Heavy Wing...need help on how to proceed.

[Battson]

This is very interesting. My right aileron sits higher than the left aileron, and the stick sits slightly to the right also. It flies hands off like this quite happily.
I believe this indicates a heavy left wing. I've tried adjusting the flaps and this made a small difference but I didn't consider adjusting the aileron turn buckle.

Incidentally, my right elevator is a degree of two higher AOA than the left and so I had attributed the aileron issue as being caused by this. The elevator bellcranks are aligned perfectly, but not the elevators themselves. I've looked at ways to resolve this, and it can be done, but not easily.

This can also be a sign of rudder imbalance. I believe one needs to trim the rudder and aileron together, as each can affect the other. When you change one axis - you will have to change the other a smaller amount.

I like using metal trim tabs which are easy to bend, as many repeated adjustments are almost always required to fine tune the ship, to the point it's totally hands off.

[Nev]

This can also be a sign of rudder imbalance.

I was trying again today to correct for this. I tried John Bickhams idea of tightening the aileron turnbarrel on my right wing. This didn't seem to help and actually seemed to make it worse (sorry John) but I wondered if I had done it the opposite way so now I've reversed it and will test it on the next flight.

Regarding the rudder, would this not show up as a skid - ball off center ? I'm currently able to fly with the ball completely centered, and wings level, hands off. But the right aileron sits higher (more reflexed) and the stick slightly right too.

Any advice or ideas gratefully considered.

[Nev]

Note - Although the aircraft was flying wings level, ball centered, we discovered later that the heading was changing. If I flew with the heading fixed, the ball was off center. It's called a steady heading side slip.

[Bcone1381]

If an aircraft flies straight hands off then It seems to me like you describe a well rigged aircraft. I wonder if the stick is slightly off because the right and left aileron cables have a very slight difference in there length. Would the stick not center up if you lengthen the right aileron cable and shorten the left an equal amount so no change in cable tension takes place?

This is the internet, beware. I am not an experience rigger, I dont understand why John B's straightened up, and what I wrote is based on theory....which can be very different than bahavoir in the laboratory.

[Nev]

It's as if it has been rigged perfectly on the ground, except when in flight in order to fly wings level, the stick is very slightly to the right, and the right aileron is slightly raised. I would have thought it could be corrected with the flaps - and some of it was. I might revisit the flaps tomorrow, but I think I've now got them set perfectly.

[Battson]

If an aircraft flies straight hands off then It seems to me like you describe a well rigged aircraft

It seems like it should work that way, doesn't it?? I was bamboozled by this assumption for the longest time, years.

The sum of forces just need to balance each other out, for the aircraft to fly hands off and in balance. However, flying hands off doesn't mean it's reached peak aerodynamic efficiency or is rigged correctly.

For a simple example, I can rig my horizontal stabilizers out of square and correct the imbalance with trim tabs on the rudder and ailerons. That does work. The plane will fly hands off and straight / level / in balance. However, I am flying a very draggy aircraft, and it could easily be worth 2 or 3 knots at the speeds we fly. Also, the forces will only balance perfectly at one airspeed (normally we trim for cruise). At any other airspeed, there would be a slight heavy wing or slight out of balance.

Supposing all that happened, I may not realise I had a problem for years, until I started measuring things during a repair....

I've yet to see a comprehensive write up or video on how to rig an aircraft - so I am still learning, however I have learnt a few things the hard way. I can say for sure that flying hands off and ball centre does not guarantee that the aircraft is rigged correctly, it may not be.

[jaredyates]

So true Battson, and I would also say that straight and level flight is a balance of things. The engine and prop make left turning tendencies. We correct those with an offset fin and other aerodyamic and mechanical measures. If the plane goes faster, the aerodynamic factors become more effective. The opposite is true if we slow down. If the engine makes more power, the left turning is greater, but if the engine makes less power, the left turning is less. Similar things happen in pitch, with the CG being forward of the center of lift, the airfoil having a pitching moment, and the horizontal stabilizer applying force downward. CG changes and speed changes both stir up the balance between those factors. If you really want to dial in a perfect balance, it will only be at one condition of engine output, cg, gross weight, and speed, unless you have an in-flight adjustment as we do in pitch. Everything else is a compromise.

