Helicopter question

[Icarusthesecond]

Chap in the pub asked me why some helicopters have a plane of rotation clockwise when viewed from above and some counter -clockwise.

I told him I would ask the experts.

So.......


Anybody know??

[Yozzer]

Some cars are Ford, others are Rover :}

There is no aerodynamic reason why but the French tend to be differant from everybody else.

To complicate matters, some tail rotors Pull, others Push!

The Lynx changed sides upon a mod a few years ago, which must have been for aerodynamic reasons, but I am unsure of specifics.

Any AAC types know

[HEDP]

Rumour has it that the Lynx tail rotor was intended to sweep up into the main rotor downwash at the front edge of its rotation thereby increasing it's aerodynamic effect. It is quoted that the design was transposed to rotate the opposite way by some error during the design/construction phase. Photocopied the wrong way round is one such story!

The Mk1 ran out of tail rotor authority quickly at high AUM/torque as did the Mk1 'GT'.

This was corrected on the conversion to Mk7 and now the benefits are that much greater tail rotor authority is available. Add to this an increase in chord and a benefit is that the length of the blade is reduced significantly and still have greater authority.

Hope this helps,

HEDP

[Wizzard]

I asked this question many years ago and my POF instructor postulated thus:

The very early experimental helicopters had two rotors on booms to the left and right of the fuselage, because they were contra-rotating there was no requirement for a tail rotor.

When the aircraft were broken up after the test programmes, one set of rotors went to the USA for further research and one set stayed in UK/Europe. From that move any helicopter developed in the States had rotors rotating counter-clockwise when veiwed from the top and in Europe they went the other way.

But, I hear you ask, why do Wastelands aircraft have the SPAM direction of rotation? Because they started off producing Sikorsky aircraft under licence and just carried on the motion.

It seemed like a fair explanation at the time but I'm always open to other guesses.


Wiz

[SilsoeSid]

Chap in the pub asked me why some helicopters have a plane of rotation clockwise when viewed from above and some counter -clockwise. I think its something to do with the way the blades are put on. :=
Or perhaps the way the gearbox turns, or was it the rotation of the engine output shaft. :confused:

[airborne_artist]

And remember that they go the other way round in the Southern hemisphere, just like the bath water.

Try a search on Rotorheads, or PM Nick Lappos (a regular contributor there).

[Icarusthesecond]

SS

So you don't know then.

Thanks for your post. It was the most hilarious one I think I have ever read
:ugh: :\

[MightyGem]

The Lynx changed sides upon a mod a few years ago, which must have been for aerodynamic reasons, but I am unsure of specifics.
The Lynx t/r changed direction of rotation, not sides.

[Touchin' Down]

And remember that they go the other way round in the Southern hemisphere, just like the bath water.

Airborne_artist.... what happens when you fly over the equator then!! :ooh:

[airborne_artist]

Airborne_artist.... what happens when you fly over the equator then!!

Have you ever seen a helicopter fly over the equator? No, neither have I, and that's why ....

[Touchin' Down]

lol.... well, suppose I haven't personally, although I recon they must have to land have them trucked by road before setting off again!;)

[helidriver]

I've flown over the equator (Kenya) a few tmes in a Gazelle. Nothing wrong with the aerodynamics however beating choggies off the skids trying to get a free lift to Nairobi was entertaining!!:E

[SilsoeSid]

helidriver,

Did you not notice though, that the engineers knew where you were tasked to and put the blades on accordingly !

Thats why the aircraft were based where they were, so close to the equator.

Trips North - Clockwise
Trips South - Anti-clockwise

(or was it the other way round :confused: )

[Lafyar Cokov]

You guys don't seem to understand this at all. I think you are confused - it has nothing at all to do with whether you are in the northern or southern hemisphere. I can't believe that professional aviators would think that!!!!

Icarus - It is all to do with whether the aircraft is flying in a cyclone or an anti-cyclone. If you are flying in an anti-cylone, the blades have to oppose the air-flow due to the pressure system - thus rotate anti-clockwise when viewed from above. In a cyclone the reverse is true.

As far as I know - helicopters don't fly in the southern hemisphere.

LC - finally hoping to clarify this nonsence!!!

[Sloppy Link]

I also crossed the equator in a Scout. The only thing I remember about the spinning business was Tusker aided the process considerably. Which way does it rotate if you fly along the equator?

[joe2812]

Sloppy Link - Doesn't the big one stop and the one at the back kick in?

That's what its for right?

[Thud_and_Blunder]

I vaguely remember (do most things vaguely these days) from the 20 seconds-worth of research for my A2 that one sucks the aircraft into the air, while the other blows it luft-wards. Or is it the other way round? - can't be too sure which.

[Paul McKeksdown]

I always believed it was dependant upon which way round the crewie wound up the laggie band. That explains the reason why the crewie always walked out first!

Once the laggie band wound down the rotor wizzieness wound it up the other way. So obviously the UK helis fly in the first part of the bandiness and any garlic munching, back stabbing, frenchie things fly on the wind down.

Do I get my re-cat?

:ok: