Tag Archives: Browning .303 Mark II Machine Gun

20 May 1941

NAA test pilot Robert C. Chilton stand on the wing of P-51B-10-NA 42-106435. (North American Aviation, Inc.)
North American Aviation test pilot Robert C. Chilton standing on the wing of P-51B-10-NA Mustang 42-106435. (North American Aviation, Inc.)

20 May 1941: North American Aviation, Inc., test pilot Robert Creed Chilton took the first XP-51 for its maiden flight at Mines Field, Los Angeles, California. The XP-51 was the fourth production Mustang Mk.I built for the Royal Air Force, AG348 (North American serial number 73-3101).

The Mustang was reassigned to the U.S. Army Air Force, designated as XP-51, serial number 41-038, and sent to Wright Field, Dayton, Ohio, for evaluation.

North American Aviation Mustang Mk.I AG348 at Mines Field, California, 1941. North American Aviation, Inc., photograph 73-0-9. (Ray Wagner Collection/SDASM)
North American Aviation Mustang Mk.I AG348, Mines Field, California, 1941. North American Aviation, Inc., photograph 73-0-10. (Ray Wagner Collection/SDASM)
North American Aviation Mustang Mk.I AG348 at Mines Field, California, 1941. North American Aviation, Inc., photograph. (Ray Wagner Collection/SDASM)

Later, the XP-51 was extensively tested by the National Advisory Committee for Aeronautics (N.A.C.A.) at the Langley Memorial Aeronautical Laboratory, Langley Field, Hampton, Virginia.

Today, the restored XP-51 is in the collection of the E.A.A. AirVenture Museum at Oshkosh, Wisconsin.

North American Aviation XP-51 41-038 at the NACA Langley Memorial Aeronautical Laboratory. (NASA LMAL 27030)
North American Aviation XP-51 41-038 at the NACA Langley Memorial Aeronautical Laboratory. (NASA)

The Mustang Mk.I (NAA Model NA-73) was a single-place, single engine fighter primarily of metal construction with fabric control surfaces. It was 32 feet, 3 inches (9.830 meters) long with a wingspan of 37 feet, 5/16-inches (11.373 meters) and height of 12 feet, 2½ inches (3.721 meters). The airplane’s empty weight was 6,280 pounds (2,849 kilograms) and loaded weight was 8,400 pounds (3,810 kilograms).

North American Aviation XP-51 41-039 at NACA Langley. (NASA)
North American Aviation XP-51 41-039 at NACA Langley. Note the increased length of the carburetor intake. (NASA)

The Mustang was powered by a liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-F3R (V-1710-39) single overhead cam (SOHC) 60° V-12 engine with a compression ratio of 6.65:1. The -F3R had a Normal Power rating of 880 horsepower at 2,600 r.p.m., at Sea Level, and 1,000 horsepower at 2,600 r.p.m. at 11,000 feet (3,353 meters). It had a Takeoff and Military Power rating of 1,150 horsepower at 3,000 r.p.m., to 11,800 feet (3,597 meters). The engine turned a 10 foot, 9 inch (3.277 meter) diameter three-bladed Curtiss Electric constant-speed propeller through a 2.00:1 gear reduction. The V-1710-F3R was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.54 inches (0.928 meters) high, and 2 feet, 5.29 (0.744 meters) wide. It weighed 1,310 pounds (594 kilograms).

The Mustang Mk.I had a maximum speed of 382 miles per hour (615 kilometers per hour) at 13,700 feet (4,176 meters), the Allison’s critical altitude, and cruise speed of 300 miles per hour (483 kilometers per hour). The service ceiling was 30,800 feet (9,388 meters) and range was 750 miles (1,207 kilometers).

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right profile. (NASA LAML)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right profile. (NASA)

The Mustang Mk.I was armed with four air-cooled Browning .303 Mk.II aircraft machine guns, two in each wing, and four Browning AN-M2 .50-caliber machine guns, with one in each wing and two mounted in the nose under the engine.

