Single Tube Fuselage idea

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rotax618

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There are features of the so-called new Weedhopper that I feel are not ideal.
Why the tapered planform? A rectangular wing is simpler to build, safer structurally and more predictable aerodynamically, considering the wing can be positioned anywhere fore/aft it is not to solve any CG problem.
Ply ribs attached to alloy tubes is fraught, they are difficult to bond and any fitting that attaches by riveting will weaken the spars, perhaps fibreglass tape could be used to attach the ribs. The ribs being 1/4” thick would require that the covering needs to be stitched.
The fuselage and tail group design appears to be sound.
A simple wing for the Weedhopper would probably be better with sailcloth or similar covering with sewn in rib batten pockets like the Drifter.
 

Dillpickle

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Piny Woods, Tx
Doe
They don’t come much simpler than this.
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What kind of spars on this one? And how was the landing gear made? And (back to your Boraboo) did you just bond the fiberglass leading edge to the ribs? Or the spar as well? Any photos of that process? And how did you come up with the name?
 

rotax618

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Evans Head Australia
The name Boorabee is the local Bundjalung Aboriginal name for a Koala.
I am not too familiar with Alan‘s Ultralight, even though it seems to be Australian, from the video, the UC is probably formed aluminium plate like the CH701 which is 3/4” x 3 1/4” 6061 T6 - I’m sure that Alan’s airplane wouldn’t need plate of that thickness or width - ( the 701 UC can be cold formed using a simple hydraulic pipe bender).
The Boorabee used a heat treated 4130 1-1/4” x 0.128” wt. tubular UC legs.
The leading edge was bonded to the top of the spar tubes, The Boorabee spar is very stiff in torsion, that and having two struts gave the wing great torsional strength - the 100 litre fuel tanks formed by the ribs at the wing root also stiffened the wing for torsion and drag loads.

NOTE Alan’s flight instruments - ASI - wind on the face.
 

RogFlyer

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Lewisham
Now combine that with the Russian wing covering technique and use a Warren truss for the rib setup.
Sorry, I have done a search, but no luck other than this post. Would you point me to the "Russian wing covering technique"? Thanks.
 

Dillpickle

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Piny Woods, Tx
Sorry, I have done a search, but no luck other than this post. Would you point me to the "Russian wing covering technique"? Thanks.
Rotax 618 discusses it concerning his and other Aussie airplanes. Fiberglass is laid up on mylar over a flat surface and draped over a form whilst still in the plastic or "rubbery" stage. The the leading edge shaped form can be in sections. I think I've got that right.....
 

rotax618

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Evans Head Australia
My reference to the glass laid up on mylar sheets is the method used by Alex Strojnik for his S2 sailplane, but could be adapted for ‘mouldless’ fibreglass leading edge, or full fibreglass wing covering - where the increased weight is tolerable.
 

RogFlyer

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Ok, thanks - my apologies, I didn't connect the two. I have been hoping to run across a no-stitch fabric covering method.
As an aside, another way to get a very good surface finish on a composite mould that can be built/formed quite easily is to use gloss laminex. Here, one can get it in sheets 1.2m wide by 5m long 0.5mm (comes rolled as a coil). Room temperature gets a bend radius of 150 to 175mm and heated to 65 to 70 degrees C one can get a bend radius of 15 to 20mm. The surface needs to be planar development - single curvature.
 

rotax618

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We didn’t stitch the covering on the Boorabee, the fabric was glued to the ribs (pretty wide flange on the composite ribs) and was then stapled to the ribs using Stainless staples, fired from a pneumatic staple gun, in line with the airflow at about 200mm spacings, then fabric tape applied over the staples. The staples held extremely well in the fibreglass rib flange.
 
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RogFlyer

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We didn’t stitch the covering on the Boorabee, the fabric was glued to the ribs (pretty wide flange on the composite ribs) and was then stapled to the ribs using Stainless staples, fired from a pneumatic staple gun, in line with the airflow at about 200mm spacings, then fabric tape applied over the staples. The staples held extremely well in the fibreglass rib flange.
Thanks for the info. One rib-stitching was enough for me - and not even my plane.
 
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