Single Tube Fuselage idea

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
The idea is to use a simple tube and a cheap bender to make a very simple, very low parts count fuselage. I used 3" in the drawing just to start seeing how to do it. I can't pick the final tube size until I figure out what the loads would be. ...I don't have the magical super hero power to make a complete mental FEA in 30 seconds like some folks can.

I messed with it a little this afternoon:

OTW9.jpg OTW10.jpg I did away with the angles which let me get rid of the short "stinger" section.


OTW7.jpg OTW8.jpg I dug up an old wing I was messing with for another project that I think would would work great on this (I have to finish the wing anyway so it's "win win"). And I hate to do it but it might have to be nose dragger.
 

addicted2climbing

Well-Known Member
Log Member
Joined
Jan 27, 2012
Messages
1,180
Location
Glendale, CA
The idea is to use a simple tube and a cheap bender to make a very simple, very low parts count fuselage. I used 3" in the drawing just to start seeing how to do it. I can't pick the final tube size until I figure out what the loads would be. ...I don't have the magical super hero power to make a complete mental FEA in 30 seconds like some folks can.

I messed with it a little this afternoon:

View attachment 53534 View attachment 53535 I did away with the angles which let me get rid of the short "stinger" section.


View attachment 53536 View attachment 53537 I dug up an old wing I was messing with for another project that I think would would work great on this (I have to finish the wing anyway so it's "win win"). And I hate to do it but it might have to be nose dragger.
Once again Fritz this looks great. My concern would be any twisting moment on the tail and the small surface that the empenage is attached to. Some sort of machined cross drilled part may be needed to get more surface to attach to and transfer that load a bit better. However that all can come later after the configuration is nailed down. Another worry is elevator force acting on tube may transfer some of the force to deflection of the tube. Like when holding in a lot of up elevator for slow flight.

Marc
 

ScaleBirdsScott

Well-Known Member
Joined
Feb 10, 2015
Messages
1,289
Location
Uncasville, CT
I was sketching and what I think might be even easier to make would be to make the whole cockpit area just one consistent radius the whole way vs multiple tighter bends. The resulting fuselage looking like a large "b" or, with some flair, maybe it's more like a tennis racket. In theory one could just find some kind of massive 'mandrel' in the wild, like a dump-truck tire or a wooden wire spool, and pack a 3-4" tube full of sand and use some beast-mode to bend it around to make a big hoop (Or use an actual tubing roller as was in the OP image and do it 'proper' but either way just one big circle up front.

I was doing sketching and I'm liking the idea of the round cockpit, but using smaller dia tubes and making a pair of hoops that then have a confluence on a large dia tailboom. I'll make a better sketch that isn't a scribblefest at work tomorrow.
 

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
...My concern would be any twisting moment on the tail and the small surface that the empenage is attached to
The tail in the picture is just for perspective, I'm not sure how they would actually mount but, your right, it's going to take some head scratching. ...maybe your machined cross piece.

Another worry is elevator force acting on tube may transfer some of the force to deflection of the tube
Yeah, that looks pretty bad but I haven't look at the loads yet. One idea that might work would be some sort of tube insert that gets riveted in the tube. If the holes were pre-drilled in the tube I could slide the insert in with a broom stick, line it up (like lining up a wing rib to drill through the skins), drill the insert and blind rivet it in.

OTW Tube Insert1.jpg OTW Tube Insert2.jpg OTW Tube Insert4.jpg
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,831
Location
Thunder Bay
I was sketching and what I think might be even easier to make would be to make the whole cockpit area just one consistent radius the whole way vs multiple tighter bends. The resulting fuselage looking like a large "b" or, with some flair, maybe it's more like a tennis racket.
I was thinking the same and I came up with something sort of insect-like. "Tennis racket" is a good term for what I pictured, but with the upper tube running straight and horizontal, just like Fritz'.
 

mcrae0104

Well-Known Member
HBA Supporter
Log Member
Joined
Oct 27, 2009
Messages
3,930
Location
KBJC
...And don't call me Shirley!:roll:

(For those who are movie illiterate---Leslie Nielsen in "The Naked Gun")
You never saw Airplane! ?

[video=youtube;KM2K7sV-K74]https://www.youtube.com/watch?v=KM2K7sV-K74[/video]
 
Last edited by a moderator:

erkki67

Well-Known Member
Joined
Feb 18, 2010
Messages
2,492
Location
Romont / Fribourg / Switzerland
The Hovey Whing Ding2 had also just a single tube as a fuselage which had about the same section like this project here.

It was made of alloy to but to stabilize it it was foamed inside, if I remember it right, so tail wobbling was not an issue.

Fritz, a taildragger please attached to the engine mount......
 

erkki67

Well-Known Member
Joined
Feb 18, 2010
Messages
2,492
Location
Romont / Fribourg / Switzerland
But here splicing would become an absolute necessity

Steel cockpit and alloy tail boom

It starts to remember me at the fuselage of the dream classic, but with the engine where I liked it to have, in the nose and being a simplest taildragger and strutt braced
 

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
3" stainless is easy enough to come by here also. Weather it's steel or aluminum the tubes would probably have to be spliced, especially with CR's double boom tube idea. Maybe splitting a 3" tube and riveting it to the outside?
 
Top