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboroatory. (NASA LAML 27045)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, right three-quarter view. (NASA)

The Mk.I was 30 m.p.h. faster than its contemporary, the Curtiss P-40 Warhawk, though both used the same engine. Below 15,000 feet, the Mustang was also 30–35 m.p.h faster than a Supermarine Spitfire, which had a more powerful Roll-Royce Merlin V-12.

The XP-51 would be developed into the legendary P-51 Mustang. In production from 1941 to 1945, a total of 16,766 Mustangs of all variants were built.

North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, rear view. (NASA LMAL 27033)
North American Aviation XP-51 41-038 at NACA Langley Memorial Aeronautical Laboratory, rear view. (NASA)

Robert Creed Chilton was born 6 February 1912 at Eugene, Oregon, the third of five children of Leo Wesley Chilton, a physician, and Edith Gertrude Gray. He attended Boise High School in Idaho, graduating in 1931. Chilton participated in football, track and basketball, and also competed in the state music contest. After high school, Chilton attended the University of Oregon where he was a member of the Sigma Chi fraternity (ΣΧ). He was also a member of the Reserve Officers Training Corps (ROTC).

Bob Chilton enlisted as an Aviation Cadet in the U.S. Army Air Corps, 25 June 1937. He was trained as a fighter pilot at Randolph Field and Kelly Field in Texas, and was commissioned as a Second Lieutenant in 1938. Lieutenant Chilton was assigned to fly the Curtiss P-36 Hawk with the 79th Pursuit Squadron, 20th Pursuit Group, at Barksdale Field, Louisiana. Because of a medical condition, he was released from active duty, 1 April 1939.

At some time prior to 1940, Bob Chilton, married his first wife, Catherine. They lived in Santa Maria, California, where he worked as a pilot at the local airport.

In January 1941, Chilton went to work as a production test pilot for North American Aviation, Inc., Inglewood, California. After just a few months, he was assigned to the NA-73X.

Chilton married his second wife, Betty W. Shoemaker, 15 November 1951.

On 10 April 1952, Bob Chilton returned to active duty with the U.S. Air Force, with the rank of lieutenant colonel. He served as Chief of the Republic F-84 and F-105 Weapons System Project Office, Air Material Command, at Wright-Patterson Air Force Base, Dayton, Ohio, until 9 March 1957.

From 1958, Chilton was a vice president for Horkey-Moore Associates, an engineering research and development company in Torrance, California, founded by former North American aerodynamacist Edward J. Horkey. In 1961, he followed Horkey to the Space Equipment Corporation, parent company of Thompson Industries and Kerr Products, also located in Torrance. Chilton served as corporate secretary and contracts administrator.

Chilton married his third wife, Wilhelmina E. Redding (Billie E. Johnson) at Los Angeles, 26 July 1964. They divorced in 1972.

In 1965, Bob Chilton returned to North American Aviation as a flight test program manager. He retired in 1977.

Robert Creed Chilton died at Eugene, Oregon, 31 December 1994, at the age of 82 years.

North American Aviation XP-51 at Wright Field. (Charles M. Daniels Collection, San Diego Air & Space Museum Archives, Catalog #: 15_002838)

© 2018, Bryan R. Swopes

9 January 1941

BT308, the Avro Lancaster prototype, at RAF Ringway, 9 January 1941. (Avro Heritage Museum)
Captain Harry Albert (“Sam”) Brown, O.B.E. (Photograph courtesy of Neil Corbett, Test & Research Pilots, Flight Test Engineers)

9 January 1941: Test pilot Captain Harry Albert (“Sam”) Brown, O.B.E., (1896–1953) makes the first flight of the Avro Lancaster prototype, BT308, at RAF Ringway, Cheshire, England, south of Manchester.

