20 October 1952: At Edwards Air Force Base, California, Douglas Aircraft Company test pilot William Barton (“Bill”) Bridgeman made the first test flight of the X-3 twin-engine supersonic research airplane. During a high-speed taxi test five days earlier, Bridgeman and the X-3 had briefly been airborne for approximately one mile over the dry lake bed, but on this flight he spent approximately 20 minutes familiarizing himself with the new airplane.
Bill Bridgeman had been a Naval Aviator during World War II, flying the Consolidated PBY Catalina and PB4Y (B-24) Liberator long range bombers with Bombing Squadron 109 (VB-109), “The Reluctant Raiders.”
Bridgeman stayed in the Navy for two years after the war, then he flew for Trans-Pacific Air Lines in the Hawaiian Islands and Southwest Airlines in San Francisco, before joining Douglas Aircraft Co. as a production test pilot. He checked out new AD Skyraiders as they came off the assembly line at El Segundo, California. He soon was asked to take over test flying the D-558-2 Skyrocket test program at Muroc Air Force Base (now, Edwards AFB.) With the Skyrocket, he flew higher—79,494 feet (24,230 meters)—and faster—Mach 1.88—than any pilot had up to that time.
The Douglas X-3, serial number 49-2892, was built for the Air Force and NACA to explore flight in the Mach 1 to Mach 2 range. It was radically shaped, with a needle-sharp nose, very long thin fuselage and small straight wings. The X-3 was 66 feet, 9 inches (20.345 meters) long, with a wing span of just 22 feet, 8.25 inches (6.915 meters). The overall height was 12 feet, 6.3 inches (3.818 meters). The X-3 had an empty weight of 16,120 pounds (7,312 kilograms) and maximum takeoff weight of 23,840 pounds (10,814 kilograms).
It was to have been powered by two Westinghouse J46 engines, but when those were unsatisfactory, two Westinghouse XJ34-WE-17 engines were substituted. This was an axial flow turbojet with an 11-stage compressor and 2-stage turbine. It was rated at 3,370 pounds (14.99 kilonewtons) of thrust, and 4,900 pounds (21.80 kilonewtons) with afterburner. The XJ34-WE-17 was 14 feet, 9.0 inches (4.496 meters) long, 2 feet, 1.0 inch (0.635 meters) in diameter and weighed 1,698 pounds (770 kilograms).
The X-3 had a maximum speed of 706 miles per hour (1,136 kilometers per hour) and a service ceiling of 38,000 feet (11,582 meters).
The X-3 was very underpowered with the J34 engines and could just reach Mach 1 in a shallow dive. Its highest speed, Mach 1.208, required a 30° dive. The research airplane was therefore never able to be used in flight testing in the supersonic speed range for which it was designed. Because of its design characteristics, though, it became useful in exploring stability and control problems encountered in the transonic range.
Two X-3 aircraft had been ordered from Douglas, but only one completed.
In addition to Bill Bridgeman, the Douglas X-3 was flown by Air Force test pilots Major Chuck Yeager and Lieutenant Colonel Frank Everest, and NACA High Speed Flight Station research pilot Joseph A. Walker.
NACA flight testing began in August 1954. On the tenth flight, 27 October, Joe Walker put the X-3 into abrupt left aileron rolls at 30,000 feet (9,144 meters), first at 0.92 Mach and then at Mach 1.05. Both times, the aircraft violently yawed to the right and then pitched down.
This was a new and little understood condition called inertial roll coupling. It was a result of the aircraft’s mass being concentrated within its fuselage, the torque reactions and gyroscopic effect of the turbojet engines and the inability of the wings and control surfaces to stabilize the airplane and overcome its rolling tendency. (Just two weeks earlier, North American Aviation’s Chief Test Pilot George S. Welch had been killed when the F-100A Super Sabre that he was testing also encountered inertial roll coupling and disintegrated.) A post-flight inspection found that the X-3 had reached its maximum design load. The X-3 was grounded for the next 11 months.
Joe Walker resumed flight testing the X-3 in 1955. It’s last flight was 23 May 1956. After the flight test program came to an end, the X-3 was turned over to the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio.
18 October 1984: The first production Rockwell International B-1B Lancer, serial number 82-0001, a supersonic four-engine strategic bomber with variable sweep wings, made its first flight from Air Force Plant 42, Palmdale, California.
Rockwell test pilot M.L. Evenson was in command, with co-pilot Lieutenant Colonel L.B. Schroeder, U.S. Air Force; Major S.A. Henry, Offensive Systems Officer; Captain D.E. Hamilton, Defensive Systems Officer.
