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 National Advisory Committee for Aeronautics Langley Memorial Aeronautical Laboratory, Langley Field, Hampton, Virginia, for flight testing. This airplane was the fourth production Royal Air Force Mustang Mk.I, 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 Corps. These airplanes, assigned Air Corps 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)
20 August 1944: At 16:26 hours, North American Aviation Mustang Mk.I AG346, assigned to No. 168 Squadron,¹ 39 (Reconnaissance) Wing, Second Tactical Air Force, Royal Air Force, took off from an advance airfield, B21, at Sainte-Honorine-des-Pertes, Normandy, France.
AG346 was the very first operational Mustang Mk.I. During this mission, it was hit by intense antiaircraft fire northeast of Gacé. The Mustang’s pilot, Flight Lieutenant Denis Clark, 119758, Royal Air Force Volunteer Reserve, bailed out. He landed safely, but was captured and taken to a German prisoner of war camp at Les Hogues, a small community east of Rouen.
Flight Lieutenant Clark, along with four other prisoners of war,² was shot and killed at the camp on the afternoon 25 August 1944. A Court of Enquiry held in August 1945 found that the five men had been murdered by SS-Obersturmfürer Eugen Gutemann. Gutemann had been captured in Italy on 28 April 1945 and was held as a prisoner of war by the American forces. It is not known if he was ever brought to trial.
Denis Clark was born 17 December 1918 at Stockton-on-Tees, County Durham, England. He was the son of Sydney Clark, an electrician in the chemical industry, and Minnie Gertrude Ritchie.
In 1939, Clark was employed as a civil service clerk. He resided at 3 Crayke Road in Stockton, with his parents and maternal grandmother.
He was married to Miss Beth Ayre of Seaton, County Durham, possibly in July 1942.
Clark entered the United States at Buffalo, New York, on 16 July 1941, having traveled from Toronto, Ontario, Canada. He was trained as a pilot at the Southern Aviation School, a military contract primary flight school in Camden, South Carolina, United States, beginning in July 1941. He was one of 297 RAF pilots to train there between 7 June 1941 and 16 February 1942.
Head stone of Flight Lieuetenant Denis Clark, RAFVR. (Find-a-Grave)
On 7 February 1942 Temporary Flight Sergeant Denis Clark 945260 was promoted to the rank of Pilot Officer on probation (Temporary) 119758.
On 1 October 1942, Pilot Officer (prob.) Denis Clark was promoted to Flying Officer on probation (war substantive).
Flying Officer Clark was later promoted to the rank of Flight Lieutenant. (Date not determined)
Flight Lieutenant Denis Clark, RAFVR, was buried at Les Hogues Communal Cemetery, along with the other four victims. His head stone is engraved
GREATER LOVE HATH NO MAN THAN THIS. THAT A MAN LAY DOWN HIS LIFE FOR HIS FRIEND.
On 10 September 1945 a warrant was issued as a gratuity for the representatives of deceased officers in the amount of £172/13/7.
North American Aviation Mustang Mk.I AG346 (s/n 73-3099) at Mines Field, California, Summer 1941. Note the short carburetor intake, and compare to the photograph below. (North American Aviation, Inc.)
The very first operational North American Mustang, AG346 (North American Aviation serial number 73-3099) was the second airplane to come off the assembly line at Inglewood, California. North American test pilot Robert Creed Chilton took it for its first flight 3 July 1941. It was the first Mustang Mk.I to be equipped with its full armament.
During flight testing of the first Mk.I, AG345, Chilton and other test pilots heard a banging sound. This was determined to be a resonance in the carburetor intake tract. Also, at high angles of attack, air flow into the intake was decreased. The intake was lengthened. The resonance stopped and air flow to the carburetor was improved.
After flight testing by North American’s test pilots and Royal Air Force fighter pilots Wing Commander Chris Clarkson and Squadron Leader Michael N. (“Red Knight”) Crossley, AG346 was disassembled and crated, then shipped from the port of Long Beach, California, through the Panama Canal and on to England, arriving at Liverpool, 24 October 1941. It was taken to the Lockheed facility at Speke Aerodrome (now, Liverpool John Lennon Airport, LPL) where it was reassembled and put through additional performance and flight tests. Up to 20,000 feet (6,096 meters), AG346 was faster than any other British fighter then in service. A Mk.II reflector gun sight was installed (the same type used in the Supermarine Spitfire), as well as a British VHF radio.
