Transonic all-weather interceptor from Inglewood: the F-86D Sabre Dog

The F-86 Sabre was the most prolific US Air Force air superiority jet fighter built in the 1946-1951 time period, becoming America's chief air combat star of the Korean War by ambushing and fighting MiG-15s in the skies over North Korea. However, it should be noted that the F-86 family itself spawned a variant that would become the second all-weather jet fighter-interceptor to be built in southern California, and this aircraft was originally bestowed a distinct F-for-Fighter designation before being eventually reclassified as an F-86 variant.

The first YF-95/YF-86D prototype (serial number 50-577) on the tarmac at the North American Aviation field near Los Angeles International Airport,

On March 28, 1949, North American Aviation envisaged an all-weather interceptor variant of the F-86 Sabre under the company designation NA-164. The US Air Force showed interest in this proposal, and on April 7 North American itself felt confident enough to undertake engineering work on the production version, to which it applied the designation NA-165. The NA-164/165 differed from the F-86 in having a longer fuselage, a single 7,650 lb (34 kN) thrust General Electric J47-GE-17 turbojet, a clamshell cockpit canopy with a rear hinge, and a 30-inch nose radome on the upper lip of the air intake. The nose radome would carry an AN/APG-36 search radar for interception of enemy aircraft, and because the NA-164/165 was a single-seat aircraft in stark contrast to the F-89 Scorpion and F-94A/B being two-seaters, it required sophisticated electronic systems. Instead of the F-86's four 20-mm cannons, the NA-164/165 itself would be armed with twenty-four 2.75 inch Mighty Mouse unguided air-to-air rockets carried in a retractable tray in the aircraft's belly, although the cannon armament installation of the baseline Sabre was studied as a standby plan. On October 7, 1949, two NA-164 prototypes (serial numbers 50-577/578) and 122 examples of the NA-165 production version (serial numbers 50-455/576) were ordered and the NA-164 was given the designation YF-95 while the designation F-95A was given to the NA-165. The USSR's first successful nuclear weapons test in September 1949 prompted the USAF to order 31 more F-95As (serial numbers 50-704/734), and the YF-95 made its first flight on December 27, 1949. The YF-95 prototypes retained the cockpit canopy, flight controls, and V-shaped windscreen of the F-86A, and the rocket armament and fire-control system were not yet available when flight tests of the YF-95 began.

An F-86D Sabre Dog (serial number 52-3722) in flight 

On July 24, 1950, the F-95 was redesignated F-86D after congressional taxpayers told North American Aviation that funds could be saved if the F-95 were classified as merely an evolutionary development of the Sabre, and thus the YF-95 prototypes became YF-86D. Beginning in September and continuing for two years the Hughes E-3 fire control system was tested aboard the YF-86Ds, and in February 1951 the YF-86D began firing trials of the Mighty Mouse rockets. Deliveries of the F-86D to the US Air Force began in March 1951, and the pressure of the Korean War precipitated an order for 188 F-86D-20-NAs (serial numbers 51-2944/3131) on April 11, 1951, followed by an order for 638 F-86D-25/30/35-NAs (serial numbers 51-5857/6262 and 51-8274/8505) on July 18. Whereas the F-86D-20-NA block had the internal designation NA-177, the latter order (company designation NA-173) was originally designated F-86G when first envisaged in August 1950, differing in having 120-gallon drop tanks for combat missions but ended up being classified as F-86Ds when finalized. Unlike the YF-86D prototypes, the production F-86D had the clamshell canopy, enlarged vertical stabilizer, and a slightly lowered all-flying horizontal stabilizer. The F-86D set a new airspeed record of 698 mph (1,124 km/h) over the Salton Sea in southern California on November 18, 1952, and nine months later, that world airspeed record was shattered on July 16, 1953, when another F-86D flew over the same area at a speed of 716 mph (1,151.8 km/h). The US Air Force was so impressed by the F-86D's performance that yet another production contract for the F-86D was signed on March 6, 1952 for 901 F-86D-40/45/50-NAs (serial numbers 52-3598/4304 and 52-9983/10176), internally designated NA-190, and the final production order was placed on June 12, 1953 for 624 F-86D-55/60-NAs (serials 53-557/1071, 53-3675/3710, and 53-4018/4090), which bore the company designation NA-201. The first 238 F-86D-45-NAs were fitted with the J47-GE-17B turbojet, but the remaining F-86D-45s and all the F-86D-50/55/60-NAs used a more powerful 7,650 lb (34 kN) J47-GE-33 turbojet, which had better cooling and afterburner ignition. The last F-86D was delivered in September 1955, by which time a total of 2,506 F-86Ds (including the prototypes) had been built. The "D" suffix in the F-86D designation led USAF pilots nicknaming this aircraft the Sabre Dog.

