Can you cure "wing low"

coloradobluesky

coloradobluesky

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coloradobluesky
Ive noticed several airplanes that fly "wing low". Bring the low wing up to even with the horizon with the aileron and you turn, bring it up with the rudder and you slip. It varies a bit with speed and Im pretty sure its the prop downstroke being stronger that the upstroke, but is there a cure? What is happening aerodynamically anyway? Is it one wing has more lift than the other or something else?
 
Sounds like the airplane is not rigged properly.
 
It may be that the airplane is out of rig. I have that problem, will be fixed at annual, later this summer. On the cherokee, a few washers on the control arm of the aileron or the flap, depending on what needs to be adjusted.

The piper maintenance manual provides detailed instructions how to build the rig device - it's a piece of aluminum about 48 in long with a hole drilled at a specific location, and a bolt installed in the hole to a specific length. Lay the rig along the wing, add/remove washers until everything matches up. Dunno about a high-wing.
 
Trimming the aileron or rudder isn't going to do it. That does the same thing as pushing on the stick or rudder except it "centers" it so you dont have to push. Something like changing the angle on the wing. The planes that Ive flown that have this problem have all been high wings. Its not so bad as to be a big concern. You can bring it up with rudder and have maybe 1/3 ball out on the ball.
 
coloradobluesky said:
OK, but how do you fix it?
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There will be manufacturer's rigging instructions. For the specific model it usually starts with what reference is used to level the plane, how to check the angle of incidence to make sure it's the same on both wings, aileron/flap/rudder & elevator rigging and so forth. Lot's of work with chalk line, tape measure and plumb bobs in the hangar. It's not usually complicated to check things, just careful, time consuming work. If you are not a mechanic you will need to have one verify what you find out of alignment and perform whatever adjustments are available to correct it.
 
This might sound off the wall, but start by checking the easy things first. Level the plane laterally by placing a level across the seat tracks and jacking to level it then check the turn coordinator. If it's part of a ball off, that's your problem. A&P's don't always get them installed properly. If that don't fix the problem then proceed to checking the rigging. It's simple, and does fix some "rigging" problems.
 
One anecdote...

My Tiger would sometimes exhibit a "heavy wing", apparently unrelated to fuel load.

Thinking back, one of the flap skins was "oil canning" - popping in and out and causing a small variation of lift on that wing when it did so. I don't recall how it was resolved.

Anyway, really small things like variations in how far flaps retract and the like need to be in investigated, especially for intermittent problems.
 
Wing Low, Weet Chariot?

I had the issue on the Comanche - but thought it was uneven fuel burn(which happens in mine) and my A&P notified me he adjusted one of the ailerons or flaps - I forget which.
 
EdFred said:
Wing Low, Weet Chariot?

I had the issue on the Comanche - but thought it was uneven fuel burn(which happens in mine) and my A&P notified me he adjusted one of the ailerons or flaps - I forget which.
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Ok, I laughed.
 
I'd make sure your AP is experienced with re rigging planes, like zeroing everything out and going from there. More than a few are all out of wack because they keep getting "adjusted" over the years.
 
coloradobluesky said:
Ive noticed several airplanes that fly "wing low". Bring the low wing up to even with the horizon with the aileron and you turn, bring it up with the rudder and you slip. It varies a bit with speed and Im pretty sure its the prop downstroke being stronger that the upstroke, but is there a cure? What is happening aerodynamically anyway? Is it one wing has more lift than the other or something else?
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It would be nice to know what aircraft we are re-rigging?
Both C&P aircraft have books, start with step one square one and follow the books.

Some aircraft are bent. and rigged to compensate. and never will fly straight.
 
Tom-D said:
It would be nice to know what aircraft we are re-rigging?
Both C&P aircraft have books, start with step one square one and follow the books.

Some aircraft are bent. and rigged to compensate. and never will fly straight.
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Very true.


Side Note: My airplane doesn't have cockpit adjustable aileron or rudder trims and it seems to have a sweet spot on being loaded with just me in the front seat and a pile of weigh in the baggage. Loading it any other way seems to give it a bit of heavy wing. Also seems to depend on cruise power settings
 
Adjusting ailerons is a waste of time. If you rig one down a bit, it will just push upward and lower the other so that they're equal, and now you still have a wing-heavy airplane that has undesireable stall characteristics. Rigging a flap down is sometimes done, but that can also start the stall sooner on that side.
The maintenance manual for the model should be consulted and followed closely. I get fed up with rerigging airplanes that have been thoroughly messed up by mechanics who don't pay attention and who end up creating more problems than they solve.
 
Aileron adjustments and rudder adjustments aren't going to fix it. Perhaps length of struts would, I don't know.