Throughout World War II, 7,377 of these long range heavy bombers were produced for the Royal Air Force. The majority were powered by Rolls-Royce or Packard Merlin V-12 engines—the same engines that powered the Supermarine Spitfire and North American P-51 Mustang fighters.

The bomber was designed by Roy Chadwick, F.R.S.A., F.R.Ae.S., the Chief Designer and Engineer of A. V. Roe & Company Limited, based on the earlier twin-engine Avro Manchester Mk.I. Because of this, it was originally designated as the Manchester Mk.III, before being re-named Lancaster. Chadwick was appointed Commander of the Most Excellent Order of the British Empire, 2 June 1943, for his work.

The first prototype, BT308, was unarmed and had three small vertical fins.

Avro 683 Lancaster prototype BT308, shortly after the first flight at Manchester, 9 January 1941. (A.V.Roe via R.A.Scholefield) Photograph used with permission.
Avro 683 Lancaster prototype BT308, shortly after the first flight at RAF Ringway, Manchester, England, 9 January 1941. (A.V.Roe via R.A.Scholefield) Photograph is from The R.A. Scholefield Collection and is used with permission.

With the second prototype, DG595, the small center vertical fin was deleted and two larger fins were used at the outboard ends of a longer horizontal tailplane. DG595 was also equipped with power gun turrets at the nose, dorsal and ventral positions, and at the tail.

Avro Lancaster DG595, the second protoype of the Royal Air Force four-engine heavy bomber. This armed prototype has the twin-tail arrangement of the production aircraft. (Unattributed)
Avro Lancaster DG595, the second protoype of the Royal Air Force four-engine long range heavy bomber. This armed prototype has the twin-tail arrangement of the production aircraft. (Test & Research Pilots, Flight Test Engineers)
Air Ministry clearance form for Avro 638 Lancaster BT308. Shown on page 1 are the aircraft's engine type and serial numbers.
Air Ministry clearance form for Avro 683 Lancaster BT308. Shown on page 1 are the aircraft’s engine type and serial numbers.
Air Ministry test flight clearance form, Page 2.
Air Ministry test flight clearance form, Page 2. This form is signed by the airplane’s designer, Roy Chadwick, 5 January 1941.

The first production model, Lancaster Mk.I, was operated by a crew of seven: pilot, flight engineer, navigator/bombardier, radio operator and three gunners. It was a large, all-metal, mid-wing monoplane with retractable landing gear. It was 68 feet, 11 inches (21.001 meters) long with a wingspan of 102 feet, 0 inches (31.090) meters and an overall height of 19 feet, 6 inches (5.944 meters). The Mk.I had an empty weight of 36,900 pounds (16,738 kilograms) and its maximum takeoff weight was 68,000 pounds (30,909 kilograms).

BT308 and early production Lancasters were equipped with four liquid-cooled, supercharged, 1,648.96-cubic-inch-displacement (27.01 liter), Roll-Royce Merlin XX single overhead camshaft (SOHC) 60° V-12 engines, which were rated at 1,480 horsepower at 3,000 r.p.m. to 6,000 feet (1,829 meters). The Merlins drove three-bladed de Havilland Hydromatic quick-feathering, constant-speed airscrews (propellers), which had a diameter of 13 feet, 0 inches (3.962 meters), through a 0.420:1 gear reduction.

DG595 was used for performance testing at the Aeroplane and Armament Experimental Establishment (A&AEE) at Boscombe Down. The Mark I had a maximum economic cruise speed of 267 miles per hour (430 kilometers per hour) at 20,800 feet (6,340 meters), and a maximum speed of 286 miles per hour (460 kilometers per hour) at 20,000 feet (6,096 meters) at a gross weight of 45,300 pounds (20,548 kilograms).¹ Its service ceiling was 20,000 feet (6,096 meters) at 64,500 pounds (29,257 kilograms). It had a range of  2,530 miles (4,072 kilometers) with a 7,000 pound (3,175 kilogram) bomb load.

