why isn't there composite tube fuselage design?

I am just wondering...if composite materials are stronger and lighter
than steel, why composites tubes aren't glued together to form the
fuselage frame just like the traditional 4103 steel tubes being welded
together? Any reasons?

Shin Gou
Rans S-9
Warrenton, VA

"Shin Gou" wrote in message
oups.com...
I am just wondering...if composite materials are stronger and lighter
than steel, why composites tubes aren't glued together to form the
fuselage frame just like the traditional 4103 steel tubes being welded
together? Any reasons?

They are. It's known as "wood". :-)

Rich S.

see my recent post on the same subject .. a week back I guess.

"Shin Gou" wrote in message
oups.com...
I am just wondering...if composite materials are stronger and lighter
than steel, why composites tubes aren't glued together to form the
fuselage frame just like the traditional 4103 steel tubes being welded
together? Any reasons?

Shin Gou
Rans S-9
Warrenton, VA

I wonder how a direct comparison would fair. ie 1" OD .035" wall 4130 vs.
1" OD .035" carbon fiber? Has anyone ever seen a comparison like that?

Mike

"Shin Gou" wrote in message
oups.com...
I am just wondering...if composite materials are stronger and lighter
than steel, why composites tubes aren't glued together to form the
fuselage frame just like the traditional 4103 steel tubes being welded
together? Any reasons?

Shin Gou
Rans S-9
Warrenton, VA

looked around on the Internet and found Zivko's Leo Loudenslager
"Shark" plane's fuselage was constructed from carbon fiber tubes
bonded to titanium clusters with mag-alloy side fairings. Empty weight
950 lbs with a Lycoming IO-540 engine.

More information and background story at
http://www.zivko.com/EDGE/news/leo.html
There's a video clip for download at the bottom of the page. See how
the control surfaces move!!! Also a close-up look at the carbon fiber
tube fuselage. Impressive. Can't wait for its flight.

Now I think the conclusion of this carbon fiber tube fuselage
construction technique is: 1) it's lighter and at least as strong as
steel tube design. 2) it's more expensive than steel tube to build. 3)
it requires higher skills than steel tube welding to build. 4) this
method is not well proven in real flight (yet).

Shin Gou wrote:
Now I think the conclusion of this carbon fiber tube fuselage
construction technique is: 1) it's lighter and at least as strong as
steel tube design. 2) it's more expensive than steel tube to build. 3)
it requires higher skills than steel tube welding to build. 4) this
method is not well proven in real flight (yet).

Not only that, you've got to ask yourself whether carbon fibre tube
fuselage construction would be better than what has become the standard
for composite construction -- monocoque, stressed-skin construction.

If you're using composites why limit yourself to 1" (or whatever)
diameter tubes and so on as per steel-tube-and-fabric? Why not build
large non-circular tubes, for example.

Frank

Round is very strong. The only way you could improve on a simple round tube
for strength would be to add material in the direction that you needed more
strength, and take away material where the strength wasn't needed.

--
"Don't be misled, bad company corrupts good character."
www.LCTPaintball.com
www.LCTProducts.com

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Frank,

My response interspersed in your post:

Frank van der Hulst wrote:
Shin Gou wrote:

Now I think the conclusion of this carbon fiber tube fuselage
construction technique is: 1) it's lighter and at least as strong as
steel tube design. 2) it's more expensive than steel tube to build. 3)
it requires higher skills than steel tube welding to build. 4) this
method is not well proven in real flight (yet).


Not only that, you've got to ask yourself whether carbon fibre tube
fuselage construction would be better than what has become the standard
for composite construction -- monocoque, stressed-skin construction.
Well, a better way to phrase this question is what does composite
construction do best, & from my experience, the prepreg over stiff core
technique is much easier and doesn't require tubes or the large number
of ribs & bulkheads a monocoque design does. In fact, when pulled out of
the mold, you have a finished skin.

If you're using composites why limit yourself to 1" (or whatever)
diameter tubes and so on as per steel-tube-and-fabric? Why not build
large non-circular tubes, for example.

Frank

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"Shin Gou" wrote

There's a video clip for download at the bottom of the page. See how
the control surfaces move!!! Also a close-up look at the carbon fiber
tube fuselage. Impressive. Can't wait for its flight.

Interesting that the elevator travel for nose up is very limited, compared
to nose down's extreme. Wonder why?
--
Jim in NC