Tag Archives: N4060K

16 September 1958

North American Aviation NA-246 Sabreliner prototype, N4060K, during its first flight, 16 September 1958. (North American Aviation, Inc.)

16 September 1958: At Palmdale, in the high desert of southern California, the prototype North American Aviation, Inc., Model NA-246 Sabreliner, N4060K, took off on its first flight. The test pilots were James O’Connor (“J.O.”) Roberts, Jr., and George Dyas Mace. Following the flight, Roberts said, “The airplane handled exceptionally well in every maneuver we tried.”

The Sabreliner had been designed and built at North American’s expense to meet the U.S. Air Force specification for the UTX, a twin-engine jet that would be primarily used as a trainer for Air Force pilots in non-flying assignments but who needed to remain proficient. It could also be used as a passenger and cargo transport.

The NA-246 was flown by two pilots and could carry up to four passengers in “club seating.”

In October 1958, the Air Force ordered the Model 265 Sabreliner into production, designated T-39A-1-NA (Serial numbers 59-2868 to -2871). This aircraft could carry up to 7 passengers. In 1962, a commercial variant of the T-39A, the Model 265 Sabreliner, was certified by the Federal Aviation Administration.

North American Aviation Model 256, N4060K, during its first flight, 16 September 1958. (North American Aviation, Inc.)

The T-39A was 44 feet (13.411 meters) long, with a wingspan of 44 feet, 6 inches (13.564 meters) and overall height of 16 feet (14.874 meters). The wings were swept at 28°. It had an empty weight of approximately 9,250 pounds (4,196 kilograms) and maximum takeoff weight of 17,760 pounds (8,056 kilograms).

The Model 246 prototype was powered by General Electric J85 turbojet engines which produced about 2,000 pounds of thrust (8.90 kilonewtons). The the production T-39A used Pratt & Whitney J60-P-3 engines, rated at 3,000 pounds (13.34 kilonewtons) for takeoff.

The T-39A had a maximum allowable airspeed (VMO) of 350 knots, indicated (KIAS) (403 miles per hour/648 kilometers per hour) from Sea Level to 21,100 feet (6,431 meters). Above that altitude, speed was restricted to 0.77 Mach.

North American Aviation T-39A-1-NA, 62-4478, at the National Museum of the United States Air Force.. (U.S. Air Force)

The prototype was issued an Airworthiness Certificate by the Federal Aviation Administration 25 April 1958. The registration was cancelled 30 June 1970.

James O’Connor Roberts, Jr. (Test & Research Pilots, Flight Test Engineers)

James O’Connor Roberts, Jr., was born 17 April 1924 at Washington, D.C. He was the second son of James O’Connor Roberts, an attorney employed by the United States government, and Leah Irene Harris Roberts. He attended the Peddie School in Highstown, New Jersey, and Yale University, where he was a member of the Kappa Phi Sigma (ΚΦΣ) and Chi Psi (ΧΨ) fraternities.

Roberts enlisted in the United States Army Air Forces as an aviation cadet in February 1943.¹ He had blond hair and blue eyes, was 5 feet, 10½ inches (1.79 meters) tall and weighed 145 pounds (65.8 kilograms). He graduated from pilot training 7 January 1944 and was commissioned as a second lieutenant.

Second Lieutenant James O. Roberts, Jr., married Miss Evelyn Meryle Foss Johnson 19 January 1944 at the Walter Reed Memorial Chapel in Washington, D.C. The ceremony was officiated by Chaplain George F. Cotton. They would have four sons. (Mrs. Roberts later died and he remarried.)

Lieutenant Roberts was assigned to the Aleutian Islands where he flew the Curtiss-Wright P-40 Warhawk.

Following World War II, Lieutenant Roberts returned to Yale to complete his studies, graduating in 1946. He majored in Sociology.

North American Aviation F-86A-5-NA Sabre 48-273, 335th Fighter-Interceptor Squadron, 4th Fighter-Interceptor Group, in the markings of the Silver Sabres Aerobatic Team, at Langley Air Force Base, circa 1950. (U.S. Air Force)

Remaining in the Air Force after the war, he transitioned to the North American P-51 Mustang and the Lockheed P-80 Shooting Star. Assigned to the 4th Fighter Group at Andrews Air Force Base, he was a member of the USAF Champion Gunnery Team and the Silver Sabres Aerobatic Team, flying “slot” and solo. The team flew the North American Aviation F-86A Sabre.

4th Fighter-Interceptor Group North American Aviation F-86A Sabres at Suwon, Korea, June 1951. (U.S. Department of Defense VIRIN: HD-SN-99-03072)

The 4th Fighter-Interceptor Group deployed to Korea in 1950. On 22 December 1950, Captain Roberts was flying one of eight F-86As in an air battle against fifteen Mikoyan-Gurevich MiG-15 fighters. Roberts shot down one of the six MiGs destroyed in the battle. No Sabres were lost. He later shot down a second MiG-15.

Major Roberts resigned from the Air Force in March 1952 and joined North American Aviation as an engineering test pilot. He was involved in testing the F-86H fighter bomber variant of the Sabre, the F-100A Super Sabre, and the F-107A. Roberts was a founding member of the Society of Experimental Test Pilots.

Roberts retired from North American after thirty years.

James O’Connor Roberts, Jr., died at Salinas, California, 6 September 2008, at the age of 84 years.

¹ The Department of Veterans Affairs gives an enlistment date of 17 April 1937.

© 2024, Bryan R. Swopes