The Lancaster was designed to carry a 14,000 pound (6,350 kilogram) bomb load, but modified bombers carried the 22,000 pound (9,979 kilogram) Grand Slam bomb. For defense, the standard Lancaster had eight Browning .303-caliber Mark II machine guns in three power-operated turrets, with a total of 14,000 rounds of ammunition.

According to the Royal Air Force, “Almost half all Lancasters delivered during the war (3,345 of 7,373) were lost on operations with the loss of over 21,000 crew members.”

Only two airworthy Avro Lancasters are in existence.

The Royal Air Force Battle of Britain Memorial Flight Avro Lancaster Mk.I, PA474. This airplane was built in 1945 by Vickers Armstongs Ltd. at Broughton, Wales, United Kingdom. (Battle of Britain Memorial Flight)
The Canadian Warplane Heritage Museum’s Avro Lancaster Mk.X FM213, flies formation with an Royal Canadian Air Force CF-188 Hornet. The bomber is marked VR A and nicknamed “Vera.” FM213 was built by Victory Aircraft Ltd., Malton, Ontario, Canada. (Canadian Warplane Heritage Museum)

¹ Speeds shown are True Air Speed (T.A.S.)

© 2019, Bryan R. Swopes

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 (the “Flying Tigers”) 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-A3s, “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.

An 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).

Allison Engineering Co. V-1710-33 V-12 aircraft engine at the Smithsonian Institution National Air and Space Museum Steven F. Udvar-Hazy Center. (NASM)

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.

© 2018, Bryan R. Swopes

10 December 1938

Squadron Leader James Addams, RAF, at left, and Kelly Johnson with the Lockheed B14L, N7205, Union Air Terminal, Burbank, California, December 1938. (Unattributed)

10 December 1938: At the Union Air Terminal, Burbank, California, Squadron Leader James Addams and Squadron Leader Randle, both Royal Air Force officers, took the prototype Lockheed B14L for its first flight.

The prototype Lockheed B-14L (Hudson Mk.I, N7205) photographed during its first flight, 10 December 1938. Note the mockup dorsal gun turret and painted-out British insignia. (W.J. “Billy” Gray)

The B14L (also identified as Model 214-40-01) was a twin engine light bomber developed by the Lockheed Aircraft Company from its Model 14 Super Electra civil transport. Both types were designed by the legendary Clarence L. (“Kelly”) Johnson. The prototype was purchased by Great Britain and designated Hudson Mk.I. It was assigned the R.A.F. identification N7205.

(Los Angeles Times, Vol. LVIII, Thursday Morning, 22 December 1938, Page 9, Columns 2–4)
Squadron Leader James Addams, RAF, and Clarence L. (“Kelly”) Johnson shake hands in front of the prototype Lockheed B14L (Hudson Mk.I N7205) at Union Air Terminal, Burbank, California, December 1938. (The Honolulu Advertiser, Vol. 83, No. 18,694, Saturday, 31 December 1938, Page 2, Columns 3–6_)
Lockheed Hudson Mk.I N7205 was partially disassembled and transported to England aboard a ship. (Royal Air Force)
Lockheed Hudson Mk.I N7205 at RAF Northolt, South Ruislip, near London, England,1939. (RAF Museum PC98/173/5840/14)

Gunnery tests of the prototype were carried out near Daggett, in the Mojave Desert of southern California, 100 statute miles (161 kilometers) northeast of Burbank.

The Lockheed Hudson was a twin-engine, mid-wing light bomber with conventional retractable landing gear. It was operated by a pilot, navigator/bombardier, radio operator/gunner, and a gunner in a dorsal power-operated turret. The Mk.I was 44 feet 3-7/8 inches (13.510 meters) long, with a wingspan of 65 feet, 6 inches (19.964 meters), and height of 11 feet, 10 inches (3.607 meters). It had an empty weight of 11,630 pounds (5,275 kilograms), and maximum gross weight of 17,500 pounds (7,938 kilograms).

