Mar 062012

The Curtiss-Wright XF-87 Blackhawk was a prototype all-weather jet interceptor designed as a replacement for the Northrop P-61 Black Widow night fighter. It was a large mid-wing aircraft with four Westinghouse XJ34-WE-7 turbojets paired in underwing pods, with a mid-mounted tailplane and tricycle undercarriage. Two crew members sat side-by-side under a spacious single canopy. The XF-87 first flew on March 1, 1948 and proved to be heavy and underpowered; it ultimately lost out to the Northrop XF-89 Scorpion, which went on to have a long and distinguished career with the Air Defense Command. Three photos of the Blackhawk are shown above; as one can see, it was a sleek and handsome design undermined by inadequate engines.

Desperate to salvage something from the failed XF-87 contract, Curtiss-Wright submitted a proposal to the USAF for a turboprop fighter-bomber conversion of the XF-87 dating from December 12, 1949, 14 months after the contract for the original aircraft was cancelled. Modifications to the original XF-87 airframe were minimal, with the dual jet engine pods being swapped out for a pair of Allison 500 (XT-40) turboprop engines driving counter-rotating supersonic 10′ diameter Aero Products propellers. A ventral pannier was added housing four 20mm fixed guns and a variety of ordnance options, including 5″ HVAR rockets, missiles, and multiple bomb loads, ranging from eight 250 lb bombs to one 2,000 lb bomb. Also illustrated was a variant carrying a ventrally mounted rotating turret with four 20mm guns; these could be angled 90° and rotate a full 360°. Five different external ordnance loading possibilities were illustrated, ranging from sixty 5″ HVAR rockets to two 4,000 lb bombs. Finally, Curtiss proposed a recce version with K-37 or K-19B cameras, twelve T-9 flash bombs, and high definition radar.

According to the brochure, the proposed fighter-bomber varied from contemporary ground support aircraft in that it offered certain outstanding features for ground support operation:

  1. The turboprop engine had an endurance at sea level considerably above that of a turbojet engine.
  2. The armament of four 20 mm fixed guns and sixteen 5″ HVAR rockets were internally housed and therefore did not decrease operational high speed performance or affect aircraft range.
  3. The APS-21 radar in the nose (incorporating a 30″ diameter scanner) had an air-to-air range of 25 miles and an air-to-ground range of 200 miles.

Curtiss also probably emphasized the cost savings that could be realized by converting an existing type to the ground support role, as much of the XF-87 tooling, jigs and fixtures could be reused.

Obviously, the Air Force was not persuaded by the proposal and the XF-87 turboprop fighter-bomber never left the drawing board. The exact reasons for the rejection have not been located, but one possible reason was the complexity and expense involved in developing both the Allison turboprop engine and Aero Products propeller. The existence of other ground support types such as the Douglas B-26 Invader and the Martin XB-51 (which had not yet been cancelled) was another possible factor. This may have been one of Curtiss-Wright’s last major aircraft proposals, as it effectively abandoned the airframe business in 1950 and sold off its airplane division to North American Aviation in 1951.

All images from NARA Archives II, College Park, MD, RG 341

  One Response to “Curtiss-Wright XF-87 Turboprop Fighter-Bomber Proposal (1949)”

  1. So, how does the USAF rejection compare, timewise, with their experiences with the same engine in the XF-84H and the USN’s experience with several aircraft using it (XA2J-1, XFV-1, XFY-1, R5Y-1, etc.)? If they already had bad experiences with this engine, I can’t see Curtiss’ proposal getting any kind of enthusiastic welcome.

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