Curtiss-Wright XP-55 Ascender

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The Curtiss-Wright XP-55 Ascender (company designation CW-24) was a 1940s United States prototype fighter aircraft built by Curtiss-Wright. Along with the Vultee XP-54 and Northrop XP-56, it resulted from United States Army Air Corps proposal R-40C issued on 27 November 1939 for aircraft with improved performance, armament and pilot visibility over existing fighters; it specifically allowed for unconventional aircraft designs. A highly unusual design for its time, it had a canard configuration, a rear mounted engine, swept wings and two vertical tails. Because of its pusher design, it was sarcastically referred to as the "Ass-ender".^[1] Like the XP-54, the Ascender was initially designed for the Pratt & Whitney X-1800 engine and had to be redesigned when that engine project was cancelled. It would also be the first Curtiss fighter aircraft to use tricycle landing gear.

Design and development

Curtiss CW-24B at Langley wind tunnel

On 22 June 1940, the Curtiss-Wright company received an Army contract for preliminary engineering data and a powered wind tunnel model. The designation P-55 was reserved for the project. The USAAC was not completely satisfied with the results of these tests, and Curtiss-Wright took it upon itself to build a flying full-scale model which it designated CW-24B. The flying testbed was powered by a 275 hp (205 kW) Menasco C68-5 inline engine. It had a fabric-covered, welded steel tube fuselage with a wooden wing. The undercarriage was non-retractable.

On 10 July 1942, the United States Army Air Forces issued a contract for three prototypes under the designation XP-55. Serial numbers were 42-78845 through 42-78847. During this time, the Pratt & Whitney X-1800 H-block sleeve valve engine was experiencing serious developmental delays, and was eventually cancelled. Curtiss decided to switch to the 1,000 hp (750 kW) Allison V-1710 (F16) liquid-cooled inline engine because of its proven reliability. Armament was to be two 20 mm (0.79 in) cannon and two 0.50 in (12.7 mm) machine guns. During the mock-up phase, it was decided to switch to the more powerful 1,275 hp (951 kW) V-1710-95. The 20 mm cannons were also replaced by 0.50 in machine guns.

A special feature of the XP-55 was a propeller jettison lever located inside the cockpit to prevent the pilot from hitting the propeller during bailout.

Operational history

The first XP-55 following a testing crash.

The first XP-55 (42-78845) was completed on 13 July 1943 and had the same aerodynamic configuration as the final prototype CW-24B. The aircraft made its first test flight on 19 July 1943 from the Army's Scott Field near the Curtiss-Wright plant in St Louis, Missouri. The pilot was J. Harvey Gray, Curtiss' test pilot. Initial testing revealed that the takeoff run was excessively long. To solve this problem, the nose elevator size was increased and the aileron up trim was interconnected with the flaps so that it operated when the flaps were lowered.

On 15 November 1943, test pilot Harvey Gray, flying the first XP-55 (S/N 42-78845), was testing the aircraft's stall performance at altitude when the XP-55 suddenly flipped over on its back and fell in an uncontrolled, inverted descent. The pilot was unable to right the airplane, and it fell out of control for 16,000 ft (4,900 m) before Gray was able to parachute to safety. The aircraft was destroyed.

The second XP-55 (S/N 42-78846) was similar to the first but with a slightly larger nose elevator, modified elevator tab systems, and a change from balance tabs to spring tabs on the ailerons. It flew for the first time on 9 January 1944. All flight tests were restricted so that the stall zone was avoided.

The third XP-55 (S/N 42-78847) flew for the first time on 25 April 1944. It was fitted with four machine guns, and incorporated some of the ideas learned from the loss of the first XP-55. It was found that the aircraft's stall characteristics could be greatly improved by the addition of four-foot wingtip extensions, and by increasing the limits of the nose elevator travel. Between 16 September and 2 October 1944, the second XP-55 (42-78846), which had been modified to the same standards as the third aircraft, underwent official USAAF flight trials.

