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, (North American serial number 73-3101) and assigned registration number AG348 .

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. (Ray Wagner Collection/SDASM)
North American Aviation Mustang Mk.I AG348, Mines Field, California, 1941. North American Aviation, Inc., photograph. (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. (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.

© 2018, Bryan R. Swopes

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16–17 May 1943

Wing Commander Guy Penrose Gibson, VC, DSO and Bar, DFC and Bar. (Imperial War Museum)
Wing Commander Guy Penrose Gibson, V.C., D.S.O. and Bar, D.F.C. and Bar. © IWM (CH 11047)

16–17 May 1943: Nineteen modified Avro Lancaster B.III Special long-range heavy bombers of No. 617 Squadron, Royal Air Force, carried out Operation Chastise, a low-level night attack against four hydroelectric dams in the Ruhr Valley.

The purpose of the attack was to disrupt German steel production. It was estimated that 8 tons of water were required to produce 1 ton of steel. Breaching the dams would reduce the available water and hydroelectric power, disrupt transportation of materials on the rivers, and flood iron ore and coal mines and power plants. If the dams were destroyed, it was believed that the effects would be the same as attacks against 26 categories of industrial targets further down the Ruhr Valley.

Led by 24-year-old Wing Commander Guy Penrose Gibson, D.S.O. and Bar, D.F.C. and Bar, a veteran of 172 combat missions, the aircrews of No. 617 Squadron dropped a spinning cylindrical bomb, code-named “Upkeep”, from a height of just 60 feet (18.3 meters) over the reservoirs behind the dams, while flying at precisely 240 miles per hour (386.2 kilometers per hour).

The 9,250-pound (4,195.8 kilogram) Vickers Type 464 bomb was designed to skip along the surface and to strike the dam, and then sink to the bottom. There, a pressure detonator exploded the 6,600 pound (2,994 kilogram) Torpex charge directly against the wall with the water pressure directing the energy through the wall.

Guy Gibson's Avro Lancaster B.III Special, ED932/G, AJ-G, "bombed up" with an Upkeep bomb. © IWM (HU 69915)
Guy Gibson’s Avro Lancaster B.III Special, ED932/G, AJ-G, “bombed up” with a Vickers Type 464 bomb. © IWM (HU 69915)

Nineteen Lancasters took off from RAF Scampton beginning at 9:28 p.m. on the 16th, and flew across the North Sea at only 100 feet (30.5 meters) to avoid being detected by enemy radar. The bombers succeeded in destroying the Möhne and Eder dams and damaging the Sorpe. A fourth dam was attacked but not damaged. The last surviving bomber returned to base at 6:15 a.m. on the 17th.

Of the nineteen Lancasters launched, two were damaged and turned back before reaching the targets. Six were shot down and two more collided with power lines during the low-level night flight. Of 133 airmen participating in the attack, 53 were killed.

GIBSON, Guy, with PO Frederick M. Spafford, FL Robert E.G. Hutchinson, PO Andrew Deering and FO Torger H. Taerum
Wing Commander Guy Penrose Gibson, V.C., D.S.O. and Bar, D.F.C. and Bar, Commander No. 617 Squadron, with the crew of “G George”: Pilot Officer Frederick Mchael Spafford, D.F.C., bomb aimer; Flight Lieutenant Robert Edward George Hutchinson, D.F.C. and Bar, wireless operator; Pilot Officer Andrew Deering, D.F.C., gunner; Flying Officer Torger Harlo Taerum, D.F.C., navigator. Flight engineer Sergeant John Pulford and tail gunner Flight Lieutenant Richard A.D. Trevor-Roper are not present.  © IWM (TR 1127) 

Guy Gibson was awarded the Victoria Cross by King George VI. An additional 33 survivors were also decorated. 617 Squadron became known as “The Dambusters.” A book, The Dam Busters, was written about the raid by Paul Brickhill, who also wrote The Great Escape. A 1955 movie starred Richard Todd, O.B.E., as Wing Commander Gibson. There have been reports that a new movie is planned.

