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knife edge triming help

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Old 10-24-2011, 08:21 AM   #1
 
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Default knife edge triming help

I'm having a bitch of a time getting the mixing done prperly on my 33% pitts.

Once in knife edge it pulls hard towards me. I am always fighting to keep it level.

Which way do i go with the mixing. I am currently using a futaba 9c if that helps.

Any insight on this is greatly appreciated.

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Old 10-24-2011, 08:35 AM   #2
 
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Default Re: knife edge triming help

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Originally Posted by flysrc33 View Post
I'm having a bitch of a time getting the mixing done prperly on my 33% pitts.

Once in knife edge it pulls hard towards me. I am always fighting to keep it level.

Which way do i go with the mixing. I am currently using a futaba 9c if that helps.

Any insight on this is greatly appreciated.
I remember doing it on my 10C, so maybe I can help.

You need to go to the P-Mix section. Use rudder as master, elevator as slave. Then I would think you mix down elevator on the rudder curve, maybe it's a 5 point curve for the 9C, it is on the 10c. I'd start at something like -5% and -2% and 0 for the curve points, 5 being at max travel of the rudder. That's a start for you at least. You can also do a P-mix on ailerons to rudder if necessary after you get the elevator sorted out.

If I'm wrong, anybody on here is allowed to correct me, I think I'm right for the 9C, but not 100%
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Old 10-24-2011, 08:56 AM   #3
 
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Default Re: knife edge triming help

You are correct but in the 9C there is no curve, just a percent value. I would start at about 7 or 8 percent. It's a linear mix to the rudder, you would get the % elevator travel value programmed in at full rudder deflection. You'll need to test and readjust to fine tune it. If the plane moves toward the canopy mix in down elevator, if it moves toward the landing gear mix in up elevator.
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Old 10-24-2011, 11:40 AM   #4
 
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Default Re: knife edge triming help

You said it pulls towards you which makes no sense as the plane doesnt know where you are. If its pulling towards the canopy, you may just be too nose heavy. Make sure your CG is right first, then it may just be a biplane thing that you will have to fix on the radio.
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Old 10-25-2011, 05:16 AM   #5
 
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Default Re: knife edge triming help

I would go though this first....
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File Type: pdf TrimmingChart.pdf (15.7 KB, 124 views)
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Old 10-25-2011, 07:39 AM   #6
 
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Default Re: knife edge triming help

Also be aware that you need to try and maintain a similar airspeed when setting this up 'cause running faster or slower will change the amount of mix you need.

It'll probably need different settings for left to right vs. right to left as well.
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Old 10-25-2011, 09:10 AM   #7
 
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Default Re: knife edge triming help

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I would go though this first....
I've seen this chart before, prolly have it saved somewhere. I was taught that once CG, UP\LEVEL thrust was dialed, the next was flying a flat circle, both counter and clock. There is an oooold video in the archives here somewhere that SHOWTIME & SMOKIN JOE made a "How to" video that included all of these.

I've got it somewhere, Mith, TMan for sure has em, not sure when he's back from China


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Old 10-25-2011, 05:29 PM   #8
 
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Old 10-25-2011, 05:48 PM   #9
 
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Default Re: knife edge triming help

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Originally Posted by chumley View Post
You said it pulls towards you which makes no sense as the plane doesnt know where you are. If its pulling towards the canopy, you may just be too nose heavy. Make sure your CG is right first, then it may just be a biplane thing that you will have to fix on the radio.
Why does my plane pull toward the ground ...nomater what maneuver I do it wants to pull toward the ground...
Got to constantly control it to keep it off the ground..
Let off the sticks ...pulls toward the ground.
run out of gas in a torque roll ...pulls toward the ground.
Even pulls toward the ground on landings..
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Old 10-25-2011, 07:50 PM   #10
 
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Default Re: knife edge triming help

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Why does my plane pull toward the ground ...nomater what maneuver I do it wants to pull toward the ground...
Got to constantly control it to keep it off the ground..
Let off the sticks ...pulls toward the ground.
run out of gas in a torque roll ...pulls toward the ground.
Even pulls toward the ground on landings..
Add helium to your front tires.

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