The performance of the XP-55 was not very impressive and was often inferior to that of more conventional fighter aircraft already in service.^{[citation needed]} In addition, by 1944 jet-powered fighter aircraft were already well along in development and there was no further development of the XP-55.

The third prototype XP-55 (s/n 42-78847) was lost on 27 May 1945 during the closing day of the Seventh War Bond Air Show at Wright Field in Dayton, Ohio.^[2]

Aircraft disposition

42-78845 - crashed during vertical dive on Nov 15, 1943. Pilot bailed out.^[3]
42-78846 - on display at at the Air Zoo in Kalamazoo, Michigan. It is on long-term loan from the Smithsonian's National Air and Space Museum in Washington D.C..^[4]
42-78847 - crashed during air show at Wright Field, Ohio on May 27, 1945. Pilot killed.^[5]

Specifications (XP-55)

Curtis XP-55 Ascender side view.

Data from WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 1 ^[6]

General characteristics

Crew: one pilot
Length: 29 ft 7 in (9.0 m)
Wingspan: 40 ft 7 in (12.4 m)
Height: 10 ft 0 in (3.0 m)
Wing area: 235 ft² (21.83 m²)
Empty weight: 6,354 lb (2,882 kg)
Loaded weight: 7,710 lb (3,497 kg)
Max. takeoff weight: 7,930 lb (3,600 kg)
Powerplant: 1 × Allison V-1710-95 liquid-cooled V12 engine, 1,275 hp (951 kW)

Performance

Maximum speed: 390 mph at 19,300 ft (628 km/h)
Range: 635 mi (1,020 km)
Service ceiling: 34,600 ft (10,500 m)
Rate of climb: 2,350 ft/min (11.9 m/s)
Wing loading: lb/ft² (kg/m²)
Power/mass: 0.16 hp/lb (0.27 kW/kg)

Armament

4 × 0.50 in (12.7 mm) machine guns in the nose

References

Notes

↑ Jenkins 2008. p. 8
↑ Balzer 2008
↑ "XP-55 Ascender/42-78845." Joe Baugher's Serial Numbers. Retrieved: 10 May 2013.
↑ "XP-55 Ascender/42-78846" Air Zoo. Retrieved: 10 May 2013.
↑ "XP-55 Ascender/42-78847." Joe Baugher's Serial Numbers. Retrieved: 10 May 2013.
↑ Green and Swanborough 1977, pp. 69–71.

Bibliography

Balzer, Gerald H. American Secret Pusher Fighters of World War II: XP-54, XP-55, and XP-56. North Branch, Minnesota: Specialty Press, 2008. ISBN 1-58007-125-2.
Bowers, Peter M. Curtiss Aircraft, 1907-1947. London: Putnam 7 Company Ltd., 1979. ISBN 0-370-10029-8.
Green, William. War Planes of the Second World War, Volume Four: Fighters. London: MacDonald & Co. (Publishers) Ltd., 1961 (Sixth impression 1969). ISBN 0-356-01448-7.
Green, William and Gordon Swanborough. WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 1. London: Macdonald and Jane's Publishers Ltd., 1977. ISBN 0-356-08218-0.
Jenkins, Dennis R. and Tony R. Landis. Experimental & Prototype U.S. Air Force Jet Fighters. North Branch, Minnesota: Specialty Press, 2008. ISBN 978-1-58007-111-6.
McIntyre, Violet. Niagara Gazette, Niagara Falls, NY, 11 November 2004.

External links

Wikimedia Commons has media related to Curtiss XP-55.

NMUSAF - Curtiss XP-55
NASM article
The Plan Page - Curtiss XP-55 Ascender
XP-55 Ascender
Curtiss Wright XP-55 Ascender -USAAF Resource Center at warbirdsresourcegroup.org
Dayton Air Show History
"Flying Backwards to the Future", Popular Science, August 1945

Aircraft produced by Curtiss and Curtiss-Wright

Manufacturer
designations

Early types	No. 1 No. 2

Model letters	C D E F G GS H J K L M N PN JN R S T

Model numbers	1 2 3 4 5 6 7 8 9 10 11 12 13 14 16 17 18 19 20 21 22 23 24 26 28 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 47 48 49 50 51 52 53 54 55 56 57 58 59A/59B 60 61 62 63 64 66 67 68 69 70 71 72 73 75 76 77 79 81 82 84 85 86 87 88 90 91 94 95 96 97 98

"CA" series	CA-1

"CW" series	CW-1 CW-2 CW-3 CW-4 CW-5 CW-6 CW-7 CW-8 CW-9 CW-10 CW-11 CW-12 CW-14 CW-15 CW-16 CW-17 CW-18 CW-19 CW-20 CW-21 CW-22 CW-23 CW-24 CW-25 CW-27 CW-29 CW-32

"X" series	X-100 X-200

By role

Experimental	No. 1 Model C Tanager

Racing	No. 2 Cox Racer CR R2C R3C

Utility	Model D Model E Model F Robin Thrush

Maritime patrol	Model H HS-1L and -2L

Trainers	Model L Model JN Fledgling AT-4 Hawk AT-5 Hawk

Naval trainers	NC N2C

Fighters	18 PW-8 P-1 P-2 P-3 P-4 P-5 P-6 XP-31 P-36 P-40 XP-46 XP-53 YP-60 XP-62 XP-71 XP-87

Naval fighters	HA FC F2C F3C F4C F6C F7C F8C F9C F10C F11C XF12C F13C XF14C XF15C

Airliners	Eagle Condor II Kingbird

Naval scouts	CS GS S2C XS3C S4C SC SBC SB2C XSB3C SNC SOC SO2C SO3C

Observation	O-1 O-12 O-13 O-16 O-18 O-26 O-39 O-40 O-52

Naval observation	OC O2C O3C

Bombers	Canada B-2

Naval bombers	CT BFC BF2C XBTC XBT2C

Ground attack	A-3 A-4 A-5 A-6 A-8 YA-10 A-12 YA-14 A-18 A-25 A-40 XA-43

License production	NBS-1

v t e USAAS/USAAC/USAAF/USAF fighter designations 1924–1962

Pursuit (pre-1948) Fighter (post-1948)	P-1 P-2 P-3 XP-4 P-5 P-6 XP-7 XP-8 XP-9 XP-10 P-11 P-12 XP-13 XP-14 XP-15 P-16 P-17 YP-18 YP-19 YP-20 P-21 XP-22 P-23 YP-24 P-25 P-26 P-27 P-28 P-29 P-30 XP-31 P-32 P-33 XP-34 P-35 P-36 P-37 P-38 P-39 P-40 XP-41 P-42 P-43 P-44 P-45 XP-46 P-47 XP-48 XP-49 XP-50 P-51 XP-52 P-53 XP-54 XP-55 XP-56 XP-57 XP-58 P-59 P-60 P-61/C XP-62 P-63 P-64 P-65 P-66 XP-67 XP-68 P-69 P-70 XP-71 XP-72 P-73 P-74¹ P-75 XP-76 XP-77 P-78 XP-79 P-80 XP-81 P-82 XP-83 P-84 XP-85 P-86/D XP-87 P-88 P-89 XF-90 XF-91 XF-92 YF-93 F-94 F-95 F-96 F-97 F-98 F-99 F-100 F-101 F-102 XF-103 F-104 F-105 F-106 F-107 XF-108 XF-109 F-110 F-111/B

Pursuit, Biplace	PB-1 PB-2 PB-3

Fighter, Multiplace	FM-1 FM-2

¹ Not assigned See also: F-24 • F-117 • P-400 • post-1962 sequence

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