Can you enter a spin from a slip?

[luddite42]

Originally Posted by MauiLvrs

NOT...
All you have to do is stall with one wing more stalled than the other.
It's that simple...

Not that simple. Most of the time, stalling with unequal AoA between the two wings will NOT produce a spin. A wing might drop, but a simple wing drop during a stall does not necessarily mean there is ENOUGH lift differential (and yawing force) to produce a spin. Spiral maybe. Many don't understand that a wing drop is not necessarily a spin entry because a typical student pilot training flight does not allow the stall to progress to the point of seeing what actually develops. Students are taught to recover at the first indication of the stall, so many think they're a gnats *** away from a spin if the wing drops a little during normal power on and off stall practice.

Most pilots (who are inexperienced with spins) don't understand how much effort it takes to enter and sustain an actual spin. In most airplanes, it takes more than just stalling with the ball off center...or even well off center. Most airplanes must be forced into a spin with full rudder AND full elevator deflection. Any less than this and most airplanes are reluctant to spin. You can't simply watch the wing snap over or under, immediately recover, and proclaim that an incipient spin entry. Wait and see what happens. Unless the rudder is on the floor and the stick in your gut, I think you'll find that any (spiral) rotation that develops can be recovered simply by breaking the stall by moving the stick forward and using the ailerons right away. Try that during a real spin and the ride will suddenly get even more fun.

[Bob Axsom]

For 15 years I flew our beloved red, silver and black Piper Archer II (N8304L) to work IFR or VFR (VFR prefered for time & distance) and every day that it was VFR, before the tower opened, I would cross mid field roll into a hard right turn and slip all the way around to just before touch down on runway 19 at El Monte (EMT) without crossing the street at the north end of the airport. One morning there was a cross wind from the west that caused me to overshoot the runway centerline to the east. Banked over that hard I used the stabilator to "bring it back." It worked fine as it had for hundreds of times in the past but perhaps with not as much aggression as I applied that morning. As the plane was coming around the last part of the eastward excursion there was an attention getting burble/shudder/vibration and the plane flew through it fine but I knew bad stuff nearly happened and I became a little more cautious after that.

Bob Axsom

[60av8tor]

Originally Posted by luddite42

Most pilots (who are inexperienced with spins) don't understand how much effort it takes to enter and sustain an actual spin. In most airplanes, it takes more than just stalling with the ball off center...or even well off center. Most airplanes must be forced into a spin with full rudder AND full elevator deflection.

I recently conducted spin training, and this was one of the biggest benefits of the training - demystifying the belief that a spin is like a snake hiding in the grass waiting to strike. It really took full control input (and held) to enter. Every plane is different; this initial training was not in my plane. Next session will be in the RV. Very glad I did the training.

[L'Avion]

Consider left turn to final; hard right rudder, hard left stick, nose up - what could happen?

On a swept wing aircraft the right wing will be blanked out by the fuselage, and with the greater wind across the left wing cause a hard right roll and put one on one's back.

The ? above: can such happen with a straight wing? Not to be tried in the traffic pattern, eh?

[Bob Redman]

Good morning/evening all,

This is a good discussion, but, as usual in aviation, exceptions may lurk just around the corner.

Once upon a time I was flying a Macchi MB326H jet on a post deeper level maintenance flight. The Macchi was a joy to fly - benign - usually it would only spin with pro-spin controls, nose low, and would recover quickly by centreing the controls. Although the standard spin recovery was: throttle closed; full opposite rudder; stick centrally forward.

On this flight, as usual, I conducted a precautionary, 1G, balanced flight stall before I planned to check the spin characteristics of this particular jet. At the stall, the aircraft rapidly auto-rotated and entered a relatively flat spin although quickly I had centralised the controls. Eventually, I recovered from the spin using full forward stick, full opposite rudder, and either in-spin or out-spin aileron - after three attempts (using standard spin recovery) had made no difference to the spin. I did try both in-spin and out-spin aileron, but could neither remember then, nor now, which helped - I was surprised, and pre-occupied with altitude remaining.

