T-28 Trojan: the tricycle propeller-engined flying classroom from Inglewood

The North American Texan that I discussed in a March 2016 post is arguably the most prolific trainer aircraft ever manufactured by North American Aviation, having trained thousands of crewmen to fly technologically complex front-line combat aircraft that served with the militaries of the US and British Commonwealth in World War II. However, North American's production of piston-engine trainers for the US military did not stop with the end of Texan production despite the fact that the Jet Age had come into full swing. During my visits to the Palm Springs Air Museum, I happened to see for the first time in person another piston-powered trainer aircraft built by North America, the T-28 Trojan, and while North American surely made its mark on US combat aviation during the 1950s by manufacturing jet fighters while undertaking development of the XB-70 Valkyrie prototype supersonic bomber, what is sometimes overlooked is the fact that the T-28 not just replaced North American's own Texan as the mainstay of the US Air Force and US Navy's primary training squadrons in the 1950s but also had a secondary role as a light attack aircraft for use in the Vietnam War and by some US allies around the world.

Left: The first XT-28 prototype (serial number 48-1371)
Right: A trio of US Air Force T-28As in flight, 1960

The T-28 Trojan traces its roots back to the North American XSN2J prototype primary trainer (company designation NA-142) design, which was designed in response to a 1945 US Navy requirement for a new trainer to replace the N3N and N2S biplane primary as well as the SNJ Texans and SNV Valiant. The XSN2J first flew on February 10, 1947 and exhibited good performance, but did not enter production due to a tight Navy. Nevertheless, in response to a US Air Force requirement issued in late 1947 for a training aircraft to replace the Texan, a new trainer utilizing some design attributes of the XSN2J was conceived by North American under the company designation NA-159 along with a competing design by Douglas, which were designated XT-28 and XT-30 respectively. Like the XSN2J, the XT-28 had a squared-off vertical stabilizer with a spine at its base but utilized a tricycle landing gear and one Wright R-1300 Cyclone 7 radial engine. After inspection of mockups of the XT-28 and XT-30, in early 1948 the XT-28 was declared the winner of the USAF competition for a Texan replacement, and two XT-28 prototypes (serial numbers 48-1371/1372) were ordered. The first XT-28 prototype flew on September 24, 1949, and the Air Force ordered 266 production examples (serial numbers 49-1491/1756) of the baseline T-28 variant, the T-28A (company designations NA-171, NA-174, and NA-189), which was officially named Trojan in the early 1950s. The T-28A was 32 feet (9.75 meters) long with a wingspan of 40 feet 1 in (12.22 meters), a wing area of 268 square meters (24.90 m²), an empty weight of 5,111 lb (2,318 kg), and a gross weight of 6,759 lb (3,065 kg). Following suitability tests of the T-28A for the advanced training role at the Air Proving Ground at Eglin Air Force Base in Florida by the 3200th Fighter Test Squadron in June 1950 were deemed satisfactory by the US Air Force, production contracts were awarded for an additional 928 T-28As (serial numbers 50-195/319, 51-3463/3796, 51-7482/7891, 52-1186/1242, and 52-3497/3498) in 1950-1952. Deliveries of the T-28A to the Air Training Command began in 1950 and continued until 1953, by which time 1,194 T-28As had been built. The T-28A served a number of USAF training squadrons with the ATC in the mid- to late 1950s, replacing T-6Gs in service, but in 1957 the Air Force began phasing out the T-28A as the Cessna T-37 Tweet jet trainer began entering operational deployment, with retirement of the T-28A completed in the early 1960s, after which some T-28As were transferred to the Air National Guard to assist in proficiency training for squadrons transitioning to jet aircraft, many others were placed in storage or transferred to the air forces of Argentina, Cuba, Dominican Republic, Ecuador, Ethiopia, Mexico, Philippines, Saudi Arabia, South Korea, and Taiwan. In addition, 94 ex-USAF T-28As were given to the US Navy in the early 1960s and reserialled with BuNos 150356/150405, 150692/150716, and 153643/153659.

