I found this on a French website a while ago.

During the Second World War, Mr Fokker invented in Austria an helicopter with 2 rotors contrarotatifs, on both sides of the cell and presented to the Fuhrer. At the end of the war, wreckage of this helicopter was recovered by the Allies in Cherbourg and dismantled in England. The Americans recovered a rotor with its transmission box and the French kept the second to increase their manufacturing programme helicopters. The 2 rotors working contrarotatif, one turned to the right and one left. It can therefore be inferred that the Americans have recovered the rotor turning to the left (BELL for example) and the French rotor turning to the right (EUROCOPTER for example).

Cdt Michel DRELON
http://www.heliairmonaco.com/page-faq-langue-uk.html

Just to confuse the issue....

Eurocopter 155 and 365 rotors turn cw, viewed from above.

Eurocopter 135 rotors turn the other way. :confused:

is that so they can put american engines in them ????

Aerospatiale(Alo, AS350, AS365,etc) and Sud Aviation(SA 330 before incorporated into Aerospatiale then changed to AS330, AS332,etc) turns cw. All French.

On the German side was Bolkow and a few others ie BO-105 and BK117 most known. They turn anti clockwise.

Eurocopter combines these manufacturers and all new models designed under the Eurocopter umbrella are EC's. So, all French based EC's ie EC120, 130, 155, 225 turns clockwise as per there predesessors. German EC135 and 145 turns anti cw as per their predecessors.

I think the above is close.

the EC 135 began life as the BO-108, and its fine German ancestry made its rotor spin the "right" way.

There is absolutely no physical reason for either direction being "best"

Unless of course you want the inflow roll to go a particular way! :E

Hi Squirrel..
 

Hi matey. have emailed you a lot. No replies. Hope your ok. drop me a line if you can. All the best matey :ok:

I thought Sikorsky went back and forth a couple of times with his early machines, mostly out of mechanacial convenience, then settled on a standard. I would assume this is to help the pilot's feet know what to do.

Clockwise / Counter-Clockwise Rotation
 

I remember hearing that the Sud-Est designers wanted to make their Alouette easier for fixed wing pilots to fly so they designed it to require right pedal on takeoff, as a fixed wing does.

The Frelon's rotor hub was developed in co-operation with Sikorsky so that's probably why it has the CCW mode of rotation.

Russian helicopters also rotate CW...

There is no problem swapping from one to the other as long as you use the correct pedal for the first take off! After mostly flying CCW aircraft I found myself swapping from Lynx (CCW) to Gazelle (CW) on a daily basis - since CCW was more natural, muscle memory and ingrained habit just did it's thing, when I got into a Gaz I would always say out loud 'right pedal forward' before take off and after that it was fine.

If you want a laugh, try doing the same instructional sortie (Advanced autos for example) on two different aircraft with two different rotations, limits, handling qualities etc within an hour or so of each other - that makes you concentrate:)

A good game at Shawbury in the 80's on the Wessex was to watch the student's first lift to the hover in a CCW rotation machine (Wessex) after 80 hours in a CW (Gazelle) - often the stude would try to select the hover attitude for the Gazelle (which was the only one he knew) and promptly zip off sideways to the right with an amused QHI saying 'I have control'

I still picture the piece of string from the end of the collective to the tip of my left boot.

Handy for the gazelle, but everything after that was opposite!

So now I just 'tie' that bit of string to my right boot! :ok:


KrisDon't fixed wing ac have different rotations also?

http://www.mccullagh.org/db9/1ds2-5/...152-n971fm.jpg

http://www.militaryaircraft.de/pictu...7_2415_800.jpg

As long as it continues to go around, that the main thing.

Well, boeing engineers apparently couldn't decide which direction was best, so decided to stop all arguments and make a Helo that does both at the same time.... :}, that is how the idea of the chinny came about...
http://www.enemyforces.com/helicopters/ch47_chinook.jpg




some or all of the above may or may not be true

Which begs the questions,

Why do the front set of blades go CCW and the rear set CW, and would it make any difference if it was designed the other way round?

Yup, they do...

In the early days of flight, the American aviation industry agreed on the 'CW when viewed from the cockpit' standard and stuck with it pretty well while the rest of the world muddled around and made do with whatever rotation dropped out after reduction gears were added to their engines and whatnot.

As time went on, particularly into the 1930s, Russia in particular and Europe to a lesser extent began to standardise on 'CCW when viewed from the cockpit'.

The British had tried to implement CCW before WW2 but by that time the Rolls-Royce Merlin had already been developed for the Spitfire, which turns the prop CW. The later Griffon-engined Spits rotated CCW, causing no end of problems for pilots transitioning to later marks of the Spit.

French designs from the WW2 era also show a mix like this - for example the Dewoitine 510 rotates CW, the Dewoitine 520 rotates CCW. But post-war the French settled on the 'American' mode of rotation, probably to tap into US engineering and to win export sales in the world's biggest aviation market.

So I think the original 'right pedal' argument still stands, as long as you're not flying Russian or certain WW2 era European aircraft.

I have no idea what logic Russian designers have for making their helicopters and fixed wings both rotate in exactly the opposite to the US mode of rotation though :ugh:

For the record, the 'American' CCW rotation mode makes a lot of sense when you consider naval aircraft that must operate with large immovable objects to the right of the aircraft. Or maybe the bridge was placed there for exactly that reason. Chicken/egg?

It's like the driving on the left/right side of the road discussion, this! As a Brit I've had to defend that to my American friends waaaay too many times...

A CW Main Rotor with the PIC on the right makes sense to me. If you're in a confined area with obstacles etc & need to turn the helicopter the tail can be moved towards the RHS without requiring more power, which happens to be the side with the most visibility for the PIC. This may not have been a consideration during the design stage, but it should have been!!

One thing I found useful as an instructor sitting on the right in the 300C was if my student screwed a pinnacle up I had a good view of my exit route down and to the right :ok:

I also feel a little more relaxed setting down when the first skid to contact the ground is on the opposite side to where I'm sitting for some reason. That could be 'cos I have about 80% of my flight time in that seat though. I'm currently flying the AS355 and I feel like I'm getting used to it slowly but surely.

Does anyone else have a preferred side to fly from?