Stall Spin Question with NO RUDDER when coming wings level on final

[eetrojan]

POSSIBLY true statement:

"When using aileron deflection to roll-back to wings level on final approach at the end of the base to final turn, you can have a stall spin accident by failing to use coordinated rudder with the aileron because aileron drag will yaw the plane into a skid."


I think this is true, but I don't seem to see it discussed in the articles about stall/spin accidents.


If true, and it's really not being discussed, why does it take a back seat to the stereotypical mistake of using low rudder to increase the rate of turn when overshooting the extended centerline during the base-to-final turn?


Maybe because the likelihood of a stall is increased when the degree of skidding is increased with direct rudder forces, rather than with adverse yaw forces alone?

 

[luvflyin]

It'll yaw you into a slip, not a skid.

EDIT: disregard, you said rolling out of the turn, not into it

 

[Salty]

Just how much aileron are you using to Roll out of a turn to final?

 

[nauga]

It is with no small amount of trepidation that I post in this thread

An airplane will stall and/or depart when it reaches some particular combination of angle of attack and sideslip. I mean sideslip in the engineering sense, effectively the yaw angle between the relative wind and the body axis of the airplane. Whether it is reached in a slip or a skid is irrelevant. With that, your last sentence is essentially correct, in that you are more likely to reach and sustain a higher sideslip angle with application of rudder to tighten a turn than you are through adverse yaw rolling out on final with a reasonable control input.

Nauga,
spun up

 

[iamtheari]

You are also decreasing your load factor by rolling out of the turn, which makes the initial stall component of the stall-spin scenario less likely. Of course, it can still be done, but it’s less likely that a person will fly so badly while rolling out of the turn onto final than while trying to get the plane to turn onto final in the first place after having overshot the turn.

 

[Dan Thomas]

It is with no small amount of trepidation that I post in this thread

An airplane will stall and/or depart when it reaches some particular combination of angle of attack and sideslip. I mean sideslip in the engineering sense, effectively the yaw angle between the relative wind and the body axis of the airplane. Whether it is reached in a slip or a skid is irrelevant.

Slip or skid is indeed relevant. In a skid, the lower aileron is down, effectively increasing the angle of incidence on that side, which increases angle of attack. In a descending turn typical of the base-to-final, the inside wing is already at a bit higher AoA because of the slightly steeper helix it describes compared to the outer wing.

Go up high. Put the airplane into a low-power descent. Make a 30-degree banked turn. Skid it while pulling up some to slow the airplane. See what happens. If the airplane has any nastiness at all, it will spin to the inside. Now try that with a slipping turn instead and see if you can get it to spin as readily.

 

[luvflyin]

It is with no small amount of trepidation that I post in this thread

An airplane will stall and/or depart when it reaches some particular combination of angle of attack and sideslip. I mean sideslip in the engineering sense, effectively the yaw angle between the relative wind and the body axis of the airplane. Whether it is reached in a slip or a skid is irrelevant. With that, your last sentence is essentially correct, in that you are more likely to reach and sustain a higher sideslip angle with application of rudder to tighten a turn than you are through adverse yaw rolling out on final with a reasonable control input.

Nauga,
spun up

It's irrelevant in as much as yes, when a wing reaches the critical angle of attack it's gonna stall. Skidding or slipping isn't going to change that. What the results of that stall are going to be depending on whether the 'low inside' wing goes first and you are in a spin like right now without time to recover or the 'high outside' wing goes first and you have time to respond before it goes 'over the top' and then 'departs controlled flight' on the other side can be very relevant.

 

[nauga]

It's irrelevant in as much as yes, when a wing reaches the critical angle of attack it's gonna stall. Skidding or slipping isn't going to change that. What the results of that stall are going to be depending on whether the 'low inside' wing goes first and you are in a spin like right now without time to recover or the 'high outside' wing goes first and you have time to respond before it goes 'over the top' and then 'departs controlled flight' on the other side can be very relevant.

1) Sideslip can and will change the AOA at which an airplane departs *and* the departure characteristics. The departure isn't always a traditional stall.
2) If you're depending on the direction of a rolling and yawing departure from controlled flight to save you when turning from base to final you're too far behind already. The point is to avoid the departure altogether.

Nauga,
who prefers 'departing the pattern' to 'departing IN the pattern'

 

[dmspilot]

'departing IN the pattern'

Do that and you might become the dearly departed.

 

[luvflyin]

1) Sideslip can and will change the AOA at which an airplane departs *and* the departure characteristics. The departure isn't always a traditional stall.
2) If you're depending on the direction of a rolling and yawing departure from controlled flight to save you when turning from base to final you're too far behind already. The point is to avoid the departure altogether.

Nauga,
who prefers 'departing the pattern' to 'departing IN the pattern'

Yeah. Great quote. I may plagiarize it some day.