What are your thoughts on Nidacore?

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DrBones

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Aug 23, 2004
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Here's something that is becoming popular in boat building:

Epoxy/Fiberglassed Nidacore - Plywood Replacement

I was just wondering if it were possible to use something like this on Ultralight designs such as the Affordaplane or the Legal Eagle or others that use plywood in some parts of their construction. It should lighten the whole structure up bit while adding quite some strength.

Of course at $200 a 4' x 8' sheet it's not economical to do that for everything on a wooden airplane, but bulkheads and wing structure/ribs could be replaced with this with perhaps some weight savings making it much stronger.

From some of the builders of these planes, I've noticed that keeping within the 254 lbs limit isn't always possible due to engine weight, etc.

...just the ramblings of a boat builder who has turned his eyes to the sky... ;)
 

wsimpso1

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Well, I just looked at their web site and I am not impressed...

26 lb/32 ft^2 is about 0.8 lb/ft^2. I do not know what their glass cloth lamination is, but with fairly thick cloth, this is about right for vacuum bagged assemblies. My 3/8" foam/18 oz BIAX/22 oz TRIAX panels are lighter, but not by much, and makes a pretty stout panel.

As to using it to replace plywood, there are two typical uses for plywood. One is as a structural member that carries a squeeze load from bolts (firewall with engine mount bolts). The other is in fuselage box and wing ribs where the structure is literally nailed or stapled together to hold clamp loads while glue dries... These panels will not do for either of these applications as is. To carry crush loads wood or other strong fillers would have to be applied locally, and for fuselage box or wing ribs, you would have to reprocess the entire structure.

Besides all of that, people building airplanes with wooden box fuselages and wooden wing ribs would run you out of town for suggesting the substitution of fiberglass for wood. A big part of why they build is to work in wood...

Which leaves its use in fiberglass airplanes for bulkheads, wing ribs, fuel tank baffles, etc, where they might work very well as an alternative to making your own panels for these things....

Billski
 

orion

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Interesting stuff. When compared to the more standard core materials that are used in composite aircraft, such as Last-A-Foam (polyurethane) or Klegecell (PVC), the Nidacore is a bit lighter (4.8 pcf versus about 6.0 pcf) yet still fairly strong.

However, as with most honeycomb cores, the material is poor at anything but flat parts, unless or course you are willing to significantly increase your tooling and fabrication budget. As such, the core itself is not good for homebuilt applications - you are not likely to get a good and efficient bond - you really do need the prepreg and elevated temperature cure equipment that is used by the panel manufacturers or aerospace fabricators. This of course leads back to the discussion of the prefabricated flat panels.

The panels can be manufactured in just about any strength you wish, just by varying the number of glass laminates on either side of the core. Therefore, when discussing weights, it is important to account for the strength properties also.

Can it replace plywood? Probably, but as Billski mentioned, for areas of bolting or other concetrated loads, you will still need to incorporate some type of filler or insert that will provide the area with the sufficient crush strength.

Using the material for components such as ribs is a good idea but keep in mind that ribs are usually subject to only fairly light loads and as such, making the ribs out of something this strong would be overkill. However, to lighten up the structure you can cut out lightening holes and so there is still the possibility of achieving a good weight efficiency.

One attractive feature to me is the price. The core panels I use are from Teklam, a manufacturer that fabricates commercial and aerospace products with a wide variety of materials. They use face sheets of aluminum, graphite, S-glass and the basic E-glass, as well as Kevlar. The cores tend to be aluminum or Nomex. The physical properties are generally fantastic, as is their quality control and part consistency. However you do pay for all this. If I recall correctly, the average 4 x 8 panel of aluminum core and 7781 glass faced material (2 layers per side) comes to about $500. S-glass raises the cost to about $700 and graphite is quite astronomical.

The good news though is that despite the cost, you can get quite a few parts out of a basic panel so, when considered overall as a fucntion of the total cost of your project, the panel prices are not all that bad.

But, if this material can still deliver the structural properties, at less than half of what I normally pay, then it really does deserve a second look.
 
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DrBones

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Good point on the crush problem with these panels. I was thinking more along the lines of using fiberglass/epoxy fillets for joining onto the panels. Assumption here is that it will be used in a glued structure using epoxy as an adhesive.

..nevertheless..just thought to throw this idea about. Thanks for sharing your thoughts patiently with me :p
 

dustind

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Orion: Why does the price go up so much for S-glass or graphite? Their price increases seem to be out of line with the base material price difference.
 

orion

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You got me!

I think a part of it has to do with the volume of production. E-glass is the most common material and as such, is fairly standard in all the production runs. Materials such as S-glass are a bit more rare and rarely called for so the basic material costs tend to go up, especially if they need different processes or handling.

And of course the cost of graphite (if one can actually find any) today is higher than ever so all subsequent costs increase also.

But regarding the proportionality of the cost increase, I really don't have a pat answer although one area that I overlooked some time back is the choice of core. Some of the materials are based around the standard low cost aluminum core however other face sheets like those of graphite are generally laminated about a Nomex core, which is substantially pricier.

I haven't bought any production panels in quite some time so I don't know what the current rates might be. The last shipset of sandwich panels that I bought were salvage from a Florida outfit that specializes in aerospace materials.
 

wsimpso1

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S Glass (from our homebuilt supply sources, it is probably S2 glass which is S glass with no paper trail) is about 3X cost of E glass. S Glass made into panels is probably legit aviation grade with a paper trail, and that pumps the price again by 50%. So that accounts for about $100 per panel. I can only guess that the maker also maintains an aviation legit paper trail for every panel made of aviation grade material, which adds some more cost.

Now Boeing's new airliner and all of its tooling plus the new Airbus are sucking up all of the carbon in the world, and driving price through the roof until some more production capacity comes on line. So carbon is going to be just crazy...

Billski
 

wally

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What I have seen done with honeycomb panels (using them for floorboards and containers and cabinets) is to put inserts along the edges. They look like little funnels that go in from each side and fit together in the middle. They are usually potted in place with epoxy. Then you have nice holes to attach the panel and the fastener will not crush the edge.

The ones I know a little about are made by SHUR-LOK and by a company called: The Young Engineers.

They come in various sizes, with either a through-hole or threaded inside. Some of them can be epoxied in one side providing a blind threaded hole wherever you need to attach something.

M.C. Gill Company is another company that makes a bunch of different kinds and sizes of aerospace honecomb panels.
Wally
 
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