Apparently, there was a slight mis-rigging of the flaps, which was missed by an experienced maintenance crew, the quality control inspectors, and me.

So please remain wary, and try any new adventure at a safe altitude. You never know when you might use all the altitude you have.

[the_other_dougreeves]

Originally Posted by Bob'sRV6A

how about the AOA--is it as inaccurate as the ASI, or can it be used to prevent a stall/spin in an overly aggressive slip?

What's an "overly aggressive slip"? I've often slipped with full rudder and as much stick as necessary to maintain a forward slip.... never thought of it as overly aggressive, just very effective!

My guess is that your AOA probe will also be inop during a full slip.

TODR

[MauiLvrs]

Originally Posted by luddite42

Not that simple. Most of the time, stalling with unequal AoA between the two wings will NOT produce a spin. ...

The question was can...

[donaziza]

I used to slip my RV 8 to lose altitude in a hurry if I was high on final. Worked great. Sold that RV 8 and now have another. Guess after reading all this, I'll "slip test" the plane at 7000' the first few times just to make sure. Incidentally somebody was talking about not slipping a swept wing? You can slip an A 300 airbus---works just like a RV 8. But I've heard don't try it in a T tail airliner. Guess, as many have said, it all depends on which type of airplane.

[scsmith]

Mr N355DW is correct. You can spin over the top from a spin if you have enough rudder power to generate enough yaw-rate, and enough wing-span to create a significant velocity difference, and AOA difference between the wings. There is no better aircraft in the world for demonstrating this than a Schweizer 2-32 glider. They spin over the top beautifully.

Also, most of the commentors here are ignoring the effect of dihedral. Ailerons are not the only way of making the AOA different on the two wings.

Think about this for a minute: In straight-ahead flight, How does the airplane know the difference between a skid and a slip? There is none. The distinction only makes sense when you are turning. In straight-ahead flight, if you cross control, using wing bank to cancel the side force from yaw, you have a significant difference in angle of attack between the wings because of dihedral. Now, if you have enough elevator power to stall, one wing will stall first. And it will drop.

Disputing what Mr. Luddite said about wing drops, the dropping wing sees a BIG increase in AOA instantly. Depending on a lot of details (airfoil characteristics, wing twist, wing taper, tip shape) that dropped wing may just turn you into a spiral dive, or it may snap you into a spin. It depends a lot on the variables I mentioned above.

But certainly, get in a hard slip, and bleed the speed off agressively, and it will spin in the direction away from the slip (over the top).

Originally Posted by luddite42

Not that simple. Most of the time, stalling with unequal AoA between the two wings will NOT produce a spin. A wing might drop, but a simple wing drop during a stall does not necessarily mean there is ENOUGH lift differential (and yawing force) to produce a spin. Spiral maybe. Many don't understand that a wing drop is not necessarily a spin entry because a typical student pilot training flight does not allow the stall to progress to the point of seeing what actually develops. Students are taught to recover at the first indication of the stall, so many think they're a gnats *** away from a spin if the wing drops a little during normal power on and off stall practice.

Most pilots (who are inexperienced with spins) don't understand how much effort it takes to enter and sustain an actual spin. In most airplanes, it takes more than just stalling with the ball off center...or even well off center. Most airplanes must be forced into a spin with full rudder AND full elevator deflection. Any less than this and most airplanes are reluctant to spin. You can't simply watch the wing snap over or under, immediately recover, and proclaim that an incipient spin entry. Wait and see what happens. Unless the rudder is on the floor and the stick in your gut, I think you'll find that any (spiral) rotation that develops can be recovered simply by breaking the stall by moving the stick forward and using the ailerons right away. Try that during a real spin and the ride will suddenly get even more fun.

[txaviator]

Great discussion fellas! As a low time guy, I am learning a lot from all of your comments. Good stuff! Keep the comments coming!