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Artur Makowski
Poland
15th Dec 2013
21:07:15
Hi why my helicopter rotates left, offlain session is ok
David Bartlam
United Kingdom

16th Dec 2013
10:49:16
Artur,

There are various reasons why helicopters turn left, ill try and explain why, firstly what can cause the effect in game and then reality.

In game..

1) Flight Dynamics - in the default bell 206, the flight dynamics are incorrect which causes unrealistic rotation. There is a fix available online, I will dig the link out for you later

2) wind effects - you may be experiencing the effects of wind on the airframe

3) Joystick Calibration or keyboard sensitivity - re-calibrate your controls and ensure they have the correct null zones and are even. Minimise sensitivity. There is also a chance that Wake Vortex or rotor drag could be an issue, these effects are more with the DodoSim 206.

Real world...

Predominantly, a helicopter has one set of rotor blades and one set of tail blades which rotate at an approximate ration of 1:6.25. The rotation of the main rotor blades, which are most commonly in an anti-clockwise direction cause an undesired affect on the airframe. Basically, as the rotor blades spin, the aircraft will want to spin in the opposite direction. A good example of this is to get a remote controlled helicopter and make the blades spin. The fuselage will remain in a stable position but the blades will spin normally. Hold the rotor blades and then the airframe will spin. Or imagine a film, such as black hawk down... The tail of the helicopter is hit by a rockets, the blades spin one way but then then aircraft spins out of control in the opposite direction. To counteract this effect (Torque Reaction), we use a methods to which I'll elaborate.

1) Tail Rotor Blades - these are blades which are trimmed at a set angle on the tail. When your main blades are spinning, these blades will counteract the rotational effects and the urge for the airframe to rotate. By changing the angle of these blades (by using rudder pedals), you either overcome or add to the torque reaction effect, enabling the aircraft nose to turn (yaw) in either direction.

2) Tandem - some helicopters, such as the Chinook, Osprey etc have two sets of main rotor blades at both ends of the airframe which rotate in opposite directions, this again opposes Torque reaction. Yawning is achieved by changing the angle of attack on a set of blades.

3) Coaxial - once again, two sets of blades, this time they are above and below one another, such as the Kamov 32A-12. These have the exact same principal as the Tandems

4) Engine Power - Some helicopters only have one set of rotor blades and no tail blades, so Torque reaction hasn't been overcome, which is obviously a problem. To counteract it, there is a feed or air from the engines which is fed down the tail of the aircraft and out at the sides. To turn left, more power is required for air to be propelled to the right and vice versa. This is a tricky one to explain the concept of, but if you are interested, let me know and I'll go into detail

I hope I've been able to help, I've gone into a lot of detail with regards to real world effects. It's good to pass on knowledge so hopefully you have a better understanding of how and why aircraft yaw, and the effects that the rotor blades have on the aircraft, hence why you sometimes get the inadvertent turns.
David Bartlam
United Kingdom

18th Dec 2013
13:04:38
Artur, here's that link I said I'd find for you...

http://www.fsopen.co.uk/forum/posts/listposts.php?threadid=2682



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