trim cable question

[stamper]

I put my cables in and according to the planes the cover plate underneath with the weld on nut is supposed to be in the middle of the threaded cable end. I did that and I am about a half inch to long in order to put in the pin. I have the coupling on the end threaded as far in as I can go. Has others ran into this and did you take the cover plate off and move the cable inward or anotherwords shorten it up or do I have the adjustment wrong at the other end. It seems to me that the other end would not change anything.


any ideas for me. By the way this is a 10.. Thanks in advance

 

[Mike S]

Photo would help a lot.

 

[paul330]

The whole trim cable thing is a mystery to me. I have seen the posts on how to set it up but I still can't get the throws that are needed. It seems to me that once you manage to set the neutral position then the throw is purely dependent on the geometry of the cam and there's nothing more that can be done.

I've given up until I re-fit everything after paint when hopefully I'll have a light-bulb moment!

 

[Mike S]

It seems to me that once you manage to set the neutral position then the throw is purely dependent on the geometry of the cam and there's nothing more that can be done.

Yep. Just set it so both trim tabs are inline with the elevator trailing edges when the servo is mid stroke and you will be fine.

Whatever you do, do not stand behind the plane and have someone run the trim stop to stop while you watch the monkey motion of the tabs-----------strong men have been known to weep at the sight, and weaker men have ended up curled up in the fetal position on the hangar floor.

 

[paul330]

Well, sort of. I did that and still couldn't get the full range specified. I know it shouldn't make a difference but adjusting the end-stops does seem to affect the throw

That's why I decided to wait till after paint and start from scratch.

THINKS - don't put the words "paint" and "scratch" in the same sentence!

 

[Wayne Gillispie]

Yep. Just set it so both trim tabs are inline with the elevator trailing edges when the servo is mid stroke and you will be fine.

Whatever you do, do not stand behind the plane and have someone run the trim stop to stop while you watch the monkey motion of the tabs-----------strong men have been known to weep at the sight, and weaker men have ended up curled up in the fetal position on the hangar floor.

Yep, funny. Just don't test trim limits at anything over normal approach speeds while thinking about the twisting moment on that ONE little -3 bolt.

 

[Wayne Gillispie]

I put my cables in and according to the planes the cover plate underneath with the weld on nut is supposed to be in the middle of the threaded cable end. I did that and I am about a half inch to long in order to put in the pin. I have the coupling on the end threaded as far in as I can go. Has others ran into this and did you take the cover plate off and move the cable inward or anotherwords shorten it up or do I have the adjustment wrong at the other end. It seems to me that the other end would not change anything.


any ideas for me. By the way this is a 10.. Thanks in advance

Next trip to hangar, I will provide you with all of my "threads showing" numbers.
Took it apart for paint, went back together with my numbers and very little adjusting was needed.

I would also recommend installing either mini nutplates like I did or buying the aluminum brackets for attachment to the trim plates. Much easier to install/remove.

Another thing, if you have not ground your pitch and roll limits...go with Van's recommended minimum degree setting. Otherwise panel, mixture, throttle, leg clearances may be tight like mine, as I went with max.

 

[rleffler]

I put my cables in and according to the planes the cover plate underneath with the weld on nut is supposed to be in the middle of the threaded cable end. I did that and I am about a half inch to long in order to put in the pin. I have the coupling on the end threaded as far in as I can go. Has others ran into this and did you take the cover plate off and move the cable inward or anotherwords shorten it up or do I have the adjustment wrong at the other end. It seems to me that the other end would not change anything.


any ideas for me. By the way this is a 10.. Thanks in advance

The other end does have an impact. I had to make adjustments to both ends to make mine fit and work correctly.

 

[stamper]

Thanks

Thanks for the help. I was able to find a post and I think got it all done correctly. It was late at night when I got done but a good feeling.

 

[paul330]

The other end does have an impact. I had to make adjustments to both ends to make mine fit and work correctly.

Odd isn't it?

The servo is fixed to the cam and has a limited throw. So once you get the servo neutral and get the tab neutral, you would think that would be that.

Weird. Still can't work it out despite all the posts about it.

 

[paul330]

Aircraft is back from the paint shop and I started fitting it all back together. So, with the HS and elevators on and throws correct, I set about the trim again. I still couldn't get the throws I needed. Despite everything, I was consistently 6 degrees short of spec.

I thought I may be losing movement in cable flexing so tried tightening up the sheath - no difference. Moved the end stops - no difference. Starting rigging in the middle, top, bottom - no difference. Still 6 degrees short.

So I decided to apply logic. As I have said before, the movement and geometry of the servo and cam is fixed - there is no adjustment. So, if the throw is short, then it has to be the servo mechanism itself. Look at the plans, look at the servo assembly - light bulb moment! I had the connector from the servo to the cam up-side down

Servo out, turn it around, refit. Thirty minutes later it all works as advertised.

Sigh...........