Helicoax

The worlds first electric hcoaxial helicopter model with good flight caraterisics had proven the mechanical concept of a coaxial with Bell/Hiller bars succesfull. New toughts and the technical development of motors and batteries gave rise to the idea to build an up to date version. While maintaining the succesfull rotor concept and revolutionary differential collective pitch control for the yaw axis the following improvements were realised on Helicoax : 

  1. Enough engine power and no overheating thanks to brushless 1920/20 Lehner motor

  2. Stable rotor RPM thanks to Kontronik regulator with automatic RMP control

  3. Flight time up to 15 minutes in hover with a 12 cells NiMh 3300 mAh Sanyo pack

  4. A much simpler and more efficient inside/outside one stage counter rotating gear drive

  5. Higher rotor rpm for improved efficiency of the lower rotor and a decreased risc of rotor clash

  6. Increseased distance between rotor discs

  7. 120° electronic mixing of  the swahsplate => improved control accuracy and responsiveness

  8. PCM receiver for maximum transmission security

  9. Symtrical carbon blades ( 0,98 m rotor diameter ) for high rpm and improved blade tracking

  10. More compact and rigid frame

  11. Skid vibration damping during rotor rev up

  12. Stronger servo's

  13. Easy battery pack fixing

  14. 1940g ready for take off

Flight with the Coaxheli is amazingly stable. The machine turns left or right without the usual preferences a helicopter with tailrotor has. Helicoax does not show the typical 'left skid down' syndrome while hovering which is usualy caused by the tail rotor thrust. The yaw control is accurate and stable. No yaw corrections are required even at fast changes of the collective pitch. Optical recognition in flight is sometimes confusing however due to the absence of a tail boom.

Wind gusts have no impact an the yaw. During fast descents some yaw correction is required because the lower rotor is more affected by the changes in airflow than the upper rotor. The above listed improvements enabled real translational flights ( download flight film ( 11.5 Mb ) at medium speed.

 

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