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The deep stall

The Cessna high wing airframes don’t really go into spins by themselves, you have to hit the rudder hard and depending on the model, only left spins are possible.

I have the slightly worse-for-wear underpants proving that this is not entirely true…

(a) It must be possible to produce and to correct roll by unreversed use of the rolling control and to produce and to correct yaw by unreversed use of the directional control, up to the time the airplane stalls

That is very interesting – when did that come in? Definitely the way a PA28 etc behaves, even more so a Cirrus where the ailerons are quite effective all the way to the stall (well, inboard wing stall, that is… never tried anything aggressive in one of those, not sure what would happen in an accelerated stall and the entire wing stalling).

Using the rudder to attempt to keep wings level near the stall is the recipe for a spin entry in a modern type certified aircraft

“Picking up a wing” with rudder certainly works, but even slightly overdone can indeed trigger an asymmetric stall (and then spin). I believe the cause for spin entry in that case is actually the roll. Say left wing drops, right rudder kicked hard, the aircraft is now starting to yaw right and the left wing gets accelerated and gets more lift. the inboard wing gets decelerated and produces less lift. Roll happens, pilot smiling.

So far, so good. But a downgoing wing now has a higher angle of attack than before, and that might get it into the stall, so it snaps into the spin, and the pro-spin rudder provides nice yaw to get the rotation going.

At least that is how I understand how a spin entry works – is this correct?

Biggin Hill

High power, AofA close to critical and use of rudder also introduces some useful gyroscopic effects. A Cassidy has a good description of these in Better Aerobatics in the chapter on Flat Spins.

In a right handed engine, left rudder will cause pitch up, if you try and keep the wings level due to an incipient spin to the left, adverse yaw to the left from right aileron will be a reasonable attempt to convert your upright spin into a flat spin.

Oxford (EGTK), United Kingdom

convert your upright spin into a flat spin.

So “flat” spin is not upright? I know there are inverted spins (which I have happily avoided so far), and I understand that really mishandling some planes can turn your upright spin into an inverted spin. However, my experience has been that a “flat” spins are the result of entering a spin at a very aft C of G. During my spin testing of both a modified C 206, and a modified Caravan, I found a total difference in the spinning attitude between C of G extremes (as it is usually the spin characteristics which define the C of G limits. Unlike other types I have spun, I found that aft C of G in the C 206 and Caravan, required full and sustained nose down control input to recover, not just the “let go and wait” common to other Cessnas and a few other types. The Caravan went about one turn around, fully spun, but with the nose just slightly below the horizon when the C of G was aft. Forward, on the other hand resulted in an alarming dive attitude, achieving a peak 9200 FPM down.

That is very interesting – when did that come in?

That stall handling requirement was has been in effect in the U.S. since 1949.

“Picking up a wing” with rudder certainly works, but even slightly overdone can indeed trigger an asymmetric stall (and then spin). I believe the cause for spin entry in that case is actually the roll. Say left wing drops, right rudder kicked hard, the aircraft is now starting to yaw right and the left wing gets accelerated and gets more lift. the inboard wing gets decelerated and produces less lift. Roll happens, pilot smiling.

So far, so good. But a downgoing wing now has a higher angle of attack than before, and that might get it into the stall, so it snaps into the spin, and the pro-spin rudder provides nice yaw to get the rotation going.

Yup, that sounds correct to me.



In this spin (one of 14 full forward C of G I flew that day) I intended a left entry. I held the wings level, ball perfectly in the middle throughout the approach to stall. As you can see, it wanted to drop the right wing at the stall, but at the point I intended the entry, I applied and held full left rudder. It relented, and spun left.

Home runway, in central Ontario, Canada, Canada

You can perform inverted flat spins in appropriate aircraft, here the gyroscopic effect you are looking for on entry would be opposite to upright.

For upright, read normal.

Flat spins can also be entered from a stall turn, or what in North America they call hammerheads.

Given the fuselage length of the Caravan it is impressive it can perform a flat spin, and recover.

Oxford (EGTK), United Kingdom
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