UnPossible

UnPossible

Well Known Member
Hey - with the wings on and incidence drilled, I want to get the wing tips drilled and the ailerons and flaps all rigged correctly. Unfortunately, I'm having some trouble with the left flap.

1) Both ailerons are set to neutral as measured by the tooling holes in the wings

2) The control stick is vertical, and the aileron bell crank jig lines up for both wings

On the right side, you can see that I can adjust the flaps via the linkage so that when fully up, they are pretty much perfectly inline with the aileron.
4l5ymf.jpg



However, on the left side, the when fully up is ~0.15" below the aileron.
2j1ocp2.jpg



Looking under the plane, it appears that the flap is hitting the fuselage in the fully up position
140agpi.jpg


Are there any tricks or suggestions as to how I can get this flap up an additional 0.15"?

Thanks,
Jason
 
Rig everything perfectly - don't expect all else to be perfect

When naturally built I had to raise the trailing edge of the left wing to get the correct incidence angle. I expected the lower flap skin to extend directly under the fuselage for a gap seal in the up position. That was impossible. With the canopy deck reference plane leveled and the incidence angles of both wings correctly set the flaps were required to rotate up well past the bottom of the fuselage to align with the airfoil jig and align with the ailerons. I added a step or mild "Z" bend to the lower flap skin inboard edge to conform with the fuselage. There is a lot of craftsmanship required to work out minor problems like this but the dominant requirement is to properly rig the airplane. Once you have measure ten times to make sure you aren't incorrectly rigged then you have to accommodate all of the tolerance build-up and out of square construction conditions with some careful creative work.

Bob Axsom
 
Double check your flaps and ailerons for square.

One or both may be slightly warped. This is very common. As you can imagine a very slight warp will add up over the length of the control surface. This is not a big deal and I have seen much worse alignment than what you are showing on airplanes that are reported to fly perfectly.
As Bob stated, most of the time these machines are a series of compromises. Don't compromise on the rigging and sort out the other things later if you need to.
 
You can trim the top skin to clear the fuselage and joggle the bottom skin to make it fit flush under the fuselage and still give you the up travel you want (after you check to make sure there are no wing warp issues). Since you trimmed the lower skin at an angle rather than leaving an overlap at the trailing edge, the fit there may be a little ugly. On my six I had a similar problem and covered the fuselage in that area with clear packing tape and then did a layup to make that transition.
 
flion said:
Since you trimmed the lower skin at an angle rather than leaving an overlap at the trailing edge, the fit there may be a little ugly. On my six I had a similar problem and covered the fuselage in that area with clear packing tape and then did a layup to make that transition.
Click to expand...

FYI - the bottom skin has not been trimmed... this is the wayit came from the QB factory.

Thanks,
Jason
 
Make sure the elevator is clamped

in the neutral position as well. You said the control stick is neutral so you probably have that. I noticed when rigging mine that the elevator travel actually moves the ailerons just slightly, so it is important to have it centered when rigging. If you get behind the plane and move the elevator from stop to stop, watch what the ailerons do!

In short, the ailerons should be rigged to the tooling holes with the elevator clamped neutral.
 
Thanks for the elevator tip... I clamped the elevators to neutral and the problem is a bit better, the left flap now sit ~1/16" below the aileron.

i2jyom.jpg


After looking this over, I noticed that the 1/16" gap is pretty consistent along the entire gap between the flap and the hinge. Unless I'm missing something, the only way to resovle this is to raise the flap hinge by 1/16".

In my mind, this is quickly becoming not worth the hassle.. Is a 1/16" gap enough to do something about, or is it time to move on to attaching the wingtips?

Thanks,
Jason
 
Joggle

It is normal and expected to have to joggle the flaps a bit as shown on the earlier post. It even makes some sense when you consider that the wings are canted relative to the fuse.
 
Try this

Move the stick all the way left (or right) and fix it there. Motor the flap down to meet it(the aileron). Move the stick (aileron deflection) the other direction. If it's within 1/16" of matching the flap, just fly it and see if you can feel the difference. As some have said before, " You're building an airplane, not a watch" and "We're flying to Denver, not Mars". I worried a lot about the little differences while building, but in the end, I didn't need any trim tabs or anything to make it fly better than anything I'd flown before or since. And no one else will notice the little differences.
 
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Jason,
It appears that the top of the flap is contacting the side of the fuselage, and that is what is preventing the bottom overlap from coming fully "up". If that is the case, then trim more of the top skin. If that is not the case, then do exactly as Jim Sharkey says, and make that joggle. You are headed in the right direction........Stick(locked vertical), bellcrank (locked neutral via the jig), stick to bellcrank pushrod adjusted and installed, aileron locked neutral via the tooling hole method or if you're an "old timer" an airfoil template, then the aileron to bellcrank pushrod adjusted and installed. Now, do whatever needs to be done to align the outboard edge of the flap to the inboard edge of the "locked" aileron. It would not be uncommon for one flap skin overlap to be bent up to meet the fuselage on one side and a joggle on the other side. Once the flap is aligned with the aileron and the flaps are up,clamp the flap and aileron together, remove the aileron tooling hole jig, and install the wingtips, aligning the wingtip trailing edge to the aileron trailing edge.

