5
$\begingroup$

I have been confused about the relation of yaw and pitch in propeller powered aircraft. When such an aircraft is pitching up, will it yaw to the left or right? Conversely, when it's pitching down, which way will it yaw?

When I try this out on X-plane, the plane turns left when I take off. However, some online material insists that the plane will yaw to the right when I am pitching up. This is confusing me. What's the best explanation for this?

Improve this question
$\endgroup$
1
  • 4
    $\begingroup$ You need to know the direction of rotation of the propeller. There is no right or wrong answer when that detail is unknown. Look for answers in a search for p-factor here for an explanation. $\endgroup$
    – Peter Kämpf
    Mar 7, 2016 at 7:14

2 Answers 2

Reset to default
6
$\begingroup$

How does yaw relate to pitch?

There are four forces at play on a single engine aircraft that can cause turning tenancies or Yaw.

The main reason a single-engine propeller aircraft yaws left at T/O is due to Asymmetrical Thrust (P-Factor). At high angles of attack the right side of the propeller disc creates more thrust than the left side and this causes Yaw to the left.

Gyroscopic Precession causes a yaw to the right when an aircraft is suddenly pitched up(tail is lowered or nose is raised) and a yaw to the left when an aircraft is suddenly pitched down. (tail is raised or nose is lowered). This force is only apparent while the aircraft's Pitch is changing, once the pitching action is stopped, the force is gone. (not present in a steady nose up climb)

Slipstream effect causes a slight yaw to the left, and slight roll to the right.

Engine torque causes a roll to the left.

Most single engine aircraft today have a clockwise spinning propeller. All these forces would be the opposite if it were a counter-clockwise spinning propeller.

A more detailed explanation can be found here: Turning Tendencies

enter image description here

enter image description here

enter image description here

Improve this answer
$\endgroup$
4
  • $\begingroup$ This answer has all the right information in it, but I feel that it could be improved by highlighting those forces that are directly related to pitch change, as the OP asks. $\endgroup$
    – J W
    Mar 7, 2016 at 13:33
  • $\begingroup$ pitched up (tail is raised or nose is lowered) ... pitched down (tail is lowered or nose is raised) I'm not sure your parenthetical statements match the ones before them. Did you get those reversed or am I misunderstanding something? $\endgroup$
    – FreeMan
    Mar 7, 2016 at 13:35
  • $\begingroup$ Yes, I got it reversed. I have corrected it now. Thanks. I have also highlighted the sections pertaining to pitch and yaw. $\endgroup$
    – Mike Sowsun
    Mar 7, 2016 at 13:50
  • $\begingroup$ I had been reading up about the effects caused by forces at play but did not realize that these are different forces. I had gyroscopic precession and p-factor mixed up - this cleared everything for me. Specially fig 17-45. Thank you very much! $\endgroup$
    – atlantis
    Mar 8, 2016 at 1:32
0
$\begingroup$

From personal experience when pitching up on climb out after take off, I have to apply right rudder because the aircraft wants to yaw left. I've been told its because of engine torque at high power and slow speed.

Improve this answer
$\endgroup$
4
  • 1
    $\begingroup$ Why did this answer get a down vote? It looks okay to me, and if there is something wrong with it, I would love to know why. $\endgroup$
    – Zizouz212
    Mar 7, 2016 at 2:27
  • 2
    $\begingroup$ The main reason a single-engine propeller aircraft yaws left at T/O is due to Asymmetrical Thrust (P-Factor). Engine torque causes a roll to the left, but not yaw. $\endgroup$
    – Mike Sowsun
    Mar 7, 2016 at 10:23
  • 1
    $\begingroup$ I downvoted because this answer is incorrect. The question asks about turning tendencies related to pitch. The correct answer will include two factors: gyroscopic precession, and P-factor—(though the later is more accurately related to angle of attack, independent of pitch). Torque does cause a turning tendency, but it is entirely independent of pitch or pitch changes. $\endgroup$
    – J W
    Mar 7, 2016 at 13:29
  • $\begingroup$ Thanks for your answer. Mike's response addressed the specific question I had. Cheers! $\endgroup$
    – atlantis
    Mar 8, 2016 at 2:04

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .