SPT-HML incl. SPT5-H

SPT-HML helicopter mechanics with SPT5-H

The SPT-HML is a robust two-shaft turbine helicopter mechanism developed for models with a high take-off weight. Aluminium side plates, braces and bearing blocks are spaced 60 mm apart to provide high torsional stiffness. The long HML layout positions the turbine 85 mm farther forward to support a more favourable centre of gravity, particularly in industrial helicopter applications.

Mechanical configuration

• Choice of 12 or 15 mm main-rotor shaft, with an axial bearing fitted as standard.
• High-grade steel crown-wheel and bevel-gear transmission.
• Clockwise or counter-clockwise main-rotor direction.
• Flexible main- and tail-rotor speeds through selectable gear ratios.
• Direct tail drive or a dedicated tail gearbox.
• Servo placement directly below the swashplate for a direct linkage.
• Adjustable first-stage belt tensioner and a heavy-duty dog coupling for turbine integration.
• Twin exhaust, or single exhaust on compatible long-version installations.
• Optional tail-boom support and high-output FENESTRON drive for installations such as the H145-T2.

Rotor-speed control

The free-power-turbine arrangement does not require a centrifugal clutch. A Hall sensor measures gearbox output speed, while the JetCat ECU stores the transmission ratios and maintains the selected main-rotor speed under changing load. A transmitter throttle curve is not required. Depending on the final gearing and installation, the mechanism can support main rotors from approximately 2.0 to 2.6 metres.

Contact Orkes with the helicopter model, rotor system, required rotation direction and planned take-off weight so the shaft, gearing, exhaust and turbine configuration can be checked before ordering.