Mixed Aluminum and Fabric Construction

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Monty

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Lately I have been pondering whether a very light aircraft could benefit from the combination of Fabric and aluminum Semi-Monocoque construction.

For example:
Use fabric for all of the control surfaces.

Use fabric for the aft portion of the wing with an aluminum leading edge D cell to take all the cantilever loads.

Construct the fuselage with aluminum monocoque type construction instead of a welded tube frame.

Anybody looked at this? Any savings to be had? Or is it just a lot of complexity with no real gain?
 

BBerson

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Certainly fabric is lighter, especially when not much coating applied.
Some builders just don't like fabric.
It should be easier to build an open frame aluminum truss flat on a table than a monocoque which needs a big jig.
And open is easy to access for control installation.
 

Dana

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It wasn't unusual in the 1930s-40s to have aluminum aircraft with fabric control surfaces, or aluminum fuselage/fabric wings.

Dana
 

TFF

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You just invented the Ercoupe! Most 30s military planes ended up that mix. Cantilevered is up to you to engineer instead of wires but it really comes down to why go fabric when you only need a sheet or two more of aluminum and be done.
 

proppastie

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Somewhere Orion said he thought the lightest structure would be an aluminum structure fabric covered. On my bird all aluminum vs fabric except for D-nose is significant.
 

Pops

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You just invented the Ercoupe! Most 30s military planes ended up that mix. Cantilevered is up to you to engineer instead of wires but it really comes down to why go fabric when you only need a sheet or two more of aluminum and be done.
IF I remember correctly, the aluminum covered Ercoupe wings are 30 lbs heavier than the fabric covered wings. I have owned both. One time I ask Fred Weick at Osh what he thought about all metal Ercoupe wings. He said " Its not an Ercoupe"
 

proppastie

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Just did some calcs. and if my wing control surfaces and tail feathers are .016 alum it is aprox. 80#. One half (1/2) of that area in fabric at 6 oz/yard. is aprox. 7 lb. So if my D-nose on all my different control surfaces, wing etc. were 1/2 the area (which it is not) then fabric covered total weight would be 47# vs 80 # in alum. Oratex is 4 oz / yard, so even less if you want that. I think 1/3 or even 1/4 the total is more realistic for the area of the D-nose. 49766 sq. inch is the total area if you want to run those numbers.
 

TFF

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I would have any Ercoupe. The closest I came to buying one was a project D that had metalized wings in the back yard down the street when a kid. First one I flew in was fabric. Anyway for good or bad, no designer like someone improving their design. Anyway no one complains about the Cherokee not having fabric:) Even a hair heavier, there is almost no maintenance on a full metal wing, and I am a pro fabric guy. For most planes thats a good tradeoff. I just like wood wings. It's the switching gears; you do 85% of a full metal wing and then switching processes.
 

Monty

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I would have any Ercoupe. The closest I came to buying one was a project D that had metalized wings in the back yard down the street when a kid. First one I flew in was fabric. Anyway for good or bad, no designer like someone improving their design. Anyway no one complains about the Cherokee not having fabric:) Even a hair heavier, there is almost no maintenance on a full metal wing, and I am a pro fabric guy. For most planes thats a good tradeoff. I just like wood wings. It's the switching gears; you do 85% of a full metal wing and then switching processes.
I like wood too, but it is getting ridiculously expensive. It seems to me aluminum is a more consistent, less expensive route..Plus I HATE wood dust. I can live with wood though, composites....not so much. I hate the smell, the itch, the sticky...blech.

Living with a fabric airplane isn't too bad if you have a hangar. I'm not going to store anything on the ramp.

I think fabric is neat. You get nice curves, it smells like airplane, and looks good. I also like working with aluminum. Why not combine the two? But I'm weird..I guess all that fabric dope I used on models as a kid went to my brain. :gig:
 

Monty

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Agreed, on open structure part. I did like working on my biplane. I just unscrewed all the panels and could work on everything. That is the advantage of a truss structure with non-structural skin. It is heavy though. A trade-off.
 

BJC

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Lately I have been pondering whether a very light aircraft could benefit from the combination of Fabric and aluminum Semi-Monocoque construction.

For example:
Use fabric for all of the control surfaces.

Use fabric for the aft portion of the wing with an aluminum leading edge D cell to take all the cantilever loads.

Construct the fuselage with aluminum monocoque type construction instead of a welded tube frame.

Anybody looked at this? Any savings to be had? Or is it just a lot of complexity with no real gain?
The de Havilland Chipmunk used that construction method.


BJC
 

cluttonfred

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As others have already said, many early WWII aircraft used a combination of aluminum and fabric and even some of the iconic fighters from late in the war still used fabric-covered control surfaces. Most Ercoupes started life with fabric-covered wings as well. I actually think that a mix of aluminum (tube/gusset and/or sheet), pulled rivets, and Oratex fabric makes a winning combination for modest homebuilt aircraft: easier learning curve for beginners, readily adaptable to CNC methods, little noise, little smell, little special tooling required.

IMG_3278.jpg
 

cluttonfred

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I hope you'll share some nice pics of your uncovered wings, Percy. Fred Weick's Ercoupe wing design is definitely worth a closer look for homebuilt applications.
 
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