The slipping turn and the balance ball

[ozbeck]

I clearly have a mental block about this.

I can fly a balanced turn by applying rudder the same side as the ball. No problem. However, when it comes to understanding the theory I can not reconcile the following apparantly conflicting facts.

In the Trevor Thom example of a slipping right hand turn - the aircraft shown slipping into the turn is banked to the right and yawing left. In my logic, and understanding the further effects of controls, I would expect a banked aircraft slipping to the right to experience a yaw to the right due to the airflow on the fin and fuselage surface.

Also, when an aircraft yaws, what are the forces acting on the balance ball to make it move in the opposite direction to the yaw (thus indicating that 'same side' rudder will balance the aircraft)?

A bit nerdy possibly, but I like to understand what is going on, and hope that somebody can help me find the light switch here.

Waiting with eager anticipation!

[Deeday]

when an aircraft yaws, what are the forces acting on the balance ball to make it move in the opposite direction to the yawIf you apply right rudder with wings level (I suppose that's what you mean with yaw), the ball will move to the left because of its inertia (or you could blame the centrifugal force, although it's only an apparent one).
That's because with rudder applied and wings level the aircraft will start flying (unbalanced) along a circular trajectory and the ball will tend to go off the tangent.

[Them thar hills]

Oz
Have you done any sideslipping for real ?

You say "I would expect a banked aircraft slipping to the right to experience a yaw to the right due to the airflow on the fin and fuselage surface"
Well yes, the aircraft would normally want to yaw to the right, but you have applied left rudder balanced against right aileron, to hold it in the sideslip !

tth

[Jan Olieslagers]

Well, sorry, I can't help you to understand. Yours is a good question, that's to say, I wondered myself a long time. My instructors made me give up though. Their combined efforts made me accept that coordinating a turn is not accomplished through the brains but rather through the buttocks.
I was one of those beginners malformed by too much of MSFS - never having had to care, I had never learned to check for proper turn coordination. My various instructors had trouble enough to get me to watch the horizon as a prime reference, rather than the instruments, one went so far as to neatly cut a piece of cardboard to cover some carefully selected gauges, surprising me with it in my first badly uncoordinated turn. Another only shouted "Ah! My spine!" - the more condescending guy dryly pointed at the ball when it hit the outside.
Don't try to understand, learn to feel when it's right. Develop delicacy in your buttocks, it does help. There's lots of better uses for your brain, up there.

BTW in my very limited experience, "putting your foot on the ball" is less effective than "pulling the ball home with the stick" but I reckon this depends very much on the particular craft. Most of my relevant experience is on a Rans Coyote.

[markp123]

In a roll to the right, the aileron of the left wing is lowered, thus increasing the camber of the wing and the overall lift it produces. This gives you your roll to the right. The more lift a wing produces, the more induced drag is created.

The result of this extra drag on the upgoing wing results in the nose being "pulled" to the left, or out of the turn.

Overall result of this can be reduced by the use of differential ailerons, but it usually doesn't get rid of the effect all together, so a rudder input is needed from the pilot to maintain a balanced turn.

[Pilot DAR]

Oz, your question is fair, but is certainly one of those which is much better experienced and practiced, rather than explained in writing. It is reasonable that you have to take some time to figure this out, and you should devote an hour or so of flying to that, and nothing more, if that's what it takes.

It is likely that you are flying an aircraft which is co-operating with you in turns, most do. There is the potential in the future though, that you could fly an aircraft which is much less co-operative in respect of co-ordinating itself in turns, or even straight flight for that matter. This is something which should very much be instinct in you. Don't give up understanding it, until you know you have a grasp of it! Practical experience is the key with this one...

[larzabell]

Hi Ozbecker

I too had problems understanding what is going on so I spent some time working it out. I hope this helps.

If you roll the wings with ailerons only, lets say to the right
1. the left aileron goes down increasing the lift on that wing
increase the lift - increase the induced drag

2.because this wing is producing more drag, it slows down and pulls the nose to the left( away from the turn)

3.because the lift force is now tilted, it is no longer opposing the weight force equally. The result of the two forces is that the aircraft slips into the turn.

4. as it slips into the turn, there is now a relative airflow striking the right hand side of the aircraft. this hits the fin and pushes the tail causing the aircraft to yaw to the right ( into the turn).

So you can see that adverse yaw happens first (during entry) then it yaws into the turn.

If left unchecked it would develop into a spiral dive.

:ok: