Trimming out the plane?

25 posts in this topic

Posted (edited)

The last two flights as I'm staring to relax a little and starting to play with the trim. I have noticed that I'm constantly correcting for a left wing low tendency by pushing the stick to the right. Sometimes when I slow the plane down is much more noticeable.  

Have any of you experienced this? Can I adjust the controls or wings to counter this issue? I was going to dig back into the builder manual this weekend and see if it says anything about trim adjustment. 

Edited by NorthIdahoAvidflyer
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Posted (edited)

The left wing has an adjustable strut on the rear attachment at spar.  That could be a place to start but have others confirm before you proceed.

Edited by lv2plyguitar
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Posted

You could check your wash out with a 4' level to see if both wings are the same.  Another thing I've seen that same thing at times in one Avid or another.  Pulling in just a little bit of flaps made it go away.  Not sure why, but it worked.  JImChuk

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Posted (edited)

Do a quick check and engage a tiny amount of flaps and see if the problem doesn't go away. I have found with my Avids that if the flaps are set too flat or slightly reflexed that a wing can become heavy. if applying a tiny bit of flaps makes the problem go away, you may just need to adjust your "flaps up" to mean a bit of flap engaged.

I have run in circles before trying to adjust the wing only to run out of travel on heim, and found that engaging just a bit of flaps centers the plane and I can re-adjust the wing for level with the heim. 

I really don't know why this happens other than maybe when the flaps are totally flat, the p factor makes one deflect up and the other down from the play in the system, and having just a bit of flaps engaged overcomes this. That is speculation only and may not hold up to critical thinking, but I have definitely observed heavy wing before when flaps are super flat / reflexed.

Edited by Chris Bolkan

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Posted

I wrote my response before completely reading others' replies. I see Jim has observed the same thing regarding flaps. On my Fat Avid there is a lot of play in the aileron cables and setting the flaps for flat static on the ground, they end up reflexed in flight and I have a heavy wing. I set my flaps to look engaged pretty substantially on the ground, but in flight a look outside they look good and it flies well with no heavy wing.

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Posted

Chris you bring up another interesting thing I have noticed. My Dad had an A model Avid. It was very light and nimble on the controls. This new plane feels very wing heavy. I was kinda bummed that it didn't have the same feel as the ole A. I contributed it to the heavier plane and the extra weight in the wings. maybe this is a different issue???

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Posted

Maybe is is the same issue. Try engaging a tiny bit of flaps. If that is the problem it will also definitely become more nimble too. The heavy wing feeling ruins everything. I've never flown an A but a MKIV is a bigger plane. it should feel different, a bit heavier, but it should still be a joy to fly and feel nimble. if it isn't, something still needs correcting.

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Posted

 This has been an interesting discussion!

My Kf3 has the same heavy left wing if the flaps are fully retracted,add a little flap and the problem goes away.Maybe it's just a quirk of the early mixer geometry.I hadn't considered p factor.Anyone with a 912 Avid or Fox have the opposite wing heavy?

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Posted

I got serious p factor on take off and a little on cruise now that my prop is pitched in the sweet spot for take off and cruise. I need a little tab for the rudder but my wings are definitely level and luckily that's my only control issue. I found that after I faired all my jury struts that my controls are really sensitive. They were that way before but now at slow speeds I can really tell. Hopefully Vance only has a wash out problem and doesn't have to mess with anything to much. 

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Posted

I pulled the builder manual out tonight and did some checking. The wings are darn near perfect. The flaperons are off. The book calls for minus 3 degrees. Here is a couple of pictures taken with the wing leveled, flaps neutral and the stick centered. 

