Airplane behavior.

[silvaleonardo]

Hello Everyone, it´s been long time since I don´t post here, reason is could not fly my airplane cause Mexican authorities (long story), now everything is ok, I can fly pretty much everywhere but crowded airports.
Airplane flyes great, has some minor issues, first is in level flight with no wind if I let go the stick, left wing goes down a little, how can I fix that? Adjusting ailerons won't fix it.

[Dave S]

Leonardo,

You are correct - it is not the alierons.

A good first place to start is to consider a rather common situation that is experienced on first flights.

Commonly called "Heavy wing". If the wings were built and attached perfectly straight (which is apparently what you did), there will be counter rotational force caused by the engine torque/propeller under power which tends to raise one wing, lowering the other slowly.

The ancient and classic aviation book called Stick and Rudder by wolfgang (can't recall the spelling of his last name!) mentions this somewhere in the middle of the book regarding manufactured aircraft which indicates the heavy wing deal on the first flights of a new aircraft. Some things are as classic as the book.

The fix is minor adjustments to the lift strut rod ends to alter the wing twist very, very slightly to deal with the engine torque. I had to adjust 1/2 turn on opposite corners of the lift struts and that cured it.

Do go to the search function on this site and search for "Heavy Wing" because there is a lot of historical information on this in the archives. Many folks have contributed to the fix.

Best of luck,

[DesertFox4]

Hope this information helps. It was taken from this forum back in 2012.


Adjusting for heavy wing on a Kitfox:
(From TeamKitfox.com thread labeled “Trying to correct left roll rate in cruise flight) dated 8-16-2012. This is a reply from John McBean......
Re: Trying to correct left roll in cruise flight.
“You are entering the "Test Pilot" stage. Be sure you are qualified and comfortable with making changes and test flying your aircraft.


Knowing that you are not the builder... I would suggest a reset... assume nothing.


Check the horizontal stabilizer for correct installation..
Set the wings back to the standard known condition and start from there.


Refer to your manual. 1 degree twist and 1 degree dihedral. Check length of the rod end thread.


From that point you can adjust either side.. we will typically decrease the angle of incidence first then increase on the opposite wing if needed. try to make changes equal.


For example.. We have a slight left turn.. or a heavy left wing as they say.


We have determined that we do not have a yaw issue that is causing the left turn.


We adjust the right wing rear lift strut rod end out 1 turn... record our change and pre-flight for a test flight. Decreased Twist (wash-out)


Not enough.. so now we'll adjust the left wing rear lift strut rod end in one turn.. record our change and pre-flight for a test flight. Increased Twist (wash-out)


Still not enough.. adjust the right wing front lift strut rod end in 1 turn... record our change and pre-flight for a test flight. Decreased Twist (wash-out)


Still not enough.. adjust the left wing front lift strut rod end out 1 turn... record our change and pre-flight for a test flight. Increased Twist (wash-out)


You may need to make a 1/2 turn or maybe a 1 1/2 turn all depends on the severity of the roll rate...”

[silvaleonardo]

Thanks for answers. Will take action and post the result. Thanks again.

Leonardo Silva.

[Slyfox]

you could also just bend up the trailing edge of the heavy wing aileron. I had that problem and I took the last few inches and bent up the trailing edge of my heavy wing aileron and fixed mine.

[PapuaPilot]

I would follow John McBeans advice and definitely would not bend the ailerons.

The only thing I didn't see addressed here was how to determine if it is a rudder trim problem or if the wings are causing the heavy wing/turning tendency. To check yaw (rudder trim) use the ailerons and hold the wings perfectly level while in straight and level cruise flight. See if the ball is centered. If not the plane requires rudder trim. There are several threads and pictures on this forum showing different methods of trimming the rudder to center the ball.

Once you have taken care of the rudder trim and the ball is centered in cruise flight then you can move onto adjusting the lift strut rod ends to correct any wing heaviness.

[Slyfox]

I tried everything on controlling the wing being heavy, rudder trim, adjusting the wings themselves. I finally said enough is enough and took my 4 inch wide pliers, used on my rv for the same thing, and gently bent the trailing edge of one of the ailerons. If I didn't tell you, you wouldn't notice it. flew the plane and flew level. Now Mine had a left wing heavy, seems to me that could be because I sit on the left side, don't know. that's my experience. On my Rv it gets a heavy wing with no passenger, to cure that I tape a little wedge under the right aileron, when I have a passenger, I remove it. simple fix.