12 May 1953: A Boeing B-50A-5-BO Superfortress, 46-011, modified to carry a Bell X-2 supersonic research rocketplane, was engaged in a captive test flight at 30,000 feet (9,144 meters) over Lake Ontario, between Canada and the United States. The number two X-2, 46-675, was in the bomb bay.

The bomber was equipped with a system to keep the X-2’s liquid oxygen tank filled as the cryogenic oxidizer boiled off. With Bell’s Chief of Flight Research, test pilot Jean Leroy (“Skip”) Ziegler, in the bomb bay above the X-2, the system operation was being tested.

There was an explosion. The X-2 fell from the bomber and dropped into Lake Ontario, between Trenton, Ontario, Canada, and Rochester, New York, U.S.A. Skip Ziegler and an engineer aboard the bomber, Frank Wolko, were both lost. A technician, Robert F. Walters, who was in the aft section of the B-50 with Wolko, was badly burned and suffered an injured eye.

The B-50’s pilots, William J. Leyshon and David Howe, made an emergency landing at the Bell Aircraft Corporation factory airport at Wheatfield, New York (now, the Niagara Falls International Airport, IAG). The bomber was so heavily damaged that it never flew again.

Heavy fog over the lake hampered search efforts. Neither the bodies of Ziegler and Wolko or the wreckage of the X-2 were ever found.

After a series of explosions of early rocketplanes, the X-1A, X-1-3, X-1D and the X-2,  investigators discovered that leather gaskets which were used in the fuel system had been treated with tricresyl phosphate (TCP). When this was exposed to liquid oxygen an explosion could result. The leather gaskets were removed from the other rocketplanes and the explosions stopped.

The X-2 was a joint project of the U.S. Air Force and NACA (the National Advisory Committee on Aeronautics, the predecessor of NASA). The rocketplane was designed and built by Bell Aircraft Corporation of Buffalo, New York, to explore supersonic flight at speeds beyond the capabilities of the earlier Bell X-1 and Douglas D-558-II Skyrocket. Two X-2s were built.

In addition to the aerodynamic effects of speeds in the Mach 2.0–Mach 3.0 range, engineers knew that the high temperatures created by aerodynamic friction would be a problem, so the aircraft was built from stainless steel and K-Monel, a copper-nickel alloy.

The Bell Aircraft Corporation X-2 was 37 feet, 10 inches (11.532 meters) long with a wingspan of 32 feet, 3 inches (9.830 meters) and height of 11 feet, 10 inches (3.607 meters). Its empty weight was 12,375 pounds (5,613 kilograms) and loaded weight was 24,910 pounds (11,299 kilograms).

The X-2 was powered by a throttleable two-chamber Curtiss-Wright XLR25-CW-1 rocket engine that produced 2,500–15,000 pounds of thrust (11.12–66.72 kilonewtons)

Rather than use its limited fuel capacity to take off and climb to altitude, the X-2 was dropped from a modified heavy bomber as had been the earlier rocketplanes.

The launch altitude was 30,000 feet (9,144 meters). After the fuel was exhausted, the X-2 glided to a touchdown on Rogers Dry Lake at Edwards Air Force Base.

The X-2 reached a maximum speed of Mach 3.196 (2,094 miles per hour/3,370 kilometers per hour) and maximum altitude of 126,200 feet (38,466 meters).

Jean LeRoy Ziegler was born 1 January 1920 at Endeavor, Pennsylvania. He was the first of three sons of LeRoy Curtiss (“Lee”) Ziegler, a stationary engineer for a gas field, and Daisy Pearl Gesin Zeigler.

Ziegler attended Endeavor High School, and then studied at Pennsylvania State College for two years.

During the last week of June 1940, Ziegler enlisted in the United States Army Air Corps. He was sent to the Alabama Institute of Aeronautics at Tuscaloosa, Alabama, for Phase 1 primary flight training. He then went on to advanced training at Maxwell Army Air Field, near Montgomery, Alabama. Upon graduation, Ziegler was commissioned as a second lieutenant, 7 February 1941.

