-Curtiss-Wright XP-55 Ascender in July 1943. | Photo: SDASM Archives
FLIGHTLINE: 177 - CURTISS-WRIGHT XP-55 ASCENDER
The XP-55 was experimental fighter/interceptor designed just prior to the US' entry into WWII, but the engine was underpowered and the plane canceled.
Submitted in response to the USAAC's R-40C request, Curtiss-Wrights' CW-24 design was unlike almost anything else in the air at the time, featuring a canard, swept wings, a buried engine driving a pusher prop, and two vertical tails 7/8ths the way across the wings. Like the XP-54, the CW-24 was designed around the P&W X-1800. Curtiss-Wright received a contract for engineering data and a powered wind tunnel model in June 1940, but the USAAC was unimpressed by the results. As a result, Curtiss built a full-scale model designated the CW-24B to refine the concept. The CW-24B was of welded steel tube and fabric construction, with a wooden wing. The plane was powered by a Menasco inline 6-cylinder engine.
-The CW-24B in NACA's Langley 30 x 60 wind tunnel. | Photo: LMAL Archives.
Curtiss-Wright made changes to the design based on the wind tunnel tests, and in June 1942 the USAAF awarded the company a contract for three prototypes, designated XP-55 and given the name Ascender. Delays in and the eventual cancellation of the X-1800 engine led to the substitution of Allison's V-1710 (F16), which developed a modest 1,000hp. Planned armament of the Ascender was to be two .50cal machine guns and two 20mm cannon, but during the mockup phase the cannon were replaced by two more machine guns. The F16 model engine was also replaced with the more powerful -95, which produced 1,275hp.
-Orthograph of the XP-55. | Illustration: Richard Ferriere
The XP-55 was a small aircraft, just 29' long and with a wingspan of 40'. The plane weighed just over six thousand pounds empty, and max TO weight was 7,900lbs. In addition to the unconventional configuration, the Ascender also featured a novel propeller jettison device, developed by W Jerome Peterson, and engineer at Curtiss-Wright. The device, actuated by a lever in the cockpit, was intended to keep the pilot from being injured by the prop in case of a bail-out.
-The original patent filing by William Peterson for the prop jettison. | Illustration: W. J. Peterson
FLIGHT TEST PROGRAM
The first of the three Ascender prototypes, s/n 42-78845, was completed on 13 July 1943, and made its maiden flight 6 days later at Scott Army Airfield, located near Curtiss-wrights plant in St Louis. Initial testing showed that the takeoff run was far longer than anticipated, which technicians corrected by increasing the size of the canard as well as interconnecting the aileron up-trim with the flaps, so that the trip tab would operated when the flaps were lowered.
-The first Ascender in flight. | Photo: Ray Wagner Collection/SDASM Archives
On 15 November 1943 test pilot Harvey Gray was conducting tests of the XP-55's stall performance when the plane went inverted and fell into an flat spin. Gray was unable to break out of the dive, and the Ascender fell 16,000 feet before he bailed out. 845 impacted the ground and was destroyed.
-The crushed remains of the first XP-55 prototype after the 15 November accident. | Photo: USAAF
The second Ascender (s/n 42-78846) was largely similar to the first, but had the modifications made to 845 done at the factory. The trim tabs on the ailerons were changed from balance-type to spring-type. Maiden flight of 846 was on 9 January 1944, and the test program was restricted to avoid stalling the aircraft. Between 16 September and 2 October 1944 the plane was modified to the same specs as the third and then began official USAAF flight trials. Pilots, unconvinced by the plane's unconventional design, derisively called the plane the "Ass-ender".
-The second XP-55 in flight. | Photo: USAAF
The third XP-55 (s/n 42-78847) was the most advanced of the three prototypes, incorporating the same changes as the second, as well as a four-foot extension to the wingtips and changes to the limits of the canard travel, both of which were implemented to correct the stall characteristics of the Ascender. The 3rd was also armed with four machine guns. The maiden flight of 847 was on 25 April 1944. Tests of the second and third XP-55 found that the plane was inferior to fighters of the day, and the USAAF canceled further development of the plane in 1944.
-XP-55 number 3 on the apron. The most developed of the Ascenders, the plane was still found to be slower than contemporary aircraft. | Photo: Ray Wagner Collection/SDASM Archives
On 27 May 1945 the third XP-55 was participating in the Seventh War Bond Air Show at Wright Field in Ohio. The aircraft, piloted by William Glasgow, was flying in formation with a P-38 and P-51, when the pilot attempted a slow roll. Glasgow ran out of altitude however, and crashed, with flaming debris striking several cars on a nearby highway. Glasgow was killed, along with four civilians. The second prototype, meanwhile, was transferred to the Smithsonian Air and Space Museum, and is on long term loan to the Kalamazoo Air Zoo.
-The second XP-55 on display at the Air Zoo. | Photo: Michael Barera
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