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Flea style "Piojo Flying MiniBike"

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nestofdragons

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A story about the torsion in Flying Flea world, just to make sure you keep torsion in fuselages in mind.

Croses made several Flying Fleas. One of them was the two-seater, Airplume.
2020-08-20 Airplume.jpg
The first edition of these were know to make cracking sounds during turns. The composite cockpit needed several reinforcements to counter this cracking.

In my honest opinion it is not that easy to counter torsion in the body of the drawing you propose Erkki67. That body looks a super easy construction in wood. But reinforcing that middle part of the fuselage might make the construction a lot heavier. A redesign of the fuselage might be easier. Sad, i truly liked the simplicity of this design.
 

Mcmark

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Owings, MD
Nest, that airframe is a good looking design. What happened when they mounted the engine?
Looks like a big hairy mole on a beauty queen!
Is there more info on this Pou?
 

Victor Bravo

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In addition to his own abilities and education, and in addition to whatever engineering the Solidworks CAD program may be able to accomplish, remember Fritz also has access to some very highly qualified engineers who were involved in the American aerospace and defense programs. So whatever is necessary to avoid torsional problems can be engineered and designed properly. Whether this means changes in the fuselage materials, or thicknesses of certain parts, or the shape of certain parts, is not known yet.

Although it represents a major departure from Fritz' existing design work, a large diameter composite tube (running fore-aft underneath the small section of the fuselage, buried in between the existing wooden skins and bulkheads) could mitigate the torsion issue without changing the (pleasant) external shape of the fuselage.
 

WonderousMountain

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That's an option,
but it may be better to make a strong wood box frame,
with small flight control portal, rather than dropping in A
Tube, requiring cutouts & affixtures. Something to think about.
 

Victor Bravo

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WAIT A MINUTE !

OMFG am I brain-fart stupid or what!?

There IS a large tube running under the small portion of the fuselage already. So just sizing the diameter and thickness of that tube... as appropriate to take those interplane torsion loads... and boom, that issue is solved.

Sorry Fritz, my brain didn't catch up to this before I took a second look at the rendering in Post 541 !
 

nestofdragons

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WAIT A MINUTE !

OMFG am I brain-fart stupid or what!?

There IS a large tube running under the small portion of the fuselage already. So just sizing the diameter and thickness of that tube... as appropriate to take those interplane torsion loads... and boom, that issue is solved.

Sorry Fritz, my brain didn't catch up to this before I took a second look at the rendering in Post 541 !
Victor Bravo, is post 541 the same fuselage as the one in the 3D of Erkki67? Erkki67 refers to a Ranger design.

Erkki67, you say: "To reduce the torsion effect, both wing might be joined at the folding hinge"
I think that making a connection between both wings might prevent the wingtips of the rear wing go back and forwards, but i guess those connections are too horizontal to prevent wingtips of rear wing going up and downwards.
Hmmm, just me thinking out loud now. Would a single tube be not heavier to counter torsion than two rectangular tubes like in Butterfly? I seem to keep returning to the Butterfly a lot.
 

erkki67

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For me, there are two approaches to limit the torsion of the fuselage, either the fuselage itself is built stronger, or and you connect the wings somehow to limit the twisting between both wings. One proven layout comes in mind the Sunny Boxwing, but the Trick would be to keep the flea typical control, and keeping the overall design, cute and nimble.
 

erkki67

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Romont / Fribourg / Switzerland
Victor Bravo, is post 541 the same fuselage as the one in the 3D of Erkki67? Erkki67 refers to a Ranger design.

Erkki67, you say: "To reduce the torsion effect, both wing might be joined at the folding hinge"
I think that making a connection between both wings might prevent the wingtips of the rear wing go back and forwards, but i guess those connections are too horizontal to prevent wingtips of rear wing going up and downwards.
Hmmm, just me thinking out loud now. Would a single tube be not heavier to counter torsion than two rectangular tubes like in Butterfly? I seem to keep returning to the Butterfly a lot.
or Romibutter!?
 

erkki67

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The Aim of the Piojo, was to have a sit on top flea, a little bit like the modified HM290 flea of Harold Wickwire.

mr. Wickwire flew his flea successfull.

but if it should be a problem with the flea Lay-out as a sit on top fuselage, I’m sure Fritz could come up with a very neat sit in version of the same.
 

WonderousMountain

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A little note for the curious, my joined wing
Concept that was run through X-foil flew way
more docile when the lower wing got dihedral,
The low center of gravity/mass is probably fine,
but you will get a lot lot out of a few degrees.
 
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