Lieutenant Ziegler was assigned to Patterson Field, Fairfield, Ohio, as at transport pilot.

In September 1941, Lieutenant Ziegler, a reserve officer, was released from active duty. He was then employed by Pan American Airways-Africa, Limited. On 26 September 1941, he departed Ohio for New York, and from there traveled to Africa for a six-month assignment.

Ziegler flew the Douglas DC-3 for Pan Am in Africa and the Middle East, India, Burma and China. He is credited with being one of the first three pilots to fly cargo from Burma to China over the Himalaya Mountains, a route that would be know as “The Hump.” He flew ammunition and fuel to the American Volunteer Group (better known as the “Flying Tigers”) in China, and returned with Chinese refugees.

On 10 June 1942, Ziegler returned to the United States, arriving in Miami, Florida, via Port of Spain, Trinidad, aboard a Pan American Airways Boeing 314A, NC18612, Cape Town Clipper. (This was the last Model 314 built by Boeing.)

After a few months, Ziegler was hired by the Curtiss-Wright Corporation, Airplane Division, as a production test pilot. He was assigned to Plant 2 at Cheektowaga, New York. He would fly the P-40 Warhawk and SB2C Helldiver.

Curtiss Gets Another New Test Aviator

Military Supply Pilot Joins Buffalo Staff

    Jean L. Ziegler of Endeavor, Pa., who flew hundreds of refugees into India when the Japs swarmed through Burma last year, has been added to the production test pilot staff of the Curtiss-Wright Corporation Airplane Division in Buffalo.

     The 22-year-old flier is the second to join Curtiss here within a week. Donald Armstrong, 22, former flight lieutenant in the Royal Canadian Air Force, reported last week.

Graduate of Army School

     Ziegler entered the Army Flying School at Maxwell Field, Ala., in June 1940, and was graduated from the advanced course a year later. He was transferred to a transport unit at Patterson Field, O., where he remained until September, 1941. Then he was hired by Pan American Airways to serve as a pilot on military supply routes of the transport ferry command in Africa, India, the Middle East, China and Burma.

     When the Japs began an intensive drive toward the north in Burma, Ziegler was on of the airmen who volunteered to fly refugees into India. He carried fuel and ammunition to Burma units of the American Volunteer Group (Flying Tigers) and came out with plane loads of men women and children. The planes used were Douglas DC-3s.

     Ziegler was born in Franklin, Pa., and attended Pen State for two years before enrolling at Maxwell Field. He holds a second lieutenant’s commission in the Army Air Corps Reserve.

—Buffalo Courier Express, Vol. CVIII, No. 99, Tuesday 27 October 1942, Page 7 Column 1 and 2

On 22 December 1942, Ziegler registered for Selective Service (conscription). His draft card describes him as 6 feet, 1 inch (185 centimeters) tall, 170 pounds (77 kilograms), with brown hair, gray eyes, and a ruddy complexion.

Motor Trouble caused Test Pilot Jean L. Ziegler to crash land a Curtiss-Wright P-40 at the municipal airport Friday afternoon. He was unhurt. The plane was damaged slightly. Gasoline in an auxiliary tank ignited but firemen of Engine 27 quickly put out the flames.

—Buffalo Evening News, Vol CXXV, No. 93, Saturday, 30 January 1943, Page 3, Column 3

At 4:00 p.m., 13 March 1943, Jean LeRoy Ziegler married Miss Flora Mae Thompson at the Endeavor Presbyterian Church, in their hometown of Endeavor, Pennsylvania. The ceremony was officiated by Reverend Taylor. Miss Thompson was a fellow student at Endeavour High School. She was trained as a nurse at the Millard Fillmore Hospital in Buffalo, New York. At the time of their marriage, she had been employed there for one year. The couple would have three daughters, Sandra, Patricia, and Mary.

