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stretchedpacer
12-14-2015, 12:12 AM
This is for an experimental bushmaster with 17 foot wing panels, 8 foot flaps and 8 foot ailerons.
I finally got the cables installed and swaged today and ran the control wheels lock to lock.
Ailerons have 22 degrees of travel up and 34 degrees down. This is clearly way more than stock.
The question becomes whether this is problematic or dangerous. If anyone has any experience with this kind of aileron travel on a cub I would love to hear from you all.
I can limit the travel but hate to do so. Like everyone else, I just use what I need. I would like to just leave it as-is but if experience has shown this to be a bad idea I will limit the travel.
For those who care about the details, I got this much travel by using the equivalent of a PA-22 cable routing (some changes in geometry) with supercub aileron control horns. The control wheel is not modified and runs like any pacer or tri pacer in terms of travel.
Any insight appreciated.

Zac Weidner
12-14-2015, 08:20 AM
I would worry about the ailerons traveling that much further down than up. You would be better off to have the up travel higher than down, because the situation you have will cause the outboard wing in a turn to have more drag than usual, and it will be even more uncoordinated. It may not even be noticeable, but that's what I would be concerned about.

Pacer 24C
12-14-2015, 10:12 AM
If you have Super Cub type horns - the short horn should be on top and long horn on bottom resulting in more up than down - which would work great - more than 20 down is not effective while up to destroy lift is fine.

stretchedpacer
12-14-2015, 11:47 AM
If you have Super Cub type horns - the short horn should be on top and long horn on bottom resulting in more up than down - which would work great - more than 20 down is not effective while up to destroy lift is fine.

I agree that this is exactly how it should work. In fact, this is why I chose the supercub horn rather than the pacer horns. I was trying to get close to a PA 12 in travel (31 degrees up, 25 degrees down). I may have written my numbers down backwards too which would be embarrassing. I will have to go check the travel again to see what I have. The rigging is correct in terms of the ailerons moving correctly with the yoke so that isn't an issue.
Ill keep playing with it and if I need to, I will modify the control surfaces or the rigging to get it where it needs to be.

Jim
12-14-2015, 12:05 PM
Hi,

40 or so years back I fooled around with RC quite a bit, especially making "improvements" to their performance. A Kraft Super Fly I tricked into disaster. The ailerons were fine until the plane got real fast, then they reversed response, stick right, plane left all the way to the dirt. Earlier on that same plane one of them fluttered and tore off its hinges. Just sugggesting your being careful.

Steve Pierce
12-14-2015, 09:49 PM
I don't think you will have any issues. It is nice to have aileron control when slow and I doubt you will over control the airplane at slow speeds. I wouldn't throw full aileron deflection at cruise speed though.

Stephen
12-14-2015, 10:52 PM
I don't think you will have any issues. It is nice to have aileron control when slow and I doubt you will over control the airplane at slow speeds. I wouldn't throw full aileron deflection at cruise speed though.

Steve has a good point about not using full ailerons at higher speeds. The large ailerons and increased travel will increase load to the wing. Air speed is the critical factor. You will love having all the extra roll rate at lower approach speeds when you have gusty conditions.

stretchedpacer
12-14-2015, 11:43 PM
Thanks for the responses. I agree that full deflection at cruise speed would probably be a poor idea. Since this isn't an aerobatic aircraft I intend to keep my control deflection at something less than full throw at cruise speed. The longer wing would multiply that problem I would think. Of course, the plane is sitting on 31's so going fast probably isn't in my future!
I may just leave it as-is. Seems like I will only use the increased travel when slow in gusty conditions or once I touch down and want to keep a wheel on the ground.
Thanks again.

Grantmac
12-15-2015, 05:39 PM
I'd be more concerned with the negative differential more than total travel. Would make low-speed roll control more prone to stall the low wing.
Can you flip the horns?

Grant

Fred Mayes
12-15-2015, 10:44 PM
I'd be more concerned with the negative differential more than total travel. Would make low-speed roll control more prone to stall the low wing.
Can you flip the horns?

Grant

I used to fly Beavers you could be at cruise and quickly go full aileron deflection then back to neutral and the wings did not move much. If you do that to a Pacer I believe you could over stress the Airplane and you will be on your back. Lets don't do that at cruise.

Fred Mayes
Pacer N7478K

stretchedpacer
12-15-2015, 11:11 PM
Correction. When I previously measured the travel I was using a borrowed digital level. Apparently I was confused by it or it was off. I used my own level tonight. The travel is 25 degrees up and down. I was having a problem understanding how the system could have differential travel which is why I re-checked it. Glad I did.