Aero Vodochody XE-II
Aero Vodochody HC-2 Heli-Baby
Aero Vodochody HC-102 Heli-Baby
Aero Vodochody HC-3
The XE-II was developed into the prototype HC-2, HC-3, and HC-102 Heli-Baby two-seat general-purpose helicopter. With an all-metal fuselage/boom, fixed tricycle undercarriage and 80hp Praga DH engine driving a three-blade rotor, the prototype HC-2 flew on 3 March 1954, and an order for 200 HC-2 helicopters was announced while still flying in prototype form. It is not clear how many examples were finally delivered, but the HC-2 of 1958 served with the Czech Air Force for some years.
The HC-2 prototype is a two-seat light general-purpose helicopter, with a three-blade main rotor and two-blade anti-torque tail rotor. The main rotor blades are of wooden construction with a steel insert in leading-edge for mass balance and plywood covering armoured with fiberglass of NACA 23015 aerofoil section. The blades are fully articulated in flapping and drag planes with a single adjustable friction damper for all three drag hinges. The blades are mounted on tubular steel spars incorporating tension-torsion bars with cyclic pitch change actuated by control stick. The collective pitch lever is synchronised with engine throttle. Override settings of throttle are by means of twist-grip on pitch control lever. The individually-flapping tail rotor blades of laminated wood with fiberglass covering have the pitch controlled by rudder pedals. Additional horizontal tail surfaces are used during transition from vertical to horizontal flight. The fuselage is an all-metal semi-monocoque structure, with a non-stressed cabin enclosure. The landing gear is a fixed tricycle type, with castoring nose-wheel capable of swivelling through 360°, and oleo-pneumatic shock-absorbers on all three 260x85mm wheels. A tail-skid is fitted to avoid damage to rotor.
Powered by an 83hp Praga DH four-cylinder horizontally-opposed fan-cooled engine mounted aft of the rotor pylon, with the crankshaft centre-line inclined at 45°. Drive from engine is taken through a centrifugal clutch to the main gearbox with a free-wheel in the main gearbox for autorotation. The tail rotor is driven off the main gearbox through a universal joint and shafting. The engine / main rotor r.p.m. ratio is approximately 10 : 1, and engine / tail rotor r.p.m. ratio approximately 3 : 2. Normal fuel capacity is 40 litres.
Seating is side-by-side for two in a cabin with Plexiglas canopy. Controlled by dual overhead cyclic control sticks and collective pitch levers on the left side of each seat. Starboard controls quickly removable. No doors.
The HC.3 was an enlarged four-seater based on the HC-2 but with a four-leg undercarriage, englarged cabin section and an M-108H engine mounted above and behind the cabin. Three prototypes were tested (OK-15 to OK-17) but the type did not reach production.
Engine: 1 x Praga DH, 80 hp / 60kW
Main rotor diameter: 8.8m
Take-off weight: 580kg
Empty weight: 370kg
Max speed: 126km/h
Cruising speed: 100km/h
Engine: 1 x Praga DH, 83hp
Fuel capacity: 40 litres
Oil capacity: 8 litres