In a typical intercept mission, the F-86D's AN/APG-37 radar searched the sky in a forward direction, sweeping back and forth and up and down in a 3.5-second cycle and locating target 30 miles (48 km) away. When the target showed up as a blip on the radar scope, the pilot locked the radar onto the target and the AN/APA-84 computer determined a lead collision course. He flew this course by keeping the steering dot on his scope inside a reference circle. When the automatic tracking system indicated that there were only 20 seconds to go, the pilot steered more precisely to keep the dot in a smaller circle. The pilot chose whether to fire 6, 12, or all 24 of the Mighty Mouse rockets, and pressed the trigger. However, the actual firing instant was determined by the computer, not by the pilot, and when the computer deemed the range to be right, the rocket pack was extended and the rockets were fired. The range at which the computer fired the rockets at the target was typically about 500 yards. It took a half-second for the pack to lower, and only a fifth of a second to fire all 24 rockets. After firing, the rockets fanned out in a predetermined pattern reminiscent of a shotgun blast. When the last rocket was away, the pack automatically retracted back into the fuselage belly, and an "8" appeared on the pilot's scope, warning him that the target was only 260 yards ahead and that he had better break away..

Although the F-86D was the backbone of the USAF's Air Defense Command (ADC) for much of the early-to-mid 1950s, differences among the multitude of operational F-86D production blocks meant that they required different sets of spare parts, different instruction manuals, and different maintenance procedures, leading to maintenance and repair headaches. Therefore, the US Air Force initiated Project Pull-Out in late 1953 to withdraw all F-86Ds built prior to deployment of the F-86D-45-NA production block from operational units and upgrade them to F-86D-45 standard. Upgrades to the early production block F-86Ds included fitting them with braking parachutes and upgraded computer electronics, and when Project Pull-Out was completed in September 1955, a total of 1,128 F-86D-10 to D-40 aircraft had been modified, receiving the designation blocks F-86D-11/16/21/26/31/36/41. Several F-86Ds were deployed overseas to Europe, the Far East, and North Africa beginning in 1954, and in spite of being designed to intercept enemy bombers, the F-86D would never fire a shot in anger against enemy aircraft in its capacity as an interceptor.   

An F-86L (serial number 50-560) on display at the March Field Air Museum, photographed by me in April 2019. This aircraft was one of the first 122 production F-86Ds to be built.

