Understanding P-Factor
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- Опубліковано 21 вер 2024
- This video is about P-Factor, I use terms interchangeably like thrust and lift in the explanation, so feel free to comment if you think the words don't jive up.
The one thing that you need to keep in mind about Asymentrical Trust (P-Factor) is that it is solely dependant on the pitch. If you increase your angle of attack (AOA), you will encounter P-Factor. When the airplane has a positive AOA, you will have a higher thrust on the descending blade(s). When the AOA is negative, the ascending propellor blade(s) will produce a higher thrust.
Please keep in mind this is only for powerplants that spin the propeller to the right from the pilots' perspective.
Thank you so much! As a visual learner, this video finally solidified the text!
This is the best explanation I've seen so far to teach CFI applicants how can they explain P-factor in the most effective method.
Wow, I've spent so much brainpower trying to understand it. After 8 minutes I've got it. Brilliant explanation. I can't wait to see and hear more from these videos!! BRAVO
Gosh that was so much better than the From the Ground Up section on it. Thank you much!
Amazing. I'm doing my airline pilot exams and I've read the text 50 times and didn't get it. In 6 mins I could teach anyone what P factor is now.
This is by far the best explanation I've seen anyone give!
your applicant explanation was literally my instructors explanation. And thats what got me to this video, not knowing WHY P-Factor is a thing.
But, why does more thrust on the right side create a left turning tendency?
@@TaylorShawn With more thrust on the right than the left, the right side of the prop (and plane) is being "pulled" forward faster than the left side of the prop/plane. This will cause the airplane to turn left. Think of it as the right wheels on your car spinning faster than the left wheels. I hope that's a helpful analogy.
@@GamblerBE very helpful actually. Thank you for that.
you just made my day! I have been trying so hard to understand it and it finally came together. So THANK YOU SO MUCH.
Nicely done, sir! Keep them coming. Should have my first students in a couple weeks!
Best explanation ever! Great job as always
Thank you so much, I read the p- factors explination in diferent books and on the web but now i really understand it!! Good!
What a great explanation!
I never understood WHY na HOW the descending blade grabbed more air until you line it up with the camera and created that visualization. THANK YOU
With the aircraft pitched up, the greater resultant velocity of the downward moving prop is causing the greater lift on the downward (right) side. The downward prop has a forward velocity component (it moves down and forward), hence a greater resultant velocity. The retreating prop is opposite, hence a lesser resultant velocity. The video's description of propeller AOA is inaccurate. An increase in aircraft AOA does not mean an increase in blade AOA.
Ref: PHAK Ch. 5
Got it - please check your reply, because you start off by stating that "when the aircraft is pitched up" and then end by stating that "an increase in aircraft AOA does not mean an increase in blade AOA". I've read all of the books, and articles, and heard every way you could possibly imagine someone present this.
Let me quote from the scripture "When an aircraft is flying with a high AOA, the “bite” of the downward moving blade is greater than the “bite” of the upward moving blade. This moves the center of thrust to the right of the prop disc area, causing a yawing moment toward the left around the vertical axis. Proving this explanation is complex because it would be necessary to work wind vector problems on each blade while considering both the AOA of the aircraft and the AOA of each blade." PHAK, Page 5-32
Stop trying to make this so complicated. Give those formulas to a new private pilot student, and you'll be scrapping brain matter off the back of the classroom wall.
@@ToddShellnuttCPC Agreed - edited comment to remove formulas. Essentially all I'm saying is with a pitch-up attitude, the blade's rotational plane tilts back, so viewing the angle of attack straight on as demonstrated won't give an accurate picture- you'd have to tilt your head too. However, the increased relative velocity in forward motion effectively gives the same result... just arguing technicalities.
Very nice video! Well explained and funny!
Overall very clear. I will say that maybe emphasizing that it is all with relation to the relative wind, therefore relative with AOA, not necessarily where the nose is pointing. So if you are in a slower speed steep turn, it will show up there too.
Thank you so much for the explanation!
brilliant explanation, thank you.
i finally understand it! thanks cfi pro!
