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Heavy Wing

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dreel(at)cox.net
Guest

Posted: Fri Apr 07, 2006 12:56 pm Post subject: Heavy Wing

I have a VERY heavy left wing on my RV8A.  Full aileron trim doesn't begin to correct it.  I measured the flap angles and found the left flap to be 1 degree more up than the right flap.  I also checked the wing incidence and found them to be within 1/10 of a degree of each other.  So, I'm contemplating cranking the left flap down 1 degree and fly to test.  However, I thought I'd ask if you thought that was too big a change to make all at once from your testing experience and in addition whether a single degree would be likely to make a big difference.



A related question is how can I tell whether the flaps are in neutral trail more accurately than with the wing template.  Maybe I should be raising the right flap?  With the wing at 0 degrees incidence, it would seem that neutral trail on the flap would be a specific number of degrees as measured, say, across the top of the flap.  Do you know of such a number?  I've never seen anything like this on the list but I bet Vans design computer could spit this right out.  This would make it much easier to set the flap angle.



Dave Reel - RV8A - 3 hrs & a tired right arm.

dsvs(at)comcast.net
Guest

Posted: Fri Apr 07, 2006 1:16 pm Post subject: Heavy Wing

To set the flaps you need to first set the ailerons at 0 degrees relative to each other.  Do this by setting a straight edge along the tooling holes of the outboard wing rib and align that with the trailing edge of the aileron.  Do this fon both wings independently.  After the ailerons are set leave the straight edge attached to one wing and set the ailerons to neutral (in alignment).  The flaps in the up position should align with the ailerons at this time.  Another thing to look at is that the flaps and alireons are not at an angle to the wing inboard to outboard.  Hope this helps.  Don

 -------------- Original message ----------------------

From: "DAVID REEL" <dreel(at)cox.net>

 	  Quote: 	
		   

 

 I have a VERY heavy left wing on my RV8A.  Full aileron trim doesn't begin to 

 correct it.  I measured the flap angles and found the left flap to be 1 degree 

 more up than the right flap.  I also checked the wing incidence and found them 

 to be within 1/10 of a degree of each other.  So, I'm contemplating cranking the 

 left flap down 1 degree and fly to test.  However, I thought I'd ask if you 

 thought that was too big a change to make all at once from your testing 

 experience and in addition whether a single degree would be likely to make a big 

 difference.

 

 A related question is how can I tell whether the flaps are in neutral trail more 

 accurately than with the wing template.  Maybe I should be raising the right 

 flap?  With the wing at 0 degrees incidence, it would seem that neutral trail on 

 the flap would be a specific number of degrees as measured, say, across the top T

 of the flap.  Do you know of such a number?  I've never seen anything like this 

 on the list but I bet Vans design computer could spit this right out.  This 

 would make it much easier to set the flap angle.

 

 Dave Reel - RV8A - 3 hrs & a tired right arm.

jeffpoint

Joined: 10 Jan 2006
Posts: 72
Location: MKE

Posted: Fri Apr 07, 2006 4:11 pm Post subject: Heavy Wing

Another thing to look for is the height of the aileron relative to the 

wing.  Despite my best efforts, my left flap was 3/16 or so low at the 

outboard end.  The ailerons can be set to the proper angle and still 

cause a heavy wing.  A new aileron hinge and about an hour of worked 

cleared it right up. 



Van's has a good write-up on the heavy wing problem.



http://www.vansaircraft.com/pdf/Wing_Heavy.pdf



Jeff Point

RV-6

Milwaukee

 	  Quote:

_________________
Jeff Point
RV-6
Milwaukee WI

rv8ch

Joined: 10 Jan 2006
Posts: 250
Location: Switzerland

Posted: Fri Apr 07, 2006 10:21 pm Post subject: Heavy Wing

 	  Quote: 	
		   I have a VERY heavy left wing on my RV8A.  Full aileron trim doesn't

 begin to correct it.  I measured the flap angles and found the left

 flap to be 1 degree more up than the right flap.  I also checked the

 wing incidence and found them to be within 1/10 of a degree of each

 other.  So, I'm contemplating cranking the left flap down 1 degree

 and fly to test.  However, I thought I'd ask if you thought that was

 too big a change to make all at once from your testing experience and

 in addition whether a single degree would be likely to make a big

 difference.


