Rigging issue 1991 RV-4

[Turbofan]

After a year resto on early rv4, I've got 3 hours in ship, airplane falling off left big time, need constant right stick to hold level. Tried adjusting left aileron down couple of turns, but no avail....I was going to droop left flap slightly, any other suggestions?

[Carl Froehlich]

Recommend you not chase symptoms and start the rigging from the beginning.

Make sure you have no twist in the flaps or aileron. You will need to remove them to make this determination.

Get the flaps rigged exactly correct. Check that you don't have a rubbing flap actuator connecting rod (saw this problem in one RV-4).

Determine neutral on the ailerons and adjust. Once done carefully measure the gap between the aileron top skin and the wing trailing edge. My experience is most heavy wings is caused by ailerons either high or low at one end. To fix this call Van's and order a set of "no hole aileron brackets". Determine where the hole should be drilled in the bracket to get the aileron gap uniform across the aileron, and the same as the other side. Here a 1/8" error in hanging the aileron makes a huge difference.

When all done, get the flaps and ailerons in trail postion then see if the wingtips are mounted properly or not. As the wingtip has a large lever arm being a little out can cause a lot of problems.

Carl

[dlloyd3]

Go to Vansaircraft.com. Support heading, Construction FAQs, Heavy Wing Analysis. Start at the beginning, work to the end.
You might also want to read through the service bulletins as a few will apply to your RV.

[rv7charlie]

Just a heads-up; adjusting an aileron up or down will have no effect on a heavy wing. It will just move the neutral position of the stick, and change the effective washout (or twist, which shouldn't be there on an RV) of *both* wings.

Don't feel bad about that mistake; I have personal knowledge that you're not the 1st.....

Charlie

[rvbuilder2002]

Originally Posted by dlloyd3

Go to Vansaircraft.com. Support heading, Construction FAQs, Heavy Wing Analysis. Start at the beginning, work to the end.
You might also want to read through the service bulletins as a few will apply to your RV.

Originally Posted by rv7charlie

Just a heads-up; adjusting an aileron up or down will have no effect on a heavy wing. It will just move the neutral position of the stick, and change the effective washout (or twist, which shouldn't be there on an RV) of *both* wings.

Don't feel bad about that mistake; I have personal knowledge that you're not the 1st.....

Charlie

Lots of good advice so far (these two posts in particular).

Also, changing the rigging of the flaps does not have very much effect. It is best to just set the to the proper in trail position and fix the problem at the root cause.

It might be easier to hep if you gave some details of what types of work was part of the restoration (I.E. airframe damage repairs - particularly if it involved the control system or ailerons, etc.)

BTW, you can get a pretty good idea if there is any twist in the ailerons or flaps by measuring the angle with a digital level at each end rib while the control surface is held stationary.

[Mel]

Originally Posted by rvbuilder2002

BTW, you can get a pretty good idea if there is any twist in the ailerons or flaps by measuring the angle with a digital level at each end rib while the control surface is held stationary.

Or just sighting the trailing edge from behind. Line up the bottom of the aileron with your "Mark 1" eyeball. You will see any twist comparing the ends.
If there is any twist, you will see more of the bottom at one end or the other.

[rvbuilder2002]

Originally Posted by Mel

Or just sighting the trailing edge from behind. Line up the bottom of the aileron with your "Mark 1" eyeball. You will see any twist comparing the ends.
If there is any twist, you will see more of the bottom at one end or the other.

I totally agree Mel, and I use this technique all the time, but I rarely mentioned it because a lot of people just don't seem to have the eye / understanding for it.

[noelf]

If I am rembering correctly, there is another way to check for correct aileron rigging in the "neutral" position.

1. Remove both wing tips.
2. Insert a long dowel rod in each of the tooling holes in the outboard wing ribs (nose rib, main wing rib, and aileron rib) total of 6 rods for each wing.
3. Lay a long straight bar (or whatever) across all dowel rods. They should form a straight line.

This check does not test for aileron twist.

If you happen to know of a local builder, either a -4 or a -6, he may still have the original shipping crate plywood top cover that contains the wing planform stencil that the builter was to cut out and use to align the aileron with the wing. This method was an alternate to the "dowel rod" method mentioned above. I still have my plywood templates (made two of 'em) and someone in my area ends up using them, on average, once each year to check for rigging problems.

[Carl Froehlich]

Originally Posted by noelf

If I am rembering correctly, there is another way to check for correct aileron rigging in the "neutral" position.

1. Remove both wing tips.
2. Insert a long dowel rod in each of the tooling holes in the outboard wing ribs (nose rib, main wing rib, and aileron rib) total of 6 rods for each wing.
3. Lay a long straight bar (or whatever) across all dowel rods. They should form a straight line.

This check does not test for aileron twist.

If you happen to know of a local builder, either a -4 or a -6, he may still have the original shipping crate plywood top cover that contains the wing planform stencil that the builter was to cut out and use to align the aileron with the wing. This method was an alternate to the "dowel rod" method mentioned above. I still have my plywood templates (made two of 'em) and someone in my area ends up using them, on average, once each year to check for rigging problems.

In my opinion the plywood template is more accurate and easier to use.

Carl

[F1R]

The gear fairings alignment or misalignment can produce a rolling force.