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Hoffmann H.39 Diana



Single-seat single-engined high-wing monoplane with conventional three-axis control. 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 below by struts; wing profile Worthmann FX63-137; double-surface. Undercar-riage has three wheels in tricycle formation; suspension on nosewheel and glass-fibre suspension on main wheels. Push-right go-right nosewheel steering connected to yaw control. Brake on nosewheel. Glass-fibre/carbon fibre fuselage, partially enclosed. Engine mounted below wing driving pusher propeller.

Having already built a conventional motor glider with two seats side by side, the H36 Dimona of 1980 which has been on sale since summer 1981, aeronautical engineer Wolf Hoffrnarm has expanded his range with a single-seater microlight, the H39 Diana. He used the experience gained in building the motor glider to help his design for a microlight, which uses similar manufacturing techniques and the same wing profile, the Worthmann FX63-137.

The high wing of the H 39 is carried by two airfoil-section struts forming a V under each wing. As with the horizontal empennage, these are mounted by two bolts which allows rapid rigging and derigging, the Diana being transportable on a trailer. The wing has air brakes on the upper surface and is of constant chord for the centre section with tapering outboard sections. A wide track tricycle undercarriage gives this ultralight motor glider great stability on the ground and encourages its use on all terrain.

The prototype was shown for the first time in public at the Aero 83 salon at Friedrichshafen on static display. The motor used is the Konig SD570 four-cylinder radial, limited to 3500rpm (26hp) instead of the normal 4000rpm (28hp), since the Diana uses it in direct drive form.

Length overall 18.4 ft, 5. 60 m.
Height overall 5.7ft, 1.75m.
Wing span 32.8ft, 10.00m.
Chord at root 4.4ft, 1.33m.
Chord at tip 3.1ft, 0.93m.
Dihedral 4 deg.
Sweepback 0 deg.
Tailplane span 9.8 ft, 3. 00 m.
Fin height 3.9 ft, 1.20 m.
Total wing area 135 sq.ft, 12.5 sq.m.
Total aileron area 12.1 sq.ft, 1.12 sq.m.
Fin area 6.2 sq.ft, 0.58 sq.m.
Rudder area 4.1 sq.ft, 0.38 sq.m.
Tail-plane area 18.1 sq.ft, 1.68 sq.m.
Total elevator area 7.8 sq.ft, 0.72sq.m.
Wing aspect ratio 8/1.
Wheel track 4.9ft, 1.50m.
Wheelbase 7.0ft, 2.13m.
Nosewheel diameter overall 10 inch, 26 cm.
Main wheels diameter overall 13 inch, 32 cm.
Engine: Konig SD570, hp at 3500 rpm.
Propeller diameter 42 inch, 1.07 m.
No reduction.
Max static thrust 132 lb, 60 kg.
Power per unit area 0.19 hp/sq.ft, 2.1 hp/sq.m.
Fuel capacity 5.3 US gal, 4.4 Imp gal, 20.0 litre.
Empty weight 2101b, 95kg.
Max take-off weight 4751b, 215kg.
Payload 2651b, 120kg.
Max wing loading 3.52 lb/sq.ft, 17.2 kg/sq.m
Max power loading 18.31b/hp, 8.3kg/hp.
Load factors; +6.0, -3.0 ultimate.
Max level speed 62 mph, 100 kph.
Never exceed speed 84 mph, 135 kph.
Max cruising speed 62 mph, 100 kph.
Economic cruising speed 44 mph, 70 kph.
Stalling speed 24 mph, 38 kph.
Max climb rate at sea level 590ft/min, 3.0m/s.
Min sink rate 240 ft/min at 28 mph, 1.20 m/s at 45 kph.
Best glide ratio with power off 15/1 at 40 mph, 65 kph.
Take-off distance 130 ft, 40 m.
Land-ing distance 115 ft, 35 m.
Service ceiling 14,400 ft, 4400 m.
Range at average cruising speed 93 mile, 150 km.




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