Helicopters

[bluesareus]

I noticed whilst watching the Helicopter arriving with the Olympic Flame at Lands End that the rotor was going anti-clockwise is there a reason for this

[Philtaz]

Doesn't matter which way they spin on a helicopter engine, it's all about the angle of the blades.

[wolf63]

Yes - there is a reason for everything. Might be a good[i reason or might be a [i]bad] reason though.

Sorry couldn't help myself - hope someone answers your query soon.

[wolf63]

Yes - there is a reason for everything. Might be a good[ireason or might be a [i]bad] reason though.

Sorry couldn't help myself - hope someone answers your query soon.

[HowardKennitby]

Helicopter blades have an aerofoil cross-section so they can only work in one direction. I don't think there is any convention on which way they go.

[Philtaz]

But the blades on a Chinook et al contra-rotate Howard so provided you have the correct blade set in a single engined heli I'm guessing it doesn't matter which way the rotor spins.

[Vicasso]

Had you been looking down on the helicopter, the blades would be going clockwise :-)

[ChuckFickens]

The tail rotor wouldn't be very effective if you decided to suddenly change the rotation direction of the main blades though :)


There is no reason or convention that sets which way the main blades go, some manufacturers make them with clockwise rotation, some with counter-clockwise.

[HowardKennitby]

This is a good simulation of how the rotor hub and swash plates work

http://www.youtube.com/watch?v=83h6QK-oJ4M&feature=related

[Vicasso]

Single engine helicopters have a small vertical propeller mounted on the tail to counteract the 'fuselage spin' which would begin to occur as the helicopter left the ground.

[wildwood]

howardkennitby, this has to be one of the most interesting clips I've seen. do I understand it right that when the craft is moving in a horizontal plane the angle of the blades changes up and down with every full rotation, thus making the craft tip and move?

I originally thought the whole shaft tipped slightly but this is a cleverer method, although at the speed of rotation there must be a lot of motion going on around the swashplate.

[HowardKennitby]

Wildwood

Yes, that is how it works. There are 2 sorts of pitch settings for the rotor blades - Collective and Cyclic. The Collective gives a fixed amount of pitch change to all the blades and is the basic lift generator. The Cyclic pitch adds a variable component as the blades rotate giving direction control.

[beso]

In fact the tilt of the individual blades is compensated for the forward motion of the aircraft which would otherwise produce more lift on the advancing blade than the relatively retreating blade.

[chakka35]

Two questions:

1. Were you watching it live or on TV?

2. Anti-clockwise looking from where? Blades going clockwise when viewed from above are going anti-clockwise when viewed from below. The terms are not absolute.