¼ turn flange question

Rivethead · #1 10-04-2008, 02:37 PM

I'm about to begin installing the flange on my firewall for a 1/4 turn attachment system (Mil Spec). I'm wondering if it's necessary to radius the flange at the bottom corners of the fuse or could I make two straight unbent flanges one for along the bottom of the fuse and the other for up the side? I plan to scallop the flanges and except for leaving a radius piece of the flange intacked to support the cowling I don't see a real need to make the flange one piece since I wont be putting a fastener in the radius. Any thoughts would be a help. Links to builder sites with examples would be a really big help. Thanks

scard · #2 10-04-2008, 02:44 PM

My opinions having done this:
Separate pieces for bottom, sides, and top. DON'T scallop the sides, I did and have considered redoing it after 200hrs. The top rear corners of the bottom cowl get caught in the scallops when installing the cowl. No need to have any flange material around the bottom corners.

Rivethead · #3 10-04-2008, 03:08 PM

Awesome, Thanks for the quick reply. No scallops..OK, I'll take that as good constructive information. What about scallops across the top, they look so cool it seems a shame not to have a few

.

scard · #4 10-04-2008, 04:37 PM

Quote:

Originally Posted by Rivethead

Awesome, Thanks for the quick reply. No scallops..OK, I'll take that as good constructive information. What about scallops across the top, they look so cool it seems a shame not to have a few

.

Yeah, the scallops work fine across the top and on the bottom pieces.

alpinelakespilot2000 · #5 10-04-2008, 05:41 PM

Quote:

Originally Posted by Rivethead

Awesome, Thanks for the quick reply. No scallops..OK, I'll take that as good constructive information. What about scallops across the top, they look so cool it seems a shame not to have a few

.

You pretty much have to scallop at the top. If you don't, the attach strip will tend to angle up, preventing the cowl from laying flush.

dhall_polo · #6 10-06-2008, 06:49 PM

I just finished doing Skybolt fasteners. I posted pics of my camloc install to my website.

I went with a "no hinge" cowling, and I'm very happy so far with the Skybolt camlocs and installation. As others have said, scalloping is required around the top cowling, but you should be able to get by without scalloping everywhere else. The bottom flanges do angle upwards a bit, but they do so uniformly.

I've read about how others have not enjoyed hinge installation or the user-friendliness of the hinges thereafter. I thought the Skybolt camloc install was straightforward. Granted, it was a fair amount of work. It reminded me of doing the 1000 platenuts on the wing spar. Lots a repetitive steps, rinse, repeat.

At the very least, there's a modest weight advantage in scalloping as it removes a lot of excess metal. I think it looks better with the scallops, but that's subjective, and not many will ever see it. The fit around the front of the cowling is tight, and maybe it would be harder to install/remove the cowling with unscalloped trim along the sides.

One thing I would modify from Skybolt's instructions: They have you cut 4" wide attach strips to start with, and then you trim excess later. I think that was a great waste of material. 3" wide would be plenty.

Good luck!

sprucemoose · #7 10-06-2008, 06:59 PM

Scott knows of what he speaks regarding the bottom cowl hitting the scallops along the side of the firewall. Not a major issue but a PITA when installing the lower cowl solo.

You will need to scallop the top, as it curves down slightly and it is easier to bend the individual scallops. I made mine from a bunch of 1-foot sections, made it much easier to work with.

Some pics here:

http://home.mindspring.com/~rv6/RV6site/plenum.htm

Rivethead · #8 10-06-2008, 07:56 PM

Thanks for showing me your pics, it helps out a lot.

frazitl · #9 10-07-2008, 10:07 AM

and I'm using Milspec fasteners. Look very similar. They only call for 1 1/2" flange with a 5/8" spacing from the edge of the fiberglass. What dimensions did you guys end up with? I'm a little concerned with the camlocs that close to the aft edge of the fiberglass.

RV7ator · #10 10-07-2008, 11:20 AM

Watch that your placement of the receptacles above and below the upper engine mount attach points allows room for the receptacle - so it doesn't foul the engine mounts. I expect this would also be a concern about the lower outboard bolts if you're using 1/4s on the lower cowl sides. If using hinges on the sides, provide a scallop relief above where you must withdraw the pins vertically.

Drill #40 tooling holes and cleco the cowl to the strips when fitting. It's much faster than trying to use the 1/4s at this stage. Also, it precisely relocates the cowl each and every time (there will be many) you remove/replace. Match drill 1/4s' centers last thing.

John Siebold