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Wanted Aluminum honeycomb flat stock

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Holden

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I am looking for a source for Aluminum honeycomb.

or

Is there a company out there that makes alumunum honeycomb with aluminum flat sheets bonded to the Aluminum honeycomb?

What is used in bonding aluminum sheets to honeycomb? Are there high temperature (400F) bonding compounds available? Is a large press needed or can vacuum bagging system be used?

What I am looking for is similar to a composite sandwich with fiber glass and Nomex in between, but made out of Aluminum. These panels must be able to be walked on with proper support.

Thanks you,
 
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Shirley airport MA
Few years back when BD-17 came out I asked them where they get the aluminum honeycomb
They use on fuselages and they told me you can’t buy it off the shelf, that its made by some company only on custom order/specification basis, I never saw it sold anywhere but its awesome material and apparently very expensive.
 

orion

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Of course BD said that, he just didn't want anyone copying his ideas. The fact is that sheet faced honeycomb panels are available from a number of sources within the US. Due to the variety of customer applications, most fabricators do not stock the sandwich panels but will manufacture them to your requiremetns. They keep the raw materials on hand to make just about anything you want.

You can also at times find the panels surplus or on an overstock basis. Several years ago I ran across an outfit in Florida that seemed to stock a wide variety of sandwich materials. The company is Acme Industrial Surplus. Their phone number is 407-328-1280. I haven't called them in quite a while so I can't guarantee they're still around though.

The material was originally developed for use as commercial airliner floor boards. The original design requirement was a concetrated load as is applied by a woman with high, stilleto heels - those used to virtually destroy the old floors of commercial airliners.

The aluminum is bonded using sheet bonding compounds, layered within the aluminum materials. The bonding agent sheet (usually a form of epoxy or phenolic resin) is activated by the high temperature and pressure of the 250 ton (or higher) press.

Although a vacuum bag might work, it will most likely not be able to generate the pressure and temperature necessary, although off the top of my head, I don't remember the temperature requirement.

The supplier I use is Teklam of So. Calif. Go to www.teklam.com for a listing of their stadard products.

Costwise, yes it can be pricey. A four-by-eight sheet of half inch aluminum core with .020" face sheets will run you probably about six or seven hundred dollars. However, when you consider the performance, it is unlikely that you could build something from scratch that performs as well, any cheaper.
 
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Wow that’s one great link this Teklam place.
I don’t know if anyone would want to copy what they do on BD-17 but when I saw how they glue those fuselage panels together with an L angle shape bent thin aluminum stripes in the corners and how they build the wings by “gluing” the plastic rotomolded ribs to the aluminum tube spar it made my skin crawl. This is one plane I wouldn’t fly but that’s another subject.
Anyway, thanks for the link.
George
 

Holden

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Hello George,

Do you have a link that shows what you meant by your comment on the BD-17?
 

Holden

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Orion,

Thank you for the reply. I enjoy reading your posts.

Can the panels be formed over a 2 D curve/arc, such as wing skin?

From your web page it would appear you are using an Aluminum based honeycomb system with a glass outer plate. Are you forming skin panels out of the Aluminum honeycomb, or just the flat fuselage portions? Why not use Nomex like many others do, such as Lancair?

How do you join the pieces?

Is there a way to make the panels water proof like a closed cell foam, such as Aerex?
 

wsimpso1

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i do not have a faced aluminum honeycomb source, but as a fallback, Applied Vehicle Technology is an outfit that supplies composite materials of many types, and they list aluminum honeycomb in 2'x4' and 4'x8' sheets, .125,.250, .375, .500, .750 thick with .25 cell size. This is NOT faced with aluminum, however. Perhaps they can offer bonding to make completed panels to suit you. They do a lot a fabricating for their race car business.

They do offer glass and carbon faced Nomex honeycombs if you could use that instead... They are in Indiana, 317-546-6840. I can vouch for their integrity and quality products, as well as speedy service.

Billski
 

orion

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Good morning all;

Just a couple of quick notes. There are a whole number of suppliers of honeycomb cores however, unless you have the facilities and systems to use them to good advantage, they are not all that applicable to homebuilt airplanes. For instance, you cannot put a face sheet on through wet layup - the resin just flows out of the fabric into the core and pools in the cells. This results in a heavy layup and poor adhesion of the face sheet.

Also, as a comment to the last post, for most structural applications, epsecially ones where you have a lot of vibration, cyclic loading, etc., you want to stick with cores with an 1/8" cell size. The .25" cell size is generally not considered structural for aircraft work (although I guess that would depend on the application).

Nomex cores are substantially lighter (although the aluminum core is not all that heavy) but the Aramid based paper cores are much more expensive.

Holden, regarding your questions, yes the standard honeycomb core material can, to a limited extent, be draped over a single axis curved surface. However, for more curvature and for reasoanble compound curvatures, there is available a special honeycomb core where the cells are shaped a bit differently thus alowing the core to be draped over more complex shapes.

The materials I'm looking at are aluminum core with a glass skin. Some parts will use unidirectional S-glass, others just 7781. Actually, I am hoping to end up using just the 7781 throughout just due to the issues of cost. Right now here at the shop I have some left over panels of the S-glass (virtually indestructible), as well as a bunch of Nomex cored Graphite skinned sheets. The latter are extremely expensive so I am being very choosy as to where I use them.

But to answer you question, the basic reasoning behind what I'm doing has to do more with cost and ease of construction than with some form of optimum structure. As such, the panels are used for the fuselage components, the wing ribs and shear webs, and the horizontal and vertical stabilizers. The only molded parts will be the wing tips, the cowl, and the leading edge of the wing.

