The McDonnell F-101 Voodoo twin-engined fighter was originally designed as a long range escort fighter to accompany the bombers of the Strategic Air Command if they were ever called upon to carry out their mission of nuclear strike against the Soviet Union. The Voodoo was destined never to serve in this particular role--it eventually emerged as a tactical reconnaissance aircraft, as a long-range interceptor, and as a nuclear strike aircraft. It was the first production fighter capable of exceeding 1000 mph in level flight. Only the reconnaissance version ever saw combat, flying the fastest combat missions ever flown (with the exception of the SR-71) during flights over North Vietnam. However, it was not without its flaws--in all its versions, the Voodoo had a tendency to pitch up into a nose-high attitude without warning, a problem which was caused by the way in which air flowed over its wings and under its high tail.
The earlier McDonnell F-88 escort fighter had been unsuccessful in attracting any production orders, since the Air Force had assumed that the high performance of the B-47 and B-52 jet bombers would make escort fighters unnecessary in any future conflict. However, during the Korean War, the USAF had found that the Republic F-84 Thunderjet fighters escorting streams of B-29 bombers attacking targets along the Yalu River in North Korea were incapable of protecting their charges against attacks by the faster MiG 15. The more capable F-86 Sabre lacked the range and endurance to provide effective escort. In order to meet this critical need for an effective long-range escort fighter, the USAF had originally planned on using the Republic F-84F Thunderstreak. However, the Strategic Air Command (SAC) also wanted a much longer-range escort fighter, one with sufficient range to accompany the Convair B-36 intercontinental bomber on its missions. In February 1951, the USAF issued a requirement for a fighter to fill this need.
Lockheed, North American, Northrop, Republic, and McDonnell all submitted proposals. Lockheed submitted both the F-90 and the F-94, North American resubmitted the F-93, and Northrop proposed an escort version of the F-89 Scorpion all-weather interceptor. Republic came up with three separate submissions, the F-91 Thunderceptor, the F-84F, plus another version of the F-84F powered by a turboprop engine. As its entry, McDonnell proposed a larger and more powerful version of its XF-88 penetration fighter prototype.
The McDonnell submission was judged the winner of the competition in May of 1951. In October of 1951, the USAF released fiscal year 1952 funds previously allocated to the F-84F and F-86F program to get McDonnell's proposal into production right away. A program similar to that used in the development of the F-100 Super Sabre was to be employed, one in which the ordinary prototype stage in development would be completely skipped and full production be instituted right from the start. As the initial production aircraft rolled off the line, they would be tested and any changes deemed necessary would be introduced on later aircraft to come off the line. It was hoped that this strategy would get the new fighter into service as quickly as possible. This was a high-risk strategy, one which would give the Air Force a new plane in a hurry if everything went as planned, but one which would risk the high costs and long delays of a lot of in-service modifications should unexpected problems turn up during flight testing. However, considering that the McDonnell proposal was basically a scaled-up XF-88 rather than a truly "new" design, the risks were considered minimal.
On November 30, 1951, the new and improved F-88 was assigned the designation F-101. A Letter of Intent for the development of the McDonnell proposal was issued on January 3, 1952.
In December of 1951, the McDonnell team lead by Edward M. Flesh recommended that the F-101 be powered by a pair of afterburning Allison J71 turbojets. This nearly tripled the thrust of the pair of Westinghouse J34s that had powered the XF-88A, and was twice the thrust of the Westinghouse J46s proposed for the production F-88.
However, the Air Force thought that even this additional power was still not enough, and was in favor of using a pair of even more powerful Pratt & Whitney J57 afterburning engines. Unfortunately, the use of the more powerful J57 engines required some major design changes. Although the engines were to be placed in the same location as they were in the XF-88, the air intakes in the wing roots had to be redesigned and considerably enlarged to accommodate the increased air flow requirements. Since considerably more fuel had to be carried, the fuselage had to be lengthened and widened, increasing the internal fuel capacity more than threefold (2341 versus 734 US gallons). Provisions were made for the fitting of a pair of 450-gallon external tanks.