[whee]

Wouldn’t it be awesome to know what speed, or other metric, to aim for when considering optimum rigging. I know my airplane has some rigging inefficiencies but I’ve not been successful in correcting them in the past and I’m not convinced I can achieve better than I currently have. I also don’t want to make it worse so I do nothing.

I think of the stock 85hp Luscombe that held a speed record in the early 50s at 124mph and the C180 that could cruise at over 200mph. Those airplanes must have had optimized rigging and I’d like to know how they got there.

[marcusofcotton]

[QUOTE=whee;n71645

I think of the stock 85hp Luscombe that held a speed record in the early 50s at 124mph and the C180 that could cruise at over 200mph. Those airplanes must have had optimized rigging and I’d like to know how they got there. [/QUOTE]

Perhaps optimized for those conditions, may have been miss rigged for cruise or low-end performance.

[Nev]

I wanted to add how we addressed this issue (similar to what others did) and some other information about it that I discovered while resolving it.

In my case, the aircraft flew wings level but with the right aileron slightly raised. This was the first indication of a small rigging issue. Over several weeks I re-rigged the whole aircraft several times to ensure everything else was fine. Kev D (post #2 on page 1) was a huge help.

Symptoms
The symptoms in my case were:

- one aileron higher than the other in wings level flight - slight roll input required.
- wings level, ball centered, the heading would slowly change.
- wings level, fixed heading, the ball would be off center indicating a steady heading side-slip.
- when refueling it often took a lot more fuel to fill one tank than the other. Fuel was either transferring between tanks, or burning more from one tank.
- at the initial weight and balance one wheel weight was 12 lbs heavier than the other (heavy wing).

Cause
In hindsight I realize the cause of the whole issue was probably that I installed the magnetometer and landing light both in the left wing, to make use of the same cable conduit. The combined weight is around 2 lbs on a long arm. This also indicated a 12 lb higher weight on the left wheel (short arm)when we weighed the aircraft. (I didn't understand the significance until much later). It appears that the slight roll input required to counter the heavier wing is also creating a yaw (continuous adverse yaw) due to the increased aileron drag, resulting in the side slip condition.

Fix
I installed washers under the "light" wing as Kevin suggested and this helped, but didn't completely solve the issue. Kev mentions HERE that using washers raise the hinge line reduces the camber of the wing.

Next, we adjusted the flap pushrods (acting as ailerons in the retracted position) to counter the slight tendency to roll left. We managed to balance it out with the rigging and mostly solved the issue. I plan to also try balancing the wings with a small counter weight to remove the heavy wing altogether. If I was building again I would distribute items evenly between the wings to avoid the heavy wing issue altogether. It was a real head-scratcher at the time and took a number of weeks to resolve.

[Utah-Jay]

Interesting about the heavy wing. It has been my plan all along to put my magnetometer in the right wing to try to have more balance with the pitot system in the left wing. I will also have a camera power supply box in the right wing to power a strut mounted camera. Yes I hate camera batteries. I am hoping things balance out. I am just a bit OCD about things so for once maybe it is working in my favor

[svyolo]

I put everything in the right wing as well, hoping to balance out my not insignificant buttocks in the left seat.

[Bcone1381]

I didn't take that into consideration and will probably have a heavy wing.  Maybe I'll put a pound or two ballast in the lighter wing if the scales show things are all kitty-wompus.

[Nev]

If I did it again I'd either balance them evenly, or put the same components in the right wing instead of the left to offset my own weight when solo. Anyway, hopefully posting here saves someone else the same issue or at least makes the trouble-shooting and fixing much quicker.

[stinger]

I also had a heavy wing. The correction is adjust both aileron bracket on the light wing by means of a single washer under each bracket mount to wing spar raising the aileron very slightly on the light wing.. I am going by old memory but it works in other words adjust as necessary ! Stinger