Slipping and Skidding ?

[Tacitus]

Could someone explain me why slipping and skidding occur? Also why, for example, when a slip occurs during a turn rudder pressure must be applied to the same direction? And what happens during a skid and how do you coordinate the rudder with the ailerons? I’ve read the theory but it looks a little bit confusing though. Thanks in advance

[shortstripper]

I don't have time for an in depth answer, but to get the ball rollinh (so to speak :p ) the easiest way to keep the ailerons and rudder co-ordinated is to keep the slip ball (turn and slip/turn coordinator) central. After a while it all becomes natural anyway.

I'm sure you'll soon get a better answer too!

SS

[Nimbus265]

In a slip, the rate of turn is too slow for the angle of bank.

The aircraft's tail is slipping in towards the direction of the turn. To correct this either decrease the angle of bank or use more rudder to increase the rate of turn ( or both).

In a skid the rate of turn is too fast for the angle of bank.

The aircraft's tail is skiding away from the direction of the turn. To correct, increase the bank angle or use less rudder to decrease the rate of turn (or both).


Ball in = SLIP = Stick Less Increase Pedal

Ball out = SkiD = Stick inKrease Decrease pedal

Well it works for me!

[Chimbu chuckles]

More likely adverse yaw. As you roll into a left turn, for instance, the right aileron has been displaced downwards...that increases the camber of the outer portion of the wing as well as the affective angle of attack which both work to produce more lift which causes you to bank. More lift = more induced drag which causes the nose to swing towards the outside of the turn...hence rudder is needed towards the inside of the turn to balance the aeroplane so that it's longitudinal axis is tangential to the arc of the turn.

Modern aircraft don't have much adverse yaw but they do have some so you need to use rudder to balance a turn...unless, like in a Bonanza, the aircraft is fitted with a spring interconnect between aileron and rudder that does it for you.

If you are skidding then probably either too much rudder in a turn or P factor if in a high powered aircraft in a climbing turn.

[mazzy1026]

Next time you do your preflight check, notice how the up going aileron goes higher than the downward one - this is to increase drag on the wing going down which in turn reduces adverse yaw.

:ok:

[robin]

In gliders where keeping the aircraft 'clean' is of some importance, we used to train pilots to keep the ball in the middle by 'kicking' it there

ie if the ball is to the left push with left foot
if the ball is the the right push right foot

The yaw string is much more sensitive, and, I seem to remember, works in the opposie sense

[Nimbus265]

Robin,

You're correct with regard to the yaw string. Most are fitted with a piece of tape at the front end of the canopy. Some clubs make this triangular, so that the yawstring 'points' .

Therefore if the string 'points' left - more left boot required and visaversa.

[Mike Cross]

Next time you do your preflight check, notice how the up going aileron goes higher than the downward one - this is to increase drag on the wing going down which in turn reduces adverse yaw.
That's called differential aileron, however it's not vastly effective. You might also notice that on some a/c the hinge point of the aileron is below and to the rear of where it joins on to the wing. The effect is to allow the leading edge of the upgoing aileron to tilt down so it sticks out into the airflow to increase drag on that side and counteract the adverse yaw.

[bookworm]

Also why, for example, when a slip occurs during a turn rudder pressure must be applied to the same direction?

In the absence of other factors, aeroplanes tend to slip out of turns. The angling of the lift force provides the central force required to make the centre of gravity go round in circles, but it still requires a yawing moment to make the heading of the aircraft yaw in the corresponding fashion. That yawing moment is usually quite small, and can come from the rudder or failing that it will come from having a slight out-of-turn sideslip angle: a slip.