Why do Eurocopter rotors turn the wrong way?

[Bronx]

Just wondered.

Anyone know?

:confused:

[Lu Zuckerman]

To: Bronx

When the French first entered the helicopter race their engines turned the wrong way as opposed to American engines. To get their rotors to turn the same way as the Americans they would have to put an additional gear set in their transmissions.

Now I believe they have that extra gear set as American engines can power some of their helicopters and French engines can power some American helicopters.


:E

[S76Heavy]

Is not the Turbomeca Arriel that's fitted to the 76A+ modified to have the power turbine rotating in the opposite direction while the rest of the enigine remains the same? I have never heard of extra gear sets with these engines, although they drive both the French way (Dauphin) and the American way (S76).

[NickLappos]

The straight word I have read is that the early helicopter days after WWII were decisive.

The first helos at SUD (much later to become EC) were copies (built from parts) of the relatively successful FW 223 twin rotor.
The French started single rotor helicopter work with half that basic drive train, but chose the half that turned the "wrong" way.

Remember, the engines were developed for the aircraft in those days, and they were all pistons (and easy engouh to reverse rotation).

Here is a web site that discusses those days, but does not specify the directions of rotation:

http://www.helis.com/timeline/aerospatiale.php

[Helinut]

Its only French Eurocopter helicopters that "go the wrong way" - German ECs, the EC135, for example, does the decent thing.

[CyclicRick]

Pray why is it the wrong way?
Ergonomically speaking I think it's more logical. Left arm up left foot down is a lot more awkward.
PS: I am NOT French

:D

[ferrydude]

So as to remain consistant and continue the tradition of doing everything the "wrong" way.

[Dynamic Component]

Bronx,

Did you not mean to say "the right way"?:}
And NO-I'm not French either:ok:

[ATN]

Hi, all,

Igor Sikorsky first came to France before moving to the US of A and I once heard or read that he was the one who started making choppers with rotor turning clockwise. This is partly confirmed with the russian birds turning the same way as the EC. Now the question is, when and why did the Sikorskys started spinning the other way ?

ATN

[212man]

76heavy,
I do hope you are saying that with your tongue in your cheek!

To the thread...who can say which is right? Having flown both directions of rotation I can't say it makes a blind bit of difference; you look out the window and move which ever pedal you need to compensate for unwanted yaw. The only time it warrants consideration is for turns at high torque in windy conditions, or snappy rolls at highish torque settings .

[NickLappos]

One hopes we all use "right" and "wrong" way as a humerous label!

Note that Igor's first helo spun the "wrong" way, can't say why it changed, but I'll check into it!

http://www.centennialofflight.gov/essay/Rotary/Sikorsky_VS300/HE8G2.htm

helinut, For what its worth, the BO-108 originally turned the "right way" but when EC took over Boelkow, they 108 became the EC 135 and it grew a fenestron and the rotor spun backwards!! Look up a net photo of the 108 to see!

[AirJockey]

The advantage you have with rotors going the "wrong" way is when you do sling and long-line operations. This because the machines will hang right skid low and you will get a better view on your load in hover. Also with the door off this will give you an advantage over the load. (MD500 are an exception of course).

:ok:

[diethelm]

I try to focus on whether or not they are turning.........

[Head Turner]

I fully agree with CyclicRick. The French way is the more logical and simpler to comprehend. May I add here and await all the flax that the American/ but actually Russian/ helicopters have got it wrong and should 'modernise' by adopting the other simple things like metrication. US gallons, Fahrenheit, Feet and Inches - really that all should have gone long, long ago. The American way is a joke! And can lead to all sorts of errors. That's the one thing that's good about Europe, we're forward thinking and the innovators of the world.

[cpt]

The reason I have been given is and also read somewhere in a book (if I remember well, written by Patrick Boulet, a french helicopter test pilot) is the one that Nick Lappos has already given; it comes from one of the transmission gear of that WW2 german twin rotor helicopter(FW220...?).
Personally I don't mind the way it turns, providing the needle remains in "the green"....

[Lu Zuckerman]

To:cpt

The reason I have been given is and also read somewhere in a book (if I remember well, written by Patrick Boulet, a french helicopter test pilot) is the one that Nick Lappos has already given; it comes from one of the transmission gear of that WW2 german twin rotor helicopter(FW220...?).

As Nick had indicated the French took the rear rotor and transmission from a helicopter that had two rotors and two transmissions both of which turned in opposite directions.

Since they had their choice do you think that the greatest influence governing their choice is the engine that would power this rear rotor turned in the opposite direction from an American engine.

Not knowing the construction of the rear transmission I can only assume that the input gear sets were designed to turn in the direction that powered the rear transmission and they were opposite from the front gear box.


:E