Low aspect ratio sport plane ideas

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cluttonfred

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So given my remarkable graphic talents,
I took upon my person the solemn duty
Of remaking the Venerable P.C 140 bird.
As to fit our traditional 12x12feet rooms.
View attachment 125549
Key: One square equals 6"

Some notes on discovery, the elevator has to be trimed to account for Vert. Fin's travel. Pretty satisfying wheel pant position, propeller 60" - four blade wood advised. Showing main spar approximately 13ft & 1/2 length, internal drag brace shown as solid lines leading from the center. Junkers trailing edge flaps 1ft, design needing review.

Cute, but for me the advantage of the Piana-Canova planform is that the straight-line construction makes for a simpler build. Once you start introducing curves you may as well go with an Arup, Zimmerman, or circular wing. Here is an excerpt from a period journal article that included a table of design concepts which I suspect were wind tunnel models. Not that the first two (C 22 and C23) are actually high-wing designs, which is an interesting idea as it eliminates the need for long landing gear and the awkward cockpit entry.

I am also very interested by the bottom center design (C 32) in which the wing taper looks like it was designed for a straight spar from tip to top at about 25% chord. That could make for a very attractive solution in terms of the build--main spar, leading- and trailing-edge tubes, control-surfaces hinged on the trailing edge tubes, strong ribs, all covered in fabric, done. That could be an attractive approach for high- or low-wing LAR designs.

piana-canova numbered designs excerpt.jpg
 

rotax618

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I really don’t understand why a circular or eliptical wing would be any more difficult to build than a diamond shaped wing, a circular/eliptical wing doesn’t need ribs, David Rowe used stringers bent over 3 or 4 lightweight spars - you could use blue foam infill to stiffen them - the sem-span of the wings is probably going to be less than 8ft - how many ribs will that need?
 

cluttonfred

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I really don’t understand why a circular or eliptical wing would be any more difficult to build than a diamond shaped wing, a circular/eliptical wing doesn’t need ribs, David Rowe used stringers bent over 3 or 4 lightweight spars - you could use blue foam infill to stiffen them - the sem-span of the wings is probably going to be less than 8ft - how many ribs will that need?

Here's a quick sketch of what I had in mind...purple are main and false spars with angle or tube caps and sheet webs, though I am not really sure that the false spar would be necessary. Blue and green are leading- and trailing-edge aluminum tubes, orange are built-up truss ribs of aluminum tube or angle. This is a 4,0 m span x 4.0 m maximum chord wing with the ribs on 50 cm spacing. The AR would be 2.0 (a little lower once the control surfaces added) and the wing would be 48 cm thick along the centerline with a 12% thickness airfoil. You could certainly also add more ribs if you wanted to but regardless this would go together very, very quickly. The main spar and the leading-and trailing-edge tubes form rigid triangles (bracing gussets at intersections not shown) so I don't see that any other drag or anti-drag bracing would be required. Plain or Junkers elevators and ailerons could be hinged to the trailing edge tubes.

PS--I should add that my sketch below shows the wing leading edge down in keeping with the Piana-Canova concept sketches in my previous post, think kite not arrowhead. ;-)
Untitled presentation (6).jpg
 
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rotax618

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A more stable vortex would form on that planform if the sweep from the nose to the false spar was less than the sweep from the false spar to the tip.A0B61646-6BD2-43C3-9F62-3BB107A00C79.jpeg 47A696D6-D41C-492C-AC9B-B927031298FE.jpeg
 

nestofdragons

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Now that we are talking about rib spacing. Would 50 cm spacing not be too much if you want to cover it with fabric? I fear a lot of sink between the ribs. Sorry, not so familiair with that kind of spacing. My Hm14/360 had 33 cm only between ribs.
I like the idea of using only caps over a few spars and having no D-tube, just overal covering with fabric. Sounds like easy to do and very light.
 

cluttonfred

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Now that we are talking about rib spacing. Would 50 cm spacing not be too much if you want to cover it with fabric? I fear a lot of sink between the ribs. Sorry, not so familiair with that kind of spacing. My Hm14/360 had 33 cm only between ribs.
I like the idea of using only caps over a few spars and having no D-tube, just overal covering with fabric. Sounds like easy to do and very light.

I have done absolutely zero analysis on rib spacing, I just chose a 50 cm spacing for a quick and dirty sketch. In this example, you could easily add false ribs back to the main spar between the actual ribs to better support the leading edge fabric.
 

Riggerrob

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Regarding the P.C. 140: Raise the lower edge of the rudder (which is the movable portion, rather than the vertical tail), instead of opening up the horizontal area. If you gap the horizontal planform, it will introduce airflow disturbance in that area, creating issues.

Yes, and you can extend the rudder vertically to compensate for the triangle cut off the bottom edge.
 