An early-production T-28B in flight, 1954

Despite having not ordered the XSN2J into production due to a tight fiscal climate in the late 1940s, the US Navy continued shopping for a successor to the SNJ Texan. In 1952, two T-28As (serial numbers 51-7527/7528) were acquired by the Navy for evaluation testing, receiving the BuNos 137636/137637 while being given the company designation NA-199 by North American. Evaluation tests of the T-28A showed that the Trojan required substantial modifications in order to meet Navy training requirements, including airframe strengthening to withstand the “drop-in” landing technique, a more powerful piston engine with a three-bladed propeller for better approach and wave-off characteristics, a hydraulically-operated speed brake in the belly, a fully-castering nosewheel, and a lower profile canopy. In response, North American developed a carrier-based version of the Trojan with a belly-mounted speed brake and one Wright R-1820-9 radial engine driving a three-bladed propeller, the T-28B (company designations NA-200 and NA-219). On September 2, 1952, a Navy contract was signed for 489 T-28Bs (BuNos 137638/137810, 138103/138367, and 140002/140052), and deliveries of the T-28B to the Naval Air Training Command began in 1953, continuing until 1955. The T-28C (company designations NA-226, NA-252, and NA-307) was a T-28B with arrestor hooks, strengthened landing gear, and shorter propellers with wider blades, designed to meet a new US Navy requirement for a carrier-qualification trainer, and in June 1954 production contracts for 372 T-28Cs (BuNos 140053/140077, 140449/140666, 146238/146293, and 154658/154729) were signed. The first flight of the T-28C occurred on September 19, 1955, and deliveries were made to US Navy units from 1956 to 1957; the T-28C batch with BuNos 154658/154729 was canceled before any could be built. The T-28B and T-28C were used for training student aviators at NAS Whiting Field and NAS Saufley Field in Florida as well as NAS Corpus Christi in Texas, and they served NATS units until the early 1980s, when they were retired from service as Beechcraft T-34Cs began reaching Navy training squadrons; before long, in late 1959, T-28Cs used for carrier-qualification training were supplanted in that role by the Lockheed T2V/T-1 SeaStar jet trainer. The Japanese Air Self-Defense Force was the only foreign operator of the T-28B, with one T-28B delivered to the JASDF in 1955 and given the serial number 63-0581; the company designation NA-218 was assigned by North American Aviation to the T-28B for the JASDF.

Top: Two T-28D Nomads (serial numbers 53-8367 and 53-8368, originally BuNos 138112 and 138127 respectively) in South Vietnamese markings during Operation Farm Gate, early 1960s.
Bottom left: Ex-USAF T-28A (serial number 51-3663), one of 148 T-28As converted to T-28S Fennec standard by France, photographed by me at the Palm Springs Air Museum on March 11, 2023.
Bottom right: A T-28S Fennec (ex-USAF T-28A serial number 51-7799) of the French Air Force in flight, 1960

