(Chris Jordaan) Xp-55 Ascender, MODELE, jchudzinski, ebook, pdf

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Curtiss Xp-55 Ascender
Xp-55 Ascender
Ascender
A futuristic shape 50 years ago!
The Curtiss XP-55 Ascender was designed to respond to Circular Proposal R-40C, issued on
November 27, 1939. It called for a fighter with a top speed, rate of climb, manoeuvrability,
armament, and pilot visibility, which would be far superior to those of any existing
fighter. The Army mentioned in R-40C that they would consider aircraft with
unconventional configurations. 50 responses were narrowed down to four by the
end of 1940. The designs considered for further study were designs submitted by Bell,
Curtiss, Northrop and Vultee.
The Curtiss entry, designated CW-24 and supervised by Donovan Berlin, was the most
unconventional of the four finalists. The CW-24 was a swept-wing pusher aircraft with
canard (tail-first) elevators. Curtiss proposed to use the new and untried Pratt & Whitney
X-1800-A3G (H-2600) liquid-cooled engine, mounted behind the pilot's cockpit and driving a
pusher propeller. Projected maximum speed was no less than 507 mph!
On November 15, 1943, test pilot Harvey Gray was flying the XP-55 through stall tests
when it fell into an uncontrolled, inverted descent. The plane fell for 16,000 feet before
Gray parachuted to safety. The aircraft was destroyed in the ensuing crash.
The second XP-55 (42-78846) was similar to the first one, apart from a slightly larger
nose elevator, modified elevator tab system and a change from balance tabs to spring tabs
on the ailerons. It flew on January 9, 1944, but flight tests were restricted to avoid the
stall zone until the third XP-55 had been tested.
On June 22, 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. Curtiss-Wright took it upon itself to build a flying full-scale model designated
CW-24B. The CW-24B was powered by a 275 hp Menasco C68-5 engine, had a fabric-
covered, welded steel tube fuselage, a wooden wing and fixed landing gear. The aircraft was
tested at Muroc Dry Lake (later Edwards AFB) in California, and its maiden flight was on
December 2, 1941. With a maximum speed of only 180 mph due to low engine power, the CW-
24B proved the basic feasibility of the concept. Early flights indicated that it was
directionally unstable. The auxiliary wingtip fins were increased in area and moved four feet
farther outboard on the wings and the wingtips were made longer. Further improvement was
obtained by adding vertical fins to both the top and the bottom of the engine cowling. 169
flights with the CW-24B were made at Muroc between December 1941 and May 1942.
The third XP-55 (42-78847) flew on April 25, 1944. Fitted with four machine guns, it
incorporated the ideas learned from the crash investigation of the first XP-55. Stall
characteristics were improved by adding wingtip extensions of greater area and by
increased nose elevator travel. An artificial stall warning device was introduced, and
between September 16 and October 2, 1944, the second XP-55 (42-78846), upgraded to
the same standard as the third aircraft, underwent USAAF trials. The trials indicated
that the XP-55 had satisfactory handling characteristics during level and climbing flight,
but at low speeds and landings the pilot tended to overcontrol on the elevators due to a
lack of useful "feel". Stall warning was insufficient, and stall recovery involved excessive
loss of altitude. Engine cooling was also a problem.
During the flight testing of the CW-24B, work on the CW-24 fighter project continued. On
July 10, 1942, a USAAF contract was issued for three prototypes under the designation XP-
55. Serial numbers were 42-78845/78847 powered by the 1275 hp Allison V-1710-95 engine
and armed with 0.50-inch machine guns.
Inferior to more conventional fighters already in service and with jet-powered fighter
aircraft clearly the way of the future, no production was undertaken and development was
abandoned.
The first XP-55 (42-78845) completed on July 13, 1943, had essentially the same
aerodynamic configuration as the final CW-24B. Its maiden flight on July 19, 1943, was
piloted by J. Harvey Gray, Curtiss's test pilot. Increasing the nose elevator area solved an
excessively long takeoff run and the aileron up trim was interconnected with the flaps so
that it operated when the flaps were lowered.