	


Dave,



While flying, if you bring your flaps down just a hair, do you

notice any difference in the wing heaviness?  I'd personally be

more inclined to bring the right flap up a hair rather than move

the left flap down.  Of course, this makes a lot of assumptions

about your exact installation.  Do you have any "guru" builders

in your area who could come have a look?



The other suggestions have been great, and I've read here

on the list that you can get a lot of effect from the aileron

squeezing method.



Good luck - and let us know what you learn!

-- 

Mickey Coggins

http://www.rv8.ch/

#82007 finishing

do not archive

_________________
Mickey Coggins
http://www.rv8.ch/

khorton01(at)rogers.com
Guest

Posted: Sat Apr 08, 2006 3:38 am Post subject: Heavy Wing

On 7 Apr 2006, at 16:51, DAVID REEL wrote:



 	  Quote: 	
		   



 I have a VERY heavy left wing on my RV8A.  Full aileron trim  

 doesn't begin to correct it.  I measured the flap angles and found  

 the left flap to be 1 degree more up than the right flap.  I also  

 checked the wing incidence and found them to be within 1/10 of a  

 degree of each other.  So, I'm contemplating cranking the left flap  

 down 1 degree and fly to test.  However, I thought I'd ask if you  

 thought that was too big a change to make all at once from your  

 testing experience and in addition whether a single degree would be  

 likely to make a big difference.


	


I believe one degree of flap assymetry could make a significant  

difference.  I would have no concern about making that whole change  

at once, as you have more than enough aileron authority to counter  

the effect of a one degree flap change.

 	  Quote: 	
		  

 A related question is how can I tell whether the flaps are in  

 neutral trail more accurately than with the wing template.  Maybe I  

 should be raising the right flap?  With the wing at 0 degrees  

 incidence, it would seem that neutral trail on the flap would be a  

 specific number of degrees as measured, say, across the top of the  

 flap.  Do you know of such a number?  I've never seen anything like  

 this on the list but I bet Vans design computer could spit this  

 right out.  This would make it much easier to set the flap angle.


	


I don't have any advice on the best way to measure flap angle.  But,  

from a performance point of view, it is better to err on the side of  

having the retracted position too high than to have it too low.



Kevin Horton         RV-8 (finishing kit)

Ottawa, Canada

http://www.kilohotel.com/rv8

lhelming(at)sigecom.net
Guest

Posted: Sat Apr 08, 2006 6:23 am Post subject: Heavy Wing

---

larywil(at)comcast.net
Guest

Posted: Sat Apr 08, 2006 9:15 am Post subject: Heavy Wing

Dave,

I had a lot of trouble with my -4 after bird damage and repair to my main 

gearleg fairing. A heavy wing condition was ultimately cured by carefully 

re-adjusting my gear leg fairings. One clue to my problem was that when the 

aircraft was held in a level condition, the skid ball was off by a couple 

of diameters. I just thought I might add a few more complications to your 

problem solving.



Louis

-

Louis I Willig

1640 Oakwood Dr.

Penn Valley, PA 19072

610 668-4964

RV-4, N180PF

190HP IO-360, C/S prop

Charles Heathco

Joined: 10 Jan 2006
Posts: 201

Posted: Sat Apr 08, 2006 5:26 pm Post subject: Heavy Wing

I had a heavy rt wing on my 6a when I bought her, my friend Mike took a look at her and said that the wing had been built with a slope that couldnt be corected, so I pulled the left flap up a bit and the rt one down a bit, took care of it. When I had my cherokke, i had same problem, and did the same thing, Charles Heahco

jsflyrv

Joined: 03 Jan 2006
Posts: 22

Posted: Sat Apr 08, 2006 7:29 pm Post subject: Heavy Wing

charles heathco wrote:



 	  Quote: 	
		  



I had a heavy rt wing on my 6a when I bought her, my friend Mike took a look at her and said that the wing had been built with a slope that couldnt be corected, so I pulled the left flap up a bit and the rt one down a bit, took care of it. When I had my cherokke, i had same problem, and did the same thing, Charles Heahco



  




	


Charles when you say your friend took a look did he measure it some way 

or an "eyeball" look? I would think that it would

be pretty hard to see without some precise measuring. Just curious as to 

how he determined a warped wing?