IF YOU DO IT THIS WAY YOUR AIRPLANE WILL FLY STRAIGHT AND LEVEL WITH THE STICK NEUTRAL!

THE PRESSURE REQUIRED TO HOLD THE "STICK" NEUTRAL( and therefore, the ailerons neutral, and therefore the wings NOT banking), CAN BE RELIEVED BY CHANGING THE TRAILING EDGE RADIUS OF ONE OF THE AILERONS!!!!

A "squeeze" can set you free!:D

Regards,
 
Flap alignment

Check for twists in flaps and ailerons which is easy to get when building those surfaces before you go too far. I set them on a flat surface like a workbench and weighted one end down until it was on the flat surface and then checked to see if the opposite end was also flat on the surface. Then all the suggestions in prior posts should help. Mine were pretty straight but I ended up with a pretty good joogle on the bottom skin of my flaps. Shaping the root end of the flap took some time and a lot of fitting.

Dick DeCramer
Northfield, MN
RV6 N500DD flying since 2004
RV4 Rebuild flying 2005
RV8 Fuselage
 
Hawkeye7A said:
I didn't need any trim tabs or anything to make it fly better than anything I'd flown before or since.
Click to expand...

Some airplanes "cheat"! :D

They build in offset vertical stabs, so you don't need a trim tab like my classic tailed 6. :)

L.Adamson --- RV6A
 
L.Adamson said:
Some airplanes "cheat"! :D

They build in offset vertical stabs, so you don't need a trim tab like my classic tailed 6. :)

L.Adamson --- RV6A
Click to expand...

My RV-6 flies straight with feet off at cruise. No rudder tab and no deliberate VS off-set. YO-360-A1A with 72/85 FP.

Just another data point.
 
Another thing to watch for to make sure when the flaps are all the way down, you still have enough of the leading edge of the flap that curves under the wing. There has been a number of accidents (it happened to my friend as well) that the leading edge popped up and when the flap was raised, it messed up the upper wing skin. Raising the flap to match the aileron would help in that aspect as well. All you need to do is to bend the bottom skin of the flap just as it showing the pix by Jim.
 
BTW

BTW - my RV-6 does fly straight and true at cruise but when I slow to traffic pattern speed and lower the flaps I need a fair amount of right aileron trim.

Anyone else notice this?

Jim Sharkey
 
Thank for all the pictures of the "joggles". What I'm still struggling with is that I don't think a joggle will solve my problem. If you look at the last picture that I posted,you can see that there is a pretty consistent 1/16" height difference the entire span where the flap meets the aileron.


If I joggle the bottom of the flap, it should take care of the difference at the trailing edge, but the 1/16" difference will still be there where the flap and aileron meet upwith the wing.

Is there any way that I can move the aileron down 1/16" of an inch, or the flap assembly up? I've thought about drilling out 4-5 of the rivets that attached the flap hinge and insert a 1/16" spacer.... any other ideas or am I not thinking about this correctly?

Thanks,
Jason
 
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jsharkey said:
BTW - my RV-6 does fly straight and true at cruise but when I slow to traffic pattern speed and lower the flaps I need a fair amount of right aileron trim.

Anyone else notice this?

Jim Sharkey
Click to expand...

no, but wouldn't that make sense because your plane is trimmed for straight and true at a certain power and speed. when you reduce that you have less prop airstream flow affecting control surfaces, and it should feel a bit "out of trim". It would take an amazing plane to fly straight and level at all power and speed ranges.
 
Agreed....

....in pitch and yaw - but roll?

Just wondered what others experience on their aircraft that are flying.

Jim Sharkey
 
jsharkey said:
....in pitch and yaw - but roll?

Jim Sharkey
Click to expand...

Maybe! The rudder can affect the aircraft attitude (roll) if it's trimmed for speed but not for slow flight and a significant speed change is made. Yes, there would be some yaw, but maybe not noticed because of the many other things going on in slowing the plane down for a landing. How many RV's have an extra trim tab on the rudder to keep the plane flying straight at speed? What is the effect with a speed change on those RV's with that trim tab?
 
UnPossible said:
Thank for all the pictures of the "joggles". What I'm still struggling with is that I don't think a joggle will solve my problem. If you look at the last picture that I posted,you can see that there is a pretty consistent 1/16" height difference the entire span where the flap meets the aileron.


If I joggle the bottom of the flap, it should take care of the difference at the trailing edge, but the 1/16" difference will still be there where the flap and aileron meet upwith the wing.

Is there any way that I can move the aileron down 1/16" of an inch, or the flap assembly up? I've thought about drilling out 4-5 of the rivets that attached the flap hinge and insert a 1/16" spacer.... any other ideas or am I not thinking about this correctly?

Thanks,
Jason
Click to expand...

Jason,
Don't worry about the 1/16 inch it's no big deal! Just align the trailing edges.
 
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