joining aluminum sheets techniques

Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
The advice that an aluminum dirigible won't fly is not borne out by
reality. Do a websearch for Schwarz airship. It was aluminum and flew
in 1897. That's right, eighteen ninety seven. Then there was the Navy
ZMC airship which flew for ten years back in the forties.
One "advantage" of an aluminum skin is that the skin holds the lift
gas, saving the weight of internal separate bags. Also, aluminum,
being stiff, can add some monocoque strength to the frame.
I'm thinking of employing some corrugated alum. for added stiffness
and reduced drumming. It doesn't look nice but might work well.
Any ideas? [negatives not needed ;-]

dirigible designer wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
The advice that an aluminum dirigible won't fly is not borne out by
reality. Do a websearch for Schwarz airship. It was aluminum and flew
in 1897. That's right, eighteen ninety seven. Then there was the Navy
ZMC airship which flew for ten years back in the forties.
One "advantage" of an aluminum skin is that the skin holds the lift
gas, saving the weight of internal separate bags. Also, aluminum,
being stiff, can add some monocoque strength to the frame.
I'm thinking of employing some corrugated alum. for added stiffness
and reduced drumming. It doesn't look nice but might work well.
Any ideas? [negatives not needed ;-]




He didn't say it wouldn't work.

Just that at this scale it would ne too heavy to fly.

double - square - cube relationship...

Richard

"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.

Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely difficult.

As to glues, I would suggest going to McMaster-Carr's website
(http://www.mcmaster.com/) and browse some of the categories under
"Fastening and Sealing". Perhaps a mix of some blind or solid rivets (to
provide structural strength) combined with a construction adhesive (to
provide a seal and some shear strength) might work?

Anyway, I'd suggest you try buying some likely candidates and try some
small-scale experiments.

Also, I believe there is a patent for the rivet machine that was invented
in order to build the ZMC airships, but I don't have the patent number
handy. But check patent 1,706,830. It is the main patent related to the
ZMC airship design. It should also hopefully provide a starting point for
finding the other patents related to the work done on the ZMC airships.

I'm thinking of employing some corrugated alum. for added stiffness
and reduced drumming. It doesn't look nice but might work well.

Well, the ZMC-2 used something like 0.006 inch thick aluminum. You can
now get hard-temper aluminum foil from MacMaster-Carr that is 0.002 inch
thick. But wider rolls (less joining needed for the same surface area)
are available down to 0.003 inch thick. Soft-temper of course can be had
down to 0.0007 inch thick. About the temper of house-hold aluminum foil,
though.

Corrugated is going to drive your raw material cost up (unless you build
equipment to corrugate the raw sheets or foil yourself). And I would
expect it would impose a large drag penalty, too.

Lastly, it is really hard to build working reduced-scale prototype
airship designs. They don't scale down well.

Good luck!

Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.

Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.


What about welding it?

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.

Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.


What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying to
use a flux of some kind (something to deal with the formation or thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys of
aluminum.

Jim Logajan wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.

What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying to
use a flux of some kind (something to deal with the formation or thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys of
aluminum.

I just tried my hand at welding aluminum this past weekend. I'm putting
a fuel tank together. Unless you have some major jigs, the sheets will
warp all to hell before you get halfway down a joint.

I welded 4 aluminum gas tanks ( I busted the first two in an incident) and
one oil tank for my Baby Belle. I don't remember having much warpage, but I
also recall someone telling me to tack the things in a lot of places before
finishing the seam welds. The things pressure tested to 14' of water the
first time with no pin holes. Now if that doesn't prove luck is better than
skill I'll eat a welding rod. I also welded some aluminum beer cans
together, but they wouldn't hold mashed potatoes after I finished with them
let alone a liquid.
--
Stuart Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478
(760) 408-9747 general and layout cell
(760) 608-1299 technical and advertising cell

www.vkss.com
www.experimentalhelo.com


"Ernest Christley" wrote in message
...
Jim Logajan wrote:
"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote:
Jim Logajan wrote:
"dirigible designer" wrote:
Thanks for the suggestions to my question of how to join aluminum
sheets [without rivets] for making a dirigible.
Hi "dd" (Allen?). I am familiar with the history of aluminum airships.