The name *Ascender* had originated as a joke by a Curtiss engineer. The name stuck, and
eventually became official.
One XP-55 survives today. Its fuselage is on display at the Paul Garber facility in Suitland,
Maryland.
Model design by Chris Jordaan -- chrisj@aviation.denel.co.za
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Xp-55 Ascender
Ascender
CONSTRUCTION NOTES:
XP-55 SPECIFICATIONS:
1. Cut and assemble parts A to I in alphabetical order. Use glue sparingly and check correct
alignment of parts.
2. Cut slots for the canard only when assembly of fuselage is complete up to part "I".
3. Slip the canard "J1 and J2" into position before glueing "K" to finish the nose.
4. Glue the top fin into position "M and N".
5. Cut bottom of "A, D, G and H" to fit centre-wing stubs "O and P", do not fold leading edge
of wings to a sharp edge. Bend and glue trailing edges, then place a large flat surface i.e.
hard-cover book over wing and press down slightly. Do not flatten completely.
6. Finish rest of wings working from the inside out. Stabilizers P3 and O3 must be parallel to
the fuselage and the wing must have a dihedral of ± 3°.
7. Roll and glue bottom scoop "Q" in position before fitting the bottom fin "R".
8. If the landing gear is to be fitted cut holes on the white circles printed on the fuselage
and main wing. Colour the doors printed on the aircraft with a black marker. Note that only
the small door of the front landing gear must be coloured.
9. Roll parts 1, 7a and 7b. Assemble the landing gear as indicated. Note that parts 7a to 13a
form the left leg, 7b to 13b the right leg.
Engine: 1275 hp Allison V-1710-95 (F23R)
twelve-cylinder liquid-cooled Vee engine.
Armament: Four 0.50-inch Colt-Browning M2 machine guns.
Maximum speed: 390 mph at 19,300 ft.
Maximum range: 1440 miles.
Climb rate: 7.1 min. to 20,000 ft.
Service ceiling: 34,600 ft.
Weight:
7939 pounds maximum.
Wingspan:
44 feet 0 1/2 inches.
Length:
29 feet 7 inches
Height:
10 feet 0 3/4 inches
Wing area:
235 square feet.
X4
OO
O3
X3
M
OO
O2
N
OO
O1
H
L
X2
C
G
II
I
D
X1
PP
P3
A
B
PP
P1
E
PP
P2
JJ
J2
F
O, P
PROFILES:
R
K
Q
JJ
J1
1
13a
7a
6
10a
5
4
12a
X1
8a
2
X2
X4
11a
X3
3
9a
Model design by Chris Jordaan -- chrisj@aviation.denel.co.za
Curtiss
Curtiss Xp-55
O,
Ascender
Model design by Chris Jordaan
Xp-55 Ascender
Ascender
*
Cut away after fuselage is complete
*
C
*
*
Landing light "X"
*
K
X
z
I
F
*
1
E
*
*
*
H
12a
N
B
G
5
A
D
Trim to fit if necessary
Y
12b
Z
Q
3
J2
M
Y
R
Glue to top of F
W
11a
J1
O3
P3
11b
13b
13a
chrisj@aviation.denel.co.za
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Xp-55 Ascender
Ascender
Model design by Chris Jordaan
Xp-55 Ascender
9a
9b
Cut slots for propeller blades before rolling.
Glue blades into position before glueing L to
part I
L
O2
O1
O
7a
P
P1
7b
10a
10b
P2
2
6
4
8a
8b
chrisj@aviation.denel.co.za
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Ascender
Model design by Chris Jordaan
Xp-55 Ascender
Ascender
*
Cut away after fuselage is complete
*
C
*
*
Landing light "X"
*
K
X
z
Captain Mark Twain
I
F
*
1
E
*
*
*
H
12a
N
B
G
A
5
D
Trim to fit if necessary
Y
12b
Z
Q
3
J2
M
Y
R
Glue to top of F
W
11a
J1
O3
P3
11b
13b
13a
chrisj@aviation.denel.co.za
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Curtiss
Curtiss Xp-55
Curtiss Xp-55 Ascender
Xp-55 Ascender
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