[JulianEdgar]

Originally Posted by freebeard

Off topic, but I really appreciate Structural technology at its finest. I've never seen an up-close examination of the truss work in the classic airships.

The 'flanged' holes are created by dimple dies.

Yes, the 1930s airships are just stupendous. If postage didn't cost me an arm and leg, I'd send you a gratis copy of my Discovering Engineering that Changed the World book. I think you'd love it. Lots of really cool stuff - the chapter on airships also covers hovercraft, another incredible technology.