After 3 hours, 20 minutes, the B-1B landed at Edwards Air Force Base where it would enter a flight test program.
The Rockwell International B-1B Lancer is a supersonic intercontinental bomber capable of performing strategic or tactical missions. It is operated by a flight crew of four.
The B-1B is 146 feet (44.50 meters) long, with the wing span varying from 79 feet (24.08 meters) to 137 feet (41.76 meters). It is 34 feet (10.36 meters) high at the top of the vertical fin. The bomber’s empty weight is approximately 192,000 pounds (86,200 kilograms). Its Maximum Takeoff Weight (MTOW) is 477,000 pounds (216,634 kilograms). The payload is up to 75,000 pounds (34,019 kilograms).
The bomber is powered by four General Electric F101-GE-102 turbofan engines, mounted in two-engine nacelles under the wing roots. These are rated at 17,390 pounds of thrust (17.355 kilonewtons) and produce 30,780 pounds (136.916 kilonewtons) with “augmentation.” The engine has two fan stages, a 9-stage axial-flow compressor and a 3-stage turbine. The F101-GE-102 is 180.7 inches (4.590 meters) long, 55.2 inches (1.402 meters) in diameter and weighs 4,460 pounds (2,023 kilograms).
It has a maximum speed of Mach 1.2 at Sea Level (913 miles per hour, or 1,470 kilometers per hour). The service ceiling is “over 30,000 feet” (9,144 meters). The Lancer’s maximum range is “intercontinental, unrefueled.”
It can carry up to 84 Mk.82 500-pound (226.8 kilogram) bombs, 24 Mk.84 2,000-pound (907.2 kilogram) bombs or other weapons. The aircraft was designed with the capability to carry 24 B61 thermonuclear bombs, though, since 2007, the fleet no longer has this capability.
100 B-1B Lancers were built between 1983 and 1988. As of September 2016, 62 B-1B bombers are in the active Air Force inventory. Two of these are in the test fleet.
To comply with the START weapons treaty, B-1B 82-0001 was scrapped at Ellsworth Air Force Base, South Dakota, in the mid-1990s.
14 October 1947: At approximately 10:00 a.m., a four-engine Boeing B-29 Superfortress heavy bomber, piloted by Major Robert L. Cardenas, took off from Muroc Air Force Base (now know as Edwards Air Force Base) in the high desert north of Los Angeles, California. The B-29’s bomb bay had been modified to carry the Bell XS-1, a rocket-powered airplane designed to investigate flight at speeds near the Speed of Sound (Mach 1).
Air Force test pilot Captain Charles Elwood (“Chuck”) Yeager, a World War II fighter ace, was the U.S. Air Force pilot for this project. The X-1 airplane had been previously flown by company test pilots Jack Woolams and Chalmers Goodlin. Two more X-1 aircraft were built by Bell, and the second, 46-063, had already begun its flight testing.
Captain Yeager had made three glide flights and this was to be his ninth powered flight. Like his P-51 Mustang fighters, he had named this airplane after his wife, Glamorous Glennis.
Bob Cardenas climbed to 20,000 feet (6,096 meters) and then put the B-29 into a shallow dive to gain speed. In his autobiography, Yeager wrote:
“One minute to drop. [Jack] Ridley flashed the word from the copilot’s seat in the mother ship. . . Major Cardenas, the driver, starts counting backwards from ten. C-r-r-ack. The bomb shackle release jolts you up from your seat, and as you sail out of the dark bomb bay the sun explodes in brightness. You’re looking at the sky. Wrong! You should have dropped level. The dive speed was too slow, and they dropped you in a nose-up stall. . .
“I fought it with the control wheel for about five hundred feet, and finally got her nose down. The moment we picked up speed I fired all four rocket chambers in rapid sequence. We climbed at .88 Mach. . . I turned off two rocket chambers. At 40,000 feet, we were still climbing at .92 Mach. Leveling off at 42,000 feet, I had thirty percent of my fuel, so I turned on rocket chamber three and immediately reached .96 Mach. . . the faster I got, the smoother the ride.
“Suddenly the Mach needle began to fluctuate. It went up to .965 Mach—then tipped right off the scale. . . .”
—Brigadier General Charles E. Yeager, U.S. Air Force (Retired), Yeager, An Autobiography, by Chuck Yeager and Leo Janos, Bantam Books, New York, 1985, Pages 120, 129–130.