On 1 September 1947, Skip Ziegler was involved in an interesting incident at the National Air Races in Cleveland, Ohio. Flying his Curtiss-Wright XP-40Q-2A-CU Warhawk, NX300B, he had qualified in thirteenth place for the twelve airplane field in the Thompson Trophy Race. But a faster airplane, NACA test pilot Howard Clifton  “Tick” Lilly’s Bell P-63A-7-BE King Cobra, NX69901 (42-69063), flown by William Bour, which had qualified, was also in earlier race. With only ten minutes between the two races, starters thought that P-63 might not be ready in time for the start of the Thompson. They allowed Ziegler to take the seventh place in the starting lineup.

Bour did make it to the starting line in time, but officials failed to tell Ziegler to withdraw. The twelve-airplane race started with thirteen airplanes.

During the fourteenth lap of the twenty-lap race, Ziegler was in fourth place when the engine of his XP-40Q caught fire. He bailed out in front of the viewing grandstands and parachuted to the ground, suffering a broken leg. His airplane crashed and was destroyed. (This was the second crash during the race. Only six airplanes finished.) Cook Cleland won the Thompson Trophy with his #74 Goodyear F2G-2 Corsair, N5577N (Bu. No. 88463).

By 1949, Ziegler and his family had moved to Los Angeles, California, where he was employed as a test pilot for North American Aviation, Inc. On 26 September 1949, he took off from Vultee Field, Downey, California, on the first flight of the XT-28, 48-1371, the first of two prototype trainers for the U. S. Air Force. This would go into production as the T-28A Trojan.

On 1 October 1950, Ziegler became the chief test pilot for the Bell Aircraft Corporation. He was involved in testing Bell’s experimental aircraft at Edwards Air Force Base in California.

On 20 June 1951, he took the experimental variable-sweep Bell X-5, 50-1838, for its first flight. Ziegler would deploy the X-5’s variable sweep wings in flight for the first time on 27 July 1951.

Three days earlier, 24 July 1951, Ziegler made the first glide flight in the new Bell X-1D, 48-1386. This was a second-generation supersonic rocketplane built of the Air Force. This research aircraft was instrumented for the investigation of aerodynamic heating. Its nose gear was damaged on landing. This would be the X-1D’s only successful free flight. On 22 August 1951, following an internal explosion, it was jettisoned from its EB-50A mother ship and destroyed on impact with the desert floor.

On 8 October 1951, Ziegler made the twentieth and final contractor’s flight of the X-5 before turning over to its Air Force test pilot, Major Frank Kendall (“Pete”) Everest.

On 27 June 1952, Ziegler made the first glide flight of the new, swept-wing Bell X-2 Mach 3 research rocketplane. The second X-2, 46-675, was the first of the two to fly.

On 14 February 1953, the Bell X-1A, 48-1387, made its first first powered flight with Skip Ziegler in the cockpit. The X-1A, like the X-1D, was a second second generation version of the X-1 series. Originally ordered by the Air Force, it had been taken over by the National Advisory Committee for Aeronautics (NACA). Delays caused by a redesign of the fuel system and lack of funding resulted in it being competed three years behind schedule.

Ziegler demonstrated the successful operation of the X-1A with all four chambers of its Reaction Motors XLR-11-RM-5 rocket engine on 26 March 1953. During a flight on 10 April 1953, Ziegler encountered a low-frequency vibration in its elevators, limiting the rocketplane to 0.93 Mach. During another flight on 25 April 1953, the X-1A’s fuel system turbopump oversped. Ziegler shut down the rocket engine and jettisoned the remaining fuel before gliding to a landing.

As described above, Jean LeRoy Ziegler was killed on 13 May 1953 as a result of an internal explosion of the second Bell X-2. His body was never recovered.

© 2025, Bryan R. Swopes