I slammed that Like button AND the SUBSCRIBE button too! Thanks for keeping the funny bits and rolling with it! More Examiners and CFIs should be like you! Hugs from South Texas Flying Club in Corpus Christi, TX KCRP!
Thank you, Todd!
Thank you for posting this and your other videos.
Very helpful
When pitching up the relative wind should also be coming at an angle towards the propeller. And not straight and parallel with the ground?
In the video, I am talking about the airplane being still on the runway right before rotation. In this case, the direction of flight is straight ahead and parallel with the ground. Relative wind is associate with the flight path. If we were off the ground, that would be a different story.
Thank you!
I only start to understand P-factor, after I took the T/W training!
thank you very much , better that 1000 words in text
Awesome stuff!
Love it your funny but well explained
Best explanation ever!
I like the introduction! I had to stop laughing before I could comment... I don't know how many people have tried to explain "P-Factor" like you mimicked...lol Great job, thanks for keeping it short! When are we going to see PAST?
Thank you for that explanation!
Would it then follow that on descent, the thrust would be asymmetric, but in the other direction? I don't have a propeller in front of me to visualize what that would look like.
You are correct. It would then be a right turning tendency. Watch you turn coordinator in your next sescent, you'll see!
@@toddshellnutt540 Wow, thank you for the reply! I'm not a PPL student yet, so I don't have an aircraft to try this on yet!
I'm trying to fully think through what would happen on the descent, but I don't want to presume that you would answer. (Maybe someone out there could?) Other than P-factor, which we just discussed, I'm guessing the following would also happen on descent:
- Gyroscopic precession would also create a right yaw.
- I'm guessing the prop's slipstream is not going to be very effective at a decreased speed.
- I'm guessing the propeller's torque will always create a leftward yaw because the prop's spin never changes direction. However, it would be diminished because the engine is throttled down.
So is it fair to say that on descent, you experience a slight yaw to the right that's not as strong as the left yaw you get on takeoff?
Every source I look at uses the same ten words to describe these concepts, but nothing takes it apart the way your explanation did. So thank you!
@@tedsword
- Gyroscopic Precession would be a left-turning tendency, but only during the initial pitch down position, as it is only present when changing the pitch attitude. During takeoff, it is only a left-turning tenancy for a conventional gear airplane.
- The spiraling slipstream would still produce a left-turning tendency, just now as much, since it is dependant on the rotational speed of the prop.
- Torque would stay the same, and you're correct it would be diminished if you reduce the power.
Hope this helps!
@@toddshellnutt540 Thank you again for your reply. As someone who is genuinely trying to understand these concepts rather than regurgitate them, I really appreciate it.
I read your reply, but got really hung up on gyroscopic precession and had some things backwards because a lot of other videos I've seen have left out juuust enough detail to make it confusing.
Now that I finally get it, it's really easy to understand. But it took a long time to clear that mental hurdle.
I know other comments have been calling for more videos on other forces. If you ever have the time, I think it would be great!
Thanks again for your help!!
So does that mean P factor doesn't occur in fixed pitch prop?
You say near min 5 that in order to have asymmetric thrust you change the blade angle.
You change the blade angle by adjusting the pitch of the airplane.
this is so accurate! specialy 1:10, so funny
Hey Todd, Is there any way you could explain why the descending blade has a higher AOA instead of the ascending blade when pitching up? and why can't it be the ascending blade which has a higher AOA?
Then why do i need right rudder while on the runway?
Due mainly to torque. The airplane is wanting to roll onto the left wheel, which acts similar to a breaking effect.
@@ToddShellnuttCPC My CFI demonstrated that by standing in front of the plane. If you are standing in front and you'd pull the plane with only one side of the propeller, which way would it go?
You might need right rudder on the runway if you're flying a tailwheel aircraft because the nose is already pitched up, unless or until you raise the tail.
Whenever we rotate, wouldn’t the prop be facing away from the ground rather than towards the ground?
ChrisFeuerborn Are you looking at the video from left to right or from right to left? The airframe is understood to be on my right hand.
😅😅😂😂 ... Great Humor