Beechcraft Model 34 - Design and Development

Design and Development

The design was a four-engine high-wing monoplane with tricycle undercarriage, originally designed for 14 (three abreast seating with six additional seats mounted on the side) and eventually converted to take 20 passengers. The side "couch seats" were also able to be folded away so that cargo could be carried internally in the cabin. Individual storage space was provided for each passenger seat on the fuselage side above the seat. In order to accommodate a larger cargo load, a cargo hatch was located near the pilot's compartment.

The unusual aspects of the design were the butterfly or V-tail and engine layout that led to its popular nickname, "Twin Quad." The four engines were buried in the wings, with each pair of engines connected to a single propeller via clutches and a common gear box. The engines were horizontally opposed eight-cylinder air-cooled Lycoming GSO-580s (GSO denoting Geared Supercharged and Opposed, with each engine featuring a built-in reduction gear box in addition to the common propeller gear box). The engines were rated at 400 horsepower at 3,300 rpm. The tail was unusual because unlike the vertical and two horizontal surfaces found on most aircraft, the Twin-Quad's was a two-surface V-tail similar to the tail fitted to Beechcraft's other new product at the time, the Model 35 Bonanza. The V-tail configuration was flight-tested on a twin-engine Beech AT-10.

Another, but more conventional, design aspect was that the belly was made strong enough to sustain minimal damage in the event of a "wheels-up" landing, with built-in integral landing keels or "skids." The wing measured 70 ft (21 m) from tip to tip and the fuselage was 53 ft (16 m) long. With the top of the V-tail almost 18 ft (5.5 m) above the ground and a design maximum take off weight (MTOW) of 20,000 lbs, the Model 34 is to date the largest and heaviest Beechcraft civil design, with only the smaller XA-38 Grizzly military aircraft outweighing it.