26 April 1948: At Muroc Field (now known as Edwards Air Force Base), in the high desert of southern California, North American Aviation test pilot George Welch put the prototype XP-86 Sabre, 45-59597, into a 40° dive and broke the Sound Barrier. It is only the second U.S. aircraft to fly supersonic. The first was the Bell X-1, piloted by Chuck Yeager, only a few months earlier.
Or, maybe not.
In his book, Aces Wild: The Race For Mach 1, fellow North American Aviation test pilot Albert W. Blackburn makes the case that George Welch had taken the prototype XP-86 Sabre supersonic on its first flight, 1 October 1947, and that he had done so three times before Chuck Yeager first broke the Sound Barrier with the Bell X-1 rocketplane, 14 October 1947. Blackburn described two runs through the NACA radar theodolite with speeds of Mach 1.02 and 1.04 on 13 November 1947.
Mr. Blackburn speculates—convincingly, in my opinion—that Secretary of the Air Force W. Stuart Symington, Jr., ordered that Welch’s excursions beyond Mach 1 were to remain secret. However, during a radio interview, British test pilot Wing Commander Roland Prosper (“Bee”) Beamont, C.B.E, D.S.O. and Bar, D.F.C. and Bar, stated that he had flown through the Sound Barrier in the number two XP-86 Sabre prototype (45-59598). Once that news became public, the U.S. Air Force released a statement that George Welch had flown beyond Mach 1 earlier, but gave the date as 26 April 1948.
It wasn’t long after the first flight of the XP-86 on October 1, 1947, that Welch dropped into Horkey’s [Edward J. Horkey, an aerodynamicist at North American Aviation] office at the Inglewood plant. He wanted to talk about his recent flight and some “funny” readings in the airspeed indicator. He had made a straight-out climb to more than 35,000 feet. Then, turning back toward Muroc Dry Lake, he began a full-power, fairly steep descent.
“I started at about 290 knots,” Welch was explaining to Horkey. “In no time I’m at 350. I’m still going down, and I’m still accelerating but the airspeed indicator seems stuck like there’s some kind of obstruction in the pitot tube. I push over a little steeper and by this time I’m through 30,000 feet. All of a sudden, the airspeed indicator flips to 410 knots. The aircraft feels fine, no funny noises, no vibration. Wanted to roll off to the left, but no big deal. Still, I leveled out at about 25,000 and came back on the power. The airspeed flicked back to 390. What do you think?”
“. . . You may be running into some Mach effects. . . .”
— Aces Wild: The Race For Mach 1, by Al Blackburn, Scholarly Resources Inc., Wilmington, Delaware, 1999, at Pages 147–148.
The “funny” reading of the airspeed indicator became known as the “Mach jump.” George Welch was the first to describe it.
The Sabre became a legendary jet fighter during the Korean War. 9,860 were built by North American, as well as by licensees in Canada, Australia and Japan.
George Welch had been recommended for the Medal of Honor for his actions as a P-40 Warhawk fighter pilot in Hawaii, December 7, 1941. He was killed while testing a North American Aviation F-100A Super Sabre, 12 October 1954.
23 April 1941: At North American Aviation’s Inglewood, California factory, test pilot Louis Sanford Wait takes the very first production Mustang Mk.I, AG345, (c/n 73-3098) for its first flight.
The Royal Air Force had contracted with NAA to design and build a new fighter with a 1,200 horsepower Allison V-1710 supercharged 12-cylinder engine. The first order from the British Purchasing Commission was for 320 airplanes, and a second order for another 300 soon followed.
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 cam (SOHC) 60° V-12 engine with a compression ratio of 6.65:1. The -F3R had a Maximum Continuous Power rating of 880 horsepower at 2,600 r.p.m. at Sea level, and 1,000 horsepower at 11,000 feet (3,353 meters). It was rated at 1,150 horsepower at 3,000 r.p.m. for Take Off and Military Power. The Allison V-12 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-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 inches (0.734 meters) wide. It weighed 1,310 pounds (594 kilograms).
The Mustang Mk.I had a cruise speed of 311 miles per hour (500.5 kilometers per hour) at 75% power, and a maximum speed of 384 miles per hour (618 kilometers per hour) at 19,000 feet (5,791 meters). The airplane could reach 20,000 feet (6,096 meters) in 8.80 minutes. The service ceiling was 32,000 feet (9,754 meters) and its range was 640 miles (1,030 kilometers).
The 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. Four Browning .303 Mk.II machine guns were also installed, with two in each wing.
The Mk.I was 30 m.p.h. (48 kilometers per hour) faster than its contemporary, the Curtiss P-40 Warhawk, though both used the same engine. Below 15,000 feet (4,572 meters), the Mustang was also 30–35 m.p.h (48–56 kilometers per hour) faster than a Supermarine Spitfire, which had the more powerful Roll-Royce Merlin V-12.
