Coordinated turns

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filhere

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Jul 8, 2020
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I own a new to me STOL aircraft. It seems to have a tendency to turn right and skid left which I can’t quite figure out. Any insights welcome.



In slow flight with flaps out and high engine revs to maintain altitude, wings level and with the balance ball centred with some right rudder, it turns to the right.



Also, in a left hand circuit in the base to final left hand turn at slow but safe speed, it requires significant right rudder.


In both situations, it doesn’t feel in the seat of my pants like the aircraft is skidding left before I add right rudder.


In the slow flight, the fact that wings are level and the aircraft is turning right, makes me think the use of right rudder is causing a skid into a right hand turn.

In the left base to final left turn, when I add right rudder to centre the ball, it then feels in the seat of my pants like the aircraft is slipping to the left.

Could it be a faulty balance ball, faulty aircraft design or faulty pilot?

Any insights welcome! Thanks.
 

N804RV

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Jun 9, 2013
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Mount Vernon, WA
Which way does the prop turn (as viewed by the pilot)? And, when you trim it up for cruise, does the ball stay centered with your feet off of the rudder pedals?

I suspect your airplane may be rigged so that in cruise flight the nose will stay centered. But, in slow flight you have to compensate for slipstream. I believe this was also common in the Hawker Hurricane.
 

TFF

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Apr 28, 2010
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Memphis, TN
First, you need to check the rigging of the aircraft. You need to know the incidence of the wings, stabilizer; both sides. Root and tip. Off set and engine incidence along with rudder. Control throw for each part that moves, up and down. It’s all guesswork until it’s mapped out.

The guesswork on my side has probably not a lot of dihedral effect and a lot or P factor. How does it act clean and fast with low power? Climb up, nose it over, pull the power and see how it acts then. See if it is flap or speed related.

Pilot wise, I can only speak to my experience. I have only flown a Champ twice and hope to more soon, but I can’t keep the ball straight worth anything yet. No other plane I have flown laughs at you like it. Adverse yaw is one thing, but it’s crazy if all you have flown is nose draggers.

Those are the places I would start at.
 

Dan Thomas

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Sep 17, 2008
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That ball instrument is mounted cockeyed in the panel. That's the only thing that makes sense here. Level the airplane laterally and see what the ball says. I bet it will be off to the right.
 

Geraldc

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Nov 12, 2011
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nz
That ball instrument is mounted cockeyed in the panel. That's the only thing that makes sense here. Level the airplane laterally and see what the ball says. I bet it will be off to the right.
you can check this with a free version of A-EFIS on your phone
 

filhere

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Jul 8, 2020
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Awesome.
you can check this with a free version of A-EFIS on your phone
Downloading now.
Yes it flies straight with ball centred in level flight.
With flap out it needs a little left aileron to fly wings level (not turning).
Maybe flaps are not balanced for slow flight?
 

filhere

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Jul 8, 2020
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P
Which way does the prop turn (as viewed by the pilot)? And, when you trim it up for cruise, does the ball stay centered with your feet off of the rudder pedals?

I suspect your airplane may be rigged so that in cruise flight the nose will stay centered. But, in slow flight you have to compensate for slipstream. I believe this was also common in the Hawker Hurricane.
prop turns clockwise from the pilot’s POV. Also, with flap out it needs a little left aileron in straight and level. I’m thinking maybe the flaps are not balanced?
 

Pilot-34

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Apr 7, 2020
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If it’s amateur built is there any chance the wings flaps and ailerons are not the same size from side to side?
 

wsimpso1

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I own a new to me STOL aircraft. It seems to have a tendency to turn right and skid left which I can’t quite figure out. Any insights welcome.



In slow flight with flaps out and high engine revs to maintain altitude, wings level and with the balance ball centred with some right rudder, it turns to the right.



Also, in a left hand circuit in the base to final left hand turn at slow but safe speed, it requires significant right rudder.


In both situations, it doesn’t feel in the seat of my pants like the aircraft is skidding left before I add right rudder.


In the slow flight, the fact that wings are level and the aircraft is turning right, makes me think the use of right rudder is causing a skid into a right hand turn.

In the left base to final left turn, when I add right rudder to centre the ball, it then feels in the seat of my pants like the aircraft is slipping to the left.

Could it be a faulty balance ball, faulty aircraft design or faulty pilot?

Any insights welcome! Thanks.
Is it a RANS? Sound like my wife's S6. She recognized your symptoms immediately. First thing we did was neutral out rudder needs in cruise. In her wire braced tail, we changed the warp of the vertical fin by adjusting the wires. Other designs will benefit from a fixed tab on the rudder. Lots of info about on how to do this.

The remaining stuff in the wife's plane looks like either not enough coordination (rudder) while rolling in and out plus some over-banking tendency when established in turns, which means learn to hold a tiny bit of compensating rudder in turns, but you have avoid letting yourself skid turns - the stall/spin dragon lurks here. Her airplane does the same thing in both left and right turns. If your airplane does different things left and right, you have got a wing and/or control and/or instrument rigging issue. Wing incidence at root and tips, neutral vs deflected positions of control surfaces, etc, are all ahead of you then.

Oh, and making sure the instrument with the ball is straight is great advice.

Billski
 
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