Chuck Yeager and flown the XS-1 through “the sound barrier,” something many experts had believed might not be possible. His maximum speed during this flight was Mach 1.06 (699.4 miles per hour/1,125.7 kilometers per hour).
The Bell XS-1, later re-designated X-1, was the first of a series of rocket powered research airplanes which included the Douglas D-558-II Skyrocket, the Bell X-2, and the North American Aviation X-15, which were flown by the U.S. Air Force, U.S. Navy, NACA and its successor, NASA, at Edwards Air Force Base to explore supersonic and hypersonic flight and at altitudes to and beyond the limits of Earth’s atmosphere.
The X-1 is shaped like a bullet and has straight wings and tail surfaces. It is 30 feet, 10.98 inches (9.423 meters) long with a wing span of 28.00 feet (8.534 meters) and overall height of 10 feet, 10.20 inches (3.307 meters). Total wing area is 102.5 square feet ( 9.5 square meters). At its widest point, the diameter of the X-1 fuselage is 4 feet, 7 inches (1.397 meters). The empty weight is 6,784.9 pounds (3,077.6 kilograms), but loaded with propellant, oxidizer and its pilot with his equipment, the weight increased to 13,034 pounds (5,912 kilograms). The X-1 was designed to withstand an ultimate structural load of 18g.
The X-1 is powered by a four-chamber Reaction Motors, Inc., XLR11-RM-3 rocket engine which produced 6,000 pounds of thrust (26,689 Newtons). This engine burns a mixture of ethyl alcohol and water with liquid oxygen. Fuel capacity is 293 gallons (1,109 liters) of water/alcohol and 311 gallons (1,177 liters) of liquid oxygen. The fuel system is pressurized by nitrogen at 1,500 pounds per square inch (10,342 kilopascals).
The X-1 was usually dropped from a B-29 flying at 30,000 feet (9,144 meters) and 345 miles per hour (555 kilometers per hour). It fell as much as 1,000 feet (305 meters) before beginning to climb under its own power.
The X-1’s performance was limited by its fuel capacity. Flying at 50,000 feet (15,240 meters), it could reach 916 miles per hour (1,474 kilometers per hour), but at 70,000 feet (21,336 meters) the maximum speed that could be reached was 898 miles per hour (1,445 kilometers per hour). During a maximum climb, fuel would be exhausted as the X-1 reached 74,800 feet (2,799 meters). The absolute ceiling is 87,750 feet (26,746 meters).
The X-1 had a minimum landing speed of 135 miles per hour (217 kilometers per hour) using 60% flaps.
The three X-1 rocketplanes made a total of 157 flights with the three X-1. The number one ship, Glamorous Glennis, made 78 flights. On 26 March 1948, with Chuck Yeager again in the cockpit, it reached reached Mach 1.45 (957 miles per hour/1,540 kilometers per hour) at 71,900 feet (21,915 meters).
The third X-1, 46-064, made just one glide flight before it was destroyed 9 November 1951 in an accidental explosion.
The second X-1, 46-063, was later modified to the X-1E. It is on display at the NASA Dryden Research Center at Edwards Air Force Base.
Glamorous Glennis is on display at the Smithsonian Institution National Air and Space Museum, next to Charles A. Lindbergh’s Spirit of St. Louis.
14 October 1947: Twenty minutes before Captain Charles E. (“Chuck”) Yeager broke the sound barrier with a Bell X-1 rocketplane, North American Aviation Chief Test Pilot George S. Welch put the swept-wing XP-86 prototype, serial number 45-59597, into a shallow dive from 37,000 feet (11,278 meters) and accelerated. In direct violation of orders from the Secretary of the Air Force to not do so, Welch broke the “sound barrier.”
Witnesses on the ground heard the distinctive “B-BOOM” double-shock as the aircraft exceeded the speed of sound. Welch was the first to observe “Mach jump” as the airspeed indicator momentarily indicated higher due to the compression of air in front of the aircraft.
Estimates are that the XP-86 reached Mach 1.02–1.04 on this flight.
12 October 1954: North American Aviation Chief Engineering Test Pilot George S. Welch, testing the ninth production F-100A-1-NA Super Sabre, serial number 52-5764, made a planned 7.3 G pullout from a Mach 1.55 dive to verify the aircraft’s design limits.
A Boeing B-47 Stratojet crew flying at 25,000 feet (7,620 meters) reported that Welch’s F-100 winged over and began a rapid descent, passing within four miles (6.4 kilometers) of their position and diving at a very high speed. The aircraft appeared to be under control but then suddenly disintegrated.
The Super Sabre had encountered Inertial Roll Coupling. It went out of control and then disintegrated. Its nose folded over the windshield, crushing Welch in his seat. The vertical fin broke away. The ejection seat fired but because of the supersonic speeds the parachute was shredded.
Welch was still alive when rescue teams arrived. He died while being flown to a hospital by helicopter.
Inertial roll coupling led to the death of test pilot Mel Apt when his rocket-powered airplane, the Bell X-2, went out of control at Mach 3.2 It nearly killed Chuck Yeager when he lost control of the Bell X-1B at Mach 2.4. It is a complex phenomenon which I will briefly attempt to explain:
To increase maximum speed of transonic and supersonic airplanes during the late 1940s and early 1950s, their wings and tail surfaces were made smaller in order to decrease aerodynamic drag. At the same time, the fuselage became longer and the placement of engines, armament, landing gear, fuel, etc., within the fuselage concentrated the airplane’s mass near its center. While the gyroscopic effects of the turbojet engine contributed some degree of longitudinal stability, the torque effect made rolls to the left occur more easily, but with a higher rate than a roll to the right. The resistance to a change in attitude—inertia—decreased at the same time that the control surfaces’ ability to control the airplanes’ attitude also decreased. The airplanes became unstable.
When George Welch tried to pull the F-100 out of its supersonic dive, the airplane’s speed began to decrease as the angle of attack increased. The wings’ ability to stabilize the natural roll instability of the fuselage’s concentrated mass was lessened, and the ailerons could not provide sufficient control to counteract this rolling tendency. The low vertical fin of the original F-100A did not provide adequate directional stability. The Super Sabre rolled and then yawed, entering a side slip. This caused the Super Sabre to pitch down and it was suddenly out of control in all three axes. The physical forces exceeded the strength of the aircraft structure and it came apart.¹
[Aerodynamicists and Aeronautical Engineers: Your corrective comments are welcome.]
Following the death of George Welch, NACA High Speed Flight Station research test pilot Albert Scott Crossfield spent three months conducting flight tests of the F-100A, demonstrating its inertial roll coupling characteristics using three different vertical fins. F-100A-5-NA 52-5778 was Crossfield’s test aircraft.
The North American Aviation F-100 Super Sabre was designed as a supersonic day fighter. Initially intended as an improved F-86D and F-86E, it soon developed into an almost completely new airplane. The fuselage incorporated the “area rule,” a narrowing in the fuselage width at the wings to increase transonic performance, similar to the Convair F-102A. The Super Sabre had a 49° 2′ sweep to the leading edges of the wings and horizontal stabilizer. The ailerons were placed inboard on the wings and there were no flaps, resulting in a high stall speed in landing configuration. The horizontal stabilizer was moved to the bottom of the fuselage to keep it out of the turbulence created by the wings at high angles of attack. The F-100A had a distinctively shorter vertical fin than the YF-100A. The upper segment of the vertical fin was swept 49° 43′.
There were two service test prototypes, designated YF-100A, followed by the production F-100A series. The first ten production aircraft (all of the Block 1 variants) were used in the flight testing program.
The F-100A Super Sabre was 47 feet, 1¼ inches (14.357 meters) long with a wingspan of 36 feet, 6 inches (11.125 meters). With the shorter vertical fin, the initial F-100As had an overall height of 13 feet, 4 inches (4.064 meters), 11 inches (27.9 centimeters) less than the YF-100A.
The F-100A had an empty weight of 18,135 pounds (8,226 kilograms), and gross weight of 28,899 pounds (13,108 kilograms). Maximum takeoff weight was 35,600 pounds (16,148 kilograms). It had an internal fuel capacity of 755 gallons (2,858 liters) and could carry two 275 gallon (1,041 liter) external fuel tanks.
The early F-100As were powered by a Pratt & Whitney Turbo Wasp J57-P-7 afterburning turbojet engine. It was rated at 9,700 pounds of thrust (43.148 kilonewtons) for takeoff, and 14,800 pounds (65.834 kilonewtons) with afterburner. Later production aircraft used a J57-P-39 engine. The J57 was a two-spool axial flow turbojet which had a 16-stage compressor, and a 3-stage turbine. (Both had high- and low-pressure stages.) The engine was 15 feet, 3.5 inches (4.661 meters) long, 3 feet, 5.0 inches (1.041 meters) in diameter, and weighed 4,390 pounds (1,991 kilograms).
The Super Sabre was the first U.S. Air Force fighter capable of supersonic speed in level flight. It could reach 760 miles per hour (1,223 kilometers) at Sea Level. (Mach 1 is 761.1 miles per hour, 1,224.9 kilometers per hour, under standard atmospheric conditions.) Its maximum speed was 852 miles per hour (1,371 kilometers per hour) at 35,000 feet (10,668 meters). The service ceiling was 44,900 feet (13,686 meters). Maximum range with external fuel was 1,489 miles (2,396 kilometers).
The F-100 was armed with four M-39 20 mm autocannons, capable of firing at a rate of 1,500 rounds per minute. The ammunition capacity of the F-100 was 200 rounds per gun.
North American Aviation built 199 F-100A Super Sabres at its Inglewood, California, plant before production shifted to the F-100C fighter bomber variant. Approximately 25% of all F-100As were lost in accidents.
George Welch was born George Lewis Schwartz, Jr., in Wilmington, Delaware, 10 May 1918. He was the first of two sons of George Lewis Schwartz, a chemist at the Dupont Experimental Station in Wilmington, and Julia Welch Schwartz. His parents changed his surname to Welch, his mother’s maiden name, so that he would not be effected by the anti-German prejudice that was widespread in America following World War I.
He studied mechanical engineering at Purdue University, Indiana, and enlisted in the Army Air Corps in 1939. Welch graduated from pilot training at Kelly Field, Texas, and on 4 October 1940, was commissioned as a second lieutenant, U.S. Army Air Corps.
George S. Welch is best remembered as one of the heroes of Pearl Harbor. He, along with Second Lieutenant Kenneth M. Taylor, were the only two fighter pilots to get airborne from Haleiwa Auxiliary Airfield during the Japanese surprise attack on Hawaii, 7 December 1941. Flying a Curtiss P-40B Warhawk, he shot down three Aichi D3A “Val” dive bombers and one Mitsubishi A6M2 Zero fighter. Taylor also shot down four Japanese airplanes. For this action, Lieutenant General Henry H. “Hap” Arnold recommended the Medal of Honor, but because Lieutenants Welch and Taylor had taken off without orders, an officer in their chain of command refused to endorse the nomination. Both fighter pilots were awarded the Distinguished Service Cross.
During the War, Welch flew the Bell P-39 Airacobra and Lockheed P-38 Lightning on 348 combat missions. He had 16 confirmed aerial victories over Japanese airplanes and rose to the rank of Major. In addition to the Distinguished Service Cross, George Welch was awarded the Silver Star, the Distinguished Flying Cross with two oak leaf clusters (three awards), the Air Medal with one oak leaf cluster (two awards), the Presidential Unit Citation with two oak leaf clusters (three awards), American Defense Service medal with one service star, American Campaign Medal, Asiatic-Pacific Campaign Medal with one silver and one bronze star (six campaigns), and the World War II Victory Medal.
Welch received the nickname, “Wheaties,” because he was the first military officer to be featured on a box of Wheaties cereal. (Wheaties, “The Breakfast of Champions,” was a toasted wheat bran cereal produced by General Mills. It normally featured champion athletes on its distinctive orange-colored boxes.)
Suffering from malaria, George Welch was out of combat and recuperating in Australia. There he met Miss Janette Alice Williams and they were soon married. Welch returned to the United States with his new wife. They had a son, Giles, born in October 1947. Their home was in Brentwood, California.
North American Aviation approached General Arnold to recommend a fighter pilot who could bring his combat experience to testing new fighters. Welch was one of two that General Arnold suggested. The general authorized Welch’s release from active duty so that he could join North American. Welch held the rank of major, Air Reserve, from 13 November 1944 to 1 April 1953.
Welch went on to test fly the North American P-51H Mustang, FJ-1 Fury, F-86 Sabre and F-100 Super Sabre.
George Welch made the first flight of the XP-86 prototype, 1 October 1947. There is some evidence that on that flight, and during a subsequent flight on 14 October, Welch exceeded the speed of sound while in a dive. It has been said that during the Korean War, while teaching U.S. Air Force pilots how to best use the F-86 Sabre, he shot down several enemy MiG-15 jet fighters.
George S. Welch is buried at the Arlington National Cemetery, Section 6, Site 8578-D.
¹ Recommended: Coupling Dynamics in Aircraft: A Historical Perspective, by Richard E. Day, Dryden Flight Research Center, Edwards AFB, California. NASA Special Publications 532, 1997.