The Brochocki BKB-1 was a Canadian

mid-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple wings. A monoplane has inherently the highest efficiency and lowest drag of any wing config ...

, single-seat,

experimental An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs whe ...

tailless glider that was designed and constructed by Stefan Brochocki with assistance from Witold Kasper and A. Bodek. The designation indicated the contributions of all three men. The aircraft was intended to study flight above the stall angle.Rogers, Bennett: ''1974 Sailplane Directory, Soaring Magazine'', page 94. Soaring Society of America, August 1974. USPS 499-920

Design and development

The BKB-1 was constructed in 1959 and built entirely from wood. The wing was swept, had a 9.5:1

aspect ratio The aspect ratio of a geometry, geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side—the ratio of width to height, when the rectangl ...

and employed a

NACA The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...

8-H-12

airfoil An airfoil (American English) or aerofoil (British English) is a streamlined body that is capable of generating significantly more Lift (force), lift than Drag (physics), drag. Wings, sails and propeller blades are examples of airfoils. Foil (fl ...

. The aircraft had a very high wing area of which resulted in a light wing loading of just 3.81 lb/sq ft (18.6 kg/m²). The

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BKB-1 was originally registered in Canada as CF-ZDK-X. Later it was moved to the

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, owned by Kasper and registered as N2991G. As a

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the aircraft went through several modification states. The modifications included aerodynamic devices to improve aircraft control above the stalling angle. These reduced the

stall speed In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack exceeds its critical value.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. ...

to and resulted in a 200 ft/min (1.0 m/s) rate of descent while stalled. This allowed stalled landings with no ground roll. As a result of these and other design changes the aircraft was designated as the BKB-1A, the "A" indicating

aerobatics Aerobatics is the practice of flying maneuvers involving aircraft attitudes that are not used in conventional passenger-carrying flights. The term is a portmanteau of "aeroplane" and "acrobatics". Aerobatics are performed in aeroplanes and gl ...

. The aircraft was intended to be fully aerobatic, including tumbling maneuvers. Kasper had a plan to produce the aircraft and the developmental derivative Kasper Bekas, which mount different wings to a common fuselage, as a single kit, with the choice of wings, but it seems none was actually produced.

Operational history

The sole BKB-1A was destroyed on 6 November 1971 near

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, when a pilot conducted unauthorized aerobatics in the aircraft, subjecting it to an estimated negative 30 g during a high-speed inverted descent. The 31-year-old commercial pilot, who had a total of 3000 flying hours and five hours on type, was wearing a parachute, but did not bail out and was killed in the accident. The

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cited as cause factors that the pilot misjudged the aircraft's speed and overstressed the airframe to failure.

Variants

;BKB-1 :Early configuration of the aircraft ;BKB-1A :Later configuration of the same aircraft with modifications for parachute flight above the stalling angle and also aerobatics.

Specifications (BKB-1)

Notes

References