The Beechcraft T-34 Mentor is an American propeller driven, single engine, military trainer aircraft derived from the Beechcraft Model 35 Bonanza.
The earlier versions of the T-34, dating from around the late 1940s to the 1950s, had piston engines.
These were eventually succeeded by the upgraded T-34C Turbo-Mentor, powered by a turboprop engine.
The T-34 remains in service more than seven decades after it was first designed.
The T-34 was the brainchild of Walter Beech, who developed it as the Beechcraft Model 45 private venture at a time when there was no defence budget for a new trainer model.
Beech hoped to sell it as an economical alternative to the North American T-6/SNJ Texan, then in use by all services of the U.S. military.
Three initial design concepts were developed for the Model 45, including one with the Bonanza’s signature V-tail, but the final design that emerged in 1948 incorporated conventional tail control surfaces for the benefit of the more conservative military (featuring a relatively large unswept vertical fin that would find its way onto the Travel Air twin-engine civil aircraft almost ten years later).
The Bonanza’s fuselage with four-passenger cabin was replaced with a narrower fuselage incorporating a two-seater tandem cockpit and bubble canopy, which provided greater visibility for the trainee pilot and flight instructor.
Structurally, the Model 45 was much stronger than the Bonanza, being designed for +10g and −4.5g, while the Continental E-185 engine of 185 horsepower at take-off (less than a third of the power of the T-6’s engine) was the same as that fitted to contemporary Bonanzas.
Model 73 Jet Mentor
In 1955 Beechcraft developed a jet engined derivative, again as a private venture, and again in the hope of winning a contract from the US military.
The Model 73 Jet Mentor shared many components with the piston-engined aircraft; major visual differences were the redesigned cockpit which was relocated further forward in the fuselage and the air intakes for the jet engine in the wing roots, supplying air to a single 920 lbf (4.1 kN) Continental J69 jet engine in the rear fuselage.
The first flight of the Model 73, registered N134B, was on 18 December 1955.
The Model 73 was evaluated by the USAF, which ordered the Cessna T-37, and the USN, which decided upon the Temco TT Pinto.
After initial testing at the Naval Air Test Center at NAS Patuxent River, Maryland, the Navy tested the feasibility of using the TT Pinto as a jet-powered trainer for primary flight training in 1959, but discontinued use of the aircraft by December 1960 and discarded all examples, returning to the piston-powered T-34B Mentor and North American T-28 Trojan for its primary flight training requirements.
The Beechcraft Model 73 was not put into production and the sole prototype is displayed at the Kansas Aviation Museum.
T-34C Turbo-Mentor
After a production hiatus of almost 15 years, the T-34C Turbo-Mentor powered by a Pratt & Whitney Canada PT6A-25 turboprop engine was developed in 1973.
Development proceeded at the behest of the USN, which supplied two T-34Bs for conversion.
After being re-engined with the PT6, the two aircraft were redesignated as YT-34Cs, the first of these flying with turboprop power for the first time on 21 September 1973.
Mentor production restarted in 1975 for deliveries of T-34Cs to the USN and of the T-34C-1 armed version for export customers in 1977, this version featuring four underwing hard points.
The last Turbo-Mentor rolled off the production line in 1990.
Since the late 1970s, T-34Cs have been used by the Naval Air Training Command to train numerous Naval Aviators and Naval Flight Officers for the U.S. Navy, U.S. Marine Corps, U.S. Coast Guard, and numerous NATO and Allied nations.
With over 35 years of service, the T-34C has been completely replaced by the T-6 Texan II.
Variants
YT-34
Prototype, three built.
T-34A
US Air Force trainer.
Replaced by the Cessna T-37 around 1960 (450 built).
T-34B
US Navy trainer.
Used as a trainer until 1976, when VT-1 and VT-5 were decommissioned.
It was replaced by the T-34C (423 built by Beechcraft). T-34Bs were flown by pilots assigned to the Navy Recruiting Command until the mid-1990s.
YT-34C
Two T-34Bs were fitted with turboprop engines and were used as T-34C prototypes.
T-34C Turbo-Mentor
Two-seat primary trainer, fitted with a turboprop engine.
T-34C-1
Equipped with hard points for training or light attack, able to carry 1,200 lb (540 kg) of weapons on four under-wing pylons.
The armament could include flares, incendiary bombs, rocket or gun pods and antitank missiles.
Widely exported.
Turbo-Mentor 34C
Civilian version
Allison Turbine Mentor
Conversion of surplus T-34 Mentors to be powered by Allison Model 250 turboprop engines.
Model 73 Jet Mentor
Powered by a 920 lbf (4.09 kN) Continental J69-T-9 turbojet engine.
