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Adverse Yaw

Old 02-27-2004, 06:02 PM
  #1  
billh34
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Default Adverse Yaw

I have a GWS E-Starter that when banked right (using the ailerons) yaws left. Banked left it yaws right. Is there a simple way (using one servo) to reduce the "down" aileron throw without changing the "up" throw? Or is there some other cure for this problem? Ideas would be appreciated.
Old 02-27-2004, 07:01 PM
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crashingagain
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Default RE: Adverse Yaw

You can set the up down throws with your computer radio or if you have a regular radio you can use the circular servo arms that have the holes drilled all over the place. Throw up and down then depend on the wholes you use
Old 03-07-2004, 10:43 AM
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rcman-RCU
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Default RE: Adverse Yaw

If your servo is mounted on the bottom of the wing, the holes for the pushrods should be in front of the center of the servo arm. This will give you more up travel on the ailerons than down travel. If the servo is on top of the wing, the holes need to be behind the center point. This will correct the adverse yaw.

If you have a programmable radio, just mix some same rudder with the ailerons.
Old 03-08-2004, 02:13 PM
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SooprDink
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Default RE: Adverse Yaw

Find someone who is an AMA member that has a subscription to Model Aviation. This months issue has a good article that explains some of the "physics of flying". It explains how to compensate for these problems.

rcman has your solution. Mix in some rudder with your turns. If you dont have a computer radio then as you roll left with the ailerons, give the plane just a little left rudder throughout the turn. Just my .02 cents. Happy flying!!!
Old 03-17-2004, 01:30 PM
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billh34
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Default RE: Adverse Yaw

Thanks guys for the advice. I have moved the holes on the servo as was suggested. Now I am waiting for the snow to melt and the wind to stop to see how it works. Thanks again, Billh34
Old 03-29-2004, 10:20 AM
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Jason Beach
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Default RE: Adverse Yaw

Another good way to over come this is to use your rudder when turning. Each time you use your ailerons, add a little rudder in the same direction. A well done coordinated turn can be a beautiful thing, and it helps train you to use your left thumb for something other than pushing forward.

Jason
Old 03-30-2004, 04:38 AM
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KLRico
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Default RE: Adverse Yaw

Way too many people I know either don't know or don't care about coordinating turns with rudder. I hate flying without it.
Old 03-30-2004, 11:37 AM
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RCaillouet3
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Default RE: Adverse Yaw

The reasons for your model doing this this 2 fold. The factors are called "P-Factor" and "Gyroscopic Procession" to full scale pilots. The reasoning behind these are simple.

Gyroscopic Procession is that a gyro is constantly trying to resist motion! So that when you turn an airplane, the gyro created by the spinning of a prop, wants to continue to go stright. This results in the prop making the airplane initially want to turn outside of the turn selected (nose goes one way while plane goes another.)

P-Factor has to do with the fact that any movement induced to a spinning gyro we cause the motion to be react at 90 Degrees in rotation from the point of induced movement. An example: a tail dragger is taking off with a standard rotating engine (clock wise when viewed from back to front,) the pilot selects down elevator force to raise the taill off the ground. What happens to the airplane ... it turns left! The reason for this is that simply you are applying a forward pressure to the top of the prop disk (imagine a prop being moved from nose up tp level and you can see the movement) the resulting force on the prop disk is to move the right side of the disk forward as well, thus making the airplane turn left!

Now how do these work together? Simple. You make a bank change and try to turn. Now you are applying a force on the prpo that wants to conteract all of the things you want it to do!

Easiest way to correct for it? Simple again! Use a small amount of rudder into the turn as you are applying aileron and elevator to make the turn!

If you don't have rudder, the only thing that may work is to reduce rpm while starting the turn. This makes the prop disc have less energy and thus allows the airplane to turn easier. This has a down side though in the fact that it slows the airplane, thus bringing you closer to stall.

Hope this helps.

Reg
Old 03-31-2004, 05:35 PM
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Jason Beach
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Default RE: Adverse Yaw

Though P-factor can be an explination for many things, I don't believe it is the cause of adverse yaw. If the gyroscopics of a spinning propeller were to blame, we wouldn't see the effects until the plane started to turn, in the case of adverse yaw, the problem starts when tipping the plane in preparation for the turn.

In my understanding this is caused by one side of the wing creating more drag than the other. The cure can be to limit the downward travel on the ailerons (keeping the rudder out of the equation for now). Say we're tiping the plane to the right, the left aileron goes down forcing the left side of the wing upwards and vise versa on the right. Since it causes more drag to move the left side up than it takes to drop the right wing, you will get uneven drag from left to right. This causes the nose to yaw left. If you were to provide the left aileron with less travel down while keeping the same up travel on the right your drag will be closer to equal for each side therefore not causing adverse yaw.

Depending on the servo setup this can be difficult to set up. The best solution IMO is to learn to use your rudder.
Old 04-01-2004, 12:46 AM
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RedBarronBen
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Default RE: Adverse Yaw

BillH34,
Listen to what SooprDink and Jason Beach are saying, they know what they are talking about. RCailouet3 must be on drugs. Don't listen to him. I suspect you do too since you at least new the correct terminology. If you are a begining pilot, read on. If you are an experienced pilot and are just trying to improve the characteristics of this model, nevermind.
Bill, you could maybe use differential aileron throws or even get an expensive radio to do coordinating of aileron and rudder mixing for you, but this is the thing - if you are really interested in learning how to fly, then learn how to coordinate your turns now on this trainer. You have at least been smart enough (or lucky enough) to get a trainer with all three axis of control, take advantage of it and learn how to use all your controls. It doesn't have to be pretty at first. Try doing different things and see how it affects the airplane's flight. If it isn't making sense, ask the question or read about the mechanics of flight in some of these articles the SooprDink was talking about. One day you'll want to make a cross-wind landing and you will be glad you learned how to use both the ailerons and rudder together, but that is another flying lesson... let's not get you more confused right now!
Good luck,
RedBarronBen
Old 04-01-2004, 02:48 PM
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RCaillouet3
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Default RE: Adverse Yaw

