Stalling & Spinning

[whatunion]

plenty of stuff out on the internet to challenge most of your theories.

the following might explain stall characteristics that seem to be unknown by some of the high calibre current instructors


TAMING THE STALL

We've gone on a bit about what a stall is, and some techniques to prevent stalling our planes when we don't want to. Now we'll look at how we can tame a planes stall characteristics somewhat.

But first, we need to look at how different wings stall. In general, as angle of attack (AOA) is increased, a straight wing, like on most trainers, will first start to stall inboard, at the wing root near the fuselage. And that's good. Although there is a loss of lift, all the messed up airflow is near the root, and the tips are still flying, meaning we also have aileron control out there where it's most effective. So we get a nose drop, but the plane stays reasonably level and we don't lose control.

But tapered wings are more efficient, and we'll see them on most higher performance planes. And the more highly tapered the wings are, the more likely they will stall first out at the wing TIPS. Stalls on such planes are very different; when a wing stalls first at the tips, a wing drops, you have no aileron control, and a simple stall instantly becomes a snap roll. Your first indication of a stall is when the plane flips onto its back, out of control!

Summarizing, we can see that if the stall begins out at the wingtips, we'll see a wing drop (often violently). But if the stall begins at the wing root, all we get is a nose drop, with the plane still under some control. What we'd prefer should be pretty obvious!

So what's the answer? How do we make a plane do its stalling properly, in at the wingroot?

Washout is one answer. This is best done during the building stage, and involves "twisting" each wing during construction so that the tips "fly" at a slightly lower angle of attack than at the root, near the fuselage. Normally only a matter of about 2 degrees difference, (see fig.) the lower AOA at the tips mean that the root will always stall first. Many kits, even for straight winged planes, include washout in construction - as the wing is laid out on the building board, the trailing edge is set up higher out near the tip of the wing, giving you washout when the wing is complete.

Another way to accomplish the same thing is to use a different airfoil out near the wingtips; one that naturally stalls at a higher angle of attack than the airfoil at the root. This is very easily accomplished when cutting a foam wing, but is seldom seen in built-up construction. "NASA droops" will do this also, and could be added to an existing wing. The NASA droop is a leading edge "anti-stall" modification, usually applied to the outer 35-40% of a wing. (see fig.)

The easiest method to modify an existing plane to cure nasty stalling habits is the use of stall strips. Applied to the inner 20-25% of the wing, the stall strip is a small change to the leading edge that produces turbulence to that part of the wing at higher angles of attack, causing the stall to begin at the root. (see fig) Thus we will have a slightly higher stall speed, but the stall will at least be manageable. Plus - the beauty of the stall strips is that you can just pin them on and experiment till you get the effect you want, then make them permanent!

So if you have a vicious stalling plane on your hands, don't just try to cope till you crash it - add some droops or stall strips - let the plane age gracefully, THEN crash it!

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Heres another one; notice why stall strips are fitted, nothing to do with your explanation of providing buffetting at the stall!!!!

this is off the web, nothing to do with me


Stall recovery for the Glasair RG is typical of most conventional aircraft; lower the nose with forward stick, and add power. The stall characteristics are predictable in both power off and moderate power on stalls. Just before the stall, slight buffeting is felt, giving an early indication of the stall.

The Glasair RG should not be intentionally stalled with any heavy baggage in the baggage compartment unless it is securely fastened down. When practicing stalls, be sure to check the air space for any conflicting traffic.Stall recovery for the Glasair RG is typical of most conventional aircraft; lower the nose with forward stick, and add power. The stall characteristics are predictable in both power off and moderate power on stalls. Just before the stall, slight buffeting is felt, giving an early indication of the stall.

The Glasair RG should not be intentionally stalled with any heavy baggage in the baggage compartment unless it is securely fastened down. When practicing stalls, be sure to check the air space for any conflicting traffic.

NOTE
Stall strips are mandatory on the Glasair RG to induce the wing roots to stall first. Without these stall strips properly installed, the stall is unpredictable and can be rather erratic.
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i fly a large jet transport which has leading edge spoil strips. it is part of the pre-flight check to ensure these strips are present. this strip has nothing to do with stall buffet, it ensures that the roots stall before the roots to prevent wing tip stalling. on T tail swept wing a/c it is a requirement that a stick shaker and pusher is fitted. the stick shaker provides the stall warning.

I flight tested a C152 with stall strips attached to the leading edge in 1980 at wichita(cessna) i can assure you that there was no wing drop in the app config. with the same a/c with the strips removed it reverted to the normal wing drop.

so beagle i am afraid m1 was very far away from being spot on!