Blades Rotor

Posted on | March 18, 2009 | Comments Off

Blades Rotor

Why do the rotor blades on US helicopters rotate a different way to all other countries helicopters?

If looking from above, US helicopters blades rotate clockwise but helicopters from all other countries (apparently) rotate anti-clockwise. Is this true and if so, why?
Thanks

First, let's get some facts straight.

In general, US helicopters rotate counterclockwise when viewed from above (you said clockwise).

It is also true that Russian and many European helicopters rotate clockwise (and it's not just the Puma).

Helicopters with two main rotors will always have them rotating in opposite directions.

The helicopter was not invented in the US. However, Sikorsky, Bell, and others did make the first production helicopters and deserve much of the credit for refining the helicopter design and making it practical. See the following:

http://www.vectorsite.net/avheli_1.html

http://www.centennialofflight.gov/essay/Rotary/early_20th_century/HE2.htm

http://en.wikipedia.org/wiki/Helicopter

Robinson helicopters do rotate counterclockwise as well. Check out the first part of this video of a R44 starting up:

Now, to the matter at hand. I did find one article on the question here:

http://www.aerospaceweb.org/question/helicopters/q0212b.shtml

The first thing you will notice is that it is not just Americans who make helicopters that rotate counterclockwise, despite what a few completely ignorant and asinine answers on here would have you believe.

I would add to what this article says that the helicopter was developed independently by many pioneers all over the world. This process happened over the course of many years, and that development happened a long time ago. The idea that someone decided to do things differently because they wanted to be different from other nationalities is ludicrous. The initial pioneers made their aircraft one way or another, and subsequent designs just followed that convention. It is just a coincidence that some developed theirs one way, and others made them the opposite.

I agree with John B that it would be nice or them to adopt one global standard, but manufacturers like Bell and Sikorsky have been doing it one way for decades, and they will have little incentive to change. The directions are merely an inheritance from the arbitrary decisions made by early pioneers, and it looks like we are just stuck with differing conventions.

One other interesting thing is that Sikorsky's VS-300 had a clockwise rotor as you can tell from the direction of the leading edges in these photos:

http://www.sikorskyarchives.com/vs300iis.html

His subsequent R-4 model had a counterclockwise rotor.

WindyNation's 80 Inch WindGrabber Power Rotor Blade Set -- Wind Turbine

RC Helicopters are becoming so popular that it attracts many new enthusiasts everyday. Upon getting their hands on this new enjoyable hobby, many beginners become puzzled when they know that RC helicopters come labeled either as "fixed pitched" or "collective pitch". For this reason, many new pilots have come to wonder what exactly the difference between the two is.

To understand how these two pitch setups differ, the first step is to come to know what "pitch" means. The "pitch" of a helicopter is the angle of the main rotor blade. Generally, the measurement of this "pitch" angle is done relative to the horizontal plane. Helicopters generate lift by rotating their rotor through the air. With a fixed pitch helicopter, when the rotor spins faster, more lift is generated and the helicopter ascends. On the other hand, slower rotor rotation generates less lift and the helicopter descends. For collective pitch helicopters, the pitch of the blade becomes another factor in the lift generating equation. In this setup, the lift can also be altered by the angle (pitch) in which the main rotor blade is positioned. To put it another way; while to rotor is rotating at a constant speed, the lift generated can be altered by changing the pitch alone.

Now that we know the technical difference between the two pitch setups, the next question is: how does it affect my flight? Quite simply, a collective pitch helicopter is more responsive, agile, and smoother to fly. Nevertheless, there is a tradeoff. They are much harder to learn, require a more complicated transmitter, and cost much more than fixed pitched helicopters. They also have more moving parts, which means they break more easily and requires more maintenance.

So which one should you choose to fly? Fixed pitch or collective pitch? It all comes down to your own choice and how serious you are with this hobby. A fixed pitch helicopter has fewer moving parts, making it more ideal for beginner as it requires less maintenance. Many also claim that a fixed pitch helicopter is easier to fly (but this claim is often challenged by avid pilots). Also, most of the helicopters that are fixed pitch comes in an RTF (Ready to Fly) set, and usually includes a radio transmitter (which won't work on collective pitch models though). However, if you plan to stay in this hobby for a long time and fly in more demanding ways, then perhaps making a bigger investment and getting a collective pitch helicopter will be worth while.

About the Author:

Interested in the amazing hobby of Electric RC Helicopters?Tara Soonthornnont is an Electric RC Helicopter enthusiastwho maintains a website dedicated to it.Check Out http://www.electric-rc-helicopter.com

Article Source: ArticlesBase.com - Fixed Pitch Vs Collective Pitch RC Helicopters

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