Help from real world GA pilots, Slip / Turn Indicator

Nearly every plane in every sim I’ve flown the Slip/Turn Indicator does little to nothing and does not seem to be accurate to what I would expect in real life, the only planes that seemed to work as expected are in FSX, the Grumman Goose and the Beaver I think was the other, the ball actually moved as I think it should and when I applied rudder I was able to see accurately the amount I needed to apply.

In real GA planes how does the ball behave, when rolling left does it freely roll left and when rudder is applied return to center and the same for rolling right?

I find that in all the sims I don’t really need to use the rudder except for taxi manoeuvres.

Please advise on what is the correct behaviour in real life.

Many thanks guys.

Cheers

Martin

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Imagine you are driving your car in a straight line with a slip indicator. The ball will now be centered. When you turn right the ball will move left, and you are pushed to the left in your seat. When you turn left it’s the other way around. The ball moves even though the car doesn’t roll.
The slip indicator does the same thing for a plane. If you push the rudder to one side and keep the wings level with ailerons you will see and feel the same things as you did in your car.
Let’s say now you are flying straight and level with the ball centered, and you decide to turn left. You roll the aircraft left but you don’t change rudder input. If it were the case that the airplane would now not change heading but keep flying straight ahead with a bank angle, what you would see is that the ball would move way over to left and you would feel yourself being pushed to the left because of gravity. However this is not how aircraft behave. When you roll left the airplane will also turn left, even if you don’t change your rudder input. You will not feel as if you are being pushed to the left very hard, only slightly: rolling left pushes your body to the left in your seat, but turning left pushes your body to the right in your seat. These two cancel each other out for the most part. You will only need a little bit of left rudder to get the ball to center.

So this is a long way of saying that the ball only cares about your lateral acceleration, and nothing else.

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I am a trainee pilot. The slip ball in my plane is very responsive and while I will normally feel the issue - plane is out of balance - before I glance at the slip ball and start correcting its a very useful instrument for me.

Neither MSFS2020 or my other sim Xplane make good use of the slip ball.

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So basically I’m right, the only ones that work correctly seem to be the 2 I mentioned in FSX, the ball in both of those planes moves as I would expect and when I apply a little rudder I can center the ball ok and coordinate the turn. Both Laminar and Asobo should look at this issue as it reduces the sims ability as a training aid IMHO.

I must try the converted Goose, see if it still works properly in that one.

Thanks for your input guys.

:+1:

Great post… I had been wondering why I couldn’t get a coordinated flight state too.

Plus it’s not just the “ball” or the slip/skid/turn indicators. Some aircrafts seem to have significant and inherent yaw issues as described in Still NO Adverse Yaw Effect on C152 and C172

Was looking for solution to this, ball doesn’t seem to do anything when I roll left or right, it does however respond to rudder! Using 172 with steam gauges on reverb g2 - the only plan I ever use.

The ball does respond to rudder input but it’s no good if you can’t tell how much rudder you need cus it don’t move enough in the first place. It’s the same in all the sims I’ve used, a couple of planes seem close but none seem to do it right, it’s as though the math is wrong, like the calculation is including forces that have yet to be applied but it’s applying them anyway, then you apply rudder and the ball shoots off in the other direction throwing the plane all over the place.

I do wish they (all sims that is) would correct this issue.

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