By 1/3 of a ball out, I mean if I step on the rudder to create that much slip, it brings the low wing up to level. It is correct on the ground so far as the ball reading level when the plane is level on the ground. So its not the ball being off. The plane basically is close to in rig. Just have to figure out how to control this without rudder or aileron (again, you can bring the low wing up to level with aileron, but it causes the plane to turn. Ditto rudder)

I think its due to one of the propeller effects. There are several propeller effects. It may not be fixable in all power settings and load configurations. Just a little off, Ive noticed several planes do it, might be just one of those things...
 
During my annual my mechanic discovered that the wing is rigged to turn left and the trim tabs are set to compensate. When the ailerons are even with the wings, the yoke is about 10 degrees off. The trim tabs are basically stealing energy by fighting the ailerons. We are going to rerig to level it all out.
 
Sounds like someone rigged it to get the low wing out, then had to use aileron tabs to get it so it wasnt turning. Before you change it, flatten the airleron tabs and see if you have any appreciable speed difference (do a before and after speed run). The difference might be so slight you cant measure it.

I know I took the wheel pants off my Husky and could not measure any appreciable speed decrease. Nor can I see any MEASURABLE speed difference with 1/2 ball slip, which suprised me.
 
Adjusting the struts for washout helped with my 8A's rigging. Have you adjusted the rudder trim tab in any of these planes?
 
The rig procedure is different for every type aircraft. If you don't follow the procedure, it's hit or miss on getting the rig correct. On my Stinson, you have to rig the wing before rigging the ailerons or flaps. Rig it without following the procedure and it will not fly correctly and control throws will be out of limits.
 
Dan Thomas said:
Adjusting ailerons is a waste of time. If you rig one down a bit, it will just push upward and lower the other so that they're equal, and now you still have a wing-heavy airplane that has undesireable stall characteristics. Rigging a flap down is sometimes done, but that can also start the stall sooner on that side.
The maintenance manual for the model should be consulted and followed closely. I get fed up with rerigging airplanes that have been thoroughly messed up by mechanics who don't pay attention and who end up creating more problems than they solve.
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I will first reset factory neutral setting and have the owner go fly it. 4 out of 5 will come back and say "WoW nice"
 
Had that on a 172 trainer. Adjusted the wing aft attached point bushings (they are excentric) per the AMM and fixed it. Took about an hour.
 
coloradobluesky said:
Ive noticed several airplanes that fly "wing low". Bring the low wing up to even with the horizon with the aileron and you turn, bring it up with the rudder and you slip. It varies a bit with speed and Im pretty sure its the prop downstroke being stronger that the upstroke, but is there a cure?
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Aileron and rudder very seldom operate in isolation. My guess is you have to being up the wing with aileron and apply enough rudder to prevent it from turning. Sounds like one or the other isn't working by itself.

As others have said, rigging could take care of it, but it's not going to be a single correction, either.
 
A heavy wing isn't uncommon. What causes it may be as simple as a flap not retracting all the way and you may not even recognize it. Identify the cause before you start chasing the symptom.
 
edessa said:
Had that on a 172 trainer. Adjusted the wing aft attached point bushings (they are excentric) per the AMM and fixed it. Took about an hour.
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and that is how 99% of the out of rig aircraft get that way.
 
edessa said:
No, that is how they are fixed the correct way. Following the AMM and Cessna tech support.
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What did I say in post #7?
Were you not fixing a messed up rigging? How did it get that way?
The guy prior to you did what?
 
My mech thinks its prior damage history causing mine. I took it to the maintenance folks at OSU to have it rigged professionally and they threatened me with unspecified "airworthiness issues" once they realized they didn't know what they were doing and couldn't fix it. My own A&P has moved the eccentric bolts to their stops and even dropped the right flap a skosh. Still, the right wing drops requiring frequent tugs on the yoke. Early in its life, it was put down in a white out on the side of a hill and he thinks the fuselage is out of sorts. I can't see it, but he swears he can.

Sometimes in cruise I can fly hands off for a while, but most of the time I'm making little corrections. Personally I'd love to have it fixed, but in the end I'd spend way too much gas money for something I hardly notice anymore.
 
Once the ball is confirmed level with the seat rails and once the flight controls are confirmed rigged, and when you are sure the rudder is deflected to where it needs to be at cruise, if it still wants to roll, check the nose gear and main wheel spats for proper rigging (up and down, and toe in/out). As a last resort, you might be able to slide wingtips fore or aft or in or out to create more or less lift on its respective wing.
 
This thread reveals that a whole lot of pilots (like 98%) did not start out as kids flying free flight model airplanes.
If they had we would not be having this thread.
It's not too late. Build a couple of hand launched gliders and learn the basics of rigging.
 
Big difference between the rig being out of adjustment and having a tweaked fuselage. There are ways to verify if the fuselage is straight and that the empannage is set correctly too. If the tweaking is bad enough to be visible to a reasonable eye, then it needs to be closely checked to determine what has been done incorrectly. Until you can verify the fuselage is straight and the tail is on within spec, you will never get the rig correct.
 
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