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Heavy right wing question

togaflyer

Well Known Member
I have read the postings on a heavy wing, but most seems to be due to a heavy left wing. I know all the postings are also applicable to the right wing, but just want to see if I?m missing something. In the hanger, everything lines up. Reflex position, both ailerons line up with flaps and wing tips. In flight, I notice the left aileron trailing edge is approximately 1/4 to 1/2 inches deflected down below the trailing edge of the wing tip. Right aileron is aligned close to the wing tip, slightly upward. Made some adjustments to take out any play, but no change. Ailerons are rigged properly. Aileron trim works and takes out the roll, but takes a lot of trim to do so. I did some gas burn in the right tank, and burnt around 30-36 lbs of fuel. Both Garmin servo and Van?s trim installed in the right wing.

On another note, this is a great cross country airplane. Been hitting 160 knots true, 13.5 ROP in an unpainted plane. Already done multiple trips from Georgia to the Keys. Wife said it is more comfortable than the Saratoga we had. The 4.5 years to build it had, on occasions, tested me to my limits. The final results justified the time, the blood, the sweat, and the many negative four letter words (I normally don?t use), to build it.
 
I?d guess your rigging is off.

One point, make sure you rig the ailerons with the elevator clamped in neutral (trail). The stick movement is not linear and will pull the ailerons. Once done:
- Verify the flaps are really all the way up.
- Verify ailerons really aligned with the flaps
- Verify you don?t have an aileron hanging low or high (various ways to measure - like is the gap between the aileron and wing skin the same along the length of the aileron and the same between the ailerons?).

Not to be a pain but you should expect better than 160 at 13.5GPH. You have the wheel pants on? If not, another sign that rigging needs work.

Carl
 
+1
Rigging is amazingly sensitive to the vertical height of the ailerons. With all surfaces neutral, stand in front of the wing and sight down the top surface. Your sight line should flow smoothly from the end of the wing onto the top of the aileron. Compare left and right sides. If one aileron is higher than the other, that wing will be heavy. Vans sells undrilled aileron brackets just for this purpose.
 
Are your flaps both set perfectly equal? Our right flap is 1/4" - 1/2" lower than the fuselage on the inboard edges which I think is what is causing our heavy left wing. Plane was purchased this way, going to fix it during condition / when paint is done.

You could also check your flaps angle against the lower wing skin. Are they perfectly level to the lower wing skin? I think that's reflex if they are.
 
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Thanks. Looks like I will start from the beginning and double check everything to make sure I didn’t miss something. Then I will also check the aileron position in regards to the hinges.
 
Rigging

Bob Turner is dead-on about the sensitivity to rigging. To get it right, it's important to start in the right place, which is the flaps. Fully up, which is the reflex position, the flap motion should be limited by contact with the rear wing spar (check this with the flap pushrod disconnected). Next, with the flap all the way up (touching the spar), the trailing edge should be level with the bottom of the fuselage. This is the position at which the flap motor should just run out of travel. If the flap is hanging down below the bottom of the fuse, it's probably being held out there by the pushrod adjustment being too long and the flap motor running out of travel before the flap is pulled all the way up. With the flap push rods properly adjusted and the flaps properly aligned in the reflex position, the ailerons can then be adjusted to match the flaps. Couple of caveats here: #1 - As Carl stated, it's important to secure the ELEVATOR in the neutral trail position before adjusting the ailerons (easily done with tape). #2 - Make sure the control stick is centered, this should already be close if you've followed the plans. Once the ailerons are adjusted, the wingtips can be evaluated.

Once you're all rigged up nice with wheel pants and gear fairings, 160ktas will be your economy cruise setting at 9.5gph LOP... :D
 
Like most builders, I never made a single mistake during my build on the plane, but just in case I did miss something, I’m definitely starting from the beginning on this.

One question, If flaps are in the reflex position and against the spar and the trailing edge is above the bottom of the fuselage, maybe around 1/8 inch. Any issues. Do I keep it against the spar or make them even with the fuselage bottom.
 
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Flaps Reflex

The plans reference the stop against the spar as the definitive reflex position. If it were mine, I would use that reference and not worry too much about 1/8 of an inch of alignment with the fuse bottom. It is important to make sure the left and right are evenly matched, however. If they're not even it might be necessary to adjust the high side flap down a bit with the pushrod, so it matches the other one that's up against the spar. The actual flap angle can be measured with a digital level (or a smartphone) held along the flap rib closest to the fuselage. This is also a handy way to check for twist in the flap by checking the angle of each rib from one end of the flap to the other.
 
flaps

Are your flaps both set perfectly equal? Our right flap is 1/4" - 1/2" lower than the fuselage on the inboard edges which I think is what is causing our heavy left wing. Plane was purchased this way, going to fix it during condition / when paint is done.

You could also check your flaps angle against the lower wing skin. Are they perfectly level to the lower wing skin? I think that's reflex if they are.

Agreed, only fixed surfaces like flaps will change a heavy wing. Ailerons just accommodate. Lower the flap on the heavy wing slightly. Oh, fuel in balance will also cause one side to be heavy.
 
One more place to check is your individual elevator alignment. I found that a slight (1/4" at the counterbalance leading edge) misalignment between the left and right elevators will affect the roll of the airplane which manifests as a heavy wing.
 
Wing tips

One comment for those still building. Defer wingtip fit up until after you mount the wings and do all the rigging - and have a couple of other people check the rigging as well. Once you are really sure the rigging is correct, then fit the wingtips.

I know the plans tell you how to do this with the bell crank jig and such - but why not wait until you can fit the wings on the plane? I?ve seen a lot of RVs that had rigging problems and a few ended up redoing the wingtips. Fixing this is possible by cutting the trailing edge and doing glass work, but I offer it is easier just to do it right the first time.

