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Old 06-14-2018, 09:56 AM
Marc Bourget Marc Bourget is offline
Join Date: May 2013
Location: North Ca
Posts: 362

Originally Posted by Kerry Pinkerton View Post
Remember that strength is in geometry. Look at some of the stuff that Bill Trombley has recently posted. Flanged holes don't just look cool, they add strenght. Lips and beads add stiffness. Backer plates add strength to areas where things are going to be bolted on. A compound curve is vastly more rigid than simple rolls or flat planes.

Referencing a NACA report, actually, depending on the size and approach, lightening holes generally add weakness, which flanges recover, to a limited extent.

If you roll a bead on the inside of the flange, if spacing and size recommendations are followed, you can approach the properties of an undisturbed sheet.

That said, non-aircraft builders usually use metal that's more than required for the particular loads, so flanged holes may be "OK".

Just raising the point for general knowledge.

Last edited by Marc Bourget; 06-14-2018 at 09:57 AM. Reason: Added "the properties" to 2nd paragraph.
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