by Larry Davis
This is the story of Project FOLLOW-ON, the upgrading of the F-86D. But first a little history. The F-86D first flew on 22 December 1949. At that time it was designated the F-95A which was later changed to F-86D as it was easier to get Congressional funding for an existing aircraft type, rather than an all new type. Besides, the F-95A/F-86D did use a large number of parts and systems common to the F-86E, including wings and tail surfaces.
The F-86D was the first Air Force fighter aircraft to have an all-rocket armament, with 24 2.75" Mighty Mouse rockets housed in a retractible tray under the forward fuselage. It was also one of the first to have an afterburner on the engine, which increased available thrust by a full third, from 5200 lbs i n the J47-GE-27 used in the F-86F, to a whopping 7500 lbs. in the J47-GE-17B in the F-86D. It needed the extra thrust as the D was almost 600 lbs. heavier than the F-86F.
Production of the F-86D started in March 1951, and ended after North American had built a total of 2504 aircraft. The F-86D served with every major Air Force Command throughout the Free World, and was the primary air defense weapon against the Soviet bomber threat.
But by the mid-1950s, the Soviet threat was such that the Air Force needed an all-new supersonic jet interceptor. It was known as the "1954 Interceptor", which became the Convair F-102 Delta Dagger. But it wouldn't be available until 1956 and the Air Force needed an interceptor to fill the gap technologically. The answer was Project FOLLOW-ON, the upgrading of a number of F-86D airframes with improved technology, i.e. something called SAGE.
SAGE was short for Semi-Automatic Ground Environment, and it had been developed at MITs Lincoln Laboratory in 1953 for use in the "1954 Interceptor". It was quite simply, a real time Data Link between the ground radar stations and the interceptor pilot, giving him `real time' information - target speed, altitude, range and bearing. SAGE equipment included the AN/APR-39 Data Link, AN/ARC-34 Command Radio, AN/ APX-25 Identification Radar, and AN/ARN-31 Glide Slope Receiver.
And while the SAGE modifications were taking place, the Air Force took the opportunity to upgrade the rest of the
F-86D airframe. The wings were modified with the extended 6-3 leading edge, but with slats. And the wingtips were extended one foot on each tip. The powerplant would be the J47-GE-33 which offered 7650 lbs. of thrust. Cooling problems found on the early F-86Ds were handled with an additional pair of scoops on the fuselage above the trailing edge of the wing.
Even' though the new version of the F-86D was some 2200 lbs heavier than the F-86F-30 fighter, the aircraft was equal in top speed at 693mph @ sea level and 616 mph @ 40,000 feet. The Air Force authorized Project FOLLOW-ON in late 1955 to convert a total of 981 F-86D aircraft to (now-designated) F-86L specifications.
The first aircraft was test flown in October 1956, and it wasn't long before Air Force crews began taking delivery.
1Lt. Richard Graham took delivery of the first production F-86L on 23 November 1956 and flew it back to the
317th FIS at McChord AFB. The final F-86L conversion came off the assembly line in November 1957.
Project FOLLOW-ON aircraft were all based on existing F-86D-10 through D-60 airframes. The Air Force made a minor change to the block number adding "1" to each block number. Thus a D-10 became an L-11, a D-30 was an
L-31, etc. However, the later block numbers, D-50, D-55, and D-60 simply changed the letter; i.e. L-50, L-55, and L-60.
Although the first F-86Ls were delivered in late 1956, the introduction of the F-102A and the F-104A meant a short first line life for the L. The first F-86Ls were phased into the Air National Guard as early as 1957 when the 159th FIS, Florida ANG, began conversion to the upgraded interceptor. The last unit to fly the F-86L was the 196th FIS, California ANG, which retired the type in 1965 in favor of the `1954 Interceptor', the Convair F-102A.
No portion of this article may be used or reprinted without permission from the President of the F-86 Sabre Pilots Association or the editor of Sabre Jet Classics magazine.
Return to Classics Page