What is P-FACTOR? | The Asymmetric Blade Effect 

Glad you liked it!

I had to watch it a couple times to fully grasp the concept. It’s short, clear, and concise.

Thank you! Cheers!

Gyroscopic precession is only a factor when changing pitch or yaw (but you never notice it during yawing moments). Once you're on-pitch gyroscopic precession ceases. For example consider a helicopter going so impossibly fast that it's got retreating blade stall. Will the helicopter roll to the side of the stalled retreating blade? NO! It will pitch UP due to gyroscopic precession.

That's interesting that even at such small scale this effect is evident.

@@flightclubonline i think it has such an effect because the planes are so light

Oh I see. This makes sense. Thank you!

Pilot? Oh ok

​​@@kuartz.I think some planes actually did that (keyword: did, not anymore)

Bill Kershner defines P-Factor as "Propeller Disc Asymmetric Loading" in his book "The Advanced Pilot’s Flight Manual (6th Edition)". I am fairly certain that P stands for propeller as P-factor cannot exist without a rotating disc of some kind.

Another thing that I think it's a fun fact, is that P is one of the letters that isn't mirrored in any way. So it could represent an unbalance

@@afoxwithahat7846 p and q are often depicted as perfect mirror images of each other in lowercase. My kid (and many others) initially had a very hard time seeing the difference between the two

@@afoxwithahat7846 interesting but i dont think someone thought that far 😁

@@afoxwithahat7846 P also is the first letter of Pilot, and they can be unbalanced sometimes. 😉

Sorry to hear that.

Thanks for the most simp and irrelevant comment on RU-vid.

Yes, of course you can. What is the name of your channel?

@@flightclubonline it will be "Emin Bayar" again.Thank you :))

At 1:30, the white line is the up-going blade's relative airflow. The green arc (that looks like a line) is the up-going blade's angle of attack. That's my fault. I should have made the images bigger.

@@flightclubonline No, the images are fine, I just did a little sketching of airflow and pitch myself and get it know.

You are right. This video’s explanation is wrong. Both ascending and descending blade’s AOA are not that different. The only thing changes remarkably by P-Factor is each blade’s strength of the relative wind. As the descending blade’s relative wind, which is perpendicular to the propeller shaft, is combined with the airspeed(airplane’s relative wind), the descending blade’s AOA decreases and its relative wind vector increases. On the other hand, the strength of ascending blade’s relative wind doesn’t change that much while the AOA decreases. As a result, AOA on each side of the propeller remains similar but the descending blade’s strength of relative wind becomes bigger. I don’t know if you could check my writing but i can e plain it with a picture if you message me.

You're so welcome!

Glad it helped!

The force (really) moment on a spinning object isn't transferred 90 degrees ahead. That's a misconception about how gyroscopic motion works. For a free (or nearly free) rotating body, like a helicopter rotor, the spinning body precesses when a torque is applied. It's a nice mnemonic to say that the force is transferred 90 degrees ahead, and that gives the right prediction of which way the body will precess, but it's not that the force is somehow redirected. For example, if you were to attached the axle of a bicycle wheel to a rigid load cell (a sort of electronic scale), and applied a force to the rotating wheel, the load cell wouldn't measure the force as occurring 90 degree out of phase with the application, it would measure it as occurring just where it was applied. But if you were to hold the axle in your hand, and apply a torque to the axle, the wheel would precess in a direction apparently 90 degrees out of phase with the application of the force. In the case of a propeller aircraft, if the pilot applies controls to keep the nose pointed in a fixed direction, there is no precession, and so all the forces must be in equilibrium. That means that an aerodynamic moment (right rudder) must be applied that exactly counteracts the P-factor.

Glad it helped

If the prop shaft is tilted upwards, the down going blade does travel further. Greater the angle+airspeed greater the thrust difference

It actually does. When you apply higher power settings in order to accelerate but still at a low speed the gyroscopic effect is amplified

Thank you kindly!

Glad it helped! Good luck.

That's too bad. No student pilot should ever have to endure a flight instructor who can't explain something as BASIC as p-factor.

It seems it has to do with the plane's fly path. If it's not perpendicular with the motion of the propeller, there's a difference the angle of attack due to different airspeed. An airplane doesn't always travel in the same direction of it's propellers. As for the helicopters, they can alter the pitch of the blades with the cyclic to correct any imbalance. 1:07

I"m not a former aerospace engineer, but I think this phenomenon has more to do with the gyroscopic energy.

It is when the plane it self traveling horizontally but the nose is pointed up. (In reality when going slow the nose is gonna be pointing higher the the direction of travel) Helicopters have something called swashplates what account for movement which automatically changes the angle of attack of the blades to avoid it

I don't think that it changes based on the direction the plane is flying, but during the moment in which the airplane is changing its pitch angle. We know that the tendency of the airframe is to rotate around its CG, therefore the bottom blade will travel a longer distance when pitching up, or a shorter distance when diving the airplane. The moment that the rotational movement around its CG stops, the blades will match the AOA once again.

@@DiamondBlade_101 the helicopter compensates for the forward speed. The advancing blade will travel through the air faster than the retrieving blade. The system compensates for the difference by increasing the angle of attack of the retrieving blade, otherwise the helicopter would have a tendency to roll left the faster it goes.

Thank you so much for your feedback.

Happy to help!

While you did a good job explaining the spiraling slipstream cause of left turning tendency, it doesn't belong here as P-Factor and Spiraling Slipstream are entirely different causes of left turning tendency.

Thank you for the kind words.

Awesome, thank you!

You're most welcome

You're welcome

Thank you for your feedback.

Thanks!