Hudson Mark III, V8977: cabin interior with pilot’s position on the left. Photograph taken at Eastleigh, Hampshire. Photographed 24 July 1942. (Imperial War Museum, Royal Air Force Aircraft 1941–1959: ATP Collection (GSA 325). © IWM ATP 10925F )

The Hudson Mk.I was powered by two air-cooled, supercharged, 1,823.129-cubic-inch-displacement (29.875 liter) Wright Aeronautical Division Cyclone 9 GR-1820-G102A radial engines with a compression ratio of 6.3:1. They had a normal power rating of 900 horsepower at 2,200 r.p.m., at Sea Level, and 1,100 horsepower at 2,200 r.p.m. for takeoff.  The engines drove three-blade adjustable pitch propellers through a 0.6875 gear reduction. The GR-1820-G102A was 4 feet, 0.12 inch (1.222 meters) long, 4 feet, 7.10 inches (1.400 meters) in diameter, and weighed 1,275 pounds (578 kilograms).

The Hudson Mk.I had a cruise speed of 220 miles per hour (354 km/h), and maximum speed of 246 miles per hour (396 km/h) at 6,500 feet (1,981 meters). Its service ceiling was 25,000 feet (7,620 meters), and its range, 1,960 miles (3,153 kilometers).

The Hudson was armed with two fixed, forward-firing .303-caliber (7.7 × 56mmR) Browning Mk.II machine guns located above the bombardier’s compartment, two .303 Mk.II guns in a power-operated Boulton Paul Aircraft Ltd. dorsal turret and a fifth flexible mount .303 machine gun was located in a ventral position. Each of these guns were capable of firing at a rate of 1,150 rounds per minute.

The bomber could carry four 250 pound (113 kilogram) bombs, or ten 100 pound (45 kilogram) bombs in an internal bomb bay.

“Armourers secure 250-lb GP bombs in the bomb bay of a Lockheed Hudson of No. 224 Sqyadron RAF at RAF Leuchars, Fife, Scotland.” (Flight Lieutenant Stanley Devon, RAF/Imperial War Museums CH 979)

British purchasing Commission contracted for 250 Hudson Mk.I bombers, 23 June 1938. Deliveries began in February 1939, with the 250th Hudson Mk.I delivered in October 1939.

Lockheed built 2,941 Hudson bombers in a number of configurations. 351 of these were Hudson Mk.Is.

Lockheed Hudson Mk.I N7220 (B14L-1616) at Grand Central Air Terminal, Glendale, California, circa 1938. The Boulton Paul dorsal gun turrets would be installed after arrival in Great Britain. (AirHistory.net)
Hudson Mark I, N7326 ‘ZS-F’ (B14L-1622), of No. 233 Squadron RAF based at Aldergrove, County Antrim, preparing to take off from Leuchars, Fife.
IWM CH 2429
Lockheed Hudson twin-engine bombers being assembled. (Lockheed Martin)
Lockheed Hudson assembly line. (Lockheed Martin)
Lockheed AT-18A-LO Hudson 42-55569, s/n 414-7291.
Lockheed Hudson (SDASM)

© 2023, Bryan R. Swopes

25 November 1940

The prototype de Havilland DH.98 Mosquito, W4050, takes off on its first flight at Hatfield, 25 November 1940. (BAE Systems)

25 November 1940: De Havilland Aircraft Company’s Chief Test Pilot, Geoffrey Raoul de Havilland, Jr., and engineer John Walker, made the first flight of the DH.98 Mosquito prototype, E0234, at Hatfield, Hertfordshire, England. The prototype’s Royal Air Force identification was W4050. The multi-role combat aircraft was constructed primarily of layers of balsa covered with layers of birch, then a layer of doped cotton fabric. It was powered by two Rolls-Royce Merlin V-12 engines.

