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Mathews Pup


Single-seat single-engined biplane with three axis control. Wings have unswept leading and trailing edges, and constant chord; conven-tional tail. Wings braced by struts and transverse X-cables; wing profile double surface. Undercarriage has three wheels in taildragger formation. Tailwheel steering. Aluminium-tube framework. Engine mounted between wings driving tractor propeller.
Like the CCC, the PUP from Lyle Mathews is only sold as a set of plans. The PUP (Perfect Ultralight Plane) is a single-seater biplane with its lower wing of shorter span than the top. The top wing is supported by a tubular framework which forms the cockpit and also acts as the mount for the tractor engine fitted in the nose of the PUP and on which the two triangular main gear legs are mounted. The wings are supported by interwing struts and flying and landing wires in an X configuration, in the tradition of the old biplanes. The conventional tail and the steerable tail wheel are carried on a rectangular section, aluminium spar of 1 x 3 inch (25 x 76 mm). For simplicity the PUP has a metal structure built with gussets and pop rivets. The prototype formed its first flight at the beginning of 1983 using a Lloyd 22hp engine which Lyle Mathews then re-placed with a Kawasaki TA440.
Plans cost $15 in the US and Canada, $20 elsewhere in 1982.

Engine: Kawasaki TA440, 38.5 hp
Propeller diameter and pitch 54 x 30 inch, 1.37 x 0.76 m
Power per unit area 0.26 hp/sq.ft, 2.9 hp/sq.m
Empty weight 248 lb, 112kg
Max take-off weight 450 lb, 204kg
Payload 202 lb, 92kg
Wing span 24.0ft, 7.31 m
Constant chord 5.0 ft, 1.52 m
Sweepback 0 degs
Total wing area 143 sq.ft, 13.3 sq.m
Max wing loading 3.15 lb/sq.ft, 15.3 kg/sq.m
Max power loading 11.7 lb/hp, 5.3kg/hp
Cruising speed 40mph, 64kph
Stalling speed 28mph, 45 kph
Max climb rate at sea level 600 ft/min, 3.0 m/s.



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