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Broc Libellule Mk.III

broclibellule3


At the European microlight salon at Lyon-Bron in September 1982, Bernard Broc showed the prototype of the new single-seat three-axis microlight, this time with a T-tail. As Aviasud had earlier given the name of Libellule MkII to the prototype which was destined to become the Sirocco, Bernard decided on the spot that he would name the machine Libellule MkIII to prevent confusion. Retaining the Fledge wing of his earlier model, the Libellule Mk.III not only acquired a T-tail but also a totally enclosed cabin. Bernard intended to replace the existing wing with a mid-mounted cantilever design of composite construction and a Worthmann FX63-137 profile, which is very deep and gives high lift, with the aim of improving the glide angle to around 22/1. This project gave rise to the prototype Epervier twin engined aircraft.


Single-seat single-engined high-wing mono-plane with conventional three-axis control. Wing has swept back leading and trailing edges, and constant chord; T-tall. Pitch control by fully flying tail; yaw control by fin-mounted rudder and tip rudders; roll control by one-third-span spoilers; control inputs through stick for pitch/roll and pedals for yaw. Wing braced from above by kingpost and cables, from below by cables, double-surface. Undercarriage has three wheels in tricycle formation with additional tailskid; steel-spring 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 fuselage totally enclosed. Engine mounted below wing driving pusher propeller. Epoxy, polyester and glass-fibre for T-tail and supporting boom.
The Libellule MkIII has the option of a 26 hp JPX PUL425 engine in place of the 24 hp Konig SC430. Our data is based on the latter version. The Libellule MkIII is only produced in small numbers, availability being limited to 15 machines per year maximum in 1983.

Engine: Konig SC430, 24 hp at 4200 rpm.
Propeller diameter and pitch 43 x 24 inch, 1. 10 x 0.60 m.
No reduction.
Power per unit area 0.15hp/sq.ft, 1.6hp/sq.m.
Fuel capacity 6.6 US gal, 5.5 Imp gal, 25.0 litre.
Length overall 19.8 ft, 6.00 m.
Height overall 8.2ft, 2.50m.
Wing span 32.9ft, 10.00m.
Constant chord 4.1ft, 1.50m.
Dihedral 10degs.
Tailplane span 8.2 ft, 2.50 m.
Fin height 3.9ft, 1.20m.
Total wing area 161 sq.ft, 15.0 sq.m.
Total spoiler area 8.6 sq.ft, 0.80 sq.m.
Fin area 12.9 sq.ft, 1.20 sq.m.
Rudder area 6.5 sq.ft, 0.60 sq.m.
Total elevator area 25,8 sq.ft, 2.40sq.m.
Wing aspect ratio 6.6/1.
Wheel track 4.9 ft, 1. 50 m.
Wheelbase 4.7 ft, 1.40m.
Nosewheel diameter overall 13 inch, 33 cm.
Main wheels diameter overall 16 inch, 40 cm.
Empty weight 2321b, 105kg.
Max take-off weight 5521b, 250kg.
Payload 3201b, 145 kg.
Max wing loading 3.40 lb/sq.ft, 16.7 kg/sq.m.
Max power loading 23.01b/hp, 10.4kg/hp.
Load factors design; +4.5, -2.5 ultimate.
Max level speed 56 mph, 90 kph.
Never exceed speed 75 mph, 120 kph.
Max cruising speed 50 mph, 80 kph.
Economic cruising speed 44 mph, 70 kph.
Stalling speed 24 mph, 40 kph.
Max climb rate at sea level 300 ft/min, 1.5 m/s.
Min sink rate 325 ft/min at 31 mph, 1.6 m/s at 50 kph.
Best glide ratio with power off 14/1 at 34 mph, 55 kph.
Take-off distance 165 ft, 50 m.
Land-ing distance 250 ft, 75 m.
Service ceiling 10,000 ft, 3050 m
Range at average cruising speed 622 mile, 1000 km.

Engine: JPX PUL425, 26 hp.
Fuel capacity 6.6 US gal, 5.5 Imp gal, 25.0 litre.
Length overall 19.8 ft, 6.00 m.
Height overall 8.2ft, 2.50m.
Wing span 32.9ft, 10.00m.
Constant chord 4.1ft, 1.50m.
Dihedral 10 degs.
Tailplane span 8.2 ft, 2.50 m.
Fin height 3.9ft, 1.20m.
Total wing area 161 sq.ft, 15.0 sq.m.
Total spoiler area 8.6 sq.ft, 0.80 sq.m.
Fin area 12.9 sq.ft, 1.20 sq.m.
Rudder area 6.5 sq.ft, 0.60 sq.m.
Total elevator area 25,8 sq.ft, 2.40sq.m.
Wing aspect ratio 6.6/1.
Wheel track 4.9 ft, 1. 50 m.
Wheelbase 4.7 ft, 1.40m.
Nosewheel diameter overall 13 inch, 33 cm.
Main wheels diameter overall 16 inch, 40 cm.
Load factors design; +4.5, -2.5 ultimate.
Never exceed speed 75 mph, 120 kph.

 

 


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