Sir Geoffrey de Havilland, Jr, with a DH.98 Mosquito, 14 October 1943. (Photo by Reg Speller/Fox Photos/Getty Images 3320005)

The construction materials took advantage of plentiful supplies of wood, and also made workers who were not in the standard metal aircraft industry able to take part.

The prototype was rolled out 19 November 1040, painted overall yellow.

The prototype de Havilland DH.98 Mosquito, E0234, outside the Assembly Building, 19 November 1940. (BAE Systems)

The prototype had a wingspan of 54 feet, 2 inches (16.510 meters), and its gross weight was 19,670 pounds (8,922 kilograms). W4050 was powered by two liquid-cooled, supercharged, 1,648.96-cubic-inch-displacement (27.01 liter) Rolls-Royce Merlin Mk.21 single overhead camshaft (SOHC) 60° V-12 engines, producing 1,460 horsepower at 3,000 r.p.m. at 10,000 feet (3028 meters), with 10 pounds (0.69 Bar) of boost, and driving three-bladed de Havilland Hydromatic propellers through a gear reduction.

The prototype DH.98 Mosquito,now marked W4050, in the field behind Salisbury Hall (where it was designed and built) just before its first flight, 25 November 1940. (HistoryNet)

The DH.98 had been predicted to be 20 miles per hour (32 kilometers per hour) faster than the Supermarine Spitfire, but was actually much faster. In testing, the prototype reached 392 miles per hour (631 kilometers per hour) at 22,000 feet (6,706 meters). Improvements were continuously made, and with 2-stage superchargers, W4050 reached a maximum 437 miles per hour (703 kilometers per hour). The DH.98 prototype had a service ceiling of 34,000 feet (10,363 meters) and range of 2,180 miles (3,500 kilometers).

The production fighter variant, the Mosquito F. Mk.II, was 41 feet, 2 inches (12.548 meters) long with a wingspan of 54 feet, 2 inches (16.510 meters) and height of 15 feet, 3 inches (4.648 meters) in 3-point position. The wings had 1½° incidence with approxmatey 2½° dihedral. The leading edges were swept aft 2½°. The total wing area was 436.7 square feet (40.6 square meters). The fighter’s empty weight was 13,356 pounds (6,058 kilograms) and the maximum takeoff weight was 18,649 pounds (8,459 kilograms). The Mk.II had a total fuel capacity of 553 gallons.

The Mk.II had a cruise speed of 265 miles per hour (426 kilometers per hour) at 15,000 feet (4,572 meters) and maximum speed of 380 miles per hour (612 kilometers per hour) at 21,400 feet (6,523 meters).

Mosquito bomber variants could carry four 500 pound bombs, or two 2,000 pound bombs, but were otherwise unarmed. Fighters were equipped with four Hispano Mk.II 20 mm autocannon and four Browning .303-caliber Mk.II machine guns in the nose.

6,411 DH.98 Mosquitoes were built in England, 1,134 in Canada and 212 in Australia. It was produced in bomber, fighter, night fighter, fighter bomber and photo reconnaissance versions.

The prototype DH.98 Mosquito, W4050, at Hatfield, Hertfordshire. (Royal Air Force)

W4050’s (the prototype’s Royal Air Force identification) fuselage was damaged while taxiing at Boscombe Down, 24 February 1941, and had to be replaced with one intended for a second prototype, W4051. It remained at de Havilland and was used to test different engines, armaments and versions. After a series of tests conducted in December 1943, the prototype Mosquito was permanently grounded. It was used as an instructional airframe and later placed in storage.

In September 1958, W4050 was turned over to the de Havilland Aircraft Heritage Centre. Today, the restored prototype DH.98 Mosquito is at the museum at London Colney, Hertfordshire, England.

The Mosquito prototype with camouflauged upper surfaces as it appeared at Boscombe Down, (de Havilland Aircraft Museum)
The Mosquito prototype with camouflaged upper surfaces as it appeared at Boscombe Down, 1941. (de Havilland Aircraft Museum)

© 2020, Bryan R. Swopes