Robertson B1-RD

Single-seat single-engined high-wing mono-plane with conventional three-axis control. Wing has unswept leading edge, swept for-ward trailing edge, and tapering chord; cruciform tail. Pitch control by elevator on tail; 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 above by kingpost and cables, from below by cables; wing profile; single-surface (double-surface optional). Undercarriage has three wheels in tail-drag-ger formation; nylon rope suspension on all wheels. Push-right go-right tailwheel steering connected to yaw control. No brakes. Alumi-nium-tube/steel tube framework, with option-al pod. Engine mounted at wing height driving tractor propeller.

 

The B1-RD was designed by Glenn and Bruce Bashforth and the first production models were delivered in June 1982, production having begun at one per day but scheduled to increase up to two aircraft per day. The single-seater has a remarkably low stalling speed for a semi-rigid winged micro-light, and is sold ready to fly for $6595 or as a kit for $5995 in 1983. The B1-RD in standard form originally had the Cuyuna 215R 20 hp engine and was only fitted with the 430R as an option, but this was later standard and could be replaced by the new ULII-02 Cuyuna.

A number of options are offered including custom sails, remote starter and choke kit for $50, 20 inch (51 cm) wheels $35, windscreen $50, chrome fenders and hardware $40, chromed axle $40, tow hook with quick release $50, strobe light $200, double-surface wing $500, electric start $350, instruments, floats, parachute and storage bags.

Engine: Cuyuna 430R, 30 hp at 5500 rpm
Propeller diameter and pitch 72 x 36 inch, 1.83 x 0.91 m
V-belt reduction, ratio 3.1/1
Power per unit area 0.19 hp/sq.ft, 2.0 hp/sq.m
Fuel capacity 4.0 US gal, 3.3 Imp gal, 15.1 litre
Length overall 21.0 ft, 6.40 m
Height overall 7.2ft, 2.18m
Wing span 32.0ft, 9.75m
Mean chord 5.1ft, 1.54m
Dihedral 3 deg
Sweepback 0 deg
Tailplane span 10.0 ft, 3.05 m
Total wing area 162 sq.ft, 15.1 sq.m
Total aileron area 18.0sq.ft, 1.67 sq.m
Fin area 3.0 sq.ft, 0.28 sq.m
Rudder area 13.0 sq.ft, 1.21 sq.m
Tailplane area 30.0 sq.ft, 2.79 sq.m
Total elevator area 15.0 sq.ft, 1.39 sq.m
Wing aspect ratio 6.3/1
Wheel track 5.0 ft, 1.52 m
Wheelbase 16.0 ft, 4.87 m
Tailwheel diameter overall 5 inch, 13 cm
Main wheels diameter overall 16 inch, 40cm
Empty weight 220 lb, 100kg
Max take-off weight 500 lb, 227kg
Payload 280 lb, 127 kg
Max wing loading 3.09 lb/sq.ft, 15.1kg/sq.m
Max power loading 16.7 lb/hp, 7.6kg/hp
Load factors +3.0, -2.0 design
Max level speed 50 mph, 80 kph
Never exceed speed 75 mph, 121 kph
Max cruising speed 38 mph, 61 kph
Stalling speed 15 mph, 24 kph
Max climb rate at sea level 850 ft/min, 4.3 m/s
Min sink rate 300 ft/min at 30 mph, 1.5 m/s at 48 kph
Best glide ratio with power off 8.54 at 30 mph, 48 kph
Take-off distance 75 ft, 23 m
Landing distance 50 ft, 15 m
Service ceiling 14,000 ft, 4270 m
Range at average cruising speed 125 mile, 201 km