an order for the production of this aircraft for the Tactical Air Command.

The mission was changed to a nuclear-armed fighter-bomber (strategic fighter) and the XF-88 was redesigned as the F-101 Voodoo that had its first flight on September 29, 1954. The new design was considerably larger and designed around the more powerful Pratt & Whitney J57 turbojet. The larger engines required modification to the engine bays and inlets (to allow greater airflow to the engine). To alleviate a pitch-up phenomena identified during flight tests of the Douglas D-588-2 Skyrocket (with a control surface configuration similar to the XF-88), the horizontal tail was relocated to the top of the vertical tail, giving the F-101 its signature "T-tail".

The Voodoo's career as a fighter bomber was relatively brief but reconnaissance versions served for some time with extensive service during the Cuban missile crisis and the Vietnam War.

Since the beginning of the Korean War at the US Air Force there was an urgent need for improved fighter escort, as existed in the presence of the aircraft could not compete with the MiG-15, which have been equipped with the Air Force of North Korea and China. It was an order for the The first F-101A fighter flew on September 29, 1954 and demonstrated during the flight supersonic speed.

The successes of the high-speed research airplanes in the late forties had led to thinking at Langley about a possible "propeller research-airplane," and the flight division eventually succeeded in promoting such a project. Aimed primarily at potential long-range military applications, it was developed as a joint effort with the services; the Air Force provided the XF-88B airplane and the test propellers and associated equipment, and the Navy provided the turbojets and the T-38 turboprop engine which was installed in the nose of the XF-88B to power the test propellers.

Unfortunately, this program did not start to produce results until the mid-fifties when interest in high-speed propellers had almost disappeared. Three propellers were eventually tested at flight speeds up to slightly above Mach 1 on the XF-88B . By the time the results were analyzed in 1957, the Subcommittee on Propellers for Aircraft had been disbanded, eliminating a main heading on this subject in the NACA Annual Report. Thus, in the 1958 (Final) NACA Annual Report there was only an obscure reference to these interesting data, the crowning achievement of a difficult and costly project, under the heading "Low-Speed Aerodynamics." Peak efficiency of 80 percent had been measured at Mach 0.95 on a thin "supersonic" propeller, generally confirming the levels indicated in the Langley high-speed wind tunnel programs.

Modification XF-88A
Wingspan, m 12.09
Length, m 16.50
Height, m 5.26
Wing area, m2 35.52
Weight, kg
empty aircraft 5507
normal takeoff 6904
maximum take-off 7460
engine type 2 THD Westinghouse J34-WE-15
Thrust unforced kN maximum 2 x 1633
afterburner 2 x 21 90
maximum speed, km / h
at ground level 103 2
on high 1136
Practical range, km 2795
maximum rate of climb, m / min 2438
Service ceiling, m 12010
Crew 1
Armament: six 20-mm guns



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Page last modified: 01-12-2015 19:17:09 ZULU