Tip: Van's electric flap actuator system

[MrNomad]

The design of Van?s electric flap actuator system leaves much to be desired (IMO). As the flap actuator rod goes up and down, it twists left and right causing the flap actuator detent rod to bind in its narrow switching track.

Vans issued SERVICE BULLETIN 7-4-12 designed to stop the jackscrew from disconnecting from the flap actuator rod, but this does little or nothing to stop the flap actuator detent rod from binding in its narrow track.

We believe we came up with a solution to stop the twisting motion. Using a steel washer we machined to have a concave shaped hole, the inner, tapered circumference of the washer bears against the convex bearing limiting its rotation (left and right) without limiting its rotation around the flap actuator weldment shaft.

In other words, the bearing operates normally but does not swing around causing the flap actuator detent rod to bind in its narrow track.

We welcome comment on this suggestion. I suspect some folks have not had a problem as designed (yet) and others simply tolerate the matter altogether.

[RVbySDI]

Any chance of seeing some pictures? "Worth a thousand words" and all that! Since I am not flying but have installed the motor in its mount I am interested in understanding what you are talking about here.

[Bill Phillips]

pictures, pictures, we need pictures !

[JonJay]

I copied another builders suggestion in a prior post (cant find it though). Bolt the Lower Rod End on the outside of the lower bracket with a longer bolt and a spacer (aluminum tubing) on the inside of the lower bracket. This allows the Actuator Arm to align straight with the body of the Actuator/Motor through its entire travel. It works very well and even though it is cantilevered on the outside of that lower bracket, it is plenty strong. No need to machine something special although I admire your ingenuity.

[MrNomad]

Originally Posted by Bill Phillips

pictures, pictures, we need pictures !

On the following website, please note the examples of similar parts and a better explanation of how we solved the problem.

Lots of people have helped Chet and I during the last 14 months so send me a phone number if you wanna talk about it.

We work on the RV9 EVERY DAY 7am to 1pm Tucson time. If the earth rotates, we work on the plane. We're gonna fly this thing before end of summer.

http://www.arizonaairparks.com/rv-flaps.htm

[erich weaver]

Barry - is it possible that a properly sized o-ring would do the job?

erich

[MrNomad]

Originally Posted by erich weaver

Barry - is it possible that a properly sized o-ring would do the job? erich

No, I don't think an O-RING will work because the shape of the washer has to match the shape of the inner bearing else it will bind the inner bearing and impede its rotation around the bolt. What you want to reduce is left and right rotation, not rotation around the shaft. An O-RING will not afford that benefit that's why we used steel. Plus, O-RINGS wear rather quickly. I would NOT use an O-RING.

Suffice to say, if you can find a washer that has the bolt size and an exterior dimension that is slightly larger than the inner bearing, you're halfway there. We used a 1 & 1/4" countersink and drilled the concave angle into a steel washer with the right dimensions. In essence, you're beveling the inner edge of the washer so it fits around the inner bearing surface.

I tested our solution about 50 times and it remained perfect.

I just spoke to Stein and told him of the idea. He asked me to email the idea to him so that he could decide if it warrants his company's attention. Personally, I think someone should release a "fix" because if you install Vans service bulletin and safety wire the device, each time the shaft rotates it will stretch the safety wire eventually rendering it useless.

I describe the relationship between the washer and the bearing surface as follows: Take your right hand and make it into a fist. Take your left hand and cup it over your right. Your left hand is the modified washer, the right hand is the inner part of the bearing. Both should move together and slide easily on the AN bolt that passes thru.

Feel free to send me a phone number if you like.

barry "at" arizonaairparks.com

[DrHolling]

Seems like you are trying to limit one of the attributes of the design of a Heim joint. You could acheive the same result by replacing the Heim joint with a clevis. Rotates about the long axis of the bolt but can't rotate perpendicular to the bolt. I would think the Heim joint was chosen to compensate for any variations in alignment. I am just starting on the center section of the fusalage. When I set things in place the shaft seems to run slightly off parallel with the arc of the flap torque tube attachment point.

Maybe I have something not quite right or it may lineup better after it is riveted.

Dave
RV-7A
Working on the fuse (finally)