Beech Aircraft Corporation had long been recognized as a leader in the design of general aviation aircraft, but along with its successes there have been a number of would-be Beechcrafts that never made it to market.
Introduced in 1981, the turbocharged Model B36TC Bonanza was Beech Aircraft’s answer to high-performance, turbocharged aircraft being offered by competitors, particularly Cessna Aircraft Company’s T210N Centurion that entered service in 1980. The company had not offered a turbocharged Model 35 since 1970 when the V35B-TC was unveiled (only seven were built before production ended that year). In 1979, however, the company reentered the turbocharged segment when the six-place A36TC made its debut.
In an effort to take performance to a higher level, both in terms of speed, altitude and cabin comfort, development of a turbocharged, pressurized Model 36 began in 1978. Designated as the Model T36TC, the experimental aircraft was built strictly as a flying proof-of-concept (POC) airframe. The cabin of the sole prototype, serial number EC-1, was unpressurized but did feature a Continental six-cylinder TSIO-520 with the turbocharger mounted aft of the 325-hp engine. To accommodate that modification, a 12-inch extension of the fuselage section ahead of the windshield was installed. From a visual standpoint, however, the airplane’s most salient alteration was installation of a T-tail empennage.
The sleek Beechcraft made its first flight in February 1979 with company engineering test pilots Lou Johansen and Robert Suter in the cockpit. The T36TC program was kept quiet and little is known about the flight test program, but after flying the airplane for more than 82 hours the decision was made to terminate further development. The last flight was made in January 1980 and the prototype eventually was scrapped.
Despite the end of the T36TC initiative, company officials were still enamored with the idea of a single-engine, pressurized Beechcraft. Their enthusiasm was warranted because it was clear that a market had emerged for just such a business aircraft.
The twin-engine, piston-powered Model 58P Baron offered a logical platform to test the single-engine concept and a 58P fuselage (designated serial number EJ-1) was selected as an engineering POC testbed. Chief changes included installation of different wings and a 630-shp (shaft horsepower) Garrett TPE-331-9 turboprop powerplant swinging a three-blade, fully-reversible propeller with a diameter of 92 inches. The POC, known within the company as PD (preliminary design) 336, existed solely to help Beech Aircraft engineers evaluate the compatibility of the turboprop engine and the 58P’s pressurized cabin.
Known unofficially around the Beechcraft factory as the Model 38P Lightning, the airplane took to the air in June 1982 with Lou Johansen at the controls. Although the company was mum about performance information, for the next 17 months Johansen and other test pilots flew the airplane on 133 flights. During that time the POC accumulated more than 100 hours of flight time that yielded useful information about the combination of turboprop power and pressurization.
The next step in the Lightning flight test program centered chiefly on replacement of the prototype airplane’s TPE-331-9 engine with a Pratt & Whitney Canada PT6A-40 turboprop powerplant that was flat rated to 630 shp. The purpose of the engine change was to compare the Model 38P’s performance with the Garrett engine with that of the PT6A-40. Both engines were proven workhorses and different versions already powered the Beechcraft King Air Model B100 and B200, respectively.
(BEECHCRAFT CORPORATION; SPECIAL COLLECTIONS AND UNIVERSITY ARCHIVES, WICHITA STATE UNIVERSITY LIBRARIES)
Once again, Lou Johansen had the honor of flying the re-engined Lightning on its maiden flight in March 1984. Recognizing that market conditions did not warrant further development of the airplane, company management canceled the program shortly after the initial flight. Yet, the POC continued flying. In an effort to collect as much performance data as possible that could be applied to future certification of the Model 38P, engineering evaluations continued and were conducted in accordance with FAA Part 23 rules. According to Johansen, the PT6A-40-powered airframe made 68 flights and logged more than 55 hours in the air. The PD 336 Lightning flew for the last time in August 1984. The airframe eventually was destroyed.
When it comes to experimental Beechcrafts, perhaps no better illustration of the company’s desire to marry turbine engines to an existing airframe can exceed that of the PD 290. Conceived strictly as a tool to evaluate the feasibility of mating small turbofan engines to a King Air cabin-class airframe, the PD 290 was exceedingly unique. Its most salient feature was two Pratt & Whitney JT-15D4 turbofan engines housed in specially-designed, over-wing nacelles where PT6A-series turboprop engines normally resided.
The first Model 200 airframe, serial number BB-1, was utilized as the platform to assess the aerodynamic and systems investigations. Veteran company engineering test pilot Bud Francis took the PD 290 into the air on its maiden voyage in March 1975. The airplane flew more than 93 hours during 103 test flights before the program ended in 1977. The PD 290 was the last jet engine-based program until 1986 when the company acquired the Mitsubishi Diamond business jet program and transformed that airplane into the successful Model 400 Beechjet. As for the PD 290, the airframe, sans engines, was placed in outside storage near the factory and scrapped.
Another abortive Beechcraft design that is worthy of mention is the G90 King Air. It was an outgrowth of the Model F90 that was introduced with great success in 1979. From a visual standpoint, the PT6A-135-powered F90 essentially was a Model E90 fitted with a T-tail empennage similar to that of the company’s flagship Model 200 Super King Air. In an effort to offer potential F90 customers a choice of turboprop engines, in 1980 Beech Aircraft developed an engineering testbed unofficially known as the Model G90.
The airplane was equipped with Garrett AiResearch TPE-331 turboprop engines similar to those that had been installed on the Model B100 King Air. That combination proved successful with more than 130 built between 1976 and 1983. The F90 prototype, serial number LA-1, was modified to accept the TPE-331 powerplants and was re-designated as LE-0. In addition to the Garrett engines, Beech engineers also installed a new windshield design that was more streamlined and was raked aft at a steeper angle than windshields of production F90 King Airs. Despite good performance and a promising market, the G90 program did not progress beyond the flight test phase.
The Vietnam War produced a plethora of unusual aircraft designs intended to fill a specific niche as dictated by the conflict. Among these special missions was electronic surveillance of enemy activity. To meet that requirement for the U.S. Air Force, Beech Aircraft initially modified the Model E33A Bonanza into the Model 1074 Pave Eagle I, but it was later replaced by an improved version designated as the Model 1079 Pave Eagle II.
The airplanes were based on the larger Model A36 Bonanza and featured a number of major modifications. These included tip tanks for additional endurance and a 375-hp Teledyne Continental engine that was equipped with a special reduction gearbox (RGB). The RGB allowed the propeller to turn at a significantly lower RPM compared with standard production airplanes, thereby reducing noise as the airplane loitered above a target at night, monitoring enemy communications. A version of the Model 1079, known as the QU-22B, was designed to be flown by remote control but the pilot and observer remained on board to monitor equipment and could take control of the airplane if necessary.
(BEECHCRAFT CORPORATION; SPECIAL COLLECTIONS AND UNIVERSITY ARCHIVES, WICHITA STATE UNIVERSITY LIBRARIES)
Yet another “Bygone Beechcraft” of interest is the all-composite Model 81 POC that had the potential to eventually replace the venerable Bonanza. Intended chiefly to test new engineering concepts, the single-engine Model 81 shared the Starship I’s three-surface configuration that included a small canard-type forward wing, main wing and a T-tail empennage.
If the airplane had been produced, its pressurized cabin would have seated five people in comfort while the Beechcraft sped along at the impressive cruise speed of 240 knots. The Model 81 was under design along with the twin-engine cabin class airplane that was to be powered by either piston or turbofan engines.
None of these aircraft were built, but in the mid-1980s they clearly demonstrated Beech Aircraft Corporation’s commitment to the future of business aviation.