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Autorotation

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Hey, I do in fact have permission to use this article from the author/webmaster. I need to change the article a bit, as I credit the wrong source. But I was in the middle of editing the article when it was replaced by a "this is stolen" message. If you could kindly NOT delete it this time I post it, I'd appreciate it ;) —The preceding unsigned comment was added by 209.210.142.191 (talk • contribs) 5 September 2003.

References

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The reference at the bottom of the page is http://www.copters.com Shouldn't it be http://www.copters.com/pilot/autorotation.html instead?--Taida 18:05, 18 June 2006 (UTC)[reply]

Suggestion

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This is a good start, but the whole article only really focusses on the use of autorotation in a single engine helicopter following an engine failure.

As briefly mentioned, autorotation can also be used in other emergency procedures, such as following a yaw control failure (eg tail rotor drive shaft failure). The reasons for the use of autorotation in this case is not mentioned.

It is also the designed principle of flight for some rotary wing aircraft, specifically the autogyro, but also higher speed aircraft such as the Sikorsky ABC.

Some general, easy to understand, detail on the forces on a rotor blade that keep the rotor turning is also necessary.

I will have a look at some edits over the next few weeks hopefully.

--Herb b 01:06, 30 June 2006 (UTC)[reply]

RV Mrhinelander

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I've reverted the edit by Mrhinelander. He added some technical details, but it isn't exactly formal english, and isn't implemented very well. Could someone roll these in better please? martianlostinspace 21:49, 5 July 2006 (UTC)[reply]

on 2nd thoughts, maybe it is better to leave those details in and leave a wikification sign on it. Anyone can wikify, only a few can add technicalities.--martianlostinspace 09:42, 15 July 2006 (UTC)[reply]

Here is his explanation of details:

Helicopters do not fall from the sky when their engine fails. Nifty aerodynamics keeps the main rotor turning at its normal speed, providing about as much buoyancy as a round parachute of the same diameter! As with a parachute, you can only go down, but you descend at a normal and familiar glide angle to a suitable landing spot. You _were_ staying within gliding distance of a suitable landing spot during your flight, weren't you?
"Autorotation" is the engineering name for the nifty aerodynamics that powers the main rotor and provides buoyancy. It is helpful to think of it like a parachute, because you must be going DOWN for autorotation to occur. It is critical to immediately establish this upward airflow upon engine failure. Therefore, pilots diligently practice the series of maneuvers to fly a safe landing. This series of maneuvers is also called "an autorotation."

--martianlostinspace 09:43, 15 July 2006 (UTC)[reply]

Wikify

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The wikify template is now on. Anyone have the time to clean it up, and integrate the details at the top, thanks. --martianlostinspace 16:30, 16 July 2006 (UTC)[reply]

So done, but shouldn't the entire "Common mistakes" section be deleted per WP:NOT "how to" issues? (As well as other "how to" instructions removed?) --RJFerret 20:14, 16 July 2006 (UTC)[reply]
Need to remove use of second person form in the article and change to third person. —QuicksilverT @ 18:14, 24 October 2006 (UTC)[reply]

In what way do the clocks run in the USA ?

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I think that if the blades of a rotor are going forward at the left of the aircraft, so the rotation is CLOCKWISE when seen from the above ! I would like a discussion about the pitch of the blades when doing an autorotation and minimal pitch permitted by blade design...also, what does pedaling when the motor is off ? is the tail rotor still moving with energy coming from the main ? if yes, the aim of pedaling would be to obtain a flat tail rotor (giving no force), right ? user Motunono in fr.wikipedia —The preceding unsigned comment was added by 203.173.190.18 (talk) 22:03, August 23, 2007 (UTC)

Angle of attack greater than stalling angle

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When talking about fixed wing aircraft, the article says that during stall, any increase in angle of attack will reduce lift. I believe this is incorrect, however, as after a certain angle, Cl starts to increase again.

Dhoult (talk) 16:57, 17 January 2010 (UTC)[reply]

In a wind tunnel it can be demonstrated that, as angle of attack increases beyond the stall, lift coefficient initially decreases but then increases again. However, flight at angles of attack greater than the stalling angle is unsteady, causing the aircraft's nose to drop, the aircraft to descend, its speed to increase and the angle of attack to quickly reduce to an angle less than the stalling angle. The phenomenon you have described is not observable in civil aircraft or even in conventional military aircraft - it is only observable by testing a wing in a wind tunnel.
The diagram that accompanies this article only shows the lift coefficient decreasing at angles of attack greater than the stalling angle. It does not show the phenomenon you have described. Dolphin51 (talk) 04:53, 19 January 2010 (UTC)[reply]

Relevance of yaw

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Prior to 5 April 2010, the second paragraph in this article stated the following:

In the operation of fixed-wing aircraft, autorotation is the name given to the manner in which an aircraft in a stall, or approaching the stall, displays a tendency to roll spontaneously to the right or left. A fixed-wing aircraft in a spin rolls continuously to the right or left, displaying the characteristic known as autorotation.

This paragraph was supported by in-line citation of:

  • Aerodynamics by L.J. Clancy, (Sections 16.48 and 16.49)
  • Flying Qualities and Flight Testing of the Aeroplane by Darryl Stinton (page 503)

On 5 April, the second paragraph was amended by IP 70.188.238.165 to state the following:

In the operation of fixed-wing aircraft, autorotation is a combination of roll and yaw that propagates itself and progressively gets worse due to asymmetrically stalled wings. It is the name given to the situation in which a yawing moment is introduced to an aircraft in a stall. This yawing moment results in a proverse roll which then leads to the asymmetrically stalled wings. The more stalled (inside) wing produces more drag than the less stalled (outside) wing. This condition propagates the yawing moment which in turn causes the proverse roll. A fixed-wing aircraft in a spin rolls and yaws together continuously to the right or left, displaying the characteristic known as autorotation.

This amendment emphasised that autorotation in a fixed-wing aircraft includes yawing.

The quoted text in the books by Clancy and Stinton support the idea that rolling and yawing are both essential elements in spinning, but neither support the idea that autorotation includes yawing. Therefore the in-line citations do not support the amendment made by IP 70.188.238.165. For this reason, I reverted the amendment.

The existing in-line citations support the following ideas:

  • Autorotation is a self-sustaining motion in roll
  • Spinning is a self-sustaining motion involving autorotation and yaw.

In the absence of an in-line citation to support the idea that autorotation includes yawing, this idea should be omitted from the article. Dolphin51 (talk) 01:04, 7 April 2010 (UTC)[reply]

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