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.
Louis Sanford Wait was born 28 June 1908 at Superior, Nebraska. He was the first of two children of Dr. James Enos Wait, a dentist, and Alice Caroline Harrington Wait.
Wait enlisted in the Air Corps, United States Army, as an aviation cadet, in 1929. He trained as a pilot at March Field, near Riverside, California, and at Kelly Field, Bexar, Texas. Wait graduated 27 June 1930 and received his pilot’s wings and a commission as a second lieutenant, Air Corps Reserve. (O274973) Lieutenant Wait trained as an attack pilot and was assigned to Fort Crockett, Galveston, Texas.
From 1932 to 1935, Wait, having been released from active duty, was employed as a test pilot for the Boeing Airplane Company, Seattle, Washington.
By 1937, Lieutenant Wait was assigned to Headquarters Squadron, 2nd Bombardment Group at Langley Field, Virginia, under the command of Brigadier General Robert Olds. While on 18 days leave, on 3 December 1937, Second Lieutenant Wait married Mrs. Elsie O. Callow (née Elsie Oliver) at Amityville, New York.
Wait married Mrs. Mary Elizabeth Croxen (née Mary Elizabeth Musser), 2 November 1944, in Los Angeles, California.
In August 1946, Louis Wait entered a P-51C Mustang, NX28388, in the Bendix Trophy Race. The airplane had been purchased by Jackie Cochran. She flew it in the race and finished in second place behind Paul Mantz.
In 1951, Wait was appointed general administrator of a new North American Aviation plant at the Fresno Air Terminal, Fresno, California. The plant, which employed about 400 people, manufactured and repaired parts for the T-6/SNJ Texan flight trainers, and performed modifications to F-86 Sabre jet fighters.
Louis Sanford Wait died 3 July 1963, at the age of 55 years.
6 April 1938:¹ After being shipped by truck from the Bell Aircraft Company factory at Buffalo, New York, the XP-39 prototype, 38-326, made its first flight at Wright Field, Ohio, with test pilot James Taylor ² in the cockpit. During the test flight, Taylor flew the XP-39 to 390 miles per hour (628 kilometers per hour) at 20,000 feet (6,096 meters). The service ceiling was 32,000 feet (9,754 meters).
The Bell XP-39 Airacobra was a single-place, single-engine prototype fighter with a low wing and retractable tricycle landing gears. The airplane was primarily built of aluminum, though control surfaces were fabric covered.
As originally built, the XP-39 was 28 feet, 8 inches (8.738 meters) long with a wingspan of 35 feet, 10 inches (10.922 meters). The prototype had an empty weight of 3,995 pounds (1,812 kilograms) and gross weight of 5,550 pounds (2,517 kilograms).
The XP-39 was unarmed, but it had been designed around the American Armament Corporation T9 37 mm autocannon, later designated Gun, Automatic, 37 mm, M4 (Aircraft).³ The cannon and ammunition were in the forward fuselage, above the engine driveshaft. The gun fired through the reduction gear box and propeller hub.
The XP-39 was originally powered by a liquid-cooled, turbosupercharged and supercharged 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-E2 (V-1710-17), a single overhead cam (SOHC) 60° V-12 engine with a compression ratio of 6.65:1. The V-1710-17 had a Maximum Continuous Power rating of 1,000 horsepower at 2,600 r.p.m. at 25,000 feet (7,620 meters), and Takeoff/Military Power rating of 1,150 horsepower at 3,000 r.p.m. at 25,000 feet, burning 91 octane gasoline.
The engine was installed in an unusual configuration behind the cockpit, with a two-piece drive shaft passing under the cockpit and turning the three-bladed Curtiss Electric constant-speed propeller through a remotely-mounted 1.8:1 gear reduction gear box. The V-1710-17 was 16 feet, 1.79 inches (4.922 meters) long, including the drive shaft and remote gear box. It was 2 feet, 11.45 inches (0.900 meters) high, 2 feet, 5.28 inches (0.744 meters) wide and weighed 1,350 pounds (612 kilograms).
After initial flight testing, the XP-39 was sent to the National Advisory Committee for Aeronautics (NACA) Langley memorial Aeronautical Laboratory at Hampton, Virginia. The prototype was tested in the Full-Scale Wind Tunnel. Improvements in aerodynamics were recommended and Bell rebuilt the airplane as the XP-39B with an Allison V-1710-E5 (V-1710-37) engine.
The turbosupercharger had been removed, which reduced the airplane’s power at altitudes above 15,000 feet (4,572 meters). The V-1710-37 had a maximum power of 1,090 horsepower at 3,000 r.p.m. at 13,300 feet (4,054 meters). This resulted in the P-39 being used primarily as a ground-attack weapon.
