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Dual elevator halves uneven. Setup help needed.

Old 01-31-2007, 08:20 PM
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jzinckgra
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Default Dual elevator halves uneven. Setup help needed.

I am finishing my H9 Cap232g and am having problems getting the elev halves lined up. My initial problem was the servo arms not lining up at 90 degrees for both servos. I fixed that with subtrims, but now I notice the left ele, looking from the back is ~1/8" higher than the right (neutral), even though the front of the elvator halves are flush with the rest of the stab. Could this be due to a warped ele half? At full deflection the difference is obvious as well. This is sure to cause loops that aren't round, maybe some roll too. If I use sub trims to equal the halves in the back, then the front of the ele halves aren't level (one down more than up). Either way, it seems there would be some weird differential, unplanned. What's the best thing to do here. Here are some pics.
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Old 01-31-2007, 11:45 PM
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Campy
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Default RE: Dual elevator halves uneven. Setup help needed.

ORIGINAL: jzinckgra

I am finishing my H9 Cap232g and am having problems getting the elev halves lined up. My initial problem was the servo arms not lining up at 90 degrees for both servos. I fixed that with subtrims, but now I notice the left ele, looking from the back is ~1/8" higher than the right (neutral), even though the front of the elvator halves are flush with the rest of the stab. Could this be due to a warped ele half? At full deflection the difference is obvious as well. This is sure to cause loops that aren't round, maybe some roll too. If I use sub trims to equal the halves in the back, then the front of the ele halves aren't level (one down more than up). Either way, it seems there would be some weird differential, unplanned. What's the best thing to do here. Here are some pics.
It is possible that there is some warp in the elevator halves, however, looking at the photos, it also appears that the hinge slots are not all centered. (One photo shows the right elevator half at a different height than horizontal stab, although that could just be the photo. )

Check the elevator halves with a straight edge. If they are warped you MAY be able to straighten them by shrinking the covering a bit more.

If the hinges are not lining up properly you will need to cut new hinge slots (next to the existing slots ) and rehinge it.
Old 02-01-2007, 09:16 AM
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Default RE: Dual elevator halves uneven. Setup help needed.

I'll check with the straight edge. But, yes, I was thinking if there is a slight warp, then hitting, twisting a little might help. I think the pic is a little deceiving regarding the hinge line. Not to say, the factory drilled holes for the hinge points weren't drilled on the centerline, but in person, both halves are ok.
Old 02-01-2007, 11:59 AM
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Default RE: Dual elevator halves uneven. Setup help needed.

This may sound strange, but zero all of your settings on your TX.
Plug both servos into the same channel (YES, one side will go up when the other side goes down)
Now mechanically adjust both halves so they are in the same location and the geometry is the same.
You may have to try different arms until you find two arms that put the arm on both servos at the same angle.
Once the geometry is the same and the halves are the same, then you can move it to the desired channels and reverse the slave compared to the master. Adjust the height of the control arm to the elevator to adjust the throw.


ORIGINAL: jzinckgra

I am finishing my H9 Cap232g and am having problems getting the elev halves lined up. My initial problem was the servo arms not lining up at 90 degrees for both servos. I fixed that with subtrims, but now I notice the left ele, looking from the back is ~1/8" higher than the right (neutral), even though the front of the elvator halves are flush with the rest of the stab. Could this be due to a warped ele half? At full deflection the difference is obvious as well. This is sure to cause loops that aren't round, maybe some roll too. If I use sub trims to equal the halves in the back, then the front of the ele halves aren't level (one down more than up). Either way, it seems there would be some weird differential, unplanned. What's the best thing to do here. Here are some pics.
Old 02-01-2007, 12:19 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

jzinckgra,

Here is something you may or may not know, but I thought I would pass it along. I used to use reversing y-harnesses with the adjusting dial for the elevator servos on some of my planes (at the time I only had a 6 channel radio). I noticed, escecially in the summer time that the elevator halves would be different after I turned the transmitter and receiver on. As I later learned from more than one of the veteran pilots in my club, that types of reversing harness is temperature sensative. This only means that you will need to periodically check your elevator halves before you fly your plane.

Fly safe and have fun!!!
David
Old 02-01-2007, 01:11 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

A slight warp is always possible. If that's the case (and it looks like it may be), just bend it slightly in the opposite direction, and heat the covering with a heat gun
Old 02-01-2007, 01:30 PM
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jzinckgra
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Default RE: Dual elevator halves uneven. Setup help needed.

I should have mentioned that I am using two channels (futaba TX, ch. 2, 7). No Y harnesses here.
Old 02-01-2007, 07:10 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

Just the subtrim to even them out, after you have made sure that all the mechanics are correct.
Old 02-01-2007, 10:15 PM
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jzinckgra
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Default RE: Dual elevator halves uneven. Setup help needed.

That's the problem though. If I use the subtrims to get the backside of the ele even, then the fronts aren't even.
BTW, I checked the left ele with a straight edge, and it doesn't look warped.
ORIGINAL: rc-sport

Just the subtrim to even them out, after you have made sure that all the mechanics are correct.
[sm=confused.gif]
Old 02-01-2007, 10:19 PM
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Geistware
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Default RE: Dual elevator halves uneven. Setup help needed.

If you use the setup I recommended then any difference in the zero position of the channel can be seen and adjusted. Zero which is suppose to be 1500us is not always right.
Old 02-01-2007, 10:31 PM
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Paternguy
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Default RE: Dual elevator halves uneven. Setup help needed.

This might be another case of the picture being deceptive,, but, to me it looks like a mechanical problem. The nylon conector on the right control horn apears to be lower on the screw than the left side. Again it may just be the picture.
Old 02-02-2007, 02:50 AM
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Penuts
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Default RE: Dual elevator halves uneven. Setup help needed.