As compared to the XF-88, the all-movable tailplane was moved almost to the top of the vertical tail. The wing area was increased from 350 to 368 square feet, obtained by increasing the chord of the inboard half of each wing panel. The thickness of the wing was reduced, and the ailerons were moved further inboard.
The pressurized cockpit was enclosed by a clamshell-type cockpit canopy, and the pilot was provided with an ejector seat. Rear fuselage airbrakes and a braking parachute were fitted in order to enable the plane to land on shorter runways.
Provisions were made to accommodate both types of flight refuelling systems in use by the USAF. A retractable fuelling probe was to be mounted in front of the cockpit and a refuelling boom receptacle was to be installed on top of the center fuselage.
The F-101A was to be equipped with APS-54 radar and was to be armed with four 20-mm cannon as well as three Falcon air-to-air missiles and 12 unguided rockets. For ferrying purposes, the ammunition for the four 20-mm cannon could be replaced by a single 226-gallon auxiliary fuel tank.
The mockup was inspected in July of 1952. On May 28, 1953, the USAF issued an initial contract for 39 F-101As. No prototypes were specified, since the usual prototype stage was being skipped altogether.
The coming of peace in Korea in July of 1953 removed some of the sense of urgency connected with the F-101 program. By this time, the USAF had changed its mind and wanted McDonnell to redesign the aircraft so that it could not only carry out the originally-planned long-range escort mission but could also carry out nuclear strike missions. In May of 1954, the Air Force got cold feet about the wisdom of going directly into production with the F-101A and withdrew its authorization to proceed with quantity production and decided to wait until Category II flight tests could be carried out and all the required changes could be made. The target date for the completion of these tests was set for sometime in March of 1955.
The first F-101A (53-2418) was delivered in August of 1954, right on schedule. After completing some ground trials in St. Louis, it was shipped out to Edwards AFB. It took off on its maiden flight on September 29, 1954, McDonnell test pilot Robert C. Little being at the controls. He reached Mach 0.9 at 35,000 feet. Less than a month later, maximum speed had progressively been pushed to Mach 1.4.
In the meantime, the USAF had changed its mind yet again about its requirements. They now concluded that the range of the F-101A, impressive as it was, was not nearly large enough to be able to escort SAC's bombers all the way to the target. Consequently, the Strategic Air Command no longer believed in the viability of the F-101 concept and lost any interest in the aircraft as an escort fighter. Ordinarily, this would have been the end of the line for the F-101A project, and the F-101 would have been consigned to oblivion along with its XF-88 predecessor. Fortunately, the Tactical Air Command (TAC) saw the potential of the aircraft as a nuclear-armed fighter-bomber and requested that the F-101A be acquired by them under the aegis of Weapon System WS-105A. This designation corresponded to a short-lived Pentagon fad of assigning a "WS" number to its ships, tanks, and aircraft. Consequently, the F-101A that finally emerged became a hybrid aircraft, fitted with APS-54 radar and a MA-7 fire-control system for the air-to-air role, and a LABS (Low-Altitude Bombing System) for the delivery of nuclear bombs.
On October 28, 1954, the Air Force lifted its production hold order, permitting McDonnell to proceed with full-scale production. Three other F-101As were accepted before the end of 1954. They immediately began to undergo Category I flight tests. Category II flight tests began in January of 1955, and at this time, problems appeared with engine compressor stall. A redesign of the internal intake layout and engine compressor modifications cleared up these problems.
By mid-1956 the continued testing of the 29 F-101As which had been accepted by the USAF up to that time had turned up a number of structural, propulsion, aerodynamic, and armament problems. Perhaps the most serious of these was a tendency of the aircraft to pitch-up, a problem which was never fully corrected even after much effort. Brigadier General Robin Olds, who commanded a Voodoo wing, reported that it did not take very much to make a F-101A suddenly and without warning to go into pitch-up, even while cruising. The angle of attack needed to achieve lift with full flaps and drop tanks was very close to the pitch-up stall point, where the flow of air over the wings created a downflow over the tail slab. On January 10, 1956, Major Lonnie R. Moore, a Korean War ace with 10 kills to his credit, was killed in a F-101A pitch-up mishap at Eglin AFB, Florida.
Citing numerous still-unsolved problems with the F-101, in May of 1956 the USAF ordered that production be halted yet again. Although the hold order did not last very long, F-101A production remained limited to only eight airplanes per month throughout most of the remainder of 1956. During this period, McDonnell spent most of its time in modifying existing F-101As rather than in building new ones. Some 300 USAF-recommended changes were incorporated, plus some 2000 company-devised improvements.
It took a long time for McDonnell to develop any sort of cure for the pitch-up problem. McDonnell fitted an active inhibitor which helped to clear up the pitch-up problem, at least partially. Satisfied with the active inhibitor installed by McDonnell, the Air Force finally rescinded its May production restrictions on November 26, 1956. Nevertheless, the pitch-up problem was never completely cured, and remained a nuisance throughout the Voodoo's service life. Also never resolved was a problem encountered in retracting the forward-folding nosewheel--beyond a speed of about 90 mph, it simply would not go up.
The F-101A was armed with four 20-mm cannon and could carry a single 1620 lb or 3271-lb "special store", i.e., a nuclear bomb. The F-101As were equipped with the MA-7 fire control system as well with the LABS (Low-altitude Bombing System) for toss-release of their nuclear bombs. The F-101A could not carry or deliver conventional bombs.
The first Voodoo delivered to an operational unit was a F-101A which reached the 27th Strategic Fighter Wing at Bergstrom AFB on May 2, 1957. The last of 77 F-101As was delivered on November 21, 1957. Of the 77 F-101As accepted, only 50 of them actually reached operational units. The rest were used for experimental and test purposes to iron out various bugs and never attained actual service.
On July 1, 1957, the 27th Strategic Fighter Wing was transferred to the Tactical Air Command and became the 27th Fighter-Bomber Wing. The Wing had previously operated the F-84F Thunderstreak. The F-101A was assigned the mission of nuclear strike, carrying a single nuclear bomb on its underfuselage centerline.
On September 25, 1958, an F-101A flew 1896 miles between Carswell AFB in Texas to Bermuda, completing the longest nonstop/nonrefuelled flight yet accomplished in a Century Series fighter.
Once the problem with the tendency to pitch-up had been addressed by the installation of an active inhibitor, the F-101A established an excellent safety record. In fact, the F-101A had the lowest first-year accident rate of any operational fighter in Air Force history.
The F-101A began leaving the USAF inventory in 1965-66, when 27 of them were transferred to the Air National Guard. By mid-1970, accidents, transfers, cannibalizations, and conversions had whittled down the USAF's F-101A fleet to only a couple of planes.
The ninth F-101A (53-2426) was bailed to Pratt & Whitney to serve as a testbed for the more powerful J57-P-55 engines planned for the F-101B interceptor. It was given the designation JF-101A, the "J" prefix indicating a temporary change of configuration for test purposes. The new engine installations offered an afterburning thrust of 16,000 pounds, and featured a large extension of the jetpipe to accommodate the longer afterburner section. Additional air scoops were installed underneath the rear fuselage for afterburner cooling. The JF-101A was used by Major Adrian E. Drew to set a new absolute world speed record of 1207.6 mph on December 12, 1957, taking the record away from the British Fairey Delta FD-2.
The first F-101A was bailed to General Electric in 1958 as a testbed for the J79-GE-1 turbojet. The designation NF-101A was assigned to this modification, the N prefix indicating a permanent change in configuration for test purposes. This aircraft was test flown with two J79s in 1958-59 before being retired to Amarillo AFB in Texas as a ground maintenance trainer.
