Beechcraft Model 34

Model 34 "Twin-Quad"
Role	Civil airliner
Manufacturer	Beechcraft
First flight	October 1, 1947
Retired	1949
Status	prototype only, scrapped
Number built	1 (two prototypes in production scrapped)
Unit cost	$6 million (development)

The Beechcraft Model 34 "Twin-Quad" was a prototype airliner designed and built by Beechcraft in the period between World War II and the Korean War. At this time many aircraft manufacturers in the United States anticipated a boom in civil aviation and a large number of designs left the drawing board only to ultimately fail. The Model 34 was one of these failures, partly because of its unusual design, and partly because of the thousands of ex-military transport aircraft that were available at the time for a fraction of the price of a new aircraft.

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.