I agree with paternguy it's a lot lower then the left,
I have a futaba 9c and i used two elevators servos also, make sure your connectors are the same distance from the elevators, of course this wont effect the sub trim but it will affect the distance of travel from one elevator to the other,
You have a sub trim for each elevator,level one elevator then level the other one, do that seperatly, then use your EPA for your travel ADJ. That too is done seperatly for each one.
Also i would go through your transmitter and INH any mix or funtion your not useing just to be on the safe side.
It dosn't look like you have any warp to me,just a matter of learning how to use the two elevator function,

Good Luck
Old 02-02-2007, 09:58 AM
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jzinckgra
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Default RE: Dual elevator halves uneven. Setup help needed.

You may have to try different arms until you find two arms that put the arm on both servos at the same angle.
Geist, thanks for the suggestion, but I've tried a few different Hitec servo arms and even though one of the arms lines up at 90 degrees on one servo (with TX settings zerod out), the other is about one spline off from center. This bugs me because at least with futaba servo arms, they give you the option of trying 4 (or 5 on the smaller arms) different arms all on the same servo arm. Find the one that gets you the right geometry and cut the other ones off. However, I am using Hitec servos and need the longer arms. For $75/servo, I would think that the splines should line up at neutral when the arm is put on the servo. I've not had this problem with other dual ele planes in the past.
The mechanical setup may be off a little, as others have mentioned, but isn't it moot at this point? My point is, is that making sure the front of the ele halves are flush with the stab yields the current problem. Even if I mechanically adjust so that the linkages are equal, that may solve the problem of one ele being higher than the other in the back, but now they would be unequal in the front. ONe higher, one lower. If the fronts and back were both uneven, then yes, it would be very obvious that one of the linkages needs adjusting either mechanically or via sub trims/EPA.
Old 02-02-2007, 11:16 AM
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Default RE: Dual elevator halves uneven. Setup help needed.

OK, now I see you point.
You either have your elevator not mounted properly to your stab or your stab/elevator is warped.
Old 02-02-2007, 11:35 AM
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Default RE: Dual elevator halves uneven. Setup help needed.

So im to understand that when the ele is in the nuteral position the front edge isn't on the same plain as the hor.stab its higher or lower,right?
Then the hinge line isn't centered. simple problem,it will fly that way without much of a problem but if you feel unsafe with it that way just cut the problem ele.half off and redo it. you can use a hinge guide to mark the correct location. not much of a problem to fix.
Old 02-02-2007, 12:17 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

You need to use an incident meter! It is not uncommon to have one stab a degree or two off. Measure the wing and get it to 0 and then measur the stabs with the counter balance even with the front of the stab. I am sure you have one that is off. File the alignment pin hole so the stab can be rotated slightly and screw it back down. If you go over to the Giant Scale forum there is a bunch if info about your problem. Try it, it is easy.
Old 02-02-2007, 12:51 PM
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Default RE: Dual elevator halves uneven. Setup help needed.


ORIGINAL: foxyone

So im to understand that when the ele is in the nuteral position the front edge isn't on the same plain as the hor.stab its higher or lower,right?
Then the hinge line isn't centered. simple problem,it will fly that way without much of a problem but if you feel unsafe with it that way just cut the problem ele.half off and redo it. you can use a hinge guide to mark the correct location. not much of a problem to fix.
No, I guess I wasn't clear about that. I am not referring to the leading edge of the ele not being flush with the stab, but rather where the ele tips come around towards the front of the stab. If I make both ele halves flush (see 2nd pic above), then the back left is 1/8" higher than right side.

You need to use an incident meter! It is not uncommon to have one stab a degree or two off. Measure the wing and get it to 0 and then measur the stabs with the counter balance even with the front of the stab. I am sure you have one that is off. File the alignment pin hole so the stab can be rotated slightly and screw it back down. If you go over to the Giant Scale forum there is a bunch if info about your problem. Try it, it is easy
thanks, will check with the meter.
Old 02-02-2007, 02:38 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

ok, i think i see your problem, if you lay a straight edge or something near the root of the stab and accross the ele. and hold it in place with clothes pins or something, so now the ele is on the same plain as the stab, the tip of the elevator near the leading edge of the stab is higher or lower
right??
Then you do have a warp in either the stab or the elevator, again a simple fix. just heat it up with your trusty heat gun and warp it back in place,follow me?
Or get out your biggest hammer and whak it one. that should fix it.LOL
Old 02-02-2007, 03:31 PM
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jzinckgra
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Default RE: Dual elevator halves uneven. Setup help needed.


ORIGINAL: foxyone

ok, i think i see your problem, if you lay a straight edge or something near the root of the stab and accross the ele. and hold it in place with clothes pins or something, so now the ele is on the same plain as the stab, the tip of the elevator near the leading edge of the stab is higher or lower
right??
Then you do have a warp in either the stab or the elevator, again a simple fix. just heat it up with your trusty heat gun and warp it back in place,follow me?
Or get out your biggest hammer and whak it one. that should fix it.LOL
I think the ele or the stab has some warp. I need to check this further. I like the hammer idea though
Old 02-02-2007, 06:00 PM
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Default RE: Dual elevator halves uneven. Setup help needed.

This is the same problem I had with my BME Edge. One stab/elev was 2 deg pos. and the other 1/2 negative. I adjusted them to zero (PITA) then noticed when looking at them from behind, the elevators were not even although the counterbalances matched the stabs and both read zero on the incidence meter. Strangely enough, it has no effect on flight performance. No roll trim needed in level flight or loops. It is almost they built the stabs and elevators as right hand parts without a true symmetrical airfoil and flipped every other one before covering. After test flying it, I quit worrying about it.

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