B-Model Aileron Travel at the Stick

[Spaceman]

I'm setting up my autopilot servos and I just want to make sure I'm not impeding the full range of travel for the all the controls. I think the ailerons will limit each other's travel when the wings are installed, but how far does the stick move left and right at full travel?

I noticed that without the wings installed, the stick is limited left and right by the opening in the seat pan. So I'm guessing it will travel slightly less than that with everything installed, but I guess I won't know for sure until I put the wings on. BUT, for now, the stick hits the seat before the roll servo hits its stop, so I think I'm good right? Just looking for a sanity check I guess before I call my pushrod setup good to go.

20210610_131631.jpg (2.13 MiB) Viewed 4342 times

20210610_131635.jpg (2.13 MiB) Viewed 4342 times

[pappas]

I put my Dynon roll servo under the right seat in the same spot you are placing yours with an identical access cover cut in. The seat pan did not interfere with the range of roll motion once the wings, ailerons, and servo were installed and rigged.

[Spaceman]

Thanks Lou! I think my setup here will work then if the stick hits the hole in the seat before anything else touches. I want to be sure before I rivet the seat on!

[pappas]

Yeah, the final riveting of every part that closes up a structure is always a little unnerving!

[Spaceman]

Alright I've got the ailerons rigged, but the first thing to make contact is still the stick on the seat pan! That can't actually be what's supposed to limit aileron travel, right?



I think I need double check the outboard bellcranks, and if they're correct then I guess I need to trim the hole in the seat a little bigger!

[pappas]

If I recall correctly, it was 2 1/2 years ago, what limited the sticks roll travel was the aileron counterweight meeting the upper and lower wing skins in the wingtip. But, the bell cranks need to be installed and adjusted correctly as well. I had a small issue with those on my RV-8. Once I recognized it, it was easy to remedy.

[Bryan Cotton]

Classic A model builder here, but my experience is the hole size in the seat pan is just a starting point. I did a beautiful job making those first holes to the plans, and how my fellow builders laughed!

I don't think there should be any contact.

[Spaceman]

Gotcha thanks gents. I think I will recheck the outboard bell cranks first. I went back to my blog post when I initially set them up (summer 2017?!!!?) and I don't even really know what I did so who knows how accurate it is. Now that everything is installed I can constrain the ailerons to match the flaps and I'll know they're in the neutral position I guess. Easier than trying to hold them at that ridiculous 2-29/32 above the wing skin measurement at least. If that doesn't change anything then I'll trim the seat!

[Spaceman]

Oh yeah, I had sent Kerry an email about this last year when I was trying to set up my autopilot servos without the wings installed, and here's what he said (bold added by me):

What stops the ailerons depends on each set-up. To be sure, however, the seat pan is not intended to be a stop. If the seat pan interferes with proper aileron travel after the wings have been installed and aileron rigging is underway, the seat pan must be trimmed.

There are stops built into the aileron pushrod pivot in the wing. See View G-G on drawing W02. This initial setting of the bellcrank will play a large role in your rigging.

Sometime the counter weight is a gentle stop at the extreme end do the control travel.

Until the wings are installed and rigging has begun it is impossible to say how far your ailerons will travel. They should not stop on the lower, aft spar, but they may come close.

I’d say if you want to set up the servo now, make sure it can move the stick fully side to side within the seat opening but plan on it being limited by something else once the wings are installed and rigged.

[Spaceman]

OK I fixed it! I did end up adjusting the short pushrod on the left wing to make it match the plans (I think I shortened it two turns). That caused me to have to adjust the long pushrod on that side quite a bit to reset it to neutral. The right side was good as far as I could tell so I left it alone.

Anyway, the stick still ran into the seat before anything else, so I just started enlarging the hole until it didn't touch anymore. I ended up removing about 5/8" from each side.

I checked the aileron travel before and after. Before, I got 15.7 degrees up from neutral and 9.8 down. Now that the seat is out of the way I get 18 up and 11.2 down.

20210911_115521-.jpg (21.09 KiB) Viewed 3779 times