Tag Archives: British Purchasing Commission

20 December 1941

Kawasaki Ki-48 Army Type 99 twin-engine light bomber. Allied reporting name, “Lily.”

20 December 1941: For the first time, the 1st American Volunteer Group engaged aircraft of the Empire of Japan in combat. 1st and 2nd Squadrons, based at Kunming, China, intercepted ten Kawasaki Ki-48-I Army Type 99 twin-engine light bombers of the 82nd Dokuritsu Hiko Chutai.

Japan and China had been at war since 1937. The Japanese aircraft were based at the Gia Lâm airport, near Hà Nội in occupied French Indochina. They had frequently attacked Kunming, a Chinese city at the northern end of the Burma Road, and had previously been unopposed. For this mission, the bomber squadron initially had a fighter escort, but the fighters turned back at the Indo-China/China border.

The AVG had established a network of observers which would report enemy aircraft in time for the fighters to take off to intercept them. Having received the warning of inbound aircraft, the 1st and 2nd AVG squadrons were ordered into battle.

1st American Volunteer Group fighter pilots run toward their shark-mouthed Curtiss-Wright Hawk 81-A2s, “somewhere in China.” (Defense Media Network)

Sources vary widely as to the number of AVG aircraft involved, but there may have been as many as 16 Curtiss-Wright Hawk 81-A3s from the 1st Squadron, and 8 more from the 2nd Squadron. There is a general consensus that the fighters shot down three of the Japanese bombers, and that a fourth went down while returning to base. Other sources say that only one of the ten Ki-48s made it back to its base. AVG pilots claimed five bombers shot down and two damaged. One Hawk 81 ran out fuel and was damaged beyond repair in a forced landing.

A Curtiss-Wright Hawk 81-A3 of the 1st American Volunteer Group, Kunming, China, 1942. (U.S. Air Force)
CAMCO assembly facility for Curtiss-Wright Hawk 81-A3 fighters for AVG (74250 A.C.) (SDASM)
Curtiss-Wright 81-A3, 1st American Volunteer Group, circa 1942.
AMERICAN AIRCRAFT IN ROYAL AIR FORCE SERVICE: CURTISS HAWK 81A TOMAHAWK. (CH 17252) The first Curtiss Tomahawks, Marks I and IIA, to enter squadron service with the RAF, in the hands of No. 403 Squadron RCAF at Baginton, Warwickshire. The Squadron operated the Tomahawk for only a short time, yielding them in favour of Supermarine Spitfires in May 1941. Copyright: © IWM. Original Source: http://www.iwm.org.uk/collections/item/object/205210781
AMERICAN AIRCRAFT IN RAF SERVICE 1939-1945: CURTISS HAWK 81A TOMAHAWK. (ATP 10993F) Tomahawk Mk.IIb, AK184: cockpit interior, port side. Photograph taken at Air Service Training Ltd, Hamble, Hampshire. Copyright: © IWM. Original Source: http://www.iwm.org.uk/collections/item/object/205127117
Curtiss-Wright Tomahawk Mk.IIb, AK184, at Hamble, Hampshire © IWM.

RAF order for 100 Tomahawk IIb (Curtiss-Wright Hawk 81-A2 ) was released to be available for AVG. They were built as hybrids of the Tomahawk Mk.IIb and the P-40C Warhawk, though the airplanes intended for the AVG differed in details from either the standard Britsih or American fighters. The airplanes were painted in the standard RAF brown and green camouflage patterns. The completed airplanes were knocked down, crated, then shipped from New York. They were reassembled at a CAMCO facility near Rangoon, Burma.

Two Curtiss-Wright Tomahawk Mk.IIBs on a test flight following assembly at No. 107 Maintenance Unit, Kasfareet, Egypt. Copyright: © IWM.

The Curtiss-Wright Corporation Hawk 81 was a single-seat, single-engine pursuit (fighter). It was a low-wing monoplane of all-metal construction and used flush riveting to reduce aerodynamic drag. It had an enclosed cockpit and retractable landing gear. Extensive wind tunnel testing at the NACA Langley laboratories refined the airplane’s design, significantly increasing the top speed.

The Hawk 81 was 31 feet, 8¾ inches (9.671 meters) long, with a wingspan of 37 feet, 4 inches (11.379 meters) and overall height of 10 feet, 7 inches (3.226 meters).

The Tomahawk/Warhawk was powered by a liquid-cooled, supercharged, 1,710.597ubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C15 (V-1710-33), a single overhead cam (SOHC) 60° V-12 engine, which had a Continuous Power Rating of 930 horsepower at 2,600 r.p.m., from Sea Level to 12,800 feet (3,901 meters), and 1,150 horsepower at 3,000 r.p.m. to 14,300 feet (4,359 meters) for Take Off and Military Power. The engine drove a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The V-1710-33 was 8 feet, 2.54 inches (2.503 meters) long, 3 feet, 5.88 inches (1.064 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It weighed 1,340 pounds (607.8 kilograms).

Armament consisted of two air-cooled Browning AN-M2 .50-caliber machine guns mounted in the cowling and synchronized to fire forward through the propeller arc, with 380 rounds of ammunition per gun. In British service, the Tomahawk was armed with an additional four Browning .303 Mark II machine guns, with two in each wing. The American P-40, P-40B and P-40C Warhawks had two or four Browning AN-M2 .30-caliber aircraft machine guns as wing-mounted guns.