4F8A03CB-B5C4-4C7A-B4D1-4874E9A97600.jpeg

C13F87F8-E05F-485F-A86A-BBB441E00E41.jpeg

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Posted

On my first Avid, when the flaperons were reflexed, it got rather squirlly.  Don't think the other Avids would go to negative flaperons so didn't notice it on them.  Factor that in when you go to fly it.  Maybe that will happen to you  JImChuk

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Posted

Maybe I said that wrong. Here is what the manual says 

3991B650-DD66-4DEF-A816-0F128EFC883C.jpeg

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Posted

No, you said it right, and that is what the manual says.  I also know what happened with my Avid, and others have said the same.  All I'm saying is if you set it to negative flaps, and it starts acting funny in flight, pull back a bit on the flaps.  I didn't know what was causing it when it happened to me, and it was kind of unnerving.  JImChuk

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Posted

Ok. Thanks for the clarification. In just wanted to make sure I got it right. :)

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Posted

Someone cut these too short. What can I use to replace them. I can’t find them locally. 

6466A832-DBFB-4050-AB1B-CFBC8B4B2BBE.jpeg

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Posted

How long are they.  I may have a set.  If I remember right, the F7-A belcrank improvement used a piece of 5/16" tube with couple of bolt threads welded in each end.  The regular F7 belcrank had those studs.  I changed mine out so may have the old parts still.  JImChuk

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Posted

These measure 2 3/4 but they have been cut down. They must have been 3” or more 

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Posted (edited)

I have another aileron mixer set out off my uncles wreckes bird. It was a newer airframe. I wonder if they have the updated parts?? I’ll have to check the hangar tomorrow morning. 

Edited by NorthIdahoAvidflyer

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Posted

Update/Dumb Stunt: I went to the hangar this morning and pulled out the other control mixer I had. After removing the other threaded adjuster rod I noticed they were the same exact length as the other one I had. I looked at the other side and sure enough it was longer. I went back to plane and found the same thing. 

I hate to admit this but when I took all apart the last time to clean and make sure everything was installed correctly I accidentally reinstalled the adjuster rods back in the wrong sides. After I swapped them back everything fits much better now and I had plenty of adjustment to level the ailerons. You wouldn’t believe how far they were out. Funny thing too is I could tell something didn’t feel right but it didn’t fly horrible. They were literally 2.7 degrees out from each other and the worst one was 4.3 from being level.  I’m kinda excited to fly it again to see how it feels. I bet it will be a huge difference. 

I will report back after I fly it. 

Lesson: if you do anything to your controls make sure you level the wings per the manual and recheck your control angles. If I would have rechecked this I would have found the problem immediately. I got lucky. 

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Posted (edited)

Update: flew an hour this evening and I’m happy to report the plane flys like it’s supposed too. Roll rate is back and the plane feels solid. I set the Ailerons reflexed 2 degrees. I can’t believe how bad it was before. I leaned out the idler circuit, adjusted the needles and timed the slides. Temp were great. Still would like to see more RPM on take off. The new prop is supposed to be here tomorrow. Hope to get this thing dialed in this weekend. :)

Edited by NorthIdahoAvidflyer

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Posted

F846DDC5-6C31-4FA7-8DC2-7D04D49EAA92.jpeg

8F1EB0B6-2063-4DA5-A1A4-F783BB3F53F2.jpeg

7B0EA94C-5424-4831-AEBF-42089B6AAD29.jpeg

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Posted

Glad to hear things are coming together for you!  Looks like that Belite gauge is working well.  How do you like it so far?  I was thinking about ordering one when I get to the panel.  :BC:  Randy

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Posted

Thank you Avid Randy. I like the Belight gauge a lot. It gives you at glance information and has proven to be more accurate than my steam gauge Altimeter. I do not have it hooked to a static port but I do have all the static lines ran in series to a small air filter behind the dash. When I set the B/P on the Altimeter and the Belight the Belight is reads very close to field elevation where the Altimeter is not even close. Joey likes his too. I would recommend it for sure.

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Posted

Hey northidahoflyer,

looks great. There is just one gauge in your cockpit I would reposition If I were flying your nice bird:rolleyes:...I would swap the VSI with your ASI so that when you're landing for example your eyes have a shorter distance to look between outside and the ASI for that quick speed check on very short final..

Just my 2 cents

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Posted

Now those are the kind of pictures we like to see......plane in the air in great surroundings, having fun and looking at a cool instrument panel. When are you going to take it on the short cross country to visit us in the Tri Cities???

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