7
$\begingroup$

I was taught to make steep turns with the ball centered, but this seems wrong to me. Shouldn’t the ball actually be held slightly to the inside of the turn?

My thought is that by using some cross-controlled rudder, the elevator pressure can be reduced, reducing the angle of attack and making the turn safer.

Essentially, in a 45 degree turn for example, a standard tail aircraft is turned into a V-tail. Pulling on the elevator is only half effective in keeping the nose up, the other half of the force goes to turning faster.

A knife edge is the extreme form of this, where the rudder becomes the elevator completely and the fuselage the lifting surface. No elevator is used (to keep the nose up. It’s actually used as a rudder instead).

So, if keeping the ball to the inside reduces G-force and angle of attack, keeping the plane further from the stall, why isn’t it commonly taught?

|improve this question
$\endgroup$
  • $\begingroup$ Slips are done as standard practice in large aircraft every day $\endgroup$ – Greg Taylor May 11 '17 at 10:28
  • 4
    $\begingroup$ It's rather irritating that people keep changing my question to something that completely misses the point of what I'm asking. I'm not sure if my point isn't clear or if people changing my question is confusing people to what my point is, but I give up and will stop trying to fix my question to be what I actually am asking. $\endgroup$ – Greg Taylor May 15 '17 at 10:49
  • $\begingroup$ I am seeing your comment only now. We like titles to be actual questions, and most of the edits try to obtain such result, while your edit reverted the title to a statement. See this meta discussion for some background on that decision: aviation.meta.stackexchange.com/q/1485/1467 $\endgroup$ – Federico♦ Dec 18 '17 at 8:52
9
$\begingroup$

Coordinated flight, even in turns, will minimize drag.

Therefore, there is no efficiency gain by uncoordinated flight, in turns or not.

Therefore, rudder input should be as required to center the ball.

|improve this answer
$\endgroup$
4
$\begingroup$

In writing the question, I formed what I believe is the answer, so I’m going to post it as well.

Using rudder to hold the nose up to perform a steep turn for the sake of performing a steep turn probably is a good idea. It would reduce ange of attack and g-forces felt by the passengers.

However, doing this type of steep turn serves no purpose other than demonstration. In practice, a steep turn is performed in order to change direction quickly. If rudder is used as described in the question, the rate of turn is decreased, and a steeper turn would be needed to turn at the same rate. This steeper turn would result in the same angle of attack as would have been necessary without using the rudder.

There’s no getting around the physics. In order to turn X degrees in Y minutes, it will require an angle attack of Z. You can’t change direction in the same amount of time without pulling the same g’s.

Being uncoordinated during a steep turn increases the odds of a spin. Introducing an unfamiliar rudder control into the steep turn, without any actual reference to “how much” rudder is needed, it actually increases the odds of performing the turn wrong. Therefore, it’s better to do a standard steep turn keeping the ball centered. Furthermore, practicing anything else will reduce your ability to do it safely when needed, so even for demonstration purposes, it’s not a great idea to practice it.

|improve this answer
$\endgroup$
  • 4
    $\begingroup$ Using rudder to hold the nose up to perform a steep turn for the sake of performing a steep turn probably is a good idea. I think you should be referring to having a high bank angle, not a "steep turn". Whether you are turning or not is quite irrelevant to the maneuver (or well... you are performing aerobatics, so a different set of rules apply); as you conclude later on, turning for the sake of turning should be in coordinated flight, with bank angle adjusted to the desired rate of turn. $\endgroup$ – Sanchises May 8 '17 at 15:18
  • $\begingroup$ Other terms for this maneuver is skidding turn vs slipping turn. The amount of energy consumed in a turn is reduced when the turn is coordinated. So technically, your physics analysis should include that an uncoordinated turn takes more energy to accomplish. With respect to the steeper turn requiring more angle of attack than would have been necessary without using the rudder, I am not sure that statement is true. If skidding or slipping, you may need a greater angle of attack for the same turn rate. $\endgroup$ – mongo May 9 '17 at 13:39
  • $\begingroup$ I'm not describing a skid, I'm describing a slip. $\endgroup$ – Greg Taylor May 11 '17 at 10:28

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.