Following their removal from active USAF service in 1965, twenty-nine ex-USAF F-101As (serial numbers 54-1445, 1449, 1451, 1452, 1453, 1454, 1455, 1457, 1459, 1460, 1461, 1462, 1463, 1464, 1466, 1468, 1469, 1470, 1472, 1473, 1475, 1476, 1477, 1479, 1481, 1482, 1484, and 1485, plus two others whose serials I don't know) were modified by Lockheed Aircraft Service Company of Ontario, California to serve as unarmed reconnaissance aircraft by the Air National Guard. The armament was removed and new nose cones housing cameras were installed. These aircraft were redesignated RF-101G. As compared to the RF-101A dedicated photo-reconnaissance version of the F-101A, the RF-101G had a shorter and broader nose. Along with the RF-101H (an equivalent conversion of the F-101C), they served with the 154th Tactical Reconnaissance Squadron of the Arkansas ANG, with the 165th TRS of the Kentucky ANG, and the 192nd TRS of the Nevada ANG. Beginning in 1970, these aircraft were supplemented by RF-101Cs retired from active USAF stocks. The last reconnaissance Voodoos were withdrawn from ANG service in 1979.
Serials of F-101A:
53-2418/2422 McDonnell F-101A-1-MC Voodoo 2418,2421/2425,2427 converted to JF-101A 53-2423/2430 McDonnell F-101A-5-MC Voodoo 53-2431/2436 McDonnell F-101A-10-MC Voodoo 53-2437/2446 McDonnell F-101A-15-MC Voodoo 54-1438/1443 McDonnell F-101A-20-MC Voodoo 54-1444/1452 McDonnell F-101A-25-MC Voodoo 1445 converted to RF-101G 1449 converted to RF-101G 1451,1452 converted to RF-101G 54-1453/1465 McDonnell F-101A-30-MC Voodoo 1453/1455 converted to RF-101G 1457 converted to RF-101G 1459/1464 converted to RF-101G 54-1466/1485 McDonnell F-101A-35-MC Voodoo 1466 converted to RF-101G 1468 converted to RF-101G 1470 converted to RF-101G 1472,1473 converted to RF-101G 1475/1477 converted to RF-101G 1479 converted to RF-101G 1481,1482 converted to RF-101G 1484,1485 converted to RF-101G
Specification of the F-101A:
Engine: Two Pratt & Whitney J57-P-13 turbojets, 10,200 lb.s.t. dry and 15,000 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 1009 mph at 35,000 feet. Initial climb rate 44,100 feet/min. Service ceiling 55,800 feet, combat ceiling 49,450 feet. Normal range 1900 miles, maximum range 2925 miles. Weights: 24,970 pounds empty, 48,120 pounds gross, 39,495 pounds combat weight, 50,000 pounds maximum takeoff. Fuel: Maximum internal fuel load was 2341 US gallons. A total of three under-fuselage drop tanks could be carried, bringing maximum fuel load to 3467 US gallons. Armament: Four 20-mm Pontiac M-39 cannon in the nose with 200 rpg. A single "special store" (i.e., nuclear bomb) could be carried on the underfuselage centerline.
Sources:
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McDonnell Douglas Aircraft Since 1920: Volume II, Rene J.
Francillon, Naval Institute Press, 1990.
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The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston,
Orion, 1988.
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United States Military Aircraft Since 1909, Gordon Swanborough and
Peter M. Bowers, Smithsonian, 1989.
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The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.
-
Fighters of the United States Air Force, Robert F. Dorr and David
Donald, Temple Press Aerospace, 1990.
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American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
-
Post-World War II Fighters, 1945-1973, Marcelle Size Knaack, Office of
Air Force History, 1986.
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McDonnell F-88/F-101 Voodoo Variant Briefing, Robert F. Dorr, Wings
of Fame, Vol 1, 1996.
- E-mail from Al Vermeulen with correction on the number of RF-101Gs. Swanborough and Bowers list 18 serial numbers converted, whereas Dorr and Francillon both list 29. In addition, there was a problem with the number of JF-101A conversions. Swanborough and Bowers list 7 JF-101A conversions, whereas Dorr and Francillon both list only one, the Adrian Drew plane.