An Avro Lancaster B.III Special drops an "Upkeep" bomb during tests, April 1943. (Imperial War Museum)
An Avro Lancaster B.III Special drops an “Upkeep” bomb during tests at Reculver, April 1943. Imperial War Museum, still from film, IWM (FLM 2340)
After being dropped from an Avro Lancaster, the “special mine” bounces across the water. (Imperial War Museum)
Post-strike reconnaissance photograph shows the breach of the Mohne Dam in the Ruhr Valley, 16 May 1943. (Imperial War Museum)
Post-strike reconnaissance photograph shows the breach of the Möhne Dam in the Ruhr Valley, 17 May 1943. The gap is 250 feet (76 meters) wide and 292 feet (22 meters) deep. © IWM (CH 9687)

The Avro Lancaster B.III Special was a four-engine long range heavy bomber modified to carry the Type 464 bomb. It was operated by a crew of seven: Pilot, flight engineer, navigator, radio operator, bomb aimer, nose gunner and tail gunner. The “Lanc” was 69 feet, 6 inches (21.184 meters) long with a wingspan of 102 feet (31.090 meters) and overall height of 20 feet (6.096 meters). The modified bomber had an empty weight of 35,240 pounds (15,984.6 kilograms and a maximum takeoff weight (MTOW) of 60,000 pounds (27,215.5 kilograms).

The Lancaster B.III Special was powered by the Packard Motor Car Company’s license-built version of the Rolls-Royce Merlin 24, the Packard V-1650-1 Merlin 224. These were liquid-cooled, supercharged, 1,648.96-cubic-inch-displacement (27.022-liter) single overhead cam (SOHC) 60° V-12 engines with four valves per cylinder and a compression ratio of 6.0:1. The Merlin 224 used a two-speed, single-stage supercharger. 100/130-octane aviation gasoline was required. The engine had a Normal Power rating of 1,080 horsepower at 2,650 r.p.m. and 9,500 feet (2,896 meters); Military Power, 1,240 horsepower at 3,000 r.p.m. at 11,000 feet (3,353 meters); and 1,300 horsepower at 3,000 horsepower with 54.3 inches of manifold pressure (1.84 Bar) for Takeoff. The Merlins drove three-bladed de Havilland Hydromatic quick-feathering, constant-speed propellers which had a diameter of 13 feet (3.962 meters). The propeller gear reduction ratio was 0.477:1. The V-1650-1 was 6 feet, 7.7 inches (2.024 meters) long, 2 feet, 6.0 inches (0.762 meters) wide and 3 feet, 6.6 inches (1.082 meters) high. It weighed 1,512 pounds (685.8 kilograms).

These engines gave the Lancaster a cruising speed of 200 miles per hour (321.9 kilometers per hour) and maximum speed of 272 miles per hour (437.7 kilometers per hour). The service ceiling was 24,700 feet (7,528.6 meters) and maximum range was 2,530 miles (4,071.6 kilometers).

Defensive armament for a standard Lancaster consisted of eight air-cooled Browning .303-caliber Mark II machine guns in three power turrets, nose, dorsal and tail. The Lancasters assigned to Operation Chastise had the dorsal turret deleted to reduce weight and aerodynamic drag. The gunner normally operating that turret was moved to the front turret, relieving the bomb aimer to deal with the operation of the specialized mission equipment.

7,377 Avro Lancasters were built. Only two remain in airworthy condition.

The first two modified Avro Lancaster B.III Specials assigned to No. 617 Squadron, RAF Scampton, April 1943. (Royal Air force)
The first two modified Avro Lancaster B.III Specials assigned to No. 617 Squadron, RAF Scampton, April 1943. In the foreground is ED825/G, AJ T. (Royal Air Force)
One of the two flyable Lancasters remaining, “City of London,” the Battle of Britain Memorial Flight Vickers-Armstrongs Ltd.-built Lancaster B.I, PA474. The airplane is marked as “Mickey the Moocher,” EE176, QR M. (Crown Copyright)
Victory Aircraft Ltd.-built Avro Lancaster B Mk.X FM213, marked as KB726, VR A.

Highly Recommended: The Dam Busters, by Paul Brickhill. Evans Brothers, London, 1951

© 2018, Bryan R. Swopes

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5 March 1936

The Vickers-Supermarine Type 300, K5054, during its first flight, 5 March 1936. The pilot is Captain Joseph Summers. (Supermarine Aviation Works)

5 March 1936: At 4:35 p.m., Thursday afternoon, Vickers Aviation Ltd.’s Chief Test Pilot, Captain Joseph (“Mutt”) Summers, took off on the first flight of the Vickers-Supermarine Type 300, K5054, prototype of the legendary Supermarine Spitfire, at Eastleigh Aerodrome, Southampton, England. Landing after only 8 minutes, Summers is supposed to have said, “Don’t change a thing!”

Supermarine Type 300 K5054. © IWM (ATP 8770C)
Supermarine Type 300 K5054. © IWM (MH 5215)
Supermarine Type 300 K5054. © IWM (MH 5212)
Supermarine Type 300 K5054. © IWM (ATP 8770G)

The Vickers-Supermarine Type 300 was a private venture, built to meet an Air Ministry requirement¹ for a new single-place, single-engine interceptor for the Royal Air Force. The airplane was designed by a team led by Reginald Joseph Mitchell, C.B.E., F.R.Ae.S., and was built at the Supermarine Aviation Works, Southampton, Hampshire, England.

Vickers-Supermarine Type 300, K5054. (Supermarine Aviation Works)

R.J. Mitchell was famous for his line of Schneider Trophy-winning and world record-setting Supermarine racers of the late 1920s and early 1930s, the Supermarine S.4, S.5, S.6 and S.6B.² Mitchell was appointed Commander of the Most Excellent Order of the British Empire  (Civil Division) (CBE) in His Majesty’s New Year’s Honours, 2 January 1932, for “services in connection with the Schneider Trophy Contest.”

Reginald Joseph Mitchell, C.B.E., F.R.Ae.S.

The Vickers-Supermarine Type 300 was 29 feet, 11 inches (9.119 meters) long, with a wingspan of 36 feet, 10 inches (11.227 meters) and overall height of 12 feet, 8 inches (3.861 meters). The wings had a distinctively ellipsoid shape, area was 242.0 square feet (22.48 square meters). Its empty weight was 4,082 pounds (1,151.6 kilograms) and loaded weight was 5,359 pounds (2,430.8 kilograms).

Supermarine Type 300 K5054. © IWM (MH 5205)

K5054 was powered by a right-hand tractor, liquid-cooled, supercharged, 1,648.9-cubic-inch-displacement (27.04-liter) Rolls-Royce Merlin C (“ramp head”) single overhead camshaft (SOHC) 60° V-12 engine, serial number C9 (Air Ministry serial number A111,139), which had a Normal Power rating of 1,029 horsepower at 2,600 r.p.m. at an altitude of 11,000 feet (3,353 meters), with +6 pounds per square inch boost (0.41 Bar). The engine turned aan Airscrew Co., Ltd., Watts-type two-bladed, fixed-pitch, compressed wood propeller through a gear reduction drive (possibly 0.420:1). (K5083, the prototype Hawker Hurricane, was also equipped with a Merlin C.) An improved 1,035 horsepower Merlin F engine, serial number F21 (Air Ministry serial number A115,73 ), was later installed.

Interestingly, Rolls-Royce discovered that using exhaust stacks to direct the flow of gases rearward provided an additional 70 pounds of thrust, an increase of 7% over that provided by the propeller alone. Later testing of K5054 with “fish tail” exhaust stacks increased its top speed to about 360 miles per hour (579 kilometers per hour).

Supermarine Type 300 K5054. © IWM (MH 5213)
Supermarine Type 300 K5054. © IWM (ATP 8321D)
The prototype Vickers-Supermarine Type 300, K5054, in light blue lacquer paint. (RAF Museum)

The Type 300 had a cruise speed of 311 miles per hour ( kilometers per hour) at 15,000 feet (4,572 meters), and could reach that altitude in 5 minutes, 52 seconds. maximum speed of 349 miles per hour (562 kilometers per hour) at 16,800 feet (5,121 meters). The prototype had a service ceiling of 35,400 feet (10,790 meters).

A report summarizing the flight testing of K5054 stated, “The aeroplane is simple and easy to fly and has no vices.” Visibility was good, the cockpit was comfortable, and it was a stable gun platform.

 K5054 after crash landing at Matrlesham Heath, 22 March 1937. (Solent Sky Museum)
K5054 after forced landing at Martlesham Heath, 22 March 1937. Note the “fish tail” exhaust stacks. (Solent Sky Museum)

On 22 March 1937, K5054’s engine lost oil pressure and the pilot made a belly landing on Marlesham Heath. The Spitfire was damaged, but was repaired and returned to service.

