Talk:Helicopter
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WTF^^ MATE?
Rotorhead design is a limiting factor on many helicopters. Low-G situations encountered in a semi-rigid system will result in mast bumping followed by rotor separation...making you a very sophisticated rock.
Can someone explain this and/or rewrite it? Looks kinda unprofessional.
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Misleading description of airfoil lift
It is said in the article that "an area of lower air pressure is created above the wing, and this "sucks" the aircraft up". This is highly misleading. Lift is created because of gthe opposite reaction of forcing an air mass down. The fluid dynamics of creating usable lift is quite complex and is well discussed in many places. This article should reference a more accurate description of lift creation.
- Thanks for pointing that out. Our own article on lift gets it right, so I summarised that explanation here. -- Heron 20:01, 2 Apr 2004 (UTC)
- Actually there's nothing "misleading" about the original description of lift (which is based on Bernoulli's Principle). The two descriptions are fully equivalent, as even the Wikipedia lift page says. ("The force on the wing can also be examined in terms of the pressure differences above and below the wing.") The simplistic "angled surface" description proposed by Heron is better suited for describing a lifting body while the air pressure (Bernoulli) description should be used whenever an airfoil is involved. Hopefully Heron will concede and make this fix. He should also present his credentials on this subject matter and provide reputable sources rather than taking information from other Wikipedia pages at face value.
Gyroscopic Precession
Explanation of cyclic control lead angle by reference to gyroscopic precession is common (and convenient) but incorrect. Gyroscopic precession is a phenomena resulting from conservation of angular momentum. It is only true for a rigid body. Helicopter rotors are not rigid. Many are articulated and even the so-called 'rigid rotors' are really quite flexible. Indeed, if they were rigid and were gyroscopes, gyroscopic rigidity would require huge forces to change the plane of rotation and helicopters could not be adequately manoeuvred. Cyclic lead angle is quite easily understood if, in a cyclical sequence, the difference between maximum pitch angle and the maximum flap up of one blade is examined. (i.e. Maximum pitch angle gives maximum rate of flap up but not maximum blade height). While I agree that too complex an explanation would not be appropriate in this article, I would urge that factual inaccuracies should be avoided. The Gyroscopic Precession myth has confused helicopter students for too long and should not be perpetuated.
John Annan
Why?
- when viewed from below the rotor of a French, Russian, Soviet or Ukrainian designed helicopter rotates anti-clockwise, whilst a helicopter completed in Italy, the UK or USA rotates clockwise.
Are there laws that tell helicopter designers to do so? -- Toytoy 01:46, Jan 25, 2005 (UTC)
- There are no laws as far as I know. I think it basically comes down to historical reasons. If you were trained in a clockwise helicopter, you might prefer clockwise. Any decent pilot can fly either one, you end up doing the right thing with the pedals anyway. I read in a helicopter theory book that the choice is arbitrary and the decision should be made on technical merits, e.g. engine shaft rotation, geometry of suitable transmissions etc. Madhu 16:35, 26 Feb 2005 (UTC)
Countries
The article divides its list of helicopters into "Popular US army" (including at least two aircraft in common use internationally), "Other military", and "Civilian"
Why have a special category for US army helicopters on this page? There are thousands of similar customers who buy helicopters. Wouldn't a simple military/civilian or fighting/general-military/civilian scheme seem more logical?
Ojw 18:17, 13 Feb 2005 (UTC)
Very Negative
I am interested in becoming a pilot and I find this article not very helpful. Instead of showing how the helicopter is actually mechanically controlled, like how the cyclic actually rotates the blades, all this article does is explain ways of how helicopters fail, crash, can be stalled, and destroyed. (67.83.10.27)