[VAC] Re: Aluminum Honeycomb

[David Josephson <david@xxxxxxxxxxxxx>]

Your visual is probably about right. The core is made of very thin
aluminum or composite (phenolic, Nomex, etc) bonded (glued) together and 
expanded to form (usually) hexagonal cells. Then a skin of sheet material
(again aluminum, fiberglass, carbon fiber composite etc) is bonded to
the open faces of the cells. Aircraft floors are typically a little
less than a half-inch thick (www.mcgillcorp.com/ds/floor.html). Long
before the honeycomb was developed, they used balsa wood skinned with
aluminum for somewhat the same effect.

The stuff is quite expensive; if you live near Seattle or Los Angeles
you have a better chance of finding some at an affordable price at
Boeing surplus (I guess McDonnell surplus in LA still exists?). I have
found bits and pieces at aircraft scrap yards and other metals places,
call around and see what you find.

There are some tricks to working with honeycomb. If the open edges are
exposed, you need to seal them with epoxy (A4 Metalset for instance)
to protect the exposed thin metal.  When you drill a hole larger than 
one or two cells you need to do the same.  In most aircraft floor 
panels, they mill out the skin to form a dimple into which is glued a 
sort of dished washer so that you can have a more or less flush attachment.


--
David Josephson - Josephson Engineering, Santa Cruz CA - david@josephson.com