The XP-39B, with test pilot George Price in the cockpit, was damaged when when its landing gear did not fully extend, 6 January 1940. It was repaired and test flights resumed. On 6 August 1940, Captain Ernest K. Warburton stalled the prototype on landing. The impact resulted in significant structural damage, beyond economic repair. The airplane was later scrapped.
9,584 Bell P-39 Airacobras were built during World War II. More than half were sent to the Soviet Union.
¹ Reliable sources indicate the date of the first flight as both 1938 and 1939. The Bell Helicopter Company web site, “The History of Bell Helicopter: 1935–1949” states 1938.
² James Taylor may have been Lieutenant Commander James Blackstone Taylor, Jr., (1897–1942), Naval Aviator No. 437, a well-known U.S. Navy test pilot.
³ The 37-mm Aircraft Gun Matériel M4 is a recoil-operated aircraft weapon designed by John M. Browning. It has an overall length of 7 feet, 5 inches (2.26 meters). The barrel, or “tube,” is 5 feet, 5 inches (1.65 meters) long with a caliber of 1.457 inches (37.0 millimeters) and weighs 55 pounds (25 kilograms). The barrel is part of the recoiling section of the gun and moves rearward 9-5/8 inches (245 millimeters). The weight of the gun with a loaded 30-round magazine is 306.4 pounds (138.98 kilograms). The M4 fires a high-explosive tracer round with a muzzle velocity of 2,000 feet per second (607 meters per second). Each M54 shell is 9.75 inches (248 millimeters) long and weighs 1.93 pounds, of which the projectile makes up 1.34 pounds (0.608 kilograms). The cannon has a cyclic rate of fire of 125–150 rounds per minute.
4 April 1917: Sous-Lieutenant René Pierre Marie Dorme of the Aéronautique Militaire (French Air Service) made the first flight of the famous World War I fighter, the SPAD S.XIII C.1.
Lieutenant Dorme was an ace with 18 confirmed victories. In the next seven weeks, he shot down another five enemy aircraft.
Designed by Société Pour L’Aviation et ses Dérivés Technical Director Louis Béchéreau and manufactured by SPAD as well as eight other companies, this was an improved and slightly larger version of the earlier SPAD S.VII C.1. It used a more powerful Hispano-Suiza 8Ba engine instead of the S.VII’s 8Aa, with an increase of 50 horsepower. (Later versions used 8Be engines.) Armament was increased from a single .303-caliber Vickers machine guns to two.
The SPAD was faster than other airplanes of the time and it had a good rate of climb. Though a product of France, it was used by both the Royal Flying Corps and the U.S. Army Air Service. In France, the airplane type now considered a “fighter” was called a chasseur (“hunter”). The letter “C-” in the SPAD’s designation reflects this. The “-.1” at the ending indicates a single-place aircraft.
The SPAD S.XIII C.1 was a single-seat, single-engine, two-bay biplane constructed of a wooden framework with a doped fabric covering. Sheet metal covered the engine and cockpit.
The S.XIII was 20 feet, 4 inches (6.198 meters) long.¹ The upper and lower wings had equal span and chord. The span was 26 feet, 3¾ inches (8.020 meters) and chord, 4 feet, 7-1/8 inches (1.400 meters). The vertical spacing between the wings was 3 feet, 10½ inches (1.181 meters), and the lower wing was staggered 1¼° behind the upper. Interplane struts and wire bracing was used to reinforce the wings. The wings had no sweep or dihedral. The angle of incidence of the upper wing was 1½° and of the lower, 1°. Only the upper wing was equipped with ailerons. Their span was 7 feet, 3½ inches (2.222 meters), and their chord, 1 foot, 7½ inches (0.495 meters). The total wing area was 227 square feet (21.089 square meters).
The horizontal stabilizer had a span of 10 feet, 2 inches (3.099 meters) with a maximum chord of 1 foot, 8¾ inches (0.527 meters). The height of the vertical fin was 2 feet, 7/8-inch (0.876 meters) and it had a maximum length of 3 feet, 11¼ inches (1.200 meters). The rudder was 3 feet, 10-5/8 inches high (1.184 meters) with a maximum chord of 2 feet, 2 inches (0.660 meters).
The SPAD S.XIII C.1 had fixed landing gear with two pneumatic tires. Rubber cords (bungie cords) were used for shock absorption. The wheel track was 4 feet, 10¾ inches (1.492 meters). At the tail was a fixed skid.
The airplane had an empty weight of 1,464 pounds (664 kilograms), and gross weight 2,036 pounds (924 kilograms).
Initial production SPAD XIIIs were powered by a water-cooled 11.762 liter (717.769-cubic-inch displacement), La Société Hispano-Suiza 8Ba single overhead cam (SOHC) left-hand-tractor 90° V-8 engine. It was equipped with two Zenith down-draft carburetors and had a compression ratio of 5.3:1. The 8Ba was rated at 150 cheval vapeur (148 horsepower) at 1,700 r.p.m., and 200 cheval vapeur (197 horsepower) at 2,300 r.p.m. It drove a two-bladed, fixed-pitch, wooden propeller with a diameter of 2.50 meters (8 feet, 2.43 inches) through a 0.585:1 gear reduction. (The 8Be engine had a 0.75:1 reduction gear ratio and used both 2.50 meter and 2.55 meter (8 feet, 4.40 inches) propellers.) The Hispano-Suiza 8Ba was 1.36 meters (4 feet, 5.5 inches) long, 0.86 meters (2 feet, 9.9 inches) wide and 0.90 meters (2 feet, 11.4 inches) high. It weighed 236 kilograms (520 pounds).
The airplane had a main fuel tank behind the engine, with a gravity tank located in the upper wing. The total fuel capacity was 183 pounds (83 kilograms), sufficient for 2 hours, 30 minutes endurance at full throttle at 10,000 feet (3,048 meters), including climb. There was also a 4.5 gallon (17 liters) lubricating oil tank.
The SPAD S.XIII had a maximum speed of 135 miles per hour (218 kilometers per hour) at 6,560 feet (2,000 meters) and a service ceiling of 21,815 feet (6,650 meters).
The chasseur was armed with two fixed, water-cooled, .303-caliber (7.7 mm) Vickers Mk.I machine guns with 400 rounds of ammunition per gun, synchronized to fire forward through the propeller arc. Because of the cold temperatures at altitude, the guns’ water jackets were not filled, thereby saving considerable weight.
The SPAD S.XIII was produced by nine manufacturers. 8,472 were built. Only four are still in existence.
The airplane in the photograph above is SPAD S.XIII C.1, serial number 16594. It was built in October 1918 by Kellner et ses Fils, an automobile manufacturer in Paris, France. It did not see combat, but was shipped to the United States at the end of the War and was stationed at San Diego, California. The airplane was restored by the National Museum of the United States Air Force and is painted in the markings of the airplane flown by Captain Edward V. Rickenbacker, commanding officer of the 94th Aero Squadron, American Expeditionary Forces. It is on display at NMUSAF, Wright-Patterson Air Force Base, Ohio.
The airplane in the photograph below is another SPAD S.XIII C.1, serial number 7689, also built by Kellner et ses Fils, in August 1918. It was sent to the 22nd Aero Squadron at Colombey-les-Belles and assigned to Lieutenant Arthur Raymond Brooks. Brooks’ fiancée attended Smith College and he named the SPAD Smith IV in her honor. With this airplane, Lieutenant Brooks shot down six enemy airplanes. Other pilots also flew it to shoot down another five.
After the War came to an end, 7689 was shipped to the United States and used in a Liberty Bond fund-raising tour. In December 1919, the United States Army gave the fighter to the Smithsonian Institution. It was restored at the Paul E. Garber Center, 1984–1986, and remains in the collection of the National Air and Space Museum.
René Dorme fought 120 aerial engagements, many while flying a SPAD S.VII C.1. He is officially credited with 22 victories, and may have shot down as many as 59 enemy aircraft. His personal airplane was marked with a green Cross of Lorraine. He was a Chevalier de la légion d’honneur, and had been awarded the Médalle Militaire and the Croix de Guerre with 17 Palms. Dorme was killed in action 25 May 1917 when his SPAD VII was shot down by Oberleutnant Heinrich Kroll of Jasta 9 at Fort de la Pompelle near Reims.
¹ Dimensions, weights, capacities and performance data cited above refer to SPAD S.XIII C.1 serial number 17956 (A.S. 94101), which was tested at McCook Field, Dayton, Ohio (Project Number P-154), 1921.
3 April 1941: North American Aviation test pilot Robert Creed Chilton takes his first flight—a one hour familiarization—in the company’s prototype of a new fighter for the Royal Air Force, the NA-73X, NX19998, at Mines Field. (Mines would later become Los Angeles International Airport, LAX.)
The airplane had first been flown by free-lance test pilot Vance Breese, 26 October 1940, and he had flown it several times. North American’s Chief Test Pilot, Paul Baird Balfour, on his first flight in NX19998, ran out of fuel and crash landed in a plowed field 150 yards (137 meters) west of the airfield, 20 November 1940. The prototype had flown just 3 hours, 20 minutes.
The NA-73X was repaired and Bob Chilton was assigned to complete the testing program. The airplane would become the legendary P-51 Mustang, and Chilton would continue to conduct the majority of flight testing on its improvements and modifications.
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 Repulic 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.