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Heavy Wings on RV-8

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Speedy11(at)aol.com
Guest

Posted: Thu Dec 31, 2009 7:05 am Post subject: Heavy Wings on RV-8

Has anybody out there done something other than squeezing the trailing edge  of the light wing in order to correct a heavy wing problem?  Has anyone  discovered an aerodynamic cause for a heavy wing?

 I'm stumped.

 Stan Sutterfield

 Daytona Beach

  [quote][b]

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tracy(at)rotaryaviation.c
Guest

Posted: Thu Dec 31, 2009 7:29 am Post subject: Heavy Wings on RV-8

I was confused for awhile too.  I spent days getting the wings perfectly matched for AOA before drilling the aft spar and still had a heavy left wing.  A minor squeezing of the right aileron trailing edge didn't help enough.  A slight adjustment of both flaps in the appropriate (opposite) directions was effective.  The change was not enough to notice any visual misalignment of flap trailing edges with the ailerons   As always, YMMV depending on the cause of the heavy wing.

 

Tracy Crook



On Thu, Dec 31, 2009 at 10:04 AM,  <Speedy11(at)aol.com (Speedy11(at)aol.com)> wrote:

[quote]      Has anybody out there done something other than squeezing the trailing edge  of the light wing in order to correct a heavy wing problem?  Has anyone  discovered an aerodynamic cause for a heavy wing?

 I'm stumped.

 Stan Sutterfield

 Daytona Beach

   	  Quote: 	
		  



_blank">www.aeroelectric.com

.com" target="_blank">www.buildersbooks.com

="_blank">www.homebuilthelp.com

nk">www.howtocrimp.com

_blank">http://www.matronics.com/contribution

et="_blank">http://www.matronics.com/Navigator?RV8-List

tp://forums.matronics.com



	


[b]

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carl.froehlich(at)verizon
Guest

Posted: Thu Dec 31, 2009 7:58 am Post subject: Heavy Wings on RV-8

I worked this problem on three RV-8s, including my 8A.  What I learned was that control surface rigging on an RV is not a trivial exercise.  I also learned that the “squeezing the trailing edge of the light wing” is the absolute last thing to do, and it has the least effect.  In other words, this should be considered the final “fine tuning tweak”.  

   

Here is a short list of common areas to check:  

<![if !supportLists]>1.      <![endif]>Ignore the alignment of the aileron to flap or aileron to wing tip trailing edge.  Use the templates provided by Van’s to define the “ailerons in trail position” (if you don’t have the templates use a straight edge and ruler).  Once you lock one aileron in the trail position, then adjust the aileron linkage to put the opposite aileron in the trial position.   

<![if !supportLists]>2.      <![endif]>Measure the aileron height (as compared to the wing top or bottom skin) at both inboard and outboard hinges.  Another check is to measure the gap between the wing top skin trailing edge and the forward top rivet line on the aileron with the aileron locked in the trailing position.  Of all the rigging problems I’ve seen, this is the most common.  What you may find is one end of one aileron is lower/higher or more fore/aft than the other end.  This places more aileron surface in the airstream above/below one aileron than the other – causing the asymmetric lift even though the aileron are both in the trail position.  Two ways to fix this:  

<![if !supportLists]>a.       <![endif]>Call Van’s and order a couple of “no hole” aileron hinge brackets.  The hinge brackets Van’s sells are pre-drilled.  Van’s sells no hole brackets so that you can drill the bolt hole off center – thus placing the aileron in the correct position.   

<![if !supportLists]>b.      <![endif]>Take the current bracket that needs adjustment and make the bracket to wing bolt holes into slots (in the direction you need to go) so that the bracket itself can move up/down.  This works only in the up/down direction however.  The no hole brackets allow for adjustment in both the up/down and fore/aft direction.  

<![if !supportLists]>3.      <![endif]>Once you get the ailerons right, then check for flap and wing tip alignment.  Again with the ailerons locked in the trail position, adjust each flap trailing edge to align with the aileron when the flap is in the full up position.  This may require you to reposition the fuselage flap stop.  Considering the moment arm on the wingtips, even a small misalignment can create a roll tendency.  During construction the wingtip trailing edge alignment is possible as you have some control on mounting (a good reason to delay wingtip mounting until after you complete the above steps on rigging).  If the wingtip is already mounted, you can still fix the trailing edge by cutting along the trailing edge aft seam to separate the aft wingtip top/bottom halves.  Once separated they can be adjusted to align with the aileron trailing edge, then glassed back together.  

   

Once you do all of this, fly the airplane and make minor adjustments in the left/right aileron push tubes as needed.  The acid test to tell you if you are done or not is if you have no change in roll trim with speed.  

   

Carl Froehlich  

RV-8A (525 hrs)  

RV-10 (systems install)   

       

From: owner-rv8-list-server(at)matronics.com [mailto:owner-rv8-list-server(at)matronics.com] On Behalf Of Speedy11(at)aol.com

 Sent: Thursday, December 31, 2009 10:05 AM

 To: rv8-list(at)matronics.com

 Subject: Heavy Wings on RV-8  

  

  

     

Has anybody out there done something other than squeezing the trailing edge of the light wing in order to correct a heavy wing problem?  Has anyone discovered an aerodynamic cause for a heavy wing?  

    

I'm stumped.  

    

Stan Sutterfield  

    

Daytona Beach  

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        [quote][b]

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dan.pat.b(at)gmail.com
Guest

Posted: Thu Dec 31, 2009 3:31 pm Post subject: Heavy Wings on RV-8

Stan: I had the same frustrating issue with my RV-7A, i.e., a heavy left wing.  I checked everything and made all sorts of minor adjustments to aileron and flap positions.  Nothing seemed to work.  No, I never did squeeze an aileron; and no my wife in the right seat didn't work either.  

 What I did eventually notice was a very slight difference in the upper surface, spanwise curvature of the wings, relative to each other, in the vicinity of the aftmost line of rivets in the wing itself.  Either there is a very slight difference in the positioning of the pre-punched holes, in the flap brace for example, or the parts themselves are slightly different in size.  If you look at mine very carefully you can see that the left wing has a bit more camber (more like an elongated bump) in that area than the right wing, and you can feel it with your fingers.   

 My friend and mentor, three-time repeat offender Fred Stucklen, suggested what turned out to be the perfect solution:  Avery Tools sells a "rudder trim tab," part #9883.  It's nothing more than a solid  piece of plastic, about 5" long, 1.5" from front to back and tapered from a near knife edge in the front to .25" in the rear.  I bonded it with proseal to the underside of the outboard trailing edge of the right aileron, just inboard from the wingtip.  It forces the right aileron up ever so slightly; honestly if I look at the ailerons in flight, I can't see the difference.  Problem solved for $13.50 and a bit of proseal.

 What a magnificent flying machine!  

Dan Bergeron

RV-7A, N307TB

74 hours since first flight 

on 8/4/09 at 7B2 (Northampton Airport, MA)

       

 On Thu, Dec 31, 2009 at 10:56 AM, Carl Froehlich <carl.froehlich(at)verizon.net (carl.froehlich(at)verizon.net)> wrote:

 	  Quote: 	
		                

I worked this problem on three RV-8s, including my 8A.  What I learned was that control surface rigging on an RV is not a trivial exercise.  I also learned that the “squeezing the trailing edge of the light wing” is the absolute last thing to do, and it has the least effect.  In other words, this should be considered the final “fine tuning tweak”.  

   

Here is a short list of common areas to check:  

1.      Ignore the alignment of the aileron to flap or aileron to wing tip trailing edge.  Use the templates provided by Van’s to define the “ailerons in trail position” (if you don’t have the templates use a straight edge and ruler).  Once you lock one aileron in the trail position, then adjust the aileron linkage to put the opposite aileron in the trial position.   

2.      Measure the aileron height (as compared to the wing top or bottom skin) at both inboard and outboard hinges.  Another check is to measure the gap between the wing top skin trailing edge and the forward top rivet line on the aileron with the aileron locked in the trailing position.  Of all the rigging problems I’ve seen, this is the most common.  What you may find is one end of one aileron is lower/higher or more fore/aft than the other end.  This places more aileron surface in the airstream above/below one aileron than the other – causing the asymmetric lift even though the aileron are both in the trail position.  Two ways to fix this:  

a.       Call Van’s and order a couple of “no hole” aileron hinge brackets.  The hinge brackets Van’s sells are pre-drilled.  Van’s sells no hole brackets so that you can drill the bolt hole off center – thus placing the aileron in the correct position.   

b.      Take the current bracket that needs adjustment and make the bracket to wing bolt holes into slots (in the direction you need to go) so that the bracket itself can move up/down.  This works only in the up/down direction however.  The no hole brackets allow for adjustment in both the up/down and fore/aft direction.  

3.      Once you get the ailerons right, then check for flap and wing tip alignment.  Again with the ailerons locked in the trail position, adjust each flap trailing edge to align with the aileron when the flap is in the full up position.  This may require you to reposition the fuselage flap stop.  Considering the moment arm on the wingtips, even a small misalignment can create a roll tendency.  During construction the wingtip trailing edge alignment is possible as you have some control on mounting (a good reason to delay wingtip mounting until after you complete the above steps on rigging).  If the wingtip is already mounted, you can still fix the trailing edge by cutting along the trailing edge aft seam to separate the aft wingtip top/bottom halves.  Once separated they can be adjusted to align with the aileron trailing edge, then glassed back together.  