In the late 1950s, with the Algerian National Liberation Front engaging in guerrilla warfare against French colonial rule over Algeria, 148 retired T-28As were sold by Pacific Airmotive (PacAero) in 1959 to France to be modified by Sud-Aviation into the T-28S Fennec counter-insurgency (COIN) aircraft, which had four underwing hardpoints for unguided air-to-surface rockets or 0.50-caliber machine gun pods, and one Wright R-1820-97 supercharged radial engine (thus the letter S in T-28S standing for "supercharged"). The T-28S Fennec was used by the French Air Force for airstrikes  against against Algerian independence fighters from 1959 to 1962, and after Algeria won its independence in 1962, the French Air Force sold most of the Fennec aircraft to other countries, with 65 sold to the Argentine Navy to be converted to the T-28P carrier-based attack aircraft with shortened propeller blades and arrester gear, and 25 given to the Royal Moroccan Air Force; several the Fennecs in service with the Argentine Navy and Royal Moroccan Air Force were transferred to Honduras, Tunisia, and Uruguay. For its part, in the early 1960s, PacAero modified 313 retired T-28s for the counter-insurgency, reconnaissance, search and rescue, and forward air control roles, and when these aircraft were delivered to the US Air Force, they were designated T-28D and christened Nomad. The T-28D had two underwing hardpoints for unguided air-to-surface rockets and other armament; the T-28D-5 sub-variant had ammo pans inside the wings that could be hooked up to hardpoint-mounted gun pods for greater center of gravity and aerodynamics. Three sub-variants of the Nomad differed in the variants of the R-1820 Cyclone engine, the Nomad Mark I with a supercharged R-1820-56S, the Nomad Mark II with one R-1820-76A, and the Nomad Mark III with one R-1820-80. Fairchild Hiller, in the meantime converted 72 T-28Ds to light attack aircraft under the designation AT-28D, fitting them with six underwing hardpoints and the rocket-powered Stanley Yankee ejection seat. The USAF began using its Nomads in combat in Vietnam in the Air Commando role in December 1961 as part of Operation Farm Gate, with the 4400th Combat Crew Training Squadron carrying out airstrikes against Viet Cong targets using trained South Vietnamese pilots. The USAF operated the Nomad until 1964-1965, when it was withdrawn from service and replaced by the A-1E Skyraider due to losses from ground fire and structural failures, and several ex-USAF Nomads were given to the Republic of Vietnam Air Force; various T-28Ds became inducted into the Vietnamese People's Air Force after the fall of Saigon in April 1975 and Vietnam's reunification under Hanoi's control in July 1976. The USAF and the Royal Lao Air Force, Royal Thai Air Force, and Khmer Air Force, in the meantime, used the Nomad for clandestine airstrikes against the Khmer Rouge and Pathet Lao over Cambodia and Laos, and Royal Laotian Air Force T-28Ds fitted with a camera pack behind the wing below the fuselage when used for photo-reconnaissance were called RT-28D. The CIA used the T-28D in secret operations against the Marxist Simba rebellion in the eastern provinces of the Democratic Republic of Congo in the early 1960s, and T-28D and AT-28D also served the air forces of Bolivia, Ethiopia, and Nicaragua in the late 1960s and 1970s, with several Nomads from USAF stocks delivered to those countries. The Hamilton Aircraft Company of Tucson, Arizona, undertook development of a civilian version of the Mark III subvariant of the Nomad, the T-28R Nomair, which had the R-1820-80 engine of the Mark III but had the wingspan increased by 7 feet (2.13 meters) to reduce stalling speed. The T-28R prototype, converted from an ex-USAF T-28A (serial number 50-201), first flew in September 1960 and received an FAA Type Certificate on February 15, 1962; six T-28As (serial numbers 49-1605, 49-1665, 49-1720, 50-202, 50-270, and 50-299) were modified by Hamilton Aircraft as the T-28R-1 Nomair I military trainer for use by Brazil and ten more T-28As were converted to the T-28R-2 Nomair II utility aircraft with provisions for one pilot and two rows of two passengers housed in a cramped cabin that opened from the port side (one T-28R-2 was later sold to a high-altitude photographic company).

The first YAT-28E prototype (serial number 0-21242) during a test flight in 1963. 