The “blood chit” was sometimes sewn on AVG pilots’ jackets.

The AVG pilots were employees of the Central Aircraft Manufacturing Company (CAMCO). Most were former United States military pilots who had been secretly recruited. They were required to resign their officers’ commissions. Importantly, they were all civilians—not members of the Chinese military–nor were they otherwise employed by the government of China. They each had a one year contract, 4 July 1941–4 July 1942. They were paid a monthly salary, more than three times their former military pay, and were also paid a bonus for each enemy airplane they shot down.

(Note: This article is an incomplete draft)

© 2018, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather

9 September 1940

North American Aviation NA-73X prototype, NX19998, at Mines Field, California, 9 September 1940. (North American Aviation, Inc.)

9 September 1940: North American Aviation completed assembly of the NA-73X, the first prototype of the new Mustang Mk.I fighter for the Royal Air Force. This was just 117 days after the British Purchasing Commission had authorized the construction of the prototype. The airplane was designed by a team led by Edgar Schmued. The 1,150-horsepower Allison V-12 engine had not yet arrived, so the NA-73X was photographed with dummy exhaust stacks. The prototype’s company serial number was 73-3097. It had been assigned a civil experimental registration number, NX19998.

The NA-73X was a single-seat, single-engine, low wing monoplane with retractable landing gear. It was primarily of metal construction, though the flight control surfaces were fabric covered. The airplane was designed for the maximum reduction in aerodynamic drag.  The Mustang was the first airplane to use a laminar-flow wing. The fuselage panels were precisely designed and very smooth. Flush riveting was used. The coolant radiator with its intake and exhaust ducts was located behind and below the cockpit. As cooling air passed through the radiator it was heated and expanded, so that as it exited, it actually produced some thrust.

The prototype was 32 feet, 2⅝ inches (9.820 meters) long, with a wing span of 37 feet, 5/16 inch (11.286 meters). Empty weight of the NA-73X was 6,278 pounds (2,848 kilograms) and normal takeoff weight was 7,965 pounds (3,613 kilograms).

Aeronautical Engineer Edgar Schmued with a North American P-51-2-NA (Mustang Mk.IA), 41-37322. (San Diego Air and Space Museum Archives)

The NA-73X was powered by a liquid-cooled, supercharged, 1,710.60-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-F3R (V-1710-39) single overhead cam 60° V-12 engine, with four valves per cylinder and a compression ratio of 6.65:1. It used a single-stage, single-speed supercharger. This was a right-hand tractor engine (the V-1710 was built in both right-hand and left-hand configurations) which drove a 10 foot, 6 inch (3.200 meter) diameter, three-bladed, Curtiss Electric constant-speed propeller through a 2.00:1 gear reduction.

The V-1710-39 had a Normal Power rating of 880 horsepower at 2,600 r.p.m. at Sea Level; Take Off Power rating of 1,150 horsepower at 3,000 r.p.m. at Sea Level, with 44.5 inches of manifold pressure (1.51 Bar), 5 minute limit; and a War Emergency Power rating of 1,490 horsepower at 3,000 r.p.m., with 56 inches of manifold pressure (1.90 Bar). The V-1710-F3R was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.64 inches (0.931 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It had a dry weight of 1,310 pounds (594 kilograms).

U.S. Army Air Corps flight tests of the fully-armed production Mustang Mk.I (XP-51 41-038), equipped with the V-1710-39 and a 10 foot, 9-inch (3.277 meters) diameter Curtiss Electric propeller, resulted in a maximum speed of 382.0 miles per hour (614.8 kilometers per hour) at 13,000 feet (3,962 meters). The service ceiling was 30,800 feet (9,388 meters) and the absolute ceiling was 31,900 feet (9,723 meters).

The Curtiss P-40D Warhawk used the same Allison V-1710-39 engine as the XP-51, as well as a three-bladed Curtiss Electric propeller. During performance testing at Wright Field, a P-40D, Air Corps serial number 40-362, weighing 7,740 pounds (3,511 kilograms), reached a maximum speed of 354 miles per hour (570 kilometers per hour) at 15,175 feet (4,625 meters). Although the Mustang’s test weight was 194 pounds (88 kilograms) heavier, at 7,934 pounds (3,599 kilograms), the Mustang was 28 miles per hour (45 kilometers per hour) faster than the Warhawk. This demonstrates the effectiveness of the Mustang’s exceptionally clean design.

Only one NA-73X was built. It made its first flight 26 October 1940 with test pilot Vance Breese. The prototype suffered significant damage when it overturned during a forced landing, 20 November 1941. NX19998 was repaired and flight testing resumed. The prototype’s final disposition is not known.

Originally ordered by Great Britain, the Mustang became the legendary U.S. Army Air Corps P-51 Mustang. A total of 15,486 Mustangs were built by North American Aviation at Inglewood, California and Dallas, Texas. Another 200 were built in Australia by the Commonwealth Aircraft Corporation.

The P-51 remained in service with the U.S. Air Force until 27 January 1957 when the last one, F-51D-30-NA 44-74936, was retired from the 167th Fighter Squadron, West Virginia Air National Guard. It was then transferred to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, where it is on display.

North American Aviation NA-73X prototype, left front quarter view. (North American Aviation, Inc.)
North American Aviation NA-73X prototype, NX19998, left front quarter view. (North American Aviation, Inc.)

© 2017, Bryan R. Swopes

Facebooktwittergoogle_plusredditpinterestlinkedinmailby feather