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St.Croix Aircraft Excelsior


Single-seat single-engined high-wing monoplane with conventional three-axis control. Wing has unswept leading edge, swept forward trailing edge and tapering chord; inverted conventional tail. Pitch control by elevator on tail; yaw control by fin-mounted rudder; roll control by spoilerons; 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; bungee suspension on both wheels. Push-right go-right nosewheel steering connected to yaw control. No brakes. Aluminium-tube/glass-fibre/steel-tube framework partially enclosed (totally enclosed optional). Engine mounted above wing driving pusher propeller.

The Excelsior was designed by Chad and Charles Wille with the experience gained from the construction in 1947 of a Pietenpol Aircamper by Charles, who redesigned it in 1977 as a biplane called Aerial.

The Excelsior is immediately recognisable thanks to its unusual tail, with the fin forming a keel under the horizontal tail surfaces. On it is hinged the rudder, itself mounted on the tube which forms a tail skid. Even more unusual, the pusher propeller is placed behind this tail driven by a very long shaft from the motor mounted above the wing, a flexidyne damper being used to eliminate the vibrations implicit in such a long transmission.

A variety of materials are used in the Excelsior's construction. A welded steel frame acts as the bottom of the fuselage structure and provides a mounting for the undercarriage, while the rest of the fuselage consists of aluminium tubes pop rivetted to the main transmission tube. The wings use a D-section leading edge spar with foam ribs, the wings coming jig-built from the factory. Covering is aircraft grade Dacron, heat shrunk with an iron and then doped.

The Excelsior was sold as plans for $95 or as a complete kit, in 1983.

Engine: Zenoah G25B, 20 hp at 6500 rpm
Power per unit area 0.15 hp/sq.ft, 16.2 hp/sq.m
Fuel capacity 3.0 US gal, 2.5 Imp gal, 11.4 litre
Length overall 6.1 ft, 1.83 m
Height overall 17.5ft, 5.33m
Wing span 34.6ft, 10.54m
Mean chord 3.8ft, 1.17m
Sweepback 0 deg
Total wing area 133 sq.ft, 12.4 sq.m
Wing aspect ratio 8.9/1
Wheel track 4.8 ft, 1.45 m
Empty weight 200 lb, 91kg
Max take-off weight 450 lb, 204kg
Payload 250 lb, 113kg
Max wing loading 3.38 lb/sq.ft, 16.5 kg/sq.m
Max power loading 27.5 lb/hp, 10.2kg/hp
Load factors; +4.0, -4.0 ultimate
Max level speed 75 mph, 121 kph
Max cruising speed 70 mph, 113kph
Stalling speed 20mph, 32kph
Max climb rate at sea level 600 ft/min, 3.1 m/s
Best glide ratio with power off 20/1
Take-off distance 200 ft, 60 m
Landing dis-tance 150 ft, 45 m



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