One remote possibility it to look into/experiment with aluminum
soldering. Once upon a time I did not think it was possible to solder
aluminum, but if you do a Google search on the subject you should find
some information on the subject. It's not impossible, merely
difficult.

What about welding it?

Might work with joining sheets to ribs, but sheets-to-sheets? Don't know
either way, actually. :-)

I never got around to experimenting with it, but I had considered trying
to
use a flux of some kind (something to deal with the formation or
thickening
of the oxide layer) applied between two overlapping sheets and then
applying heat using a high-temperature heat gun. Some of the heavy-duty
heat guns claim air temperatures near the melting point of some alloys
of
aluminum.

I just tried my hand at welding aluminum this past weekend. I'm putting
a fuel tank together. Unless you have some major jigs, the sheets will
warp all to hell before you get halfway down a joint.

"Stuart & Kathryn Fields" wrote in message
.. .
I welded 4 aluminum gas tanks ( I busted the first two in an incident) and
one oil tank for my Baby Belle. I don't remember having much warpage, but
I
also recall someone telling me to tack the things in a lot of places
before
finishing the seam welds. The things pressure tested to 14' of water the
first time with no pin holes. Now if that doesn't prove luck is better
than
skill I'll eat a welding rod. I also welded some aluminum beer cans
together, but they wouldn't hold mashed potatoes after I finished with
them
let alone a liquid.
--

I have welded a lot of aluminum, including successful welding of beer cans.
And I second all of Stewart’s advice. When welding .030 and up, you will
want to tack weld even as close as every two to three inches before
beginning your finishing welds. Skip welding helps as well, meaning weld
between two tacks, skip between two tacks, and weld between the next. It
will all help to avoid distortion. Also, clean, clean, clean. Scrape or buff
everything with stainless steel rotary brushes, cleaned thoroughly in
acetone or eqv. If you pick up any oil or grease anywhere, clean your
scrapers and brushes and start all over. It even helps to handle everything
with clean cotton gloves. You can leave enough oil from your bare hands to
affect the quality of your welds, unless you keep your hands washed in
acetone, which I certainly don't recommend.



As for thinner than .030 or so, good luck without good fixtures. I have seen
some soldering techniques advertised the might be very workable, but have
never tried any of them.



As for glue, I haven't tried many, but have had pretty good luck with 3M -
2216BA. I don't know how it compares to the others mentioned above, but it
has worked well for me. On a seam of .010 with a half inch overlap, I
personally think it might be workable, but haven't done it my self. And if
you plan to glue, don't for a minute underestimate the value of cleaning,
preparation and a good primer. When done correctly under aircraft
conditions, actually mixing the epoxy and gluing your seam is only about 10%
of the battle. Proper cleaning, priming and curing of the primer is actually
more critical.



Free advice, your results could easily vary.


Max

Thanks for all the ideas for joining aluminum sheets. I was amazed at
all the different versions of 3M epoxy there are. Should be one to
suit my needs. http://multimedia.mmm.com/mws/mediaw...Sum5COrrrr Q-
I'll be back in touch after I gather some materials and put a few
pieces together. high flight, Allen

dirigible designer wrote:
Thanks for all the ideas for joining aluminum sheets. I was amazed at
all the different versions of 3M epoxy there are. Should be one to
suit my needs. http://multimedia.mmm.com/mws/mediaw...Sum5COrrrr Q-
I'll be back in touch after I gather some materials and put a few
pieces together. high flight, Allen

Bonded lap seams should be fine since the loads are certainly going to
be extremely low. You should make some sample lap joints with different
adhesives and pull test them. Grumman light singles are all bonded
aluminum joints, including skin laps, and have been going strong for 40
years since the first Yankees were produced.

Your biggest problem will be having even clamping pressure on the joints
during gluing.

Bonded metal joints are not super strong in tension; the strength is all
in the shear plane. That means the parts will peel apart fairly easily
and there should be a mechanical fastener at any corner of a skin.
There was an AD to do this on the Grummans.

John