AG346 was publicly displayed for the British news media at Speke Aerodrome on 5 December 1941.
AG346 was then assigned to an operational RAF fighter squadron. It served with Nos. 225, 63 and 26 Squadrons before being assigned to No. 41 Operations Training Unit. AG346 was returned to operations with No. 16 Squadron, and finally, No. 168 Squadron.
North American Aviation Inc. Mustang Mk.I fighter, AG348, built for the Royal Air Force, at Mines Field, Los Angeles, California, 1941. North American Aviation, Inc., photograph. (Ray Wagner Collection/SDASM)
The Mustang Mk.I was a new fighter built by North American Aviation, Inc., for the Royal Air Force. The British Purchasing Commission asked North American Aviation in Los Angeles, California, to build additional Tomahawks (the RAF variant of the Curtiss-Wright P-40 Warhawk) under license from Curtiss-Wright.
North American countered with a proposal to design a completely new and superior fighter around the P-40’s liquid-cooled Allison V-12 engine, and to begin production in no more time than it would take to get a P-40 production line up and running. The Purchasing Commission agreed, and with a letter of understanding, North American began work on the NA-73X on 1 May 1940. They were to produce 320 fighters before 30 September 1941—approximately 50 per month—at a total price of $14,746,964.35.
Edgar Schmued with P-51-NA 41-37322 (Mustang Mk.IA) (San Diego Air and Space Museum Archives Catalog #: 02-S-00192)
Designed by a team led by Edgar Schmued, the prototype North American Aviation Model NA-73X, serial number 73-3097, registered NX19998, was completed 9 September 1940. After a delay waiting for the Allison V-1710 to arrive, the prototype made its first flight 26 October 1940 with free lance test pilot Vance Breese in the cockpit. This was only 179 days since work began on the project.
In a contract amendment dated 9 December 1940, the British Purchasing Commission directed that the NA-73 would be identified by the name, “Mustang.”
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).
The Mustang Mk.I 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 camshaft (SOHC) 60° V-12 engine with four valves per cylinder and a compression ratio of 6.65:1. The engine had a takeoff rating of 1,150 horsepower at 3,000 r.p.m. at Sea Level with 45.5 inches of manifold pressure (1.51 Bar), and a war emergency rating of 1,490 horsepower with 56 inches of manifold pressure (1.90 Bar). The Allison drove 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-1710-39 was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.54 inches (0.928 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It weighed 1,310 pounds (594 kilograms).
Allison V-1710-39 (F3R) V-12 aircraft engine.
This engine gave the Mustang Mk.I a maximum speed of 382 miles per hour (615 kilometers per hour) 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).
The Mustang Mk.I was equipped with four Browning AN-M2 .50-caliber machine guns, with one in each wing and two mounted in the nose under the engine and four Browning .303 Mk.II machine guns, two in each wing. The airplane carried 300 rounds of ammunition for each of the .50-caliber guns. Each of the inboard .303s were supplied with 932 rounds; and the outboard .303s, 814 rounds, each.³
The British would recommend that the Allison engine be replaced by the Rolls Royce Merlin V-12. This became the Mustang Mk.III and the U.S.A.A.F. P-51B. Eventually, over 15,000 Mustangs were built, and it was a highly successful combat aircraft.
Today, after 85 years, the Mustang is one of the most recognizable of all airplanes.
Mustang Mk.I of No. 168 Squadron, Royal Air Force. (RAF)
¹ No. 168 Squadron was a reconnaissance unit. Its motto was Rerum cognoscere causas (“To know the cause of things”)
² Warrant Officer Griffin James Young R85855, Royal Canadian Air Force, a Spitfire pilot who had been shot down 13 August 1944; Lead Bombardier Jack Martin 976272, 65th Anti-Tank Unit (The Norfolk Yeomanry), Royal Artillery, captured 21 August; an unidentified Gunner, Royal Artillery; and Private Gordon Lafayette Bryant 6969514, 117th Infantry Regiment, 30th Infantry Division, United States Army.
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 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)
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. 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)
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 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)
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)
29 December 1941: The first North American Aviation XP-51 fighter prototype, Air Corps serial number 41-038, arrived at the National Advisory Committee for Aeronautics Langley Memorial Aeronautical Laboratory, Langley Field, Hampton, Virginia, for flight testing. This airplane was the fourth production Royal Air Force Mustang Mk.I, North American serial number 73-3101.
