THE ALL-WEATHER F-86D

Equally as famous as the day fighter Sabres was the F-86D. No F-86Ds flew in the Korean War although the "D" was in the planning stages at the same time as the F-86A and F-86E. The F-86D was actually designed for a different mission and never intended for use in Korea. Its project engineers were Art Patch and Fred Prill at North American Aviation. The F-86D was also known as Air Force Weapons System 206A.

On March 28,1949, North American's Advanced Engineering Section began design studies on the Sabre Jet to produce an all-weather, "single crew" jet interceptor. On July 19, 1949, $7 million was approved by the Secretary of the Air Force to convert the Sabre into an all-weather interceptor. Developing the F-86D, or Model NA-165, with only one individual controlling the functions of two crew members was a unique departure from previous all-weather interceptors, which had two person crews: one to fly the aircraft and one to handle the enemy interception, and the Air Force at first was hesitant to support the concept. The Sabre's lone pilot was assisted by computers enabling its pilot to complete both functions. An AN/APA84 computer provided electric engine control while an autopilot, a first in Sabre Jets, stabilized the F-86 while intercepting its target. The pilot was free to control the interception using an advanced Hughes Aircraft Corporation EA Fire Control System. The F-86D thus became the first one-person all-weather interceptor. It flew during daylight, at night, and during poor weather.

On October 7, 1949, the United States Air Force allocated $79 million to order two service test YF-86Ds and 122 production Model NA-165 F-86Ds. The YF-86Ds were actually two converted F-86As, serial numbers 50-577 and 50-578. North American completed the conversions at its Inglewood factory. The new design used F-86A-5 wings which were strengthened, along with slats, canopies and forward V-shaped windscreens. The fuselages, however, were noticeably changed. They were extended and deepened to accept a J47-E-1 7 jet engine developing 5,000 pounds of thrust with electronic fuel flow control, another new concept. The engine also had an afterburner which boosted to 6,650 pounds of thrust for short intervals (the -17 engine was later replaced by the improved -17B in production F-86Ds). The vertical tail was also increased in size, and small vortex generators were fitted to the tail section. The most obvious external difference in the F-86D's fuselage was a thirty inch plastic radome placed on the forward fuselage to cover the eighteen 4inch scanner on the new AN/APG-37 search radar. The air intake beneath the radome was correspondingly lowered and widened.

To attack its enemy, the usual six .50 calibre fuselage machine guns were deleted (a first for a single-placed American fighters), and a rectangular shaped vetral tray was installed beneath the lower fuselage under the pilot. This tray (which extended and retracted rapidly during the firing process) housed twenty four 2.7 inch unguided air-to-air "Mighty Mouse" FFAR (folding fin Aerial Rockets) aimed by the Hughes E-4 system. Each rocket was forty eight inches long, weighed eighteen pounds, and had the explosive equivalent of a 75mm shell. The tray was extended only long enough for the missiles to fire and clear. The rockets were more than capable of shooting down enemy bombers. The missiles could be fired six or twelve at a time, or all twenty four at once. The rockets were usually fired within five hundred yards of the Sabre's target.

The F-86D was redesignated F-95A because only 25% of its parts were common to other Sabres. The first F-95A, serial number 50-577 (actually aYF-86D), flew on December 22, 1949 at the hands of Joseph Lynch after over one million engineering hours spent in development. The first production F-86D/F-95A flew on June 8, 1951 piloted by George Welch. It used an all-flying tall without dihedral for better control at higher speeds. The F-95A was redesignated again because it was easier to convince Congress to further develop a proven design than a seemingly new aircraft, and on July24, 1950, the F-95A returned to its F-86D designation, despite the "D" being 2,500 pounds heavier (and many other differences) than the F-86A The F-86D soon became the cornerstone of the United States Air Force's new Interceptor force, developed as a deterrent to the Soviet Union's development of the atomic bomb and strategic bomber forces.

The F~6D comprised five North American Aviation models, the NA-165, NA-173, NA-177, NA-190 and NA-201.The last two were orders made in March 1952 and June 1953. F-86Ds used serial numbers 50-455 to 50-576,50-704 to 50-734, 51-2944 to 51-3131, 51-5857 to 51-6262, 51-274 to 51-505, 52-3598 to 52-4304, 52-9983 to 52-10176, 53-557 to 53-1071,53-3675 to 53-3710, and 53-4018 to 53-440. Later, 406 F-86Ds with J47-G-33 jet engines were briefly called F86Gs. They were redesignated, however, and produced as F86Ds. This jet engine developed 5,550 pounds of thrust or 7,650 pounds with afterburner. A total of 2,504 F-Ds were produced, plus the two prototypes, at an average "fly away" cost of $343,839.00 per Sabre.