Jerry



do not archive

finn.lassen(at)verizon.ne
Guest

Posted: Sun Apr 09, 2006 5:39 am Post subject: Heavy Wing

Nope. My RV-3 had about 1.5 degrees washout. Was clearly visible when 

sighting diagonally across the wing.

So if it's bad enough you can eyeball it.



Finn



Jerry Springer wrote:



 	  Quote: 	
		  Charles when you say your friend took a look did he measure it some way 

or an "eyeball" look? I would think that it would

be pretty hard to see without some precise measuring. Just curious as to 

how he determined a warped wing?



Jerry



do not archive

dreel(at)cox.net
Guest

Posted: Mon Apr 10, 2006 9:19 am Post subject: Heavy Wing

You may recall I have reported having a VERY heavy left wing on my RV8A & was wondering if a full degree of flap deflection was too much to try at once & how to tell if the flaps are really in neutral trail position.  So, today I flew again with the 1 degree additional deflection cranked into the left flap.  This removed about half the heaviness.  Now the situation is that with full right roll trim and 15 gallons more fuel in the right tank than the left, the ailerons are near neutral.  So, there is still some work to do.



To decide to lower the left flap rather than raise the right, I measured the angle between the wing chord line and the top surface of the flap on the plane and on the wing template drawing provided by Vans.  From the drawing, neutral trail is with the flap top surface 10 degrees positive to the chord, the wing bottom surface 7 degrees negative to the chord.  Armed with this info, I used my digital level and Vans incidence setting procedure to find that the wing chord was at 4.6 degrees up as the plane sits on the gear.  The right flap was at 14.6 degrees when full up and the left flap at 13.6 degrees so I lowered the left flap into neutral trail.



Thanks for all the responses.  I have the info on heavy wings from Van's web site and am working through the problem.



Dave Reel - RV8A 4.5 hrs

Bryan Wood

Joined: 16 Apr 2006
Posts: 1

Posted: Sun Apr 16, 2006 8:57 pm Post subject: Re: Heavy Wing

I too had a heavy wing on my 9A and went through all kinds of efforts to solve it.  Like you I started with the flaps and it was not the answer!  In order to get anywhere near the point of balancing the control force out I had turned the rod end bearings 10 full turns making a flap that drooped noticably more down than the other.  The nines flaps are much bigger than the eights and should have more effect, but not enough to fix anything.



Next I tried off setting the ailerons.  On the first attempt it didn't work because the ailerons just return to trail and the stick is leaned over a little bit.  But then the idea hit of only adjusting one aileron and this did fix the problem if only in a draggy way.  My thought was like this, whether it is real or not.  Again this adjustment did fix the heavy wing.  Think of the bell crank as a cam that is off set with the aileron moving up having close to twice the travel as the opposite aileron moving down or close to twice the leverage.  With this in mind I adjusted the aileron on the light wing down in 1/2 turn increments on the rod end bearing and test flew in between.  This worked by deflecting the heavy side aileron down slightly in flight and getting rid of the heavy wing.  The result was an aileron that was down in flight though.  What I found was that if you look at the heavy wing in flight before adjusting this way you can see how much you are deflecting the aileron down to fly level.  Use this as a guage when setting the opposite aileron down.  After adjusting it down return the light side up to neutral and clamp it.  At this point look at the heavy side and see if the aileron is deflected down the amount or close to it that you saw in flight.



Lastly I got tired of this droopy aileron and pulled the ailerons and removed the brackets from the ailerons them selves.  I slotted the holes and re-installed everything.  Here is where the real magic happened.  By raising and lowering the ailerons you can fine tune and your plane will fly hands off with both ailerons neutral.  This will take patience but will be worth it.  A 1/16" movement on the outboard of the aileron had dramatically more effect than 10 full turns on the flap rod end bearing.  Amazing!



Good Luck,

_________________
Bryan Wood
9A "Flyin' the Flag"

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