Talk:Retreating blade stall

tip region

"Retreating blade stall starts at the tip region and develops inboard (one of the exam questions in Helicopter Principles of Flights)."

Is this actually true? Pilot manuals (particularly in the US, it seems) tend to religiously state that Angle of Attack is the *only* thing that induces stall. This is not true, as the example of a wing (at any angle) within a 0 airspeed environment clearly being in a stalled state shows. It does make for a simple and mostly accurate rule for pilots to follow, which is why they use it, I guess.

There are obviously various factors involved, but I was told several decades ago, that generally about 10% of the inner rotor is nearly always at stall, since it doesnt have enough airspeed to induce lift. This area expanded in the appropriate direction as the rotor approached uncontrollable conditions.

I realize that extremely flexible blades may twist so much at high speed as to induce stall also, and this certainly seems to be the modern method of making them. But in this case the load on the advancing side is much higher, and would induce more twist, thus causing that side to stall first. This is not the case in practice, and why it's called *retreating* blade stall. I wonder if the topic needs expansion or correction.07:05, 3 April 2013 (UTC)~ — Preceding unsigned comment added by 110.175.228.227 (talk)

Other forms of rotorcraft

Although this article initially mentions both helicopters and other rotorcraft, there isn't any discussion of other forms of rotorcraft, and the description of recovery techniques and causes is applicable only to helicopters. In particular, gyroplanes are another form of rotorcraft that can experience retreating blade stall, but generally do not have a collective control to be used in recovery, and are not subject to increased risk from high loads or high density altitude. A helicopter has an rpm limit arising from the powertrain that cannot be changed with load or air density and that makes many of the listed factors pertinent, but the unpowered rotor in a gyroplane is not limited in that fashion and automatically increases autorotative rpm with load and loss of density. Expanding this article to include gyroplane behavior would be worthwhile.Jonwithnoh (talk) 21:50, 7 October 2013 (UTC)

Compensation

This section should be removed as it is secondary to the discussion of retreating blade stall and contains many factual errors e.g. the statement regarding the role of the lag (or in-plane) motion of the blade is not relevant in this context. Flapping occurs due to the asymmetry of lift on the advancing and retreating blades. This is compensated by changing the pitch of the blades and hence the angle of attack. It is the high angle of attack (at the associated local freestream Mach No. that can lead to stalling). — Preceding unsigned comment added by Cabman267 (talk • contribs) 16:39, 22 November 2013 (UTC)