"dirigible designer" wrote in message
oups.com...
I'm making an eight-foot study model of a personal lifting body
dirigible design of mine. I believe the ribs will be made of
fiberglass and widely-spaced for lightness. I want the skin to be
aluminum sheet.
It would be desirable to avoid installing a rib for every seam
between sheets of aluminum. So, I would like some advice on what is
the state of the art with infallible glue joints between hard aluminum
sheets.
I imagine there is no alternative to crimping the meeting edges as
is done when sewing two sheets of cloth together.
No way am I interested in rivets.

Wow, where to start.

First, I would think you need to do a reality check, here.

How big will your full sized lifting body be? Figure the surface area of the
full sized design, and then figure how much weight the aluminum to cover
that area would weigh.

Next, figure what the volume of the full sized model is, and how much
buoyancy the helium in that volume would provide.

I think you will find that the volume of helium in the full size model would
not come close to lifting even half of the weight of the aluminum sheeting.

Once you do this, and run the numbers, I think you will not even need to
mess with the study model. The numbers will not work.

There is a reason that balloons and dirigibles are not covered with
aluminum. The areas and volumes are huge, and the only way to make it work
is with ultra lightweight and strong "fabrics."

As for not even considering rivets, I doubt you have any idea of the costs
and technology of what it takes to join aluminum without rivets. You have
friction stir welding, or glues. Friction stir is high tec and expensive to
set up. Glues are temperamental, and takes many complex steps and chemicals
to prep and bond the surface, and is also expensive, if you can even reach
the reliability needed for such an application. I won't go into the idea of
having ribs so far apart that there is not even a rib for the length of an
aluminum panel. It will not have enough support to hold its shape under
flight conditions.

I don't want to rain on your parade, but it looks to me (from how you
described your concept) that the whole idea is unworkable. If you have
further explanations that could convince me (and others) differently, go
ahead.
--
Jim in NC