[gilbernl]

Turning is simple huh? Roll left or right and there ya go...or not. It's time you got coordinated.
To begin, let's look at the physics of the various types of turns. There are 3 types of turns one makes in a plane:

Shallow turns- Where the bank angle is less than 20 degrees. In these turns, the inherent lateral stability of the plane will try to right the turn. To avoid this, constant aileron input must be applied to counter this.
Medium turns- Where the bank angle is between 20 and 45 degrees, and the lateral force of the turn counters the lateral stability of the plane.
Steep turns- Where the bank angle is greater than 45 degrees, and the "overbanking" tendency of the airplane overcomes lateral stability, and increased aileron is required to maintain control.

Great...I've told you something you already knew...well here's the kicker:
In left turn, for example, the left aileron goes up, and the right goes down. Well the right aileron being down increases lift causing the right wing to lift, but also has increased drag. This asymmetric increase in drag causes the plane to want to yaw to the outside of the turn circumference. (See diagram below). The greater the bank angle, the stronger this force is. This condition where the plane pulls outside of the turn is called skid. Also, when turning, the plane will have a tendency to loose altitude. Applying the appropriate elevator input before entering the turn will alleviate this condition.
 turnforces.png (138.59K)
Number of downloads: 21
But we're still skidding, so how do we fix this? As you enter the turn a coordinated application of yaw to in the same direction of the turn will establish a coordinated turn. Now, this is a tricky thing to get just right. If you apply too much yaw too soon, the nose will "swerve" out of proportion to the bank. Too late, and skid will occur, and require yaw correction.

In a real plane, you would be able to feel skid and slip, in XP we use the Turn coordinator. In the second image, you can see the different turn conditions, and the resulting force you would feel in a real plane.
 slipskid.png (124.6K)
Number of downloads: 49

So why care about being coordinated? First, it is necessary to conducting efficient turns in level flight. Not doing it will require you to continuously increase bank angle as the turn progresses in order to maintain the appropriate turn radius. If making a large turn, this can be impossible because you can only bank so far. Second, without coordination, constant pitch corrections will be required to maintain altitude. Finally...its how its done.

So get coordinated!

-Nick

Images taken from FAA Airplane Flying Handbook 2004

[KennyV'94]

Just a note about being coordinated, this is especially important in low speed conditions where you are near or there is a potential to be near a stall. If you inadvertently stall during a non-coordinated turn (or even if you are flying straight and level, but not coordinated, i.e. if there is a heavy crosswind at low airpspeed) the chances of entering a spin are very high. For instance, you wouldn't want this to happen on final, eh?

Just something I thought was worth adding.

-KV

[loganmccl]

KennyV'94, on Jul 14 2008, 04:43 PM, said:

(or even if you are flying straight and level, but not coordinated, i.e. if there is a heavy crosswind at low airpspeed)

The crosswind wont have an effect on coordination for straight and level flight at any speed (in a xwind landing you are cross control is a necessity so you carry a little extra speed to mitigate the risk of a stall). The slow flight it self will have an effect on coordination though (in especially in a single engine at high power settings as in a Vx climb-out or a go around) As the angle of attack increases the aircraft will pull to the left and should be countered with right rudder (during training a the most common words out of an instructor are typically "right rudder"). You could climb out with the ball out of center but it is really not very efficient. In my own tests in 37T I loose from 50-150 fpm in the climb if I don't coordinate. During cruse the plane should be well trimmed (if it does not have a rudder trim in the cockpit it probably has a bind-able aluminum tab on the rudder) so the rudder pressures should be very light. During decent slight left rudder may be warranted.

[DonkMcGonk]

thanks so much!!
but one last question, how do you hold at a point if ATC says so?

thanks,
Donkmcgonk

[Tibor]

Hello Guys,

I can see there is not too much activities in this topic since a long time, so lets shake it a bit

I fly with the MSFS since 10 years and in real life on C152 since 2 years. Now i just have received my x-plane and we try get in touch with each other

Concerning the rudder what i experience the x-plane all the time does a perfect coordinated turn without using my pedals. I have a Saitek pedal, also i had the set-up procedure and assignment in the settings (yaw), but with all plane (C172 included) the ball remains on the middle without using the pedals. Of course if i check the rudder surface from an external view i can see the movements as i use the pedal.

As i would like to practice on the x-plane a bit i would like to use the rudder as real as it is possible, but now for me it looks like "autorudder".

Any similar experience, suggestion?

Thanks,
Tibor

[gilbernl]

How is the plane you're flying configured? (IE: speed, amount of turn, flaps etc) I fly 152's as well, and I can tell you that the rudder pedals in the 152 require almost no input for coordination, if any. The plane is inherently incredibly stable, and tends to coordinate itself rather quickly. Also, keep in mind that when flying a real plane, the feedback you feel from the pedals makes you "think" you're depressing them further than you really are.

Case and point: When flying at higher speeds (IE maneuvering speed), you typically don't use/don't need the rudder in a 152...172's can be a bit of a different story, as can other non-high-winged acf.