The Bede XBD-2 was an experimental short takeoff and landing (

STOL A short takeoff and landing (STOL) aircraft is a conventional fixed-wing aircraft that has short runway requirements for takeoff and landing. Many STOL-designed aircraft also feature various arrangements for use on airstrips with harsh conditio ...

) aircraft, with several novel features such as structural use of

glass-fibre Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clot ...

and aluminium honeycomb, a suction

boundary layer control Boundary layer control refers to methods of controlling the behaviour of fluid flow boundary layers. It may be desirable to reduce flow separation on fast vehicles to reduce the size of the wake (streamlining), which may reduce drag. Boundary l ...

(BLC) system and

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

-mounted twin engines driving a

pusher configuration In an aircraft with a pusher configuration (as opposed to a tractor configuration), the propeller(s) are mounted behind their respective engine(s). Since a pusher propeller is mounted behind the engine, the drive shaft is in compression in nor ...

, shrouded single

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

. The sole example flew in the early 1960s in the United States.

Design and development

Bede aircraft was formed to develop an

aircraft of novel construction, incorporating boundary layer control. They placed the design study with the Department of Aerodynamics at the

University of Maryland The University of Maryland, College Park (University of Maryland, UMD, or simply Maryland) is a public land-grant research university in College Park, Maryland. Founded in 1856, UMD is the flagship institution of the University System of M ...

. The boundary layer was controlled with a suction system via 160,0000 upper wing and

aileron An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

surface holes, with diameters ranging from 0.020 to 0.029 in (0.51 - 0.74 mm). Aluminium honeycombs were used throughout the

as structural elements. The XBD-2 was powered by a pair of

flat-six A flat-six engine, also known as a horizontally opposed-six, is a six-cylinder piston engine with three cylinders on each side of a central crankshaft. The most common type of flat-six engine is the boxer-six engine, where each pair of opposed cy ...

piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...

s mounted inside the fuselage, driving a single

, turning within a circular shroud. The wing of the XBD-2 had an aspect ratio of 9 and 5° of dihedral. It was built around an aluminium box spar, was aluminium skinned and carried sealed all-metal ailerons. A 14 in (356 mm) Joy blower pulled air through the pinholes in the surfaces, venting it in the fuselage to cool the engines. Sealed flaps smoothly changed the wing

camber Camber may refer to a variety of curvatures and angles: * Camber angle, the angle made by the wheels of a vehicle * Camber beam, an upward curvature of a joist to compensate for load deflection due in buildings * Camber thrust in bike technology * ...

and increased its area by about 15% when extended. Apart from its use of aluminium honeycomb, the front part of the flat-sided fuselage was conventional, with a cabin with space to seat four, though mostly filled with instrumentation. Aft, two 145 hp (108 kW)

Continental O-300 The Continental O-300 and the C145 are a family of air-cooled flat-6 aircraft piston engines built by Teledyne Continental Motors.Christy, Joe: ''Engines for Homebuilt Aircraft & Ultralights'', pages 60-63. TAB Books, 1983. First produced in ...

engines were mounted one above the other. They drove the rear propeller shaft through ten V-belts via Sprag clutches to avoid engine speed synchronisation problems. The rear fuselage tapered to a vertical wedge with the propeller shaft emerging at its top. The circular shroud was attached to the fuselage by the fixed triangular

fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

mounted on the top of the fuselage, the triangular

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...

and a short boom at the bottom. The propeller rotated close to the shroud's

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

; the shroud was intended partly to reduce propeller tip losses and also to act in the place of conventional stabilizing surfaces. The fin resumed above the shroud and carried the top of a high aspect ratio

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally aircraft, air or watercraft, water). On an aircraft the rudder is used primarily to ...

behind the shroud's

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 1997. ...

, its bottom end attached to the tailboom, with a midpoint cutout to allow for

elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

movement. The elevator was supported by tailplane extensions beyond the shroud, similar to that of the fin. Structurally, the shroud was a

shell surrounding an aluminium spar and filled with

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethan ...

foam. The control surfaces were conventionally constructed from aluminium sheet. The XBD-2 had a fixed

tricycle undercarriage Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle ge ...

, with wheels enclosed in fairings. The main legs were

cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...

s, unusual at the time. After the XBD-2 first flew on 26 July 1961 it was flight tested and slightly modified to simplify future production. It was intended to lead to the BD-3, which would have been a six-seater with bigger engines, more use of honeycomb panels, retracting undercarriage and a laminar flow wing, but this was not built.

Aircraft on display

The sole XBD-2 is mounted on outdoor display at the entrance to Manitowoc County Airport.

Specifications

References

External links

Göttingen 549 airfoil
{{Bede aircraft XBD-002 1960s United States experimental aircraft Twin-engined single-prop pusher aircraft Ducted fan-powered aircraft Low-wing aircraft Aircraft first flown in 1961