by Larry Davis
What Is It? Sabrejet Classics issue 9-3. Well, we sure didn't fool anyone with our subject last issue. Several members identified the photo as a North Amencau Aviation YF-93A/F-86C. Thanks to all that sent notes and information about the subject airplane. With that in mind, we thought we should do the story of the F86C Sabre.
So what exactly was the it? In 1946, the Air Force had recognized that all the current jet fighter designs were lacking in one critical area - range. The P-86A with 200 gallon ferry tanks under the wings, had a ferry range of 1052 miles. The two other major jet fighter types, the P-80 and P-84, were similar. And inflight refueling was still a glimmer in the eyes of the engineers. And Strategic Air Command wanted jet fighters to escort their long range bombers to targets, which were now envisioned to be deep in the Soviet Union - and far outside the range of any jet fighter. They were known as "penetration fighters".
In late 1947, with the Penetration Fighter requirement in mind, North American engineers started a project to both increase the range and the speed of their swept wing fighter. Any increase in range required an increase in fuel capacity, either in bigger internal tanks or through droppable underwing fuel tanks. The engineers enlarged the entire fuselage in length, width, and depth. In addition, the wing span was increased 1' 8" on each wingtip.
Both of these changes increased the internal fuel capacity from 435 gals. in the F-86A to an incredible 1561 gals internally! And since the new penetration fighter used a modified F-86A wing, it was able to carry any of the underwing tank designs available, including the 200 gal. ferry tanks. That brought total gallonage to 1961. Unrefueled range was estimated to be in excess of 2000 miles.
All of this extra fuel meant the airplane gross weight was increased a corresponding amount, from 15,876 lbs combat weight in the F-86A, to 26,516 lbs in the F86C. The J47 didn't have enough power to keep the much heavier fighter in the transonic speed range necessary for jet combat. Pratt & Whitney had an engine available, the J48-P-6 engine which had an afterburner. The e J48 was rated at 6,250 lbs static thrust, with 8750 lbs thrust available in afterburner.
The North American engineers decided to incorporate other new items which were just then becoming available such as the SCR-720 search radar and 20mm cannons (six) in place of the standard .50 caliber armament. The heavier weight necessitated a dual-wheel main lauding gear. With the radar mounted in the nose where the air intake was on the F-86A, the engineers designed a novel set of flushmounted NACA-designed air intakes on each side of the forward fuselage. The center of the fuselage was slightly concave, giving the aircraft a distinctive "wasp-waist" appearance.
Other portions of the new penetration fighter retained their F-86A ancestry - the canopy/windscreen design, both vertical and horizontal tail design, cockpit and ejector seat, nose gear assembly, and the main portion of the wing. With all that being common with the F86A, it was natural that the aircraft be designated in the F-86 family. But Air Force decided that there were too many design changes in the penetration fighter design, and redesignated the airplane as the F-93. (The same thing occured with the initial F-86D design which was originally designated as the F-95.)
In December 1947, Air Forced ordered two prototypes of the new fighter. Six months later, Air Force added a further 118 aircraft to the contract - 18 months prior to the first airplane coming off the assembly line! However, in February 1949, Air Force suddenly cancelled the entire project. The reason was two-fold. First was the development of the B-47 Stratojet bomber, which was estimated to be so fast that it wouldn't need any fighter escort. Second was a drastic reduction in the overall defense budget.
But North American already had the two prototypes under production and made the decision to go ahead and complete the two (now-designated) YF-93As. The first aircraft, serial 48-317, made its first flight on 24 January 1950. The second YF-93A #48-318, followed shortly thereafter. In the late summer of 1950. Air Force held a fly off between the three "penetration fighter" designs - the McDonnell XF-88 Voodoo, Lockheed XF90, and the YF-93A. The Evaluation Board declared the XF-88 as the winner of the fly-off. However, the rapid development of the XB-47 and the even more formidable XB-52, made the decision null and void. There was simply no need for a penetration fighter aircraft.
Air Force took control of the two YF-93As and gained the following results from flight tests. The YF-93A's top speed was 708 mph at sea level, and 622 mph at 35,000 feet. The range was almost exactly what the engineers bad predicted, 1967 miles. Rate of climb with the J48 in 'burner was 11,9 60 feet/minute. Pretty impressive for an airplane that would never see production. When Air Force was through with the YF-93As, they turned both prototypes over to the NACA's Ames Laboratory at Moffett Fi ld for further tests and evauation.
NACA soon fitted the second YF-93A with standard intakes over the original flush-mounted units. It was found that the conventional air intakes increased performance and the first YF-93A was subsequently equipped with a set for further tests. Both aircraft finished their service careers flying as chase aircraft to the newly developed Century Series of fighters that would replace the entire F-86 series. Both air craft were removed from service in the late 1950s and scrapped.
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.
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