RV-3/4/6 Guys - Aileron Bellcrank Help

Ok guys, I know this should probably be posted in the RV4 forum, but since the same basic principle applies to the 3, 4, and 6, I put it here for a wider audience.

I would rather ask a stupid question, get laughed at, and get the right answer, than not ask and NOT get the right answer, so here you go:

You can see, that the distance from the bearing hole center to the torque tube hole centers, are NOT symmetrical. One measurement is 3.08", and the other is 3.4". This will surely change the geometry and associated aileron travel if installed incorrectly. There IS a right side up, AND an upside down, in other words.

So, I can't find anywhere, a dimensional reference that clearly, (or even vaguely) indicates which hole goes to the stick, and which one to the aileron. I feel kinda silly here, but I simply don't know. Have any of you had this issue?

I had the same questions recently.

On the -6 it's implied by the layout and scaling of the drawings on sheet 19a

Scaling the wing layout sheet 10 comes up with the same answer.

The long side goes to the stick and the short side to the aileron.

Not sure about the -4, but the 6's had an update that added small diam. washers to the control stick tube bearing at the bellcrank.

5702-75-60 washers are added. In my case I had to reform the bellcrank ends to allow for the extra 1/8 or so of thickness.

Gregg Brightwell said:

So, I can't find anywhere, a dimensional reference that clearly, (or even vaguely) indicates which hole goes to the stick, and which one to the aileron.

Click to expand...

It's been a long time for me but I recall puzzling over the bellcrank position too. RV-4 drawing 16 (10/31/86 with R6 of 8/92 incorporated) is full-scale and has the bellcrank dimensions. If you put a ruler on the installed drawing, left side center, you'll see the long arm (3 3/8 per the drawing) is connected to the stick and the short arm (3" per the drawing) goes to the aileron. I see after digging out the drawings that I wrote "long arm" and "short arm" over the appropriate arm on my drawing.

Note that this drawing (in my case) still has the small W-425 gussets that were replaced by large gussets on 1/30/92 with a new drawing that has less detail than dwg16. That drawing is unnumbered, I called it 16a and built to both.
Hope this helps.

az_gila said:

I had the same questions recently.

On the -6 it's implied by the layout and scaling of the drawings on sheet 19a

Scaling the wing layout sheet 10 comes up with the same answer.

The long side goes to the stick and the short side to the aileron.

Not sure about the -4, but the 6's had an update that added small diam. washers to the control stick tube bearing at the bellcrank.

5702-75-60 washers are added. In my case I had to reform the bellcrank ends to allow for the extra 1/8 or so of thickness.

Click to expand...

I also have a 6, but did not see an update and don't have special washers. Do you know what the purpose/intent of these small diameter washers are? I didn't notice any clearance issues when I had the pushrods installed.

Larry

Drg 16a shows top left aikeron bellcrank plate in nearly same alignment as the top view which is below it. The top view shows the 3" centred hole going to the aileron. that is how I built it and it flies well.

Thanks guys.

All of your responses provide the same answer as to which arm goes where, so I will go with that.

That said, even wih this newly acquired knowledge, I still can't make myself see this on the drawings, implied or direct.

Head scratching moment number 417 on the rv4 build.....more to come I'm sure.

Thanks, and regards,

Gregg

Gregg Brightwell said:

All of your responses provide the same answer as to which arm goes where, so I will go with that.

That said, even wih this newly acquired knowledge, I still can't make myself see this on the drawings, implied or direct.

Head scratching moment number 417 on the rv4 build.....more to come I'm sure.

Thanks, and regards,

Gregg

Click to expand...

Go to the section of the manual on rigging. Here you will find the numbers of degrees for up versus down aileron deflection. This should make you feel more comfortable that you got it "right." You can draw this out on paper. One installed direction will give a larger differential in travel than the other. It will require a protractor and a little math, but you can figure it out.

Larry