The first of two North American Aviation XT-28 prototypes, 48-1371, lands at Edwards Air Force Base 3 February 1950. (U.S. Air Force)
26 September 1949: At Vultee Field, a private industrial airport in Downey, California, North American Aviation test pilot Jean LeRoy (“Skip”) Ziegler ¹ took the first of two prototype military flight trainers, the XT-28 (NAA Model 159–2), U.S. Air Force serial number 49-1371, for its first flight. The 45-minute flight was two weeks ahead of schedule.
The Long Beach Press-Telegram reported:
New Training Plane Tested
LOS ANGELES, Sept 27. (AP) The Air Force’s first postwar training plane—North American’s T-28—has tried her wings and found they work very well.
The company announced that the twin cockpit craft—designed to train pilots for advanced high speed fighters and bombers—flew 45 minutes yesterday. Said test pilot Skip Ziegler, “It handles more like a fighter than a trainer.” He termed the flight, “completely satisfactory.”
The T-28 has a ceiling of 29,800 feet and can move 288 miles an hour. The T-6, present Air Force trainer, ceilings at 22,000 and travels 205 m.p.h. top.
One of the two North American Aviation XSN2J-1 prototypes in flight of the Southern California shoreline, circa 1946. (North American Aviation, Inc./San Diego Air & Space Museum Archives, Catalog #: 00033269)
The XT-28 was developed from an earlier North American Aviation project for the United States Navy. In 1946, NAA proposed their Model 142, as a replacement for the World War II SNJ/T-6 Texan, a trainer which had also been built by North American, and used by both the Navy and the U.S. Army Air Forces. The Navy designated the proposed airplane XSN2J-1. Two were built and assigned Bureau of Aeronautics serial numbers (“Bu. No.”) 121449 and 121450. 121449 was the first to fly, 15 February 1947.
The Navy tested both aircraft, but did not order them into production.
One of the two North American Aviation XSN2J-1 prototypes during testing at NATC Patuxent River, Maryland, October 1948. The prototype is armed with with five-inch air-to-surface rockets. (National Archives and Records Administration)
A year later, NAA made a similar proposal to the United States Air Force. The Air Force wanted a trainer to transition pilots into turbojet-powered aircraft. Similar to the XSN2J-1, the XBT-28 was changed to tricycle landing gear, a first for a miltiary trainer. The prototype’s two cockpits were laid out very similar to the new, swept-wing North American XP-86 Sabre. The Air Force ordered the airplane into production as the T-28A. The first T-28A arrived at Eglin Air Force Base, Florida, 15 June 1950, where it would tested for suitability as a flight trainer.
Prototype North American Aviation XBT-28. (T-28 Trojan Foundation)
The North American Aviation T-28 Trojan is an all-metal, two-place airplane with retractable tricycle landing gear. The dual cockpits are arranged in tandem. The T-28A was used by the United States Air Force as a primary training aircraft, while the more powerful T-28B and T-28C were employed by the U.S. Navy. The airplane was noted for its stability and handling qualities, its easy recovery from stalls and spins, and its excellent visibility.
Initially, the T-28 was built at North American Aviation’s Downey Division, in Downey, California, which at the time was primarily a farming community about 13 miles (21 kilometers) south of downtown Los Angeles, California. Production was shifted to North America’s Columbus Division in Columbus, Ohio.
North American Aviation T-28A Trojan internal arrangement. (U.S. Air Force)
The XT-28 and production T-28As were 32.0 feet (9.754) long with a wingspan of 40.6 feet (12.375 meters), and overall height of 12.7 feet (3.871 meters). The wing had an angle of incidence of 2° with 3° of negative twist, and 8° dihedral. The total wing area was 268.0 square feet (24.9 square meters). The vertical fin was offset 1° to the left of the airplane’s centerline. The prototype and early production T-28As had an empty weight of had an empty weight of 6,909 pounds (2,998 kilograms). This was increased in later aircraft to 7,282 pounds (3,303 kilograms). The Maximum Takeoff Weight (MTOW) was 7,751 pounds (3,516 kilograms).² The two prototypes had a belly-mounted speed brake. All T-28As had provisions for this installation.
North American Aviation XT-28 three-view illustration with dimensions. (U.S. Air Force)
The XT-28 and production T-28A were powered by an air-cooled, supercharged, 1,301.868 cubic inch (21.334 liter) Wright Aeronautical Division Cyclone 7 R-1300-1 (853C7BA1) 7-cylinder radial engine with a compression ratio of 6.2:1. This engine required 91/98 octane aviation gasoline. It was rated at 700 horsepower at 2,400 r.p.m., and 800 horsepower at 2,600. r.p.m. for takeoff. The engine also produced some jet thrust from its exhaust system. The engine thrust line was angled downward 5° from fuselage reference line. The R-1300-1 drove a two blade, 10 foot, 0 inch (3.048 meters) diameter Aeroproducts hydraulic variable pitch propeller through 0.5625:1 gear reduction. The engine was 4 feet, 1.12 inches (1.248 meters) long, 4 feet, 2.45 inches (1.281 meters) in diameter, and weighed 1,065 pounds, (483 kilograms).