Despite the completion of Project Pull-Out, the F-86Ds were still beset by engine failures and reliability issues with the E-4 fire control system with which they were equipped.  Thus, in the mid-1950s, the US Air Force decided to adapt numerous F-86Ds to use the Semi-Automatic Ground Environment (SAGE) datalink system, which involved use of a large, high-speed ground-based computer for handling and coordinating air surveillance data from various ground radar installations that was transmitted in real-time to a special data receiver aboard the interceptor, and then converted to an on-board system into heading, speed, altitude, target bearing, and range information to guide the pilot in his interception of an enemy aircraft. The first F-86D to have the SAGE system installed flew on December 27, 1955, and beginning in May 1956, under Project Follow-On, it and 575 more F-86Ds were fitted with not only the SAGE system but also extended wingtips and wing leading edges, and engine cooling ducts, resulting in the designation F-86L for these conversions. Thus, the SAGE-equipped F-86D-11 to F-86D-46 aircraft were redesignated F-86L-11 to F-86L-46, whereas the Block 50, 55, and 60 F-86Ds were given the designations F-86L-50 to F-86L-60. The F-86L entered service with the ADC in October, and by this time the ADC had begun withdrawing the F-86D from squadron service beginning in August of that year. Retirement of the F-86D from ADC units was complete by April 1958, and some of the F-86Ds were turned over to the Air National Guard, in which they served until 1961. The F-86L's operational career was rather brief because the deployment of the supersonic F-102 Delta Dagger and F-106 Delta Dart made the F-86L obsolete, leading to retirement of the F-86L from USAF service in 1960. The Air National Guard acquired the F-86L in late 1957 amid the ADC's deployment of the F-102 and F-106, operating F-86Ls until the summer of 1965. From 1958 to 1961, sufficient numbers of retired F-86Ds were exported to Denmark, Greece, Yugoslavia, Turkey, the Philippines, Japan, Taiwan, and South Korea. On the other hand, 17 retired F-86Ls were sold to Thailand in 1964, serving with the Royal Thai Air Force until 1976. In Yugoslav service, F-86Ds were designated L-13 (L stood for Lovac, which means "fighter" in Serbian), and a number of F-86Ds modified for reconnaissance were called IF-86D (with I standing for Izviđač, which is Serbian for "reconnaissance").

A line-up of Fiat-built F-86Ks for the Aeronautica Militare

As the USAF began taking deliveries of the F-86D, America's NATO allies in mainland Europe wanted an all-weather interceptor able to tackle the emerging threat of nuclear-armed Soviet strategic bombers. However, the sophistication of the E-4 fire control system of the F-86D along with its reliability issues meant that exporting the E-4 to US allies was not an option. In response to a USAF request in January 1953 to have Italy operate an interceptor similar in appearance to the F-86D but with cannons, on May 14, 1953, North American conceived an export version of the F-86D, the NA-205, which retained the nose radome radar of the F-86D but was armed with four 20 mm M24A1 cannons designed to operate with a new fire control system designed by North American, the MG-4, which was less technologically complex than the E-4. Two F-86Ds (serial numbers 52-3630 and 52-3804) were selected for the NA-205 project and designated YF-86K, and on May 16, North American signed an agreement with the Italian company Fiat to assemble 50 examples of the production version, the F-86K, which had USAF serials 53-8273/8322 assigned to them although they intended for export to Europe. A batch of 120 F-86Ks to be built for Norway and Netherlands (serial numbers 54-1231/1350; company designation NA-213) was ordered on December 18, and the YF-86K was first flown on July 15, 1954, while the first flight of the production F-86K took place on March 8, 1955, and the first F-86K built under license in Italy flew on May 23. The company designation NA-207 was given to the first batch of F-86Ks built by Fiat, and 171 more F-86Ks (serial numbers 55-4811/4936 and 56-4116/4160) were manufactured under license by Fiat, with North American giving the internal designations NA-221, NA-232, and NA-242 to the latter aircraft. The F-86Ks with the internal designation NA-242 differed from other Fiat-assembled F-86Ks in having slightly increased wingspan and greater wing area. Besides its cannon armament, the F-86K differed from the F-86D in havng a slightly longer nose to house the cannons and ammunition. The US-built F-86Ks (except one retained by the US Air Force were testing) were delivered to Norway and the Netherlands in 1955-1956, and of the 221 F-86Ks license-built by Fiat, 63 were delivered to the Aeronautica Militare, sixty-two went to the French Air Force, and 86 were delivered to West Germany's Luftwaffe, while the Netherlands received six and four were given to Norway. By the 1960s France, Italy, the Netherlands, Norway, and West Germany retired the F-86K from service as the F-104G and Dassault Mirage IIIC entered frontline service, and seventy-four ex-Luftwaffe F-86Ks were sold to Venezuela in 1966 (five of which were later given to the Honduran Air Force in 1969) while 40 F-86Ks previously in Italian service were sold to the Turkish Air Force, which operated them until 1969.