The prototype Spitfire stalled on landing at RAE Farnborough, 4 September 1939. After several bounces on the runway, it nosed over. The pilot, Flight Lieutenant Gilbert Stanbridge (“Spinner”) White, was severely injured. He died 9 September.

K5054 was disassembled and scrapped.

The Air Ministry ordered the Spitfire Mk.I into production before K5054’s first flight, with an initial order for 310 airplanes. The first production fighter was delivered to the Royal Air Force 4 August 1938. Between 1938 and 1948, 20,351 Spitfires were built in 24 variants.

Supermarine Spitfire of the Royal Air Force Battle of Britain Memorial Flight. (Royal Air Force)
Captain Joseph Summers

Captain Joseph Summers, C.B.E., was born 10 March 1904. He was the older brother of Group Captain Maurice Summers, who was also a test pilot for Vickers. In 1922, he married Miss Dulcie Jeanette Belcher at Sculcoates, Yorkshire. They would have several children.

In 1924, Summers received a short-service commission as an officer in the Royal Air Force. He trained as a pilot with No. 2 Flight Training Squadron, at RAF Duxford. He was hospitalized for six months, which delayed his training, but he graduated in 1924 and was assigned to No. 29 Fighter Squadron. Summers was considered to be an exceptional pilot, and with just six months’ operational experience, he was assigned as a test pilot at the Aircraft and Armaments Engineering Establishment (A&AEE) at RAF Martlesham Heath. He remained there for the reminder of his military service. In June 1929 he became a test pilot for Vickers Ltd. (Aviation Department). He became the company’s chief test pilot in 1932.

During his career as a test pilot, “Mutt” Summers made the first flights of 54 prototype aircraft, including the Spitfire, the Vickers Type 618 Nene-Viking, the Vickers Type 630 Viscount four-engine turboprop airliner, and the Vickers Type 667 Valiant, a four-engine jet bomber. He flew more than 5,600 hours in 366 different aircraft types.

“Mutt’s approach to test flying was much more in sympathy with the knee-pad than with the complicated automatic observers which nowadays are an indispensable part of test flying. He vigorously defended the feel of an aeroplane as measured by his hand or by the seat of his pants, and I believe was always suspicious of the scientific approach. . . One learned never to regard his criticism or advice lightly. In a world of science and instrumentation his judgement and horsesense often threw an unscientific but accurate light on some dark problem.” —Sir George R. F. Edwards, OM, CBE, FRS, DL, Executive Director of the British Aircraft Corporation, quoted in Flight and Aircraft Engineer, No. 2357, Vol. 65, Friday, 26 March 1954, at Page 355, Column 2.

Joseph Summers, Esq., was appointed an Officer of the Most Excellent Order of the British Empire, Civil Division (O.B.E.), in His Majesty’s New Year’s Honours, Wednesday, 9 January 1946. He was promoted to Commander of the Most Excellent Order of the British Empire (Civil Division) (C.B.E.) in Her Majesty’s Coronation Honours, Monday, 1 June 1953.

Summers died 16 March 1954 at the age of 50 years.

¹ Air Ministry Specification F.37/34 High Speed Monoplane Single Seater Fighter

² FAI Record File Number 11833, World Record for Speed Over a 3-Kilometer Course: 364.92 kilometers per hour (226.75 miles per hour). Supermarine S.4, Henri Biard, 13 September 1925.

FAI Record File Number 14999, World Record for Speed Over 100 Kilometers: 531.20 kilometers per hour (330.07 miles per hour), Supermarine S.6, Henry Richard Danvers Waghorn, 7 September 1929.

FAI Record File Number 11831, World Record for Speed Over a 3-Kilometer Course: 655 kilometers per hour (407 miles per hour), Supermarine S.6B, George Hedley Stainforth, 29 September 1931.

© 2018, Bryan R. Swopes

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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 69 feet, 4 inches (21.133 meters) long with a wingspan of 102 feet, 0 inches (31.090) meters and had an overall height of 20 feet, 6 inches (6.248 meters). The Mk.I had an empty weight of 36,457 pounds (16,537 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.

The Mark I had a cruise speed of 200 miles per hour (322 kilometers per hour) and a maximum speed of 282 miles per hour (462 kilometers per hour) at 63,000 pounds (28,576 kilograms). Its service ceiling was 19,000 feet (5,791 meters) and 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.

