DartzMan

I am in the process of building a scratch built Nieuport 17, from either Balsa USA plans or VK plans....
I have read on a few forums that the Balsa USA planes are on the heavy side
I am considering replacing the plywood with balsa laminated with 0.4mm 2024 T3 Aluminum... I believe this will save some weight and 2024 Ally is used in most structural parts in full scale planes

I would like your views please

CoosBayLumber

My Feedback: (1)

How do you plan to attach the aluminum to wood or other, and how do you plan on cutting it?

Wm.

DartzMan

good questions
I have the facilities to cnc punch the ally. will draw them up in solidworks
as far as gluing...was gunna epoxy the parts together like a sandwich.... ally - balsa - ally

Darren40

My Feedback: (2)

Have you calculated the weight savings? I'm assuming this is for the firewall. Its almost guaranteed that you'll be adding nose weight to a N17 anyway, so is there really anything to be gained on this particular project? I've got a VK Neiuport 17 NIB and there's no heavy plywood in it. For some other project where there's an appreciable amount of heavy ply back of the firewall you could easily calculate the weight savings and where that savings is relative to the CG. Then calculate what the net effect will be since the avoided weight (assuming its behind the CG) results in less added weight needed to balance. The idea of sandwiching balsa with aluminum is sound. You just have to make sure it makes sense for the project at hand.

BMatthews

Before you say this would be lighter I'd make up a sample and compare the weights to birch aircraft ply first. I seriously doubt it'll save you anything at all and may be a touch heavier.

THis would not be suitable for a firewall either where thru bolts would crush the balsa core. Also aluminium requires a good sanding followed by a wash of some form to gain the toothed surface required to bond well with epoxy. Depending on the application these joints may be critical. Also the highly different rates of expansion with heat or moisture may eventually cause the epoxy to let go of the aluminium.

I had a VK kit for a while many years ago. As I recall the model is built much like a very large rubber model with lots of sticks and ribs. If it comes out overly heavy I suspect it would be due to the added details and covering/finish selection for the most part.

g-rock

My Feedback: (1)

DartzMan,
Aluminum weighs .10# per cubic inch. 8 pound density balsa weights .00463# per cubic inch which means aluminum is 21.6 times heavier than 8# density balsa. Birch plywood is around 40# per cubic foot, or about 5 times heavier than the 8# balsa. And as Bruce stated, without treating the aluminum surface properly, it is very difficult to bond to.
Gene

fledermaus

The densities are not the only issue, however. The question is really what thickness of aluminum will give equal strength in the directions required to a given thickness of balsa or plywood. If you could substitute 0.020 aluminum for 0.125 plywood between two outer layers of wood and get the same or better strength you might come out ahead. But then, if the thing delaminates it isn't much good is it? [sm=confused.gif]

Perhaps if one drilled out a pattern of small holes through the aluminium to allow the epoxy to flow through and bond the two outer layers of wood directly it might work out? Of course, this would affect the strength of the metal too...

carlosponti

My Feedback: (1)

with the lite ply learned from airfieldmodels.com how to make my own plywood using balsa laminated. much lighter and stronger than the pre manufactured stuff.

http://www.airfieldmodels.com/inform...wood/index.htm

Rodney

I have built many of the BalsaUSA planes and they are not any heavier than other well engineered models, in fact better than many of the other brands.