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Ultra Efficient Products Invader

uep-invader3
Invader IIIB


Single-seat single-engined mid-wing monoplane with unconventional three-axis control (conventional three-axis control optional). Wing has unswept leading and trailing edges, and constant chord; V-tail. Pitch/yaw control by elevon; roll control by one-third-span ailerons; control inputs through stick for pitch/yaw/roll (optional: stick for pitch/roll and pedals for yaw). Cantilever wing; wing profile; double-surface. Undercarriage has three wheels in tricycle formation (MkIII and MkIII-B), taildragger formation (MkII); suspension on all wheels. Nosewheel steering independent from yaw control. Wood/foam/steel-tube fuselage, partially enclosed (totally enclosed optional). Engine mounted above wing driving pusher propeller. Mylar wing covering.

Conceived by Nick Leighty, the prototype Invader was seen for the first time at Sun 'n' Fun in 1982 where it won the outstanding aircraft award, which ensured considerable success every time the aircraft appeared in public. The aircraft is covered in transparent plastic which allows the whole structure of the aircraft to be seen and is proving to be a real marketing asset.

The Invader is controlled purely through a stick in the standard version, a mixer transmitting the stick movements to the ailerons and the elevons on the V-tail. It is possible, however, to build this single-seater to give conventional control using the rudder bar, which is fitted anyway to control the steering. On the MkIII type (with tricycle undercarriage) it controls the nosewheel, while on the MkII (with taildragger undercarriage) it steers the tailwheel, the undercarriage being the principal difference between the two versions. The wing is made up of a central section to which are joined the wings and the aileron controls and these are demountable for easy transport and garaging.

Offered as a set of plans for $60 in 1983, the cost of building an aircraft being reckoned at $1500 for material and 300-400h labour. Ribs are made of white block styrofoam, hot-wire cut to shape and reinforced with spruce cap strips to tie them to the spar. The geodesic structure ensures excellent rigidity and the fuselage structure is made up of 4130 chrome molybdenum steel, welded. However, the rib structure has not been well received by the European homebuilders, where there are still few people used to the idea of a 'consumable' aircraft, as these ribs have an expected life of around four years if the aircraft is garaged or covered when not in use.

At Sun 'n' Fun in March 1983 Ultra Efficient Products confirmed its intention to sell the Invader as kits during this year. At that time the machine was expected to have a Yamaha engine with reduction drive or a Zenoah G25B of 20 to 22 hp using direct drive. However, since then a MkIII-B version has appeared, similar in all respects to the MkIII but with Rotax 277 power. The undercarriage configuration does not make a significant difference to the weight or performance of the aircraft.

Engine: Yamaha, 14hp rpm
Power per unit area 0.10hp/sq.ft, 1.1 hp/sq.m
Fuel capacity 2.5 US gal, 2.1 Imp gal, 9.5 litre
Length overall 18.0 ft, 5.49 m
Height overall 4.0ft, 1.22m
Wing span 31.0ft, 9.44m
Constant chord 4.5 ft, 1.37 m
Sweepback 0 deg
Total wing area 140 sq.ft, 13.0 sq.m
Wing aspect ratio 6.9/1
Empty weight 165 lb, 75kg
Max take-off weight 380 lb, 172kg
Payload 215 lb, 98 kg
Max wing loading 2.71 lb/sq.ft, 13.2 kg/sq.m
Max power loading 27.1 lb/hp, 12.3 kg/hp
Load factors +4, -4 design
Max level speed 55mph, 88kph
Never exceed speed 60 mph, 97 kph
Max cruising speed 40 mph, 64 kph
Stalling speed 20 mph, 32 kph
Max climb rate at sea level 500 ft/min, 2.5 m/s
Min sink rate 250 ft/min at 40 mph, 13 m/s at 64 kph
Best glide ratio with power off 14/1 at 40 mph, 64 kph
Take-off distance 150 ft, 45 m
Landing dis-tance 175 ft, 53 m
Service ceiling 4000 ft, 1220 m
Range at average cruising speed 100 mile, 161 km

Engine: Rotax 277, 28hp at 6500 rpm
Propeller diameter and pitch 44 x 15 inch, 1.12 x 0.38 m
Power per unit area 0.20hp/sq.ft, 2.2 hp/sq.m
Fuel capacity 2.5 US gal, 2.1 Imp gal, 9.5 litre
Length overall 18.0 ft, 5.49 m
Height overall 4.0ft, 1.22m
Wing span 31.0ft, 9.44m
Constant chord 4.5 ft, 1.37 m
Sweepback 0 deg
Total wing area 140 sq.ft, 13.0 sq.m
Wing aspect ratio 6.9/1
Empty weight 185 lb, 84kg
Max take-off weight 400 lb, 181kg
Payload 215 lb, 98 kg
Max wing loading 2.86 lb/sq.ft, 13.9 kg/sq.m
Max power loading 20.0 lb/hp, 6.5 kg/hp
Load factors +3.5 design
Max level speed 60mph, 97kph
Never exceed speed 70 mph, 113 kph
Max cruising speed 45 mph, 72 kph
Economic cruising speed 40mph, 64kph
Stalling speed 22 mph, 35 kph
Max climb rate at sea level 500 ft/min, 2.5 m/s

Invader Mk.IIIB
Engine: Rotax 277, 28 hp
Empty wt.: 245 lbs
Max wt.: 475 lbs
Wing span: 31 ft
Wing area: 144 sq.ft.
Length: 5.49m
Aspect ratio 7:1
Length 18’
Wing loading: 3.2 lbs/sq.ft
Power  loading: 16.9 lbs/hp
L/D 14:1
Max speed mph: 60 mph
Cruise: 50 mph
Stall: 27 mph
Vne: 80 mph
Seats: 1
Takeoff roll 150 ft
Climb rate 500 fpm
Fuel capacity 1.25 USG

Invader Mk.IV Sport
Engine: Rotax 277, 28 hp
Prop: 56 x 22
Wing sapn: 28 ft
Wing area: 126 sq.ft
Empty wt: 225 lbs
Max wt: 450 lbs
Cruise: 50 mph
Stall: 27 mph
Vmax: 60 mph
ROC: 600 fpm
TO run: 150 ft
Ldg roll: 100 ft

Invader Mk.IV Sail
Engine: Rotax 277, 28 hp
Prop: 56 x 22
Wingspan: 36 ft
Wing area: 135 sq.ft
Empty wt: 225 lbs
Max wt: 450 lbs
Cruise: 40 mph
Stall: 27 mph
Vmax: 60 mph
ROC: 600 fpm
TO run: 150 ft
Ldg roll: 100 ft

 

 


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