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.

This Battle of Britain Memorial Flight Lancaster B1, PA474, is one of only two flyable "Lancs" in existence. This one was built by Vickers. It is named Phantom of the Ruhr. ( )
This Royal Air Force Battle of Britain Memorial Flight Avro Lancaster Mk.I, PA474, “City of Lincoln,” is one of only two flyable “Lancs” in existence. This one was built by Vickers in 1945. (Kogo via Wikipedia)
Avro Lancaster Mk.X FM213, of the Canadian Warplane Heritage Museum, marked VR A and nicknamed “Vera.” FM213 was built by Victory Aircraft Ltd., Malton, Ontario, Canada.

© 2018, Bryan R. Swopes

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29 December 1941

North American Aviation XP-51 Mustang 41-038 at Langley Field, Virginia, 29 December 1941. (NASA)
North American Aviation XP-51 Mustang 41-038 at Langley Field, Virginia, 29 December 1941. (NASA)

29 December 1941: The first North American Aviation XP-51 fighter prototype, Air Corps serial number 41-038, arrived at the NACA Langley Memorial Aeronautical Laboratory, Langley Field, Hampton, Virginia, for National Advisory Committee on Aeronautics flight testing. This airplane was the fourth production Royal Air Force Mustang Mk.I, identified as AG348 (North American serial number 73-3101).

The test program resulted in an improved aileron design which significantly improved the Mustang’s maneuverability. The new aileron was used on all production models.

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

41-038 was returned to Wright Field on 2 November 1942. The second XP-51, 41-039, arrived at Langley in March 1943 for continued testing.

The Mustang Mk.I (NAA Model NA-73) was a single-place, single-engine fighter of all metal construction. It was 32 feet, 3 inches (9.830 meters) long with a wingspan of 37 feet, ½-inch (11.290 meters) and overall height of 12 feet, 2½ inches (3.719 meters). The airplane’s empty weight was 6,280 pounds (25,848.6 kilograms) and loaded weight was 8,400 pounds (3,810.2 kilograms).

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

The Mustang Mk.I/XP-51 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 a compression ratio of 6.65:1 and 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 3 feet, ¾ inches (0.934 meters) high, 2 feet, 5-9/32 inches (0.744 meters) wide and 7 feet, 1-5/8 inches (2.175 meters) long. It had a dry weight of 1,310 pounds (594 kilograms).

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

The XP-51 tested at Wright Field had a maximum speed of 382.0 miles per hour (614.8 kilometers per hour) at 13,000 feet (3,962 meters) at wide open throttle, and cruise speed of 300 miles per hour (483 kilometers per hour).

Below 20,000 feet (6,096 meters), the Mustang was the fastest fighter in the world. The Mk.I was 30 m.p.h. (48 kilometers per hour) faster than its contemporary, the Curtiss P-40 Warhawk, though both used exactly the same engine. Below 15,000 feet (4,572 meters), the Mustang was also 30–35 m.p.h (48–56 km/h) faster than a Supermarine Spitfire, which was equipped with the more powerful Roll-Royce Merlin V-12.

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, rear view. (NASA)

Armament consisted of two synchronized Browning AN-M2 .50-caliber machine guns mounted in the nose under the engine and firing through the propeller, and two more .50-caliber and four Browning .303 Mk.II machine guns in the wings.

North American Aviation XP-51 instrument panel. (U.S. Air Force)

Two Mustang Mk.Is, AG348 and AG354, were taken from the first RAF production order and sent to Wright Field for testing by the U.S. Army Air Force. These airplanes, assigned serial numbers 41-038 and 41-039, were designated XP-51. They 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 XP-51 41-038 was transferred to the Smithsonian Institution National Air and Space Museum. It was restored in 1976. It is now in the collection of the EAA AirVenture Museum, Oshkosh, Wisconsin. It has a current FAA registration number, N51NA.

North American Aviation XP-51 41-038 in the collection of the Experimental Aircraft Association AirVenture Museum, Oshkosh, Wisconsin. (EAA AirVenture Museum)
North American Aviation XP-51 41-038 in the collection of the Experimental Aircraft Association AirVenture Museum, Oshkosh, Wisconsin. (EAA AirVenture Museum)

© 2018, Bryan R. Swopes

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