Staudacher

I am building an Aeroworks 33% Edge 540T and am trying to decide on a rudder pull-pull system. I am using dual 8411 servos but can't decide on what servo arms etc. to use. I would like the final arm to have an offset to get the geometry to the hinge line right. Does anyone have pictures that they can post of their setups? I am leaning towards the Nelson L207 for a final bellcrank but what should I use on the servos? If Nelson servo arms are used what servo arm should they be bolted to? Does it have to be aluminum?


thanks, Dan

Tim_Indy

Staud, I think I've the exactly the setup that you want. I too am using JR 8411 servos in a pull-pull setup on my Extra, and we both know the well documented problems with digital servos fighting each other.

Tom Wheeler (IMAC Pres) suggested using floating bellcranks, as you still get the full 360 oz/in of torque to both sides of the rudder, but it's impossible for the servos to fight each other, as each side's floating bellcrank adjusts for any mismatch in centering, end travel, etc. I've split my plane's controls in half using twin receivers. I've got one rudder servo on one receiver, and the other rudder servo on the other receiver. If one side's receiver quits for any reason (which will then free wheel that side's servos) the I've still got half travel on the rudder.

I use Airwild's MLP servo arms described at: http://www.airwildhobbies.com/MoreIn...e=product&id=1 . I also use Rocket City ball links (now sold by Nelson Hobbies) for zero play. If I used clevises, I might have been able to get by with a nylon arm, but since the ball links put a side load on the arms, aluminum is the only way to fly.

Pics are on my web site listed below (in the construction pics, click the pull-pull pic to get several more detailed pics of the install. I've had zero problems with this setup in well over 100 flights on my Extra.

calebdevries

My Feedback: (8)

Do you know where to get these floating bellcranks?

Staudacher

I built mine using an old Sig control line bellcrank that I cut and drilled. It works well so far. I have pictures of the installation at my website.
http://staudacher0.tripod.com/danshangar/id6.html
Dan

wowie

Do you have any other pictures of the rudder pull-pull setup that you installed in your plane? I've never seen that kind of system and it looks interesting. So if you could upload some more pictures that would be great.

Regards,,,,Phil