Carl
 
Agreed, only fixed surfaces like flaps will change a heavy wing. Ailerons just accommodate. Lower the flap on the heavy wing slightly. Oh, fuel in balance will also cause one side to be heavy.

Absolutely disagree. My -10 had a heavy left wing. Sighting down the top surface of the wing, the forward part of the left aileron was about 1/16? high, compared to the right aileron. I lowered the left aileron, heavy wing went away.
I?d talk to Vans before lowering a flap. I think, for structural reasons, you want it up against the aft spar.
Obbviously, fuel and passengers need to be in balance for fine-tuning.
 
The plans reference the stop against the spar as the definitive reflex position. If it were mine, I would use that reference and not worry too much about 1/8 of an inch of alignment with the fuse bottom. It is important to make sure the left and right are evenly matched, however. If they're not even it might be necessary to adjust the high side flap down a bit with the pushrod, so it matches the other one that's up against the spar. The actual flap angle can be measured with a digital level (or a smartphone) held along the flap rib closest to the fuselage. This is also a handy way to check for twist in the flap by checking the angle of each rib from one end of the flap to the other.

To add to this: On my QB wings, there was a bit of sheet trimming that was needed to allow the flap to come to a full rest against the spar. It might be worth checking that you are getting a firm resting position of the flap against the spar.

Larry
 
Absolutely disagree. My -10 had a heavy left wing. Sighting down the top surface of the wing, the forward part of the left aileron was about 1/16” high, compared to the right aileron. I lowered the left aileron, heavy wing went away.
I’d talk to Vans before lowering a flap. I think, for structural reasons, you want it up against the aft spar.
Obbviously, fuel and passengers need to be in balance for fine-tuning.

+1

Changing the vertical position of the aileron hinge fixed the heavy wing in my 6A. If you search, you'll find this has been the case for many builders. As previously stated, there are several things that could create a heavy wing and one should be comprehensive in checking / verifying them all.

Larry
 
This is all great advise. Thank you! On a side note, the lower cowling slot forward of the nose wheel fairing. How much should be left open. I have about 4 inches. Is this about right. Would closing it up closer to the fairing improve speed or cooling.
 
This is all great advise. Thank you! On a side note, the lower cowling slot forward of the nose wheel fairing. How much should be left open. I have about 4 inches. Is this about right. Would closing it up closer to the fairing improve speed or cooling.

I extended the slot forward, about another 4”; then installed a piece of sheet aluminum, with nut plates, with the original fiberglass cut out epoxied onto it, to fill the slot back to original. I remove this piece prior to removing the lower cowl, makes clearing the prop spinner much easier. I do not think you can remove the lower cowl with the prop on if you reduce the slot length.
I have no data on drag or cooling if you reduce the original cut out.
 
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Cowl Slot

There's a whole thread on extending the cowl slot a few pages back in the RV-10 forum. I'd link to it but I dunno how. :confused:
 
So I started from the beginning and this is where I’m at. Flaps checked and are resting against the spar in the reflex position. No twist in the flaps or ailerons. I rechecked the bell cranks positions and realligned the ailerons to the flaps. Trailing edges of the flaps, ailerons, and wing tips are all aligned. I checked the aileron height. It appears my left aileron, on the outboard side, is about 1/16 above the top skin at the wing trailing edge spar. Question, would this cause the left aileron to deflect down in flight, causing a roll to the right. I have not flown the plane since this recheck. I have noticed that all previous flights the left aileron is always slightly deflected downward causing a right roll. Before I do anything to the left outboard aileron hinge bracket, I want to make sure I’m going in the right direction.
 
So I started from the beginning and this is where I?m at. Flaps checked and are resting against the spar in the reflex position. No twist in the flaps or ailerons. I rechecked the bell cranks positions and realligned the ailerons to the flaps. Trailing edges of the flaps, ailerons, and wing tips are all aligned. I checked the aileron height. It appears my left aileron, on the outboard side, is about 1/16 above the top skin at the wing trailing edge spar. Question, would this cause the left aileron to deflect down in flight, causing a roll to the right. I have not flown the plane since this recheck. I have noticed that all previous flights the left aileron is always slightly deflected downward causing a right roll. Before I do anything to the left outboard aileron hinge bracket, I want to make sure I?m going in the right direction.

You have exactly the same condition I had: outboard side of elevator 1/16? high, plane flies right wing heavy. I slotted that aileron bracket, put some liquid metal goo into the hole and re-drilled to move the aileron down. Plane now flies wings level.
 
So I started from the beginning and this is where I?m at. Flaps checked and are resting against the spar in the reflex position. No twist in the flaps or ailerons. I rechecked the bell cranks positions and realligned the ailerons to the flaps. Trailing edges of the flaps, ailerons, and wing tips are all aligned. I checked the aileron height. It appears my left aileron, on the outboard side, is about 1/16 above the top skin at the wing trailing edge spar. Question, would this cause the left aileron to deflect down in flight, causing a roll to the right. I have not flown the plane since this recheck. I have noticed that all previous flights the left aileron is always slightly deflected downward causing a right roll. Before I do anything to the left outboard aileron hinge bracket, I want to make sure I?m going in the right direction.

Yes, that is the correct direction. I was misled about the position in flight. Remember this . . . the ailerons have lift, a heavy means it is not even, the deflection is to balance that. The hinge slot, alone, will balance the wing and the ailerons will be in the same position when cruise. This is not caused by push rod adjustments.

I made a drill guide to precisely locate the new holes relative to the pivot pin. The 10 hinges look just like the 7.

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