Technologies and advantages of the Sagita helicopters

How does it work ?

  • The engine drives a compressor that takes in air at the rear of the fuselage.
  • Part of the compressed air feeds the engine, the balance bypasses the engine, collects the heat of the cooling system and is eventually mixed with the engine's exhaust gases in order to raise the temperature to 100°C (212 °F).
  • The hot compressed air is then sent to the rotor and expanded in two contra-rotating Ljungström type turbines.
  • Each of these turbines drives directly one of the two contra-rotating coaxial rotors. The air exits the turbine through a circumferential gap between the two rotors.
  • The transmission system requires no lubrification, no cooling and no tail rotor drive. Its efficiency is about 85%.

 

ADVANTAGES

  • Flight safety : no tail rotor and capacity to overspeed the rotor in order to reduce the « dead man zone ».
  • Reduced maintenance due to less moving parts
  • More direct flight control with the rigid rotor blades, less CG sensitive
  • Faired hub and advancing blade on each side for high speed flight
  • The compressor increases the engine power at high altitude