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Old 03-21-2018, 12:04 PM   #121 (permalink)
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Well, when I asked the engineer if the had more information/diagrams, he told it was made of perfect ellipses. I was also imaging the lower portion had ellipses more flater, since the images gives this ilusion.
Aptera probably did some of you said... But Aptera CD was 0,11 (for the best version) while Fusion (4 riders pedal power vehicle) and SolarWorld No.1 was 0,9 and 0,97 respectivelly.





Do you think that a version 12 inches wider, keeping original lenght would reduce aerodynamic efficience ?

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IMHO the cross section shouldn't be oval in ground proximity. More flatten on the bottom or a rounded triangular shape like the ME-262. FWIW.


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Old 03-21-2018, 01:12 PM   #122 (permalink)
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Width/length is also subject to fineness ratio. Look at the 400mph class at Bonneville.

Another take on the oval cross-section: http://ecomodder.com/forum/showthrea...ion-23333.html

It addresses the super-ellipse, aka squircle.
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Old 03-21-2018, 02:34 PM   #123 (permalink)
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Quote:
Originally Posted by freebeard View Post
IMHO the cross section shouldn't be oval in ground proximity. More flatten on the bottom or a rounded triangular shape like the ME-262. FWIW.
Or convex, to increase the volume under the body and lower the pressure.
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Old 03-21-2018, 06:07 PM   #124 (permalink)
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Buckminster Fuller, on his pre-protoype Dymaxion design used an 'air keel'.
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Old 03-24-2018, 01:25 PM   #125 (permalink)
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12-inches wider

There may be data out there which might allow you to predict what the difference would be.I've no idea how one might access that.
It would be a very expensive proposition to build a test model for actual testing.
And I've no idea how you'd construct the spherical coordinate system 'cloud',CFD would require in which to test it virtually.
One consideration about the NACA/Morelli shape,is that it is inferred by the report on the 1978 CNR/Morelli/PININFARINA 'banana' car,4-passenger study;that adding the tail back to the car would NOT reduce the cars drag in any meaningful way,which,if true,would 'freeze' the drag at Cd 0.23,with no hope of going lower.
Perhaps a reason that no automaker stepped up to the plate,ready to pay a licensing fee for which to commercially produce the shape.
Also,within a few years,Pininfarina produced lower drag cars using more 'classic' streamlining tools.
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Old 03-24-2018, 02:29 PM   #126 (permalink)
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Quote:
Also,within a few years,Pininfarina produced lower drag cars using more 'classic' streamlining tools.
Which would those be? The Fiat Turbina was in 1954.

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The bodywork had undergone wind tunnel testing at the Politecnico di Torino facilities. The Turbina held the record for lowest drag coefficient on an automobile (0.14) for 30 years.
This gets back to my interest in OpenVDB and modeling CFD within Blender (which already supports OpenVDB). The sparse, shallow nature of VDB makes it fast on common hardware. Here're the original source papers: Publications
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Old 03-24-2018, 03:59 PM   #127 (permalink)
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which

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Which would those be? The Fiat Turbina was in 1954.


This gets back to my interest in OpenVDB and modeling CFD within Blender (which already supports OpenVDB). The sparse, shallow nature of VDB makes it fast on common hardware. Here're the original source papers: Publications
The original state contract for CNR spanned from 1976,through 1978.
Around 1991,Pinifarina produced a CNR2,with Cd 0.192,a notchback,and very 'conventional' in appearance.
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Old 03-29-2018, 10:04 AM   #128 (permalink)
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Morelli's diagram (in green) overlayed with SolarWorld No.1 diagram (red/blue) :




See how SolarWorld No.1 tried to make the front portion (near windshild) flatter if compared to Morelli, since it's a solar car.


Maybe the chassi could be made of this incredible bamboo fiber composite :





It resists over 1000 times it's own weight

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Old 03-29-2018, 02:40 PM   #129 (permalink)
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Once you're into a composite materials, the big competitor is hemp. And the hemp decoricator
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Old 03-29-2018, 02:49 PM   #130 (permalink)
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I guess he would have a hard time trying to get an industrial hemp supplier, plus bamboo is easily available here in Brazil.

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