Flap handle

[Bdflies]

Note: I have a Patrol and don't have any way of knowing how similar the 4 place mechanism might be.
After reading several threads about extending flap handles, I wondered about what was going on. Either the handles are short, or we have a bunch of weenies flying Bearhawk variants. Well, faced with that choice of explanations, I've declared the handle too short, cause I was never able to get the 4th notch out. I guess the latter explanation is still possible, but I'm not going there... Also, my throttle quadrant doesn't leave much room for fingers, between the handle and the enclosure.. This limits leverage by forcing the grip down a bit.
I was OK with 3 notches, on landing and knew that I'd modify the handle at some point, in the future - until a recent flight. After pulling the 2nd notch, but before releasing the handle, it slammed down so hard my watch was ejected from my wrist! I figured that I didn't pull quite enough to engage the detent into the notched piece. Pulling again, To my surprise, it wouldn't engage any notch. The button was stuck down and nothing I did would free it. Hmmm... I get to make a no-flap landing into my (not too roomy) strip. Well, a little extra speed, a little slip and a little more brakes and it went just fine. But, what happened?

To Be Continued...

Bill

[Bdflies]

I'm breaking this up, so I don't have to worry about the whole thing when I screw something up...

Well, safely on the ground and curious as heck, I set out to see what the heck happened! It took a bit of prying, with a screwdriver, to free the detent button. Once freed, I could not get the button to stick again. If it did it once, I fully expect it would do it again.
I removed the handle assembly and took it apart. Everything looked just fine. Out of curiosity, I mic'ed the ID of the handle tube, the OD of the plunger/detent and the diameter of the spring wire. The plunger to handle clearance was .061". The spring wire is .059". This leaves enough room for the spring tail to lodge between the members. This is the only explanation I can come up with, as to why the button stuck down. I have no way of knowing if these dimensions are typical of all Patrols, or if similar situations can exist on the 4 place. But, I might suggest that you check your components.
NOTE: I don't believe this is a particularly unsafe phenomenon, but rather a very surprising one.

This seemed to be a fine time to make an extended handle, with clearance for my throttle quadrant. And maybe tighter clearances to prevent another stuck button. So off I went!

Tubing was ordered and head scratching began.

Bill

[Bdflies]

Because of the quadrant clearance, I wanted to shift the lever right, a couple of inches. Because of the pivot and latch geometry, the handle itself would need to be bent a bit. Since the detent plunger would need to be inserted from the top, past the bends, I couldn't use the same latch detent mechanism.

I made a completely different latch mechanism. It's not better, it's different. It allows i sertion past the curves in the handle.
Rather than write a thousand words, see the pics attached.

Note that I machined ramps into each notch. It very smoothly engages each notch and the 3 5/8" additional length now allows easy engagement of the 4th notch!

Bill

[Bcone1381]

Thanks Bill, Your workmanship looks great.

Brooks

[Bdflies]

I appreciate that Brooks! I don't particularly recommend bending the handle, unless some specific need forces such, but I do suggest lengthening the flap handle. This thing has some real "barn doors" hanging off the back of the wing! The last notch is pure drag and I absolutely love it!

[Untainted123]

Continuing this thread because I couldn’t find a better one; I have had a lot of trouble with not being able to find the notch on any flap setting beyond the first one (and the first “fake” one), which are ramped. Notches 2, 3 and 4 are notches only and I have found it unreliable to:
1. Find the notch when deploying flaps
2. Not losing my place and taking flaps out because you are not ready for the weight when you depress the button to go to the next notch
3. Several times my flaps have fallen to the floor because with the weight on the handle, the pin doesn’t fully seat down into the notch and you don’t realize it until you let go of the handle.

I want to recut my latch mechanism to have ramps like post #3 above, with every notch having a ramp. I like to be able to simply pull up into each notch, like my Piper Warrior, and only need to push the button to release back down. I have also noticed some burring of the notch entry points, and my plans call for 2024 Al, but I was thinking of having SendCutSend make me one in 7075. Thoughts? Are there any safety/downsides I am not aware of, or is this just a preference thing?

[Nev]

I want to recut my latch mechanism to have ramps like post #3 above, with every notch having a ramp.

That's what I did after having the same experience as you did. Works much better now. I can pull each stage without having to press the button, and it self locates neatly against the catch. There's no downside.

[Untainted123]

Perfect, I am going to go with that then.

image.png image.png Flap Latch.dxf

[AZBearhawk272]

I would avoid 7075, it is higher strength but heat treat dependent, tends to stress crack easier from notch sensitivity or bending.

2 other considerations.

Construct the notches so the notch radius has a slightly lower resting position from the entry slot. This will insure the pin does not have a natural ramp to create a retract vector on the pin.

Make sure notch area in handle is reinforced with doubler as deflections under activation loads in this area will bind the inner shaft preventing free movement and locking.

Kevin D
# 272 DG
KCHD

[jaredyates]

Excellent input as always Kevin, the age of Stephen's kit might be right for it to need attention under this update also:

http://bearhawksafety.com/4-place/changejan06.html