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Long-EZ, moving PTB?


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I'm still working on my instrument panel, yesterday, the wiring was completed, so I decided to put up the canard to check if there was no contact against wire. I was very desapointed to discover that the "PTB" (the part where you have the pitch trim springs fitted, on the left elevator) jamed the normal movement of the pitch by touching the radios case.:mad:


Ok, I have 2 solutions:


-redo all my instrument panel, that really means a lot of work

-move the famous PTB on the other side of CS2 by inserting a piece of aluminium in order to move away the PTB of 1/2 inch.


What do you think about this last idea? Is it change something with safety? I believe no, the springs will be closer the frame and there is enough room to permit the PTB moving completly.


I would be happy to take advantage of your experience.



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What brand/model of radio are you installing? The Garmins are like 12" deep. Maybe if you went with a Becker [smaller depth] or a Narco.

Or maybe mount the pitch trim along the elev torque tube in a diff place?

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I have KX 125, KY97A...


Of course, if I change the radio with becker or something like that, I will have the correct space.... But it is a solution out of range with my money ;)

No room to change the place of the pitch trim...


another idea is maybe to move aft the complete instrument panel, I will check tomorrow!



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I never liked that spring system anyway. Are you familiar with the fiberglass pitch trim spring originated by Bob Davenport? Maybe you could go to that.



Here's another diagram. I could not find a good photo on the web. Bottom of the page here.


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I have this one---except for a Cozy:




Works great---have had no issues. I like the PWM (pulse width modulation) so that I can change the pitch trim drive speed. I use full speed trim for takeoff and landing---and dial it back quite a bit for cruise. Gives you very fine control.


The "fiberglass" spring may be more elegent since it can't bind----but I have never had my pitch trim bind either (but it does have the potential).

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I'm not sure if your talking about a LOngEZ?


Anyway, one of the mounting methods for the Strong Pitch system is to attach it on the right side, and it clamps to the elevator push/pull tube.


However, I installed the Strong system on the left side using the original bellcrank thats installed on the elevator. This required adding another bellcrank so the Strong actuator points backwards.


I wanted to install it on the left side to achieve some degree of control redundancy.


If its just the aft portion of the PTB thats hitting, something like this may work for you, as I don't use the aft (upper) part of the PTB, only the forward (lower) part.


Look here for a short writeup and photos;





I've been flying with this configuration for about 40 hours, I like it.


I use the pitch trim a lot during Takeoffs/langings - When my main gear is retracted/extended, it significantly changes the pitch of the plane. I've learned to hit the pitch trim up/down for about three seconds when I lower/raise the gear.



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Good evening, many thanks for all your advices


I spent the afternoon brainstorming a solution... I don't want to work several days on this problem.


Now, it is clear that put a part of aluminium in the left side of the CS2 where I could screw the PTB is not a good idea because the elevator cannot move normally.


So, one of my friend cut into a aluminium piece a new PTB. On the elevator tube, there is just enough room to put this new part with 2 or 3 rivets.


I hope to be able to post one pic tomorrow, Id like to have your opinion about this modification.



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The pitch trim I put together is straight off of the Berkut drawings. The system uses a 1/2 inch tube over the 3/8ths inch tube. The springs go over that.


That is the Berkut page in the background.

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Hi there!


Modification is working, now the elevator can move completly without the new PTB entering in contact with any obstacle...


Here below some picture of the new part that I riveted in the tube of the canard.


What do you think about this modification? In my mind, there is no problem with safety...



Posted ImagePosted Image



Posted ImagePosted Image

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