   

Once you do all of this, fly the airplane and make minor adjustments in the left/right aileron push tubes as needed.  The acid test to tell you if you are done or not is if you have no change in roll trim with speed.  

   

Carl Froehlich  

RV-8A (525 hrs)  

RV-10 (systems install)   

       

From: owner-rv8-list-server(at)matronics.com (owner-rv8-list-server(at)matronics.com) [mailto:owner-rv8-list-server(at)matronics.com (owner-rv8-list-server(at)matronics.com)] On Behalf Of Speedy11(at)aol.com (Speedy11(at)aol.com)

 Sent: Thursday, December 31, 2009 10:05 AM

 To: rv8-list(at)matronics.com (rv8-list(at)matronics.com)

 Subject: Heavy Wings on RV-8  

  

  

     

Has anybody out there done something other than squeezing the trailing edge of the light wing in order to correct a heavy wing problem?  Has anyone discovered an aerodynamic cause for a heavy wing?  

    

I'm stumped.  

    

Stan Sutterfield  

    

Daytona Beach  

   	  Quote: 	
		    www.aeroelectric.com  	
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        ==== _blank">www.aeroelectric.com .com" target="_blank">www.buildersbooks.com ="_blank">www.homebuilthelp.com nk">www.howtocrimp.com _blank">http://www.matronics.com/contribution et="_blank">http://www.matronics.com/Navigator?RV8-List tp://forums.matronics.com  [/b] 	




[b]

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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV8-List

James Baldwin

Joined: 16 Jan 2006
Posts: 23

Posted: Thu Dec 31, 2009 6:02 pm Post subject: Heavy Wings on RV-8

RV Guys,  

Many builders of all homebuilts have experienced a heavy wing even when they have been constructed meticulously.  One common reason for many has been traced to the fiberglass wingtip fairings.  A slight mismatch is particularly pronounced because of the obviously long moment arm.  If your problem can’t be solved with a minor differential flap adjustment the wingtips are the next place to consider.  One friend made a dramatic difference by slitting the trailing edge of one which looked a little off and re-glassed it in a more favorable position.  My RV8 is sensitive but any wing heaviness is easily adjusted out with the aileron spring loading trim system installed.  I note however it’s best if I burn out of the right tank first.   Just FYI.     James Baldwin  

         

  

From: owner-rv8-list-server(at)matronics.com [mailto:owner-rv8-list-server(at)matronics.com] On Behalf Of Tracy Crook

 Sent: Thursday, December 31, 2009 7:27 AM

 To: rv8-list(at)matronics.com

 Subject: Re: Heavy Wings on RV-8  

  

   

I was confused for awhile too.  I spent days getting the wings perfectly matched for AOA before drilling the aft spar and still had a heavy left wing.  A minor squeezing of the right aileron trailing edge didn't help enough.  A slight adjustment of both flaps in the appropriate (opposite) directions was effective.  The change was not enough to notice any visual misalignment of flap trailing edges with the ailerons   As always, YMMV depending on the cause of the heavy wing.

 

 Tracy Crook    

On Thu, Dec 31, 2009 at 10:04 AM, <Speedy11(at)aol.com (Speedy11(at)aol.com)> wrote:      

Has anybody out there done something other than squeezing the trailing edge of the light wing in order to correct a heavy wing problem?  Has anyone discovered an aerodynamic cause for a heavy wing?  

    

I'm stumped.  

    

Stan Sutterfield  

    

Daytona Beach  

   	  Quote: 	
		    _blank">www.aeroelectric.com.com" target="_blank">www.buildersbooks.com="_blank">www.homebuilthelp.comnk">www.howtocrimp.com_blank">http://www.matronics.com/contributionet="_blank">http://www.matronics.com/Navigator?RV8-Listtp://forums.matronics.com 	


  

  

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       [quote][b]

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Speedy11(at)aol.com
Guest

Posted: Fri Jan 01, 2010 1:04 pm Post subject: Heavy Wings on RV-8

Excellent information from everyone.  THANK YOU very much.

 I'm going to the hangar right now to get to work on it.

 Stan Sutterfield

  [quote][b]

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martin(at)gbonline.com
Guest

Posted: Mon Jan 04, 2010 5:23 am Post subject: Heavy Wings on RV-8

Stan,

 I am here now in DAB with my RV8 until spring. I am hangered at Spruce  Creek Airpark (7FL6).  I can help you.

 You may call me anytime on my cell phone 920 619 6968.

 Dick Martin

 RV8 N233M

 the fast one

 [quote]   ---

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