Page 24 - Volume 13 Number 11

Econo-Jet – the Model 73
Beech Aircraft Corporation’s Jet Mentor was built on a tight budget and performed well but lost its bid to be the U.S. Air Force’s first turbine-powered basic trainer to crosstown rival Cessna Aircraft Company’s Model 318.
by Edward H. Phillips
During the early 1950s, excitement about the “Dawn of the Jet Age” was capturing the imagination of the American public. World War II, still a very fresh memory to millions of Americans who had fought in that global conflict or lived through it, had seen the jet fighter’s combat debut as the twin-engine Messerschmitt Me-262 tore through Allied bomber formations, wreaking havoc and easily evading Allied fighters with its 500- plus mph maximum speed. In response to the German threat, the British Royal Air Force soon fielded a twin- engine jet fighter of their own, the Gloster Meteor and by 1943-1944 the United States Army Air Forces was experimenting with the Bell XP-59 powered by two jet engines provided by the British.
In addition, during 1950-1953 the escalating air war in the skies over Korea was often headline news as North American single-engine F-86 Sabre jet fighters clashed in dogfights with the much-vaunted Soviet MiG 15- and MiG 17-series jets flown by Russian and North Korean pilots. By the end of the Korean conflict in 1953, it had become painfully clear to the champions of United States military aviation that the day of the reciprocating piston engine as the “prime mover” of front-line fighter aircraft was rapidly drawing to a close.1
As early as 1945 the Army Air Forces had begun taking delivery of the single-engine Lockheed F-80 Shooting Star – the service’s first combat jet fighter that also
served with distinction as a fighter-bomber during the Korean War. A two-place, tandem-seat version designated T-33 eventually became the Air Force’s standard airframe for training new jet pilots who had already earned their wings in war-weary T-6 trainers that had been rebuilt. To bridge the wide gap between the Beechcraft T-34 and the T-33, in 1950 the Air Force began operating the North American T-28A Trojan as its basic and primary pilot training platform.2
In 1953-1954, however, the Air Force also had begun taking delivery of the Beechcraft Model 45 Mentor – a two-place, tandem-seat, piston-powered airplane that was much better suited to serve as a basic trainer than the T-28A. Recognizing that the time had finally come to bid farewell to the venerable T-6 and SNJ, in the early 1950s both the Air Force and Navy, working independently, began formulating plans to obtain a jet-powered basic trainer. Early in 1952 the Air Force conducted a design competition for a primary jet trainer and three manufacturers responded – Wichita, Kansas- based Beech Aircraft Corporation and Cessna Aircraft Company, and Dallas, Texas-based Texas Engineering & Manufacturing Company (TEMCO).
Cessna’s design was designated the Model 318 and was a “clean-sheet” airplane powered by two Turbomeca Marboré II centrifugal-flow turbojet engines, each rated at 920 pounds of static thrust. The compact powerplant
was built in the United States under license by Continental Motors, which had obtained manufacturing rights in 1951. The engine was designated as the military J-69-T-7. The engines were buried in the wing root area. Inlet air
The Beechcraft Model 73 was powered by a single Turbomeca Marboré II centrifugal- flow turbojet (military J-69-T-7) mounted
in the aft fuselage section. The lightweight Jet Mentor demonstrated excellent han- dling qualities and good performance on only 920 pounds of static thrust. Note test probe mounted on left side of the nose section. (Kansas Aviation Museum)
22 • KING AIR MAGAZINE
NOVEMBER 2019