RedBarronBen,

Sorry to tell you, but I don't use drugs! But, if you haven't noticed I AGREED WITH YOU!!!!!!! I said that RUDDER should be used for turns!
By the way, as for saying I don't know what I am doing ... well all I can say is 4000 logged hours in full scale with over 2400 in turbine powered aircraft, Airline Transport Certificate for the full scale kind, and over 100 soloed students to date on RC over the past 7 years. I don't always agree with everyone about there opinions, I merely state mine and I NEVER try to belittle others with a differing opinion than my own! I also know that there are MANY things that effect a plane, and every one of these things can be explained a different way! I don't admit to knowing everything about aviation, but I know my fair share.

Jason Beach is also correct in that the higher wing has a slightly higher angle of attack in turns thus giving it slightly more drag. I admit I had forgotten that consideration, and should have mentioned it as well. Thanks for that one Jason!


Billh34, one thing that might help is to get with a good instructor. The instructor will be able to help with this area, and give you advise right on the spot.

Reg
Old 04-01-2004, 04:41 PM
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billh34
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Default RE: Adverse Yaw

Hey guys, I didn't want to start a fight over this.

The snow has melted, the winds have slowed down some and I flew the plane yesterday. I relocated the push rods in the holes as "rcman-RCU" suggested and bought a JR XP6102 transmitter. With a small amount of rudder fed in with the aileron movement the E-Starter flies quite well, even in more wind than I feel comfortable with. Thanks all for the help and the physics lessons. Billh34
Old 04-02-2004, 11:41 AM
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Jason Beach
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Default RE: Adverse Yaw

I'm glad you got the info you needed Bill.

OK guys, lets not ruin a good thread.

Jason
Old 05-09-2004, 09:36 PM
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Default RE: Adverse Yaw

RCaillouet3,

Your description of P-factor is completely erroneous. What you did describe is one of the left turning tendencies due to gyroscopic effect, which has absolutely nothing to do with adverse yaw nor P-factor. What P-factor correctly is described as the asymmetric (uneven) loading of the up going and down going prop blades. The blade on the right makes more lift due to its higher AOA when descending than the left blade when ascending. This makes the right blade more lift thus pulling to the left; most noticeable at higher AOA's.

And nowhere did you explain adverse yaw at all. Adverse yaw is caused due to banking and the drag from aileron, thus yawing the tail in the opposite direction of the turn. (Furthermore, I would add that even what you erroneously label and describe as causing adverse yaw are really right turning tendencies of which there are more than 2 of them.)

I'm a current instrument rated full scale pilot/owner operator but you don't have to take my word for the correct info. See the links:

This is the correct description of adverse yaw and the ways it can be minimized:

Adverse yaw:

http://www.aerospaceweb.org/question...cs/q0045.shtml

P-factor:

http://www.faatest.com/books/FLT/Cha...ricLoading.htm

EDIT: to fix links


ORIGINAL: RCaillouet3

The reasons for your model doing this this 2 fold. The factors are called "P-Factor" and "Gyroscopic Procession" to full scale pilots. The reasoning behind these are simple.

Gyroscopic Procession is that a gyro is constantly trying to resist motion! So that when you turn an airplane, the gyro created by the spinning of a prop, wants to continue to go stright. This results in the prop making the airplane initially want to turn outside of the turn selected (nose goes one way while plane goes another.)

P-Factor has to do with the fact that any movement induced to a spinning gyro we cause the motion to be react at 90 Degrees in rotation from the point of induced movement. An example: a tail dragger is taking off with a standard rotating engine (clock wise when viewed from back to front,) the pilot selects down elevator force to raise the taill off the ground. What happens to the airplane ... it turns left! The reason for this is that simply you are applying a forward pressure to the top of the prop disk (imagine a prop being moved from nose up tp level and you can see the movement) the resulting force on the prop disk is to move the right side of the disk forward as well, thus making the airplane turn left!

Now how do these work together? Simple. You make a bank change and try to turn. Now you are applying a force on the prpo that wants to conteract all of the things you want it to do!

Easiest way to correct for it? Simple again! Use a small amount of rudder into the turn as you are applying aileron and elevator to make the turn!

If you don't have rudder, the only thing that may work is to reduce rpm while starting the turn. This makes the prop disc have less energy and thus allows the airplane to turn easier. This has a down side though in the fact that it slows the airplane, thus bringing you closer to stall.

Hope this helps.

Reg
Old 01-21-2024, 01:22 AM
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Wolfboy
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Originally Posted by rcman-RCU
If your servo is mounted on the bottom of the wing, the holes for the pushrods should be in front of the center of the servo arm. This will give you more up travel on the ailerons than down travel. If the servo is on top of the wing, the holes need to be behind the center point. This will correct the adverse yaw.

If you have a programmable radio, just mix some same rudder with the ailerons.
I have some questions about my rc plane servos
Old 01-21-2024, 01:23 AM
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Wolfboy
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Would anyone please give me a call or text so we can talk about my rc plane servos my number is 820-213-5733
Old 01-21-2024, 08:50 AM
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Originally Posted by Wolfboy
Would anyone please give me a call or text so we can talk about my rc plane servos my number is 820-213-5733
You might be better off starting a fresh thread for your question. A lot of us don't live in the same time zone and starting a thread will quickly get you past the 10 post threshold for being able to upload pictures.

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