Dimpled flap hinge OK?

rickmellor · #1 10-29-2006, 07:20 PM

Related to this thread, but slightly different focus...

I've riveted on my flap hinges but afterwards I started to question my approach. I dimpled all three laters: skin, brace and hinge. In retrospect I would have preferred to have dimpled the skin, CS the brace and left the hinge alone.

What do you guys think? Should I tear it all apart and do it over or will it hold the way I have it? I'll call Van's in the morning but would like to get you guys' take on it as well.

-Rick

Radomir · #2 10-29-2006, 07:27 PM

Van's is OK with dimpling the hinge... that's what they told me when I called them one time..

13brv3 · #3 10-29-2006, 07:31 PM

Quote:

Originally Posted by rickmellor

What do you guys think? Should I tear it all apart and do it over or will it hold the way I have it? I'll call Van's in the morning but would like to get you guys' take on it as well.

-Rick

Hi Rick,

I think the way you did it is absolutely fine, mostly because I just did mine that way a week or so ago. Forget about it, and move on

Cheers,
Rusty (flying in 2-3 weeks)

az_gila · #4 10-29-2006, 10:18 PM

Since the hinge is a softer material, I would ensure that the shop heads are made towards the larger end of the tolerance....

Make them all at or above the 1.5D width dimension..... there are a lot of flight loads on this hinge line at max. flap deployment speed.....

Since you dimpled after drilling, the "top" of the dimple does have an angle, and you want to ensure that this angled portion is fully covered and that the shop head bears on full thickness material.

gil in Tucson ...
Did you manage to dimple the hinge and not turn it into a pretzel??....

AntiGravity · #5 10-29-2006, 11:10 PM

I thought I read somewhere not to dimple the hinge because it will distort? I'm interested in this because I'm in a position where the flap brace is already installed though the wing skin/flap brace/ flap hinge has yet to be fitted. If I can dimple everything it sure will make life easy...

rickmellor · #6 10-30-2006, 01:14 AM

I was concerned with the shop head size so I used .5 size over the rivet length callout (4.5's I think). I was careful with the pneumatic squeezer and managed to get them to set true.

The hinge did curle over when I dimpled it. It was uniform in the way it bent and when I straightened it back out the holes were still in alignment so it didn't seem to be a problem. The bending wasn't enough to make me concerned about fatigue.

I'll check all the shop heads again to make sure the dimple edges are properly covered.

Thanks guys.

RV6_flyer · #7 10-30-2006, 05:30 AM

Quote:

Originally Posted by AntiGravity

I thought I read somewhere not to dimple the hinge because it will distort? I'm interested in this because I'm in a position where the flap brace is already installed though the wing skin/flap brace/ flap hinge has yet to be fitted. If I can dimple everything it sure will make life easy...

You are correct. You can dimple them but when you do, it distorts the hinge and it will be very difficult if not impossible to get the hinge pin in the assembly for the finished airplane. I was just looking at an RV-8 on Friday where the builder was having a very difficult time getting the hinge pin in the flap assembly on the airplane.

13brv3 · #8 10-30-2006, 06:35 AM

Quote:

Originally Posted by RV6_flyer

You are correct. You can dimple them but when you do, it distorts the hinge and it will be very difficult if not impossible to get the hinge pin in the assembly for the finished airplane.

I know that Van's prefers that you countersink, rather than dimple the hinge material, but removing much of the "soft" material makes less sense to me than dimpling it.

As a test, before doing it on a real part, I took a section of scrap hinge material, and dimpled a bunch of holes. Since this didn't seem to deform the hinge, I started dimpling all my hinges. So far, no problems.

BTW, there are a number of factors that can cause pins to be hard to install. Squishing one of the eyes with your squeezer can sure do it

Also, when you force the prepunched holes of the flap hinge to line up to the pre-punched holes on the bottom skin, the result can easily be a skin that isn't perfectly straight along the hinge line. The soft hinge will be forced to conform to this, regardless of what shape it was in originally, and the pin will be tight when assembling the flap. This doesn't seem to cause any operational problems though, and you don't have to worry about the pin working it's way out

Cheers,
Rusty

Brantel · #9 10-30-2006, 07:58 AM

Vans prefers that you countersink the middle layer not the hinge. Just like on the elevator trim tab hinge.

Dave Cole · #10 10-30-2006, 08:39 AM

Quote:

Originally Posted by Brantel

Vans prefers that you countersink the middle layer not the hinge. Just like on the elevator trim tab hinge.

And just like on the flap itself.