Wren Aircraft Wren

Single-seat single-engined high-wing monoplane with conventional three-axis control. Wing has swept back leading edge, swept forward trailing edge and tapering chord; conventional tail. Pitch control by elevator on tall; yaw control by fin-mounted rudder; roll control by half-span ailerons; control inputs through stick for pitch/roll and pedals for yaw. Wing braced from below by struts; wing profile; double-surface. Undercarriage has two wheels side-by-side with tailskid. Composite-construction fuselage totally enclosed. Engine mounted below wing driving tractor propeller. Composite construction with glass/Kevlar/graphite in an epoxy matrix over foam cores; fir, birch, plywood, pine and redwood also utilised.
The single-seater Wren was a prototype in the course of test flying and whose development has been undertaken by Mark Calder since 1981. He has made his principal parameter passive security 'crash survivability'. In January 1983, Mark Calder announced that he was going to undertake a programme of static tests on the machine, the prototype having made its first flight in the course of the previous year. The machine was to be offered with a Zenoah G25B engine or optionally a Kawasaki 440ce unit. Projected prices for the Zenoah-engined machine were $6200 ready to fly and $4400 in kit form in 1983, the Kawasaki costing $300 more in each case. Options include wheel pants $100, custom interior $125, electric start $150 including battery, floats $1500, skis $100 and custom paintwork $250 minimum.
The prototype with Zenoah engine has returned a fuel consumption of 1-2 US gal/h (1.0 Imp gal/h, 3.8 litre/h).

Engine: Zenoah G25B, 18 hp
Power per unit area 0.13 hp/sq.ft, 1.4 hp/sq.m
Wing span 36.0 ft, 10.97 m
Mean chord 3.9 ft, 1.19m
Wing aspect ratio 9.3/1
Wheel track 4.7 ft, 1.42 m
Empty weight 240 lb, 109kg
Max take-off weight 450 lb, 204kg
Payload 200 lb, 95kg
Max wing loading 3.21 lb/sq.ft, 15.7 kg/sq.m
Max power loading 25.0 lb/hp, 11.3kg/hp
Load factors; +8.5, -5.0 ultimate
Max level speed 60mph, 97kph
Cruising speed 60mph, 97 kph
Stalling speed 25 mph, 40 kph
Max climb rate at sea level 500ft/min, 2.5m/s