Slips vs skids in a CT

[Ed Cesnalis]

The flight tube thread shows how all the CT pilots see fuel transfer in terms of slips only.  

The plane prefers a slip over a skid, CTs have a lot of adverse yaw.

The pilot prefers a slip over a skid for spin avoidance.

With a slow transfer rate (ball only off small amount) its not uncomfortable either way.

I prefer using a skid with wings level because it looks correct in a CT where slipping in cruise just looks wrong but I will agree one is as efficient as the other.

 

[Ed Cesnalis]

9 minutes ago, WmInce said:

. . . inefficient as the other?

yes better said

[Mike Koerner]

Ed,

You can't skid without turning. If you correct for the turn with the ailerons then you're slipping.

Most of the time we use a slip to balance the fuel in the tanks because most of the time we want to go straight. If you happen to be circling to climb or descend, or just because that's what you like to do, then yes, you can us a skid instead (keep your speed up though, so you don't induce a spin).

I don't think there is any difference in the efficiency of using a slip or skid to transfer fuel. The transfer is proportional to the degree of miss-coordination as indicated by the ball (assuming an accurately reading ball). Think of the ball as a yaw string. It's telling you that the air is coming at the plane from the side instead of head on. It doesn't matter how you initiate that condition; the loss of efficiency is going to be the same.

Two related comments that I don't think have been clearly captured in the previous discussions:

1) I wouldn't get carried away with the fuel transfer. If the ball is more than a couple balls out to one side you'll be dumping fuel out the fuel tank vent on that side.

2) With the ball centered (or the wings level going straight if you don't trust the ball) you should see fuel in both sight tubes. If it's me, I'm already on the ground before either tank shows empty in coordinated flight... and I think I have both the longest duration and longest distance legs of any stock CT.

Mike Koerner

[Ed Cesnalis]

2 hours ago, Mike Koerner said:

Ed,

You can't skid without turning. If you correct for the turn with the ailerons then you're slipping.

 

Too little bank for the turn vs too much bank for the turn.  Your saying that only one of those definitions still fits when holding course and the other does not?

IOW you are saying if you are holding course and if your wings are level your nose has to be in the wind because you cannot skid without turning.

Its true If I pull my ball of center with rudder when cruising and set up a skid my AP will have to counter with bank but its only true after a point.  At first lets say at 1/2 ball vs a full ball I can skid along and not initiate a turn.

I'm not saying your wrong on this I'm just trying to understand.

When setting my rudder for cruise and then setting the trim why would I stop at a centered ball?  I can go a  bit farther and see the skid forces begin to effect the ball before any counter bank is needed (perhaps only 1/2 ball).  Is this area past the centered ball but before counter bank begins not a skid?

 

 

[FredG]

I believe Mike is correct.  No turn, no skid.  If you are "holding course" then the airplane is not turning.  If the airplane is not turning, then the definition "too little bank for the turn" does not apply.  

 

[Ed Cesnalis]

 

13 minutes ago, FredG said:

I believe Mike is correct.  No turn, no skid.  If you are "holding course" then the airplane is not turning.  If the airplane is not turning, then the definition "too little bank for the turn" does not apply.  

 

 

7 hours ago, Mike Koerner said:

You can't skid without turning. If you correct for the turn with the ailerons then you're slipping.

 

 

Yes Fred and Mike and I can now see it.  There is such a thing as too much bank for a zero radius turn but there is no such thing as too little. Zero is an absolute minimum here.

In practice however it sure seems as though I can.  Rudder will initiate a turn with bank but a small amount of rudder just disturbs my coordinated flight and is evidenced by my ball.

Try for your self  From coordinated flight use your rudder to begin skidding a limited amount with the AP and see if you can succeed at this without the AP needing a correction.  

[FredG]

Done it many times.  With AP on, application of rudder will initiate aircraft movement around the yaw axis (and a change in heading, a maneuver called a skidding turn).  With constant rudder deflection, AP will bank wings ("opposite" to yaw) to return to constant heading (and stop the turn).  This configuration is a slip.  

[Ed Cesnalis]

36 minutes ago, FredG said:

Done it many times.  With AP on, application of rudder will initiate aircraft movement around the yaw axis (and a change in heading, a maneuver called a skidding turn).  With constant rudder deflection, AP will bank wings ("opposite" to yaw) to return to constant heading (and stop the turn).  This configuration is a slip.  

You and Mike and Tom are correct.  Skidding means turning by definition.

One can still transfer by skidding but you are now zigzagging in cruise to do it, tacking like a sail boat.

I can be fooled in the Eastern Sierra where wind shear is generally present and no matter what I have to turn left and right to hold course.

[Ed Cesnalis]

By definition we cannot transfer while holding course with wings level.

We can however choose to slip or skid but we must use bank.

Transfer from high wing to low use a slip.

Transfer from low wing to high use a skid.

In a fuel emergency don't overthink it just keep the remaining fuel visible and have that sight tube in your scan until you land.

[WmInce]

6 hours ago, Ed Cesnalis said:

 . . "In a fuel emergency don't overthink it just keep the remaining fuel visible and have that sight tube in your scan until you land."

Bingo!

Another, simplistic, nugget of CT wisdom.

Well said Ed.