XP-55 Ascender

infobox Aircraft
name =XP-55 Ascender
type =Fighter
manufacturer =Curtiss-Wright Corporation



caption =Curtiss XP-55 Ascender in flight.
designer =
first flight =9 July avyear|1943
introduced =
retired =
status =Cancelled
primary user =
more users =
produced =
number built =3
unit cost =
variants with their own articles =

The Curtiss-Wright XP-55 Ascender (Curtiss-Wright CW-24), was a 1940s United States prototype fighter aircraft built by Curtiss. Along with the XP-54 and XP-56, it resulted from United States Army Air Corps proposal R-40C issued on 27 November 1939 calling 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." 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

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 Menasco C68-5 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 engine was experiencing serious developmental delays, and would eventually be cancelled. Curtiss decided to switch to the Allison V-1710 (F16) liquid-cooled inline engine (rated at 1,000 hp) because of its proven reliability. Armament was to be two 20 mm cannon and two 0.50 inch machine guns. During the mock-up phase, it was decided to switch to the more powerful 1,275 hp Allison V-1710-95 engine. The 20 mm cannon were also replaced by 0.50 in machine guns.

Testing and evaluation

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 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. In addition, by 1944 jet-powered fighter aircraft were already well along in development and there was no further development of the XP-55.

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.

urvivors

The third prototype (42-78847) survived flight testing but was destroyed in a crash during an air show at Wright Field in Dayton, Ohio on 27 May 1945, killing the pilot and two civilians on the ground.

The only surviving XP-55 (42-78846) was flown to Robins Air Force Base in Georgia in May, 1945. Later, it would be taken to Freeman Field before being transferred to the National Air & Space Museum at the Smithsonian Institution in Washington, D.C. For many years its fuselage was displayed at the Smithsonian's Paul Garber restoration facility in Suitland, Maryland. In December 2001, the aircraft was transferred to the Air Zoo in Kalamazoo, Michigan for restoration by Museum staff. The aircraft was found to be in overall good condition, with much of its original paint still intact. After nearly five years of restoration, the aircraft was put on display at the Air Zoo on 26 May 2006 and is on long-term loan from the Smithsonian's National Air and Space Museum.

pecifications (XP-55)

aircraft specifications

plane or copter?= plane
jet or prop?= prop
ref= "WW2 Aircraft Fact Files: US Army Air Force Fighters, Part 1" [Green and Swanborough 1977, pp. 69–71.]
crew= one pilot
span main= 40 ft 7 in
span alt= 12.4 m
length main= 29 ft 7 in
length alt= 9.0 m
height main= 10 ft 0 in
height alt= 3.0 m
area main= 235 ft²
area alt= 21.83 m²
empty weight main= 6,354 lb
empty weight alt= 2,882 kg
loaded weight main= 7,710 lb
loaded weight alt= 3,497 kg
max takeoff weight main= 7,930 lb
max takeoff weight alt= 3,600 kg

engine (prop)= Allison V-1710-95
type of prop= liquid-cooled V12 engine
number of props= 1
power main= 1,275 hp
power alt= 951 kW

max speed main= 390 mph at 19,300 ft
max speed alt= 628 km/h
ceiling main= 34,600 ft
ceiling alt= 10,500 m
armament=four 0.50-inch machine guns in the nose

ee also

aircontent
related=

imilar aircraft

*Kyūshū J7W
*Northrop XP-56
*Henschel P.75
*Miles Libellula

sequence=
XP-52 -
XP-53 -
XP-54 - XP-55 -
XP-56 -
XP-57 -
XP-58
Curtiss-Wright CW-21 • Curtiss-Wright CW-22 • Curtiss-Wright CW-24 • Curtiss-Wright CW-25
lists=
* List of military aircraft of the United States
* List of fighter aircraft

see also=

References

Notes

Bibliography

* 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.

External links

* [http://www.wpafb.af.mil/museum/research/p55.htm USAF Museum - Curtiss XP-55]
* [http://www.theplanpage.com/esp/xp55.htm The Plan Page - Curtiss XP-55 Ascender]
* [http://home.att.net/~jbaugher1/p55.html XP-55 Ascender]
* [http://www.warbirdsresourcegroup.org/URG/xp55.html USAAF Resource Center - Curtiss XP-55]
* [http://www.nasm.si.edu/research/aero/aircraft/curtiss_xp55.htm NASM article]