Beatty-Johl BJ-2 Assegai

BJ-2 Assegai
Role	Single seat competition sailplane
National origin	South Africa
Designer	W.A.T. Johl and P.J Beatty
First flight	January 1961
Number built	1

The Beatty-Johl BJ-2 Assegai was a single seat, high performance competition glider built in South Africa in the early 1960s. Only one was built; it was optimised for South African conditions and performed well there, winning two nationals and setting several records, but was less successful under European conditions at the 1965 World Gliding Championships.

The BJ-2 was a successor to the BJ-1, a 60 ft (18.3 m) span glider on which design began in South Africa in 1945 but abandoned before completion as it became clear that the new laminar flow airfoil sections offered better performance. The BJ-2 used one of the 65 series airfoils in conjunction with Fowler flaps. Its design, led by W.A.T. Johl, concentrated on high cross country glide speeds, achieved via a high wing loading and low camber, important in South African gliding conditions with strong thermals and long flights between them. Design work started in 1955 but the BJ-2 was not flown until January 1961, piloted and chiefly built by P.J.Beatty.

The BJ-2 was an almost entirely wooden aircraft, both internally and with a plywood skin on all surfaces. The single spar, 50 ft (15.24 m) span, shoulder mounted wings had three pieces, the centre one with a span of 30 ft 1 in (9.17 m), rectangular in plan, the NACA 65 wing section and no dihedral. The outer pieces were trapezoidal and had 5° dihedral, changing to a non-laminar section at the tip, with the ailerons filling all their trailing edge. The centre panel trailing edge was filled with Fowler flaps, which at maximum, 30° extension increased both the camber and the wing area, the latter by 19.5%, for low speed flight in thermals. Small wing tip bodies were added later.

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