The F-6D had a wingspan of 37 feet, 1 inch; an increased length to 40 feet, 3/4 inch; and an empty weight of 13,518 pounds. All "D"s had cockpits painted green. The F-86D could fly at 692 miles per hour at sea level. It cruised at 550 miles per hour. Its time to climb to 40,000 feet was 7.2 minutes. Its service ceiling improved to 49,750 feet with a range of 554 miles. Normal fuel capacity was 608 U.S. gallons, or 848 with droptanks. The tail height increased to 15 feet. The F-86D was equipped with full-power hydraulic aileron and horizontal tail controls with irreversible control. The artificial feel system in the ailerons and horizontal tail remained. Later "D"s used flat windscreens. The F-86D was the first Sabre using a clamshell-style canopy instead of the earlier sliding design. The clamshell canopy opened at a hinged point at its rear and was closed or opened from inside or outside the cockpit. The canopy electrically opened thirty two degrees, but could be manually operated. In an emergency, the canopy was fired up and aft of the Sabre. The seat could be ejected through the canopy if needed. Raising either armrest to the full up position fired a cartridge that jettisoned the canopy. The canopy could not otherwise be opened at speeds over 50 knots.

F-86D production began in 1951, but problems with developing both the E-3 and E-4 onboard electronics led to production delays until spring 1953, although the first "D", serial number 50-455, was accepted in March 1951, and about thirty five early F-86-1s were equipped with the less powerful HughesE-3 system, a forerunner of the E-4 fire control system. F-86Ds were constantly upgraded as newer electronics and better jet engines were developed, both of which had been far behind in develoment. The F-86D-5 was the first to use the EA system, which did not arrive at North American Aviation until December 1951, and which still did not perform correctly. It was not until April 1953 that properly equipped and fully functioning F-86D Sabres began serving with Air Defense Command squadrons. Even at that time, problems with the fuel systems caused additional engine problems, resulting in all F-86Ds being grounded by December 1953 for nearly two months. Additional effort was needed to correct these mounting prolems. This was accomplished under Project Pullout beginning in March 1954. This program cost $100 million and covered 1,128 F-86Ds which needed up to three hundred changes to correct each aircraft.

Following the F-86-5, the -10 had a powered rudder without trimtabs. The D-15 used a single-point refueling location which allowed the inner fuel tanks to be refueled from one receptacle in about five minutes for rapid turnarounds.

F-86Ds were faster than the "A"s, despite the F-86D being heavier. On November 19, 1952, Captain Slade Nash flew an F-86-20, serial number 51-2945, from El Centro Naval Air Station to the Salton Sea, a dry lake bed in southern California. His mission was to break the world speed record set by an F-86A. Captain Nash flew the required four passes over the three-kilometer course at just over one hundred feet setting a new world record at 698.5 miles per hour, breaking the F-86A's record.

The F-86-25 could release its wing tanks in combat, as could other F-86 models. The -30 added an automatic approach control but returned to a manually operated rudder with trlm tabs. The -35 added a VOR set.

On July 16, 1953, Lieutenant Colonel William F. Barns, who was assigned to North American, flew the first F-8D-35, serial number 51-145, over the Salton Sea and set a faster world speed record at 715.7 miles per hour. His "D" was unique because it used wing fences that were not built onto production F-Ds to control the air flow.

The F-8DA-40 added the J47-GE-17B jet engine producing 7,500 pounds of thrust with afterburner allowing the F-86D to climb nearly vertically. The D45 was the first to use a dragchute pack to slow the Sabre on its landing roll. The D45 had a wider tail point beneath its rudder (but above the engine exhaust) for housing the parachute pack. D45s from serial number 52-4136 used the J47-GE-33 engine, capable of pushing the F-86D at 693 miles per hour. The D-50, D-55 and D-60 were similar with several electronics modifications.

F-6Ds equipped fighter-interceptor units in the United States beginning with the 97th Squadron in March 1951. The F-6D's assignment was the air defense of the United States, except for the 4th, 40th and 41st Squadrons which were based in Japan for several years. The last F-86D was delivered to the Air Force in September 1953. In its later years, many F-86Ds were modernized and redesinated F-86L. These aircraft retained the external appearance of the "D", but were improved in many respects. The "L" was the swan song for the F-86 Sabre as an interceptor for the United States Air Force. The F-86K, an export version, had four 2Omm cannons and no rocket pod. Its fire control system was extensively changed to bring the cannons to bear. (Both the "L"and the "K" will be covered in future issues of Sabre Jet Classics in more detail)

At its peak, Air Defense Command had twenty wings equipped with F-86Ds in the U.S., Europe and the Far East. By 1956, the 87th Squadron was the last to convert to the F-86D. Because none had inflight refueling, they were usually shipped onboard aircraft carriers to other countries while partially disassembled and cocooned in an anti-corrosion outer covering. By April 1958, all F-86Ds were removed from Air Defense Command, and some were transferred to the Air National Guard which flew them until June 1961. F-86Ds later equipped several foreign air forces, including Japan, Turkey, and Denmark.


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