Flap lever installation

[BravoGolf]

I am at a point where I would like to drill the inner flap arms to the torque tube. However on the wings I purchased from another builder the flap lever was already welded to the flap torque tube. Of course this means I can not set the flap lever position after drilling the flap arms to the torque tube. I really do not want to back up by fabricating a new flap lever and torque tube to replace the welded one. Here is my plan and I am hoping those with more experience can tell me where I am going wrong.

1. I have measured / calculated the flap lever angle for flaps retracted as 32* or 5.55" forward of the center line as depicted on the drawings. I calculated the angle and measured from the aft spar to the center of the hole in the flap angle on the plans to get the distance.

(reference this drawing in this thread https://bearhawkforums.com/forum/bea...n-in-3-notches

2. As I can not move the flap lever on the torque tube I plan on positioning it at the correct angle mentioned above.

3. With the springs installed the flap arms will be held against the rubber bumper in the retracted position.

4. Drill the flap arms to the torque tube which will set the flap lever in its correct retracted position (32* forward.)

5. Any minor variations will be dealt with by adjusting the flap turnbuckles.

What am I missing here?

Thanks

[nichzimmerman]

Scott, that's effectively what I did on my 4-place wings, but I haven't mounted them to the fuselage yet to test the arrangement. If you do this now, ensure that the inboard lever angle is correct AND it is adjusted laterally (longitudinally to the torque tube axis). In other words, make sure it is sticking out of the wing root the proper distance. I adjusted mine to be centered under the rear spar bolt hole, but won't know for sure if that was the correct spot until wings are mounted.

-Nic

[BravoGolf]

Well I’m going to have to check the lateral distance issue. I’m not sure they were made long enough. I thought as long as the lever had full travel through the range of the depicted arc it was good. Can anyone confirm that? Or is there a minimum distance from the first rib to the flap lever?

[svyolo]

I don't know if the Patrol is exactly the same as the 4 place. On the 4 place, the spar and the fuselage wing attach form an inverted "V" that the flap cable dives into going to a pulley. It is a very tight fit with the cable/thimble to fit down into that V. There is very little play on either side to get it wrong. I did mine with the wings installed.

This is with the flaps set to full.

[rodsmith]

I also recommend waiting to drill the flap arms with the wings installed. The inboard flap arm has to angle forward more than you would expect in the stowed position to be able to pull full flaps without cable hardware interference with the rear wing attach fitting.

[whee]

I third waiting to drill till the wings are installed. Previous builder drilled the torque tubes but they were a bit off. After installing the wings I discovered the issue and had to remove the tubes, weld the holes, reinstall the tube then drill.

[BravoGolf]

Seems the collective knowledge is to wait, so wait it is! I’m pretty sure I will be fabricating new flap torque tubes. The one that is welded fits almost flush against the first rib.

thanks for the help

[DBeaulieu]

So...not exactly clear to me what determines or is the limiting factor associated with lateral positioning of the torque tube. Is it cable and crimp clearance between the lever and fuselage? A pic would be insightful...Thanks!

[Steve W]

Wait until you have determined if the travel of the cable to the arm is centered in the pulley. The full travel will have the cable slightly riding the side of the pulley groove at the beginning and move to the other side at full deflection. I set mine so I had a little more contact with the side of the pulley at the beginning cause of the larger amount of force needed at full deflection. There has been past discussions on this I believe where someone was indicating premature pulley and cable wear.

[alaskabearhawk]

Here's a few pics of mine. No flaps, fourth and fifth notch. And yes, there is clearance between the cable fork and the wing mount. Not much, but there is.

No flaps 1.jpg No flaps 2.jpg Fourth notch 1.jpg Fourth notch 2.jpg Fifth notch 1.jpg Fifth notch 2.jpg

[DBeaulieu]

Thanks guys...appreciate the replies and the pics...along with the tips!

[spinningwrench]

You really need to wait to drill your torque tube until the wings are mounted. The cable needs to run exactly down the center of the crotch formed by the joining of the wing spar and fuselage mounting tab. There is very little clearance for the cable nicopress fitting when the flap is in the fully extended position.