The XT-28 had a maximum fuel capacity of 125 gallons (473 liters), carried in two wing tanks. Two additional tanks were added to later production T-28As, increasing the capacity to 177 gallons (670 liters).
The T-28A had a cruise speed of 165 knots (190 miles per hour/306 kilometers per hour, and maximum speed of 247 knots (284 miles per hour/457 kilometers per hour) at 5,800 feet (1,768 meters). VNE varied from 190 knots (219 miles per hour/352 kilometers per hour) at 25,000 feet (7,620 meters) with external load, to 340 knots (391 miles per hour/630 kilometers per hour) at Sea Level, clean. The airplane’s best power off glide speed was 105 knots (120 miles per hour/194 kilometers per hour).
The T-28A could climb at a maximum rate of 1,870 feet per minute (9.5 meters per second). Its service ceiling was 24,000 feet (7,315 meters). The maximum range was 720 nautical miles (829 statute miles/1333 kilometers) in early production models, or 880 nautical miles (1,013 statute miles/1,630 kilometers) in aircraft with increased fuel capacity.
For training purposes, the T-28A could be armed with one detachable gun pod under each wing. Each pod contained a .50-caliber AN-M3 Browning Aircraft Machine Gun. These had a rate of fire of approximately 1,100 rounds per minute. Each gun was supplied with 100 rounds of ammunition. The trainer could also be equipped with a removable bomb rack for a 100-pound (45 kilogram) bomb. Three 2.25 inch (5.7 centimeters) Sub-Caliber Aerial Rocket (SCAR)—Rocket, 2.25-Inch Practice—rockets could be carried on pylons mounted to hardpoints under each wing.
The first production North American T-28A Trojan, 49-1494 (North American serial number 159-1), at the National Museum of the United States Air Force. Delivered to Wright-Patterson AFB, this aircraft was used as a static test airframe. (U.S. Air Force 050322-F-1234P-020)
A total of 1,948 T-28s were built from 1950 to 1957. 1,194 of these were T-28As. The Air Force retired its T-28As by 1959. Many USAF T-28As were pulled from storage at Davis-Monthan Air Force Base, Tucson, Arizona, and were converted to the T-28D configuration for combat operations during the Vietnam War. Others were converted to the AT-28D attack variant, which included an ejection seat.
North American Aviation test pilot Robert A. (“Bob”) Hoover, with a U.S. Navy T-28B Trojan, circa 1953. (National Museum of Naval Aviation)
XT-28 48-1371 was sent to “The Boneyard” at Davis-Monthan Air Force Base near Tucson, Arizona, 23 January 1961, and to reclamation, 18 June 1965. In 1974, it was observed, disassembled, at the Hamilton Aviation Company yard in Tucson. (Hamilton produced modified T-28s: the military T-28R-1, and the civilian T-28R-2 Nomair.)
¹ For biographical information about Skip Ziegler, please see “This Day in Aviation” for 12 Nay 1953 at: https://www.thisdayinaviation.com/12-may-1953/
Jean LeRoy “Skip” Ziegler, with the Bell X-5 at Edwards Air Force Base, 1951. (LIFE Magazine)
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.
A Bell X-2 rocketplane is loaded aboard the Boeing B-50A-5-BO Superfortress “mothership,” 46-011. (U.S. Air Force)
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)
Boeing EB-50D Superfortress 48-096 with a Bell X-2 (U.S. Air Force)
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).
Bell X-2 46-675 on its transportation dolly at Edwards Air Force Base, California, 1952. (NASA)
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.
Jean LeRoy Ziegler, circa 1940. (Niagara Aerospace Museum)
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.
Pan American Airways-Africa, Limited, routes
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.)
Boeing 314A NC18612, Clipper Cape Town. (David J. Gauthier Collection, 1000aircraftphotos.com)
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 PilotJean 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.
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.
Skip Ziegler’s Curtiss-Wright XP-40Q-2A-CU, NX300B (ex-USAAF P-40K-1-CU 45-45722), circa September 1947. (Military Matters)
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.
The first of two prototype North American Aviation XT-28s, 48-1371, lands at Edwards Air Force Base, 3 February 1950. (U.S. Air Force)
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.
The Bell X-5 had variable sweep wings. (U.S. Air Force 151021-F-DW547-002)
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.
Bell X-1D 48-1386. (Bell Aircraft Corporation)
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.
Bell X-2 46-675 after nose gear collapsed on landing at Edward Air Force Base, California, 27 June 1952. Bell Aircraft Corporation test pilot Jean Leroy (“Skip”) Zielgler is still seated in the cockpit. (National Aeronautics and Space Administration, Armstrong Flight Research Center, E-749)
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.
Bell X-1A 46-1384 (U.S. Air Force)
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.
