Curtiss-Wright CW-24 / XP-55 Ascender
|FIGHTER||Virtual Aircraft Museum / USA / Curtiss|
The Curtiss XP-55 Ascender is perhaps best known of the three pusher fighters built for a 1941 competition in response to US Army 'Request for Data R40-C' dated 20 February 1940 (the others being the Vultee XP-54 and Northrop XP-56). A flying wing in most respects, albeit with a small fuselage and a canard foreplane (with only the horizontal portion of this surface forward of the wing), the XP-55 went through numerous design changes at Curtiss's St Louis, Missouri, plant and, like its competitors, was long-delayed getting into the air although it eventually carried out a test programme which involved four airframes.
Curtiss built a full-scale flying testbed, the company Model CW-24B, powered by an 633kW Menasco C65-5 engine. The fabric-covered CW-24B went to a new US Army test site, the ultra-secret airfield at Muroc Dry Lake, California, for 1942 tests. These revealed serious stability problems which were only partly resolved by moving its vertical fins farther out from their initial mid-way position on the swept-back wing.
The full-sized XP-55 fighter was ordered in fiscal year 1942, based on the proven 1100kW Allison V-1710-F23R engine being used for the first time as a pusher. The XP-55 used a single rotation, three-bladed propeller instead of the co-axial, contra-rotating type which had been planned and which was, in fact, employed with the parallel Northrop XP-56.
The first of three XP-55 aircraft was delivered on 13 July 1943 and underwent early flights at Scott Field, Illinois. It was found that excessive speed was required in the take-off run before the nose-mounted elevator could become effective. Before this problem could be addressed, the first machine was lost during spin tests at St Louis on 15 November 1943, the pilot parachuting to safety.
The second XP-55 was flown in St Louis on 9 January 1944. The third followed on 25 April 1944 and, soon after, went to Eglin Field, Florida, for tests of its nose-mounted 12.7mm machine-guns. The XP-55 had the advantage of being constructed largely from non-strategic materials and for a time a jet version, the company Model CW-24C, was contemplated. But lingering problems, including generally poor stability, remained unsolved when the third XP-55 was returned to Wright Field, Ohio, for further tests continuing into 1945.
On 27 May 1945, at a Wright Field air show and bond rally attracting a crowd of more than 100,000, the third XP-55 took off to give a public flying display. Captain William C. Glascow flew across the field leading five other fighters in formation. Glascow made one roll before the crowd, began another, and suddenly dived into the ground inverted. The pilot was thrown from the wreckage but suffered mortal injuries, while a nearby motorist was also killed.
Few aircraft contributed more to advancing technology while remaining trouble-plagued and failing to reach production. The second XP-55 has survived and is among numerous historically valuable air-frames held by the Smithsonian Institue's National Air and Space Museum in Washington D.C.
FACTS AND FIGURES
© The foreplane was nor a canard in the true sense, but a free-floating surface with no fixed stabilizer. Its limits were 68 degrees up and down, although the down angle was restricted to 17 degrees for take-offs.
© Because of the engine location, cooling was critical and the engine could easily overheat if taxiing time was not kept to a minimum.
© Entry to the cockpit was said by test pilots ro be rather awkward, requiring a telescoping ladder that was stored behind the pilot's seat.
© The unconventional layout caused bad stall characteristics, with little stall warning and excessive altitude needed for recovery.
© The XP-55 was essentially a flying wing, having only vestigial vertical surfaces which were distributed on the rear fuselage and outer wings.
Andrew Glasgow, e-mail, 22.02.2021 jerome harmeling
I have more information about the air show as Capt. Glasgow was my cousin.