I actually have not decided that this is what I want to do (get into the kit business that is) but at least I'll build one airplane just for myself - assuming I'll get the time that is.

As far as joining is concerned, the various parts are cut with tabs and slots. As such, the entire sandwich structure is self aligning and self jigging. I haven't decided on the bonding agent as of yet but am looking at several new epoxy compounds and catalyzed urethane adhesives. Once the basick box structure is assembled, the entire fuselage gets skinned with a pre-cured two layer sheet of 7781 glass. This covers the sides, and forms the turtledeck front and back. Additional corner reinforcement will probably be done with very thin sheet steel. The material I'm looking at using is the same stuff one uses in drywall construction for reinforcing corners. It's cheap, has more than enough strength, and provides me with sufficient reinforcement and corner protection.

Making the honeycomb sandwich totally waterproof is not easy. If you choose the right fabric and resin, the skins can be pretty waterproof however that is not a guarantee, especially if you get a bit of surface damage.

I remember the Air Force had a problem with F-15 vertical stab skins separating. They use the honeycomb construction. It turned out that over time a bit of moisture got in through seepage, surface damage or just environmental conditions. No one saw this happening during inspection and maintenance but when the aircraft took to the sky, at high altitude the moisture froze, expanded, and delaminated a large portion of the stab. Not good.

Personally, I think using the honeycomb core material in a marine environment may be asking for a lot of maintenance issues. Also, due to the core's rigidity, even small impacts can cause skin delamination, something you are definitely not going to see using Airex.
 

addaon

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For a curved honeycomb panel (even simply curved), I assume that it has to be manufactured in a mold to that exact shape, rather than being formed afterwards?
 

lr27

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snip
The original design requirement was a concetrated load as is applied by a woman with high, stilleto heels
snip
I wonder how many g's they assume?
-----------
I used to have a sample piece of the stainless perforated honeycomb panel they line some jet engines with. I used it as a trivet and labeled it "product of killer bees".
 

lr27

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If they're using the same techniques as on the Tiger or Traveller (originally this series started from a Bede design), then they have the potential to work pretty well. I think these airplanes are supposed to be pretty good. There are a couple of them at my local airport.
Wow that’s one great link this Teklam place.
I don’t know if anyone would want to copy what they do on BD-17 but when I saw how they glue those fuselage panels together with an L angle shape bent thin aluminum stripes in the corners and how they build the wings by “gluing” the plastic rotomolded ribs to the aluminum tube spar it made my skin crawl. This is one plane I wouldn’t fly but that’s another subject.
Anyway, thanks for the link.
George
 

MalcolmW

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Jan 21, 2007
Messages
118
Hello, Ir27, George;

Sorry I took so long to notice your discussion. I've worked with aluminum honeycomb panels (military, high performance) using adhesive bonding, and the durability is excellent.

Unfortunately, the adhesive bonding techniques that were used required significant facilities not readily available to the typical home builder.

However, bonding aluminum is the same whether it's a single sheet or part of an aluminum honeycomb panel. My preference in adhesives are the epoxies, because they are the strongest adhesive and when applied properly, very durable. But they are not the easiest adhesive with which to work.

On this board, there have been some excellent discussions on bonding aluminum, and the work of GESchwarz leads me to believe that the methacrylate adhesives offer an easier bonding methodology, well within the work parameters employed by home builders. The methacrylate (also 'acrylic') adhesives have been used for aluminum truck body assembly and they hold up well under nasty environmental usage. Google 'Lord Chemical Adhesives' for more info.

All I can offer is the advice that "cleanliness in next to godliness" when it comes to bonding aluminum. Do NOT use scotchbrite scrub followed by a solvent rinse - not recommended. Do use a chemical etch followed by a clear water rinse (air dry, of course).

Do look up GESchwarz postings - information offered is very good and should be helpful.

MalcolmW
 
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KeithO

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Nov 29, 2009
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Location
Jackson, MI
2 outfits that I know of which manufacture honeycomb panels:
Honeycomb Panels - Stock Panels - Immediate Delivery (Colorado)
Sandwich Panels - Sandwich Panel (Zeeland, MI)

They will custom build it for you however you want it. For such special purpose materials, I think the prices are quite reasonable. Paneltec in Colorado has materials that they carry in stock but I'm not sure I would use 3000 series aluminum in an airplane. I considered using it for the coachwork on a mini motorhome, would have cost $6k for materials only, but that is several times the material in an airframe. For certain applications like oversize doors, this is a totally feasible material to use and you don't end up with something that weighs a ton.

Simple curves can be made by cutting through the surface on the inside of the bend with several narrow slots. The number of slots and spacing can be calculated by figuring to what extent the inner surface needs to be shortened to achieve the desired radius. Then a sheet of aluminum is bonded to the inside surface to restore the properties after bending the panel to the needed curve.
 

SunshinePatti

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Aug 10, 2015
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Newport, WA
Hi This is SunshinePatti.
I am new here on the site, so I hope these are appropriate questions to you...I am just getting started with my research...
I have access to NINE (and possibly more) gently-used corigated aviation aluminum sheets. (3/4" thick, 80" x 52" and all have at least one 7"-12" access hole cut out, someone would have to re-cut it for their own project.) I noticed an old post that you were looking for something similar.
The questions are: What's the best way to cut this stuff? What would be some good uses for it? (it was used for flooring, I guess these were mis-cuts) What would be a fair asking price if I were to sell them?
I am not sure if you will even get this but today is Sunday 8/9/15 and I'm not really in a hurry (and I am sure you are very busy), but any tips you can share would be sooo greatly appreciated.
Sincerely,
SunshinePatti
 
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