Riggerrob

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One of the Soviet disco-plans had radial ribs. From the top, ribs looked more like umbrellas'. It had thick, curved leading and trailing edges. I wonder if you could built a circular disco-plane with ribs that fold along vertical hinges)??????????
 

WonderousMountain

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Cute, but for me the advantage of the Piana-Canova planform is that the straight-line construction makes for a simpler build. Once you start introducing curves you may as well go with an Arup, Zimmerman, or circular wing. Here is an excerpt from a period journal article that included a table of design concepts which I suspect were wind tunnel models.
If you are really looking for a simple planeform, my suggestion would be the utterly straight leading edge. Make a light ply wing nose back to the main spar and don't fret the tips overly much, there's barely any bending moment to counter. The one currently on my Avatar right-bottom is your starting concept.

As others have mentioned, the trailing edge was not improved by modification, I was able to locate, but not duplicate PC-140 rear view, it's Fin is forward of junker elevator range of motion; In so retains the lower rudder chord. Standing firm on the fits a square room constraint, rather than LAR only.
 

bwainfan

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Fodder for discussion. Most info came from Wikipedia. If anyone has better data, let me know. Couldn't find all info on Hoffman and Arup, so assumed 250 lb payload.

Empty
Weight
Gross
Weight
PayloadWing SpanWing AreaAspect
Ratio
Wing LoadingHPPower Loading
Hatfield Little Bird24845821017.001442.013.182716.96
Arup S-2780103025019.002111.714.883628.61
Payen AP.1044175030916.25107.62.456.974018.75
Rowe UFO-3319.6766134113.20136.81.274.834215.89
Facetmobile FMX-437074037015.002141.053.465014.80
Verhees Delta46375028714.751101.986.825015.00
Hoffman900115025022.662372.174.858513.53
Baker MB-158484325918.00983.318.60859.92
(AVG)284.541.995.455216.68
Facetmobile had 46 hp
 

rotax618

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The radial spars of the Disco-plane is worth considering, the downside is that all of the wing loads are concentrated to one or two points, in any critical structure it is best to distribute loads for some redundancy, but assuming the airplane was very light, thin stringers could be attached to the tops of the radial spars to streamline the fabric covering. Another problem is that the wing section would be dependent upon the outside shape and the relative position of the vertex.
 

nestofdragons

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One of the Soviet disco-plans had radial ribs. From the top, ribs looked more like umbrellas'. It had thick, curved leading and trailing edges. I wonder if you could built a circular disco-plane with ribs that fold along vertical hinges)??????????
You just made my brain have a buzz of ideas. :D:D:D
 

henryk

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Facetmobile had 46 hp

"vortexosc" flying car 5 HP only=


=post 477... (dr Sorokodum)
 

Aesquire

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The Otto Lillienthal gliders had radial ribs/fingers/whatever.


If you modify the pictured glider with a modern hang glider control bar & harness, plus seal the center gap, it would fly even better, with more control. I'd want to run one on an open air wind tunnel test truck to verify stability, before going off a serious mountain, though. It'd be a low performance novelty. ( a modern beginner glider is so much better. )

A "Japanese umbrella" folded & plastic cardboard design, with top surface fore & aft shaping ribs, ( see pictures above ) ...mini wing fences! " might be viable. Embed carbon protrusions in the hinge lines? 3D print the wing?

 
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Aesquire

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I like the idea of a LAR with egg crate thin plywood wing construction with (CNC ?) routed wing frame. Maybe geodetic "cap" strips for smoothing & fabric glueing? Be fun to static load test.
 

Riggerrob

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The Otto Lillienthal gliders had radial ribs/fingers/whatever.


If you modify the pictured glider with a modern hang glider control bar & harness, plus seal the center gap, it would fly even better, with more control. I'd want to run one on an open air wind tunnel test truck to verify stability, before going off a serious mountain, though. It'd be a low performance novelty. ( a modern beginner glider is so much better. )

A "Japanese umbrella" folded & plastic cardboard design, with top surface fore & aft shaping ribs, ( see pictures above ) ...mini wing fences! " might be viable. Embed carbon protrusions in the hinge lines? 3D print the wing?


Oru kayaks are made of tow-ply Coroplast sheets and depend upon their pre-cast corrugated plastic sheets for sheet stiffness.
Another concept is the Tucktec kayaks made of much thicker sheets of flexible plastic (think Krazy Karpet) that depend upon single curvature for panel stiffness.
If you added low-pressure, internal inflatable bladders, you could prevent a Tucktec from collapsing inwards. But that blurs into the inflatable airmat technology invented for Goodyear's Inflatoplane.
 

henryk

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to verify stability,

=airfoils should be autostabil ("S" -shape,< 10 kg,
not "C"-shape)

f.e.= Jan Wnek from Otporyszow= 1866-69 , < 4 km flys !!!
 

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