PDA

View Full Version : WWI bipe aileron setup question.


Farmer Ted
12-21-2007, 07:06 AM
I've finished building my first bipe...a Lanier SE5a EP...


My question is on the aileron setup: This plane has dual aileron servos connected by a Y harness and ailerons on the upper and lower wings connected by a pushrod.

No matter what I do, I can't get the ailerons on the upper and lower wings to have equal throw. If I set up the lower ailerons for the correct throw, the upper has near the correct throw when going up and much more when going down. I have expiremented with different holes on the control arms, etc etc.

I have a few questions:

1st: Is it normal for bipes with dual ailerons to have different throw from upper to lower ?
(just due to the arcs that the control arms travel through)

2nd: if this isn't normal, what can I do to fix it?

3rd: if it is normal, which ailerons to I set the throws off of, upper or lower?

4th: do any bipe flyers recommend expo on the aileron servos? I've never flown with expo before but these ailerons look pretty snappy...I'm not sure what to expect. I've flown bipes on Real Flight (http://www.rcuniverse.com/buynow/keywordclick.cfm?bid_id=1820) briefly and I'm not sure how those are set up.

Thanks for any replies, this is a nice little plane and I don't want to pack it in on the maiden because of a screwy setup.

Sky Sharkster
12-21-2007, 12:05 PM
Hello Farmer Ted, Welcome to Wattflyer!
Doesn't the SE-5a have stagger? That is, the upper wing is farther forward than the lower. If so, this would put an angle on the pushrod, similar to differential on many flat-bottom airfoil wings.
The normal set-up with flat bottom airfoil wings is more up than down, by about 3:2 or 2:1. You may have to use angled control arms (If my physics are right, angled or swept rearward) on the lower wing to equalize the throw.
I believe the throws should be the same for upper and lower wings.
If you feel the total throw is too great, you can either limit the servo travel, try expo, or use dual rates. Any one of these should allow you to fly it safely to get it trimmed out.
Good Luck!
Ron

7car7
12-21-2007, 09:10 PM
Are you familiar with taking the arm off the servo and re-mounting it in a different position? This would give you differential. As Sky stated, you'll want the aileron having more travel UP than DOWN.

But I have no idea why your upper and lower would be different. Do you have a photo?