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Unequal elevator halves

Old 01-31-2014, 03:49 AM
  #26  
sensei
 
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WOW...

Bob
Old 01-31-2014, 05:01 AM
  #27  
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Originally Posted by ameyam View Post
That's what I said

Ameyam
Sorry, just re read your initial post, I have seen this before though , might be worth sending a picture to the dealer see if they can get you a proper pair .
Old 01-31-2014, 05:01 AM
  #28  
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Originally Posted by rfbenn View Post
Looking at the picture, could it be that the elevators are handed and they have been covered wrongly at the factory and you have two left hand or two right hand elevators although covered to look like a pair.
Just a thought.
That's the only way to say it & he fitted it all into one sentense! ... Shift+R improves the quality of this image. Shift+A improves the quality of all images on this page.
Old 01-31-2014, 05:26 AM
  #29  
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Originally Posted by sensei View Post
WOW...

Bob
I know my head hurts. Wouldn't be so bad but I've been dealing with a pre preg layup here at work that would be easy if others would stop complicating it. Kind of like whats happening here. At least it's Friday.
Old 01-31-2014, 05:48 AM
  #30  
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Originally Posted by opjose View Post
Normally I would agree but look closely at the photo.

The elevators are not warped from the LE to the TE.

Rather the 4-40 screw "horns" he is using are at different positions relative to each other.

The right one is slightly forward of the left. --- Geometry is wrong.
Agreed. It does not appear that anything is wrong with the parts - just the installation! Turn the clevis down on one to align the trailing edges.
Old 01-31-2014, 06:19 AM
  #31  
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Originally Posted by rgburrill View Post
Agreed. It does not appear that anything is wrong with the parts - just the installation! Turn the clevis down on one to align the trailing edges.

Your not looking at the whole picture here. He said that the LE of the counterbalances are lining up with the LE of the stab and that leaves him with a mis alignment at the elevator root. Simply moving the clevis to line up the elevators at the root is not going to fix anything. The elevator/s have a twist. Look at the construction used, it should be a fairly easy solution to twist the elevator/s the opposite direction and re-shrink the covering to straiten them out as the twist was most likely introduced during the covering process in the first place.
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Old 01-31-2014, 07:56 AM
  #32  
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exactly... I had a tough time figuring out exactly what the original poster was asking... if I may try to clarify:
when the elevator trailing edges are properly aligned and at neutral,
the elevator COUNTERBALANCES (the elevator's leading edge is where the hinges are ) are NOT BOTH at neutral.

(obviously if you were to align the counterbalances, then the elevator trailing edges would no longer be at neutral {one would be higher / lower as seen in the first picture})

1) one elevator is warped.
2) both elevators are warped.
3) the airplane was designed to have a LH and a RH elevator and this kit was built with two LH or two RH elevators.

I'm more than a little picky about having the exact same geometry for both elevator halves, (it's critical for aerobatics, not so much for sport / scale flying)

if it were my airplane, I'd fly it as is for the event, but as soon as I had a day of down time I'd cut the elevators off the airframe, fix them and re-hinge.
at minimum I'd do as had been mentioned: use a heat gun and get them to match as closely as possible

hope that helps!

Last edited by AMA 74894; 01-31-2014 at 08:00 AM. Reason: clarification
Old 01-31-2014, 09:27 AM
  #33  
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Originally Posted by ameyam View Post
Guys, just hold on.

Opjose, curt as it may seem, people learn over time. I wish you would pick that up
Some tend to overthink the small things causing them to miss the important ones and that tendancy does not disappear.


Unless the elevators are asymetrical (e.g. warbird, etc. ), a left hand elevator, recovered as a right hand elevator is for all intents and purposes a right hand elevator, particularly on a 3D plane such as yours.

First remove the elevators and try to eliminate any warping.

If you succeed re-install and align their TRAILING EDGES at center and also at both extremes.

If you cannot remove all of the warping, adjust the trailing edges at centers and extremes, then slightly re-align them so that you get the "average" position of the elevator being the same, so the effect on the plane is about equal on both halves. At best this is only an approximation.

On a 3D plane you will very much notice the warping in flight during tight loops, high alpha, and stall turns.

Last edited by opjose; 01-31-2014 at 09:36 AM.
Old 01-31-2014, 09:43 AM
  #34  
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Days past opjose..

Seems like case 3 in Jim's list. I had a go at trying to de-warp with the heatgun got a bit of level. Like someone said, the TE is now in line but the counterbalance leading edge is out. It will make the airplane fly a bit weird but with practice tomorrow, there is nothing more I can do. I did as much as was possible during the work week working a couple of hours a evening to put it together in a week after the UCD originally meant for the event had to be discarded as it would require a full recover. Now I can practice tomm & next Saturday & hope to put up a show in the event

Ameyam
Old 01-31-2014, 10:04 AM
  #35  
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Aligning the TE is more important than getting the counter balances in place because the larger surface areas are aligned.

You could take things a bit further and now de-align the warped half to sort of average things out to a SMALL degree.

Usually getting a much warping as you can out, then aligning the trailing edges will improve things greatly.

If you want to fully fix the problem you can try the following.

- Cut the elevators back out

- Remove the covering, wet the wood, set the elevator on a perfectly level surface with a larger level weight ( I use UPS batteries) , and let it sit for a couple of weeks to dry, recover.

- Or inject small amounts of water under the existing covering with a syringe then do the above but wait even longer for the wood to dry..

- Removing warping with a heat gun is a bit iffy. Different covering reacts in different ways (e.g. some expands then contracts, some contracts only, some loosens ), and you may end up introducing more warping, though initially it may seem that you are improving matters.
Old 01-31-2014, 10:44 PM
  #36  
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Hi. I'm Ken.
The fix is rather simple, and involves use of a couple of hand tools, CA and strip of matching covering. Ok?
At the intersection of the counterbalance and stab leading edge, slice the balsa sheeting on the bottom with a razor saw , in a straight line following the leading edge straight out. This cut will normally remove about a 1/64" material from the cut zone in itself. Then push the gap closed, tape it and check with the elevators in neutral. Generally you will find that this initial cut removed enough material to bring the counterbalance into correct relationship with the stab when at neutral.
If the first cut was sufficient, then wick some thin CA into the slice and I then add a 1/2" wide strip of lightweight glass cloth over joint CA'd in place for strength. Light sanding, then a strip of matching covering and your done. If more balsa has to be removed, take a straight edge, draw a straight line the required distance from the gap, and use an emery board drawn thru the slice once or twice. Usually finishes the task nicely and keeps things straight and lined up when done this way.
Try this, it will work for you if this is your problem.
Old 02-01-2014, 12:55 AM
  #37  
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Actually guys flew a couple of flights today. Didn't have a tuned engine as the muffler kept coming off. The little aerobatics I did in that time, the airplane flew well. There's no eccentricity in the loop & I am very used to how this flies. I may replace the 91 on it with the 110. The muffler threads on the 91 have stripped & I don't have a replacement right now. Didn't try any 3d though. Don't intend to do any 3d except hover at the event
Ameyam

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