Not too long after the Nomad began operations in Vietnam, North American envisaged a derivative of the T-28D with one 2,445 shp (1,823 kW) Lycoming YT55-L-9 turboprop, the NA-284, which was armed with two 0.50 in machine guns and up to 6,000 lb (2,730 kg) of weapons on twelve underwing hardpoints. On September 17, 1962, the US Air Force awarded North American a contract to convert one ex-USAF T-28A (serial number 52-1242) to NA-284 configuration, and the YAT-28E designation was assigned to the NA-284. The first flight of the YAT-28E took place on February 15, 1963, and the first YAT-28E prototype made twelve successful flights before it was lost in accident on March 27 after it went into a flat spin during high G maneuvers, killing North American test pilot George Hoskins. Despite the crash of the first YAT-28E, the US Air Force was so impressed with performance of the aircraft that it authorized the conversion of two more T-28As (serial numbers 51-3786 and 51-3788) to YAT-28Es. The second and third YAT-28E prototypes differed from the first aircraft in having an LW-2 ejection seat, a taller vertical stabilizer, and a reinforced fuselage. The second YAT-28E prototype had a 9 inch (22.86 cm) tall vertical stabilizer, and the third YAT-28E was representative of the design of the proposed production YAT-28E, featuring a redesigned flat-topped cockpit canopy that allowed clearance for the ejection seats and improved rudder control and a slightly taller stabilizer measuring 12 inches (30 cm) high. The second YAT-28E prototype flew on November 15, 1963, and the third aircraft took to the skies in July 1964, but after a joint evaluation with North American of these two aircraft over a timespan of nine months, the US Air Force concluded that further development of the YAT-28E required extensive and costly redesign, and with the advent of the North American OV-10 Bronco and Cessna A-37 Dragonfly, it chose not to order the YAT-28E into production. The second and third YAT-28Es were returned to North American in January 1965 and placed in long-term storage, but when the US Navy began shopping for a new trainer to replace the T-28B and T-28C, North American proposed a navalized version of the YAT-28E, and the third YAT-28E prototype was loaned to the Navy for evaluation tests under a joint Air Force-Navy contract. Evaluation testing of the third YAT-28E by the US Navy began on January 24, 1966 and 27 flights were conducted, but the US Navy in May 1966 pronounced the YAT-28E unsuitable for the training role due to both technical and operational drawbacks, and the proposed navalized YAT-28E never materialized. The second and third YAT-28Es were again put in long-term storage, and they were initially donated to private owners before being given to C&J Aviation in 1999 a dismantled state in Camarillo, southern California; the third YAT-28E currently awaits restoration in Camarillo, while the fuselage and tail empennage of the second YAT-28E have been in storage in a private collection in Port Hueneme since 2014.

As a side note, the T-28 design formed the basis of the AIDC T-CH-1 Chung-Hsing, the first indigenous Chinese trainer to serve with the post-World War II Republic of China Air Force (which relocated to Taiwan after the communist takeover of mainland China in late 1949), which was powered by one Lycoming T53 turboprop and had tricycle landing gear like the Trojan. Fifty-two T-CH-1 trainers were built, and the first prototype flew on November 23, 1973 followed by series production starting in 1976 and continuing until 1981.     

References:

Adcock, A., 1989. T-28 Trojan in Action. Carrollton, TX:: Squadron/Signal Publications Inc. 

Avery, N., 1998. North American Aircraft: 1934–1998, Volume 1. Santa Ana, CA: Narkiewicz-Thompson.

Darke, S.M., 2013. "The North American T-28D". Air-Britain Aeromilitaria 39 (156): 147–155.. 

Hellström, L., 2014. "T-28s in the Congo – Part 1: Stemming The Rebellion". Air-Britain Aeromilitaria  (159): 117–128.

Hellström, L., 2014. "T-28s in the Congo – Part 2: Heyday of the Trojan". Air-Britain Aeromilitaria  40 (160): 147–157.

Hellström, L., 2015. "T-28s in the Congo – Part 3: The Twilight Years". Air-Britain Aeromilitaria 41 (161): 4–17.

Johnson, E.R., 2015. American Military Training Aircraft: Fixed and Rotary-Wing Trainers Since 1916. Jefferson, NC: McFarland & Company.

Thompson, K., 1999. North American Aircraft: 1934–1998 Volume 2. Santa Ana, CA: Narkiewicz-Thompson.