XP-13

Thomas-Morse XP-13
Role	Fighter Type of aircraft
Manufacturer	Thomas-Morse
Designer	B. Douglas Thomas^[1]
Introduction	June 1929
Primary user	United States Army Air Service
Number built	1^[2]

The XP-13 Viper was a prototype biplane fighter aircraft designed by the American company Thomas-Morse Aircraft Corporation. The airplane was delivered to the United States Army in 1929, but they did not adopt it.

Design and development

This aircraft was one of several B. Douglas Thomas designs built in hopes of a production contract from the Army, following the successful Thomas-Morse MB-3 of 1919. Financed by the company, and named the "Viper", it was officially purchased by the Army in June 1929 and designated "XP-13".

The XP-13 fuselage had a corrugated aluminum skin built over a metal frame; the flying surfaces were also metal-framed, but covered with the traditional fabric. While designed to use the 600 hp Curtiss H-1640-1 Chieftain engine, (a novel 12-cylinder two-row air-cooled radial with the rear cylinders directly behind the front cylinders rather than staggered as normal in a two-row radial^[3]) for which the XP-13 incorporated a complex system of baffles to direct cooling air over the engine, the engine simply would not stay cool enough, and in September 1930 it was replaced with a Pratt & Whitney SR1340C Wasp of 450 hp. Ironically, the lower-power engine actually resulted in a speed increase of 15 mph, at least partly because of the weight savings.^[4]

In the end, the Army decided against production, Thomas-Morse was acquired by Consolidated Aircraft, and the prototype was lost to an inflight fire.

Variants

XP-13: Prototype, serial number 29-453 with 600 hp (448 kW) Curtiss H-1640-1 Chieftain hex engine^[2]

XP-13A: The XP-13 modified with a 525 hp (391 kW) Pratt & Whitney SR-1340-C enclosed in a NACA cowling, along with a revised fin and rudder^[5]

XP-14: This designation was used for a proposed Curtiss version of the Viper with the Curtiss H-1640-1 Chieftain hex engine

Operators

United States

United States Army Air Service

Specifications (XP-13 (Chieftain engine))

Data from William Green; Gordon Swanborough (1994). The Complete Book of Fighters: An Illustrated Encyclopedia of Every Fighter Aircraft Built and Flown. Salamander. ISBN 978-0-86101-643-3.

General characteristics

Crew: 1
Length: 23 ft 6 in (7.16 m)
Wingspan: 28 ft 0 in (8.53 m)
Height: 8 ft 5 in (2.56 m)
Wing area: 189 sq ft (17.6 m²)
Empty weight: 2,262 lb (1,026 kg)
Gross weight: 3,256 lb (1,477 kg)
Powerplant: 1 × Curtiss H-1640-1 Chieftain 12-cyliner two-row air-cooled radial engine, 600 hp (448 kW)

Performance

Maximum speed: 150 kn (172 mph, 277 km/h) (at sea level)
Cruise speed: 113 kn (130 mph, 209 km/h) ^[6]
Range: 168 nmi (193 mi, 312 km) ^[6]
Service ceiling: 20,775 ft (6,300 m)
Rate of climb: 1,700 ft/min (8.6 m/s) ^[6]

Armament
none

References

External links

Thomas-Morse aircraft

USAAS/USAAC/USAAF/USAF fighter designations 1924–1962, and Tri-Service post-1962 systems

1924 sequences
(1924–1962)

Pursuit (1924–1948)	P-1 P-2 P-3 P-4³ Curtiss P-4 Boeing P-4 P-5 P-6 P-7 P-8 P-9 P-10 P-11 P-12 P-13 P-14 P-15 P-16 P-17 P-18 P-19 P-20 P-21 P-22 P-23 P-24 P-25 P-26 P-27 P-28 P-29 P-30 P-31 P-32 P-33 P-34 P-35 P-36 P-37 P-38 P-39 P-39E P-40 P-41 P-42 P-43 P-44 P-45 P-46 P-47 P-48 P-49 P-50 P-51 P-52 P-53 P-54 P-55 P-56 P-57 P-58 P-59³ XP-59 P-59 P-60 P-61 P-62 P-63 P-64 P-65 P-66 P-67 P-68 P-69 P-70 P-71 P-72 P-73² P-74¹ P-75 P-76 P-77 P-78 P-79 P-80 P-81 P-82 P-83 P-84 P-85 P-86 P-87 P-88 P-89 P-90 P-91 P-92
Fighter (1948–1962)	F-38 F-39 F-40 F-47 F-51 F-59 F-61 RF-61C F-63 F-80 F-81 F-82 F-83 F-84 F-84F/J F-84H F-85 F-86 F-86C F-86D/G/K/L F-87 F-88 F-89 F-90 F-91 F-92 F-93 F-94 F-95 F-96 F-97 F-98 F-99 F-100 F-100B F-101 F-102 F-102B F-103 F-104 XF-104 F-104S NF-104A F-105 F-106³ XF-106 F-106 F-107 F-108 F-109² F-110 F-111 F-111B F-111C F-111K AFTI/F-111A EF-111A
Pursuit, Biplace	PB-1 PB-2 PB-3
Fighter, Multiplace	FM-1 FM-2
Non-sequential	F-24 P-322 P-400

Tri-service sequence
(1962–present)

Main sequence	F-1 F-1C/D F-1E/F F-2 F-3 F-4 F-4K/M F-5 G F-6 F-7 F-8 F-9 F-9F–J F-10 F-11 F-12 F-12C² F-13¹ F-14 F-15 F-15E F-15EX F-15J F-15 STOL/MTD F-16 F-16XL NF-16D F-17 F/A-18 F/A-18E/F EA-18G F-19¹ F-20 F-21 F-22 YF-22 FB-22 F-23
Non-sequential	F-35 F-35I X-35 F-117

Covert designations

Related designations

FV-12

¹ Not assigned • ² Unofficial • ³ Assigned to multiple types
See also: "F-19" • 1919-1924 sequence

Thomas-Morse aircraft
Thomas Brothers	D-5 T-2 S-4 SH-4
Thomas-Morse	MB-1 MB-2 MB-3 MB-4 MB-6 MB-7 MB-9 MB-10 R5 TM-23 TM-24 O-19 Y1O-41 Y1O-42 XP-13 Viper