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  #1  
Old 11-12-2016, 09:50 PM
mdmba mdmba is offline
 
Join Date: Jan 2016
Location: Wa
Posts: 33
Default Heavy wing at cruise

Picked up new to me -8. Once i get to cruising speed, my R wing gets "heavy" so i adjust L aileron trim to compensate. I am maxed out. Once I slow down, I need to re-adjust aileron trim back to normal. Fairly new pilot, and new to the 8. I love it, amazing bird that is for sure. Any suggestions would help.
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  #2  
Old 11-12-2016, 11:07 PM
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hydroguy2 hydroguy2 is offline
 
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Start here...heavy wing pdf
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Last edited by hydroguy2 : 11-13-2016 at 09:12 AM. Reason: fixed the link
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  #3  
Old 11-13-2016, 07:16 AM
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Carl Froehlich Carl Froehlich is online now
 
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Location: Dogwood Airpark (VA42)
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There are many steps to rigging an RV. Adjusting the linkage is just one and typicall not the fix you are looking for. Start at the flaps and make sure they are both rigged full up and match, then work out. Once you verify the ailerons really in the trail position, measure the gap between the aileron and the wing skin. Most RV heavy wings I've worked are because one or both of the aileron hinges are hung too high/low. The last step is to see how far out the wing tip trailing edge is from what should now be a properly rigged aileron. If not fabercated properly the wing tip trailing edge could be up/down a half inch or more from neutral.

If you need to redrill the aileron hinges Van's sells "no hole" hinges that alllow for the mounting bolt to be off center enough to get the alieron in line.

Several threads on this for you to read. Ignore the "squeeze the trailing edge" stuff.

Carl
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  #4  
Old 11-13-2016, 07:37 AM
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sprucemoose sprucemoose is offline
 
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Brian's link didn't work, but I think this is what he was posting.

http://vansaircraft.com/pdf/Wing_Heavy.pdf
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  #5  
Old 11-13-2016, 09:13 AM
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hydroguy2 hydroguy2 is offline
 
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Quote:
Originally Posted by sprucemoose View Post
Brian's link didn't work, but I think this is what he was posting.

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

yep...not sure why it didn't work earlier, fixed now
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  #6  
Old 11-13-2016, 10:37 AM
flyinga flyinga is offline
 
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Location: Fredericksburg, TX
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Make sure ball is centered in cruise. You may need a tab or wedge on your rudder.
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  #7  
Old 11-13-2016, 08:28 PM
Captain Avgas Captain Avgas is offline
 
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Location: Melbourne, Australia
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Default "Heavy wing" means mis-rigged

Quote:
Originally Posted by mdmba View Post
Picked up new to me -8. Once i get to cruising speed, my R wing gets "heavy" so i adjust L aileron trim to compensate. I am maxed out. Once I slow down, I need to re-adjust aileron trim back to normal. Fairly new pilot, and new to the 8. I love it, amazing bird that is for sure. Any suggestions would help.
I'm surprised that this was not picked up during the pre-purchase inspection/flight.

The term "heavy wing" is just a euphemism for a mis-rigged aircraft. It's very common in RVs because much of the rigging of the aircraft tends to take place towards the end of the project when many builders are becoming impatient to get into the air so these tasks are often not given the time and dedication they require. A roll tendency may result from one (or a number) of the following: Wing tips not in trail, flaps not in trail, ailerons not in trail, gear fairings not in trail, wheel pants not in trail, vertical stabiliser incorrectly offset, wing incidence incorrect, etc.

Once the plane is built it can be difficult to determine the real cause of the problem because it often requires a process of elimination.

The easy solution for some people is the aileron or rudder trim tab but when you see these tabs you can be sure that the aircraft is mis-rigged. The reality is that trim tabs are a quick and dirty solution that treats the symptom without addressing the underlying problem. Additionally, they rob you of speed....flying along at cruise with a trim tab on the rudder is like having a perpetual drag-inducing bootful of rudder pedal.

I find that when builders have a "heavy wing" they often focus completely on the wing area but mis-rigged gear fairings or wheel pants can also be the cause of "heavy wing". The asymmetrical drag that this can induce results in yaw, and the secondary effect of yaw is roll which you will interpret as "heavy wing".

I'm not sure that I've brought the OP any joy here. But my message is that aircraft rigging is best done properly by the original builder because rectifying a poorly rigged aircraft when the plane is flying can be very very time consuming.
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Last edited by Captain Avgas : 11-14-2016 at 06:41 AM.
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  #8  
Old 04-23-2017, 03:27 PM
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Champ Champ is offline
 
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Location: Kingsville, Ontario, Canada
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Smile Fixed It!

At 12 hr we still had a heavy right wing. Took almost full left trim to fly without roll hands off. Tried lowering the right side flap by pushrod adjustment but that didn't help much. Caliper checked both aileron trailing edge thicknesses at each rib and found the left averaged .364" and the right .330". Used a cleco side grip on the caliper to make sure the measurement was always at the same distance from the trailing edge. Carefully squeezed the left aileron & got the average thickness to match the rights average to .001". Woohoo -it flew hands off with aileron trim neutralized.

We have been flying with no wheel pants but put them on today and added 8 kts to cruise speed. Was 161 kt TAS at 75% and 11.8 gph, with pants 169.

Turn coordinator ball just touches the right mark so not sure it's worth messing with.

Added - I didn't like the way the aileron elevations lined up way back when I rigged them during build so I got a set of undrilled hinges from Vans & spent a lot of time measuring and realigning. Also slit the trailing edge of the wing tips to get flaps, ailerons & wingtip elevations & trailing edges to all line up. It was a bit of work but probably helped to get no roll with just a little squeeze of the left aileron.

Now at 14.4 Hr and loving it.
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Last edited by Champ : 04-24-2017 at 07:50 AM. Reason: Added info
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  #9  
Old 04-23-2017, 05:44 PM
Robert Anglin Robert Anglin is offline
 
Join Date: Mar 2008
Location: houston, texas
Posts: 667
Default Ditto Dennis and Van's.

Yes this is very common. Do all the stuff on the Van's posting first and in the order they are set out,. then adjust your trailing edges last. You can not only squeeze them down, but you can blunt them a little larger if you want with a small hammer and a block of wood. Go slow as it does not take a lot to change the forces on these control surfaces at high speed. Hope this helps, Yours, R.E.A. III #80888
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  #10  
Old 04-23-2017, 06:53 PM
Tankerpilot75 Tankerpilot75 is offline
 
Join Date: Jan 2015
Location: Oklahoma City, OK
Posts: 170
Default Also look at your elevator

When I purchased my RV7A the elevators were not "even" - in fact there was about an inch and a half difference between the two sides trailing edge. This caused a severe rolling moment at higher cruise speeds. It literally tried to roll me upside down. This rolling moment was almost negligible at traffic pattern airspeed.

Since you're relatively new to both flying and RVs you might be feeling a roll moment as opposed to heavy wing. Higher airspeed can exaggerate both. If your elevators are the same then definitely follow the Van's heavy wing guidelines to better identify the cause of the problem.

Don't assume because the airplane has been flying for a while that everything was built and rigged correctly. Remember the empennage is the first thing a new RV builder tackles and it's when their skill sets are just developing. Mine was built in 2008 and I bought it in 2015. The elevator problem was a build issue that the builder made compensating rigging adjustments later on to correct. The aircraft was flown for almost seven years with this problem.

I can also attest that not all pre-buys are equal. If your inspection was done by a "normal" A&P and not someone extremely familiar with RVs it's likely his/her focus was more engine and prop oriented than RV build oriented. I strongly recommend you contact a local EAA tech rep in a chapter near you who knows RVs and have him guide you through the analysis process. It will save you both time and money.

Good luck.
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