Aerodynamic aspects of an old GoOne 3 velomobile

[aerohead]

I don't see any exposed fasteners. Are you using an adhesive bonding material to attach the gap-closure material?
It's a real clean installation! Professional looking.

[beate]

Originally Posted by aerohead

I don't see any exposed fasteners. Are you using an adhesive bonding material to attach the gap-closure material?

Yes, i am using epoxy. That material is cardboard soaked up with epoxy. Surprisingly strong...

[aerohead]

The newest tail for 'SPIRIT' was skinned entirely with polyester resin-soaked cardboard, temporarily T-pinned to an underlying clear-heart, red cedar wood skeleton, attached to a welded electric metal tubing ( EMT ) frame.
I did fiberglass, and then use polyester-based body filler on the 'outside' surface of the cardboard. Then primer and automotive top-coat.
When I become 'rich and famous' I'll graduate up to epoxy. It's far and away superior.

[beate]

BTW, i am going to give the tailbox a 2nd chance. Not that i expect too much - but i can use it as a bsos to extend it. Again using cardboard.

It'll probably remain some kind of testbed, not for everyday use - 1st of all as a full fairing will cover the air outlets in the back and even wors my back light.

[freebeard]

I get extending it, but are you planning to alter the shape (add a fin or something)?

[aerohead]

Originally Posted by beate

BTW, i am going to give the tailbox a 2nd chance. Not that i expect too much - but i can use it as a bsos to extend it. Again using cardboard.

It'll probably remain some kind of testbed, not for everyday use - 1st of all as a full fairing will cover the air outlets in the back and even wors my back light.

It could make for remarkable performance.
Dr. Kamm and Fachsenfeld's research indicated that, of a symmetrical wing section, the 'aft-body', past the maximum thickness, was responsible for a 892% drag reduction ( Cd 0.58-to- Cd 0.065 ).
And specific to 'wing sections', compared to say, a conventional saloon-type passenger car, bringing the rear to a 'point' maximizes drag reduction, regardless of the tail length. Truncating it as a 'chopped-off section' is the 'worst thing we can do.

[beate]

And that's the reason why i would like to try elliptical cross sections of the back. There are some remarks (examples!) in the textbook of Hucho that these maybe at least not worse than the tipped tails. If done right, of course. Does anyone have links to more systematic research on such tails - the 2 dimensional case might be even more interesting for a velomobile than the (rotationally symmetric) 3D-case.

A truncated tail is not necessarily that bad - see for example the Quest velomobile.

[beate]

Quick not: i added two skirts to the existing tailbox covering the suspension arm.

Test drice: apparently a *very* moderate gain in speed against the wind. Of course also a reduction when the wind comes from the back, and uphill the additional weight matters. So in average no improvement because all effects more or less cancel out.

[freebeard]

There are some remarks (examples!) in the textbook of Hucho that these maybe at least not worse than the tipped tails.

Not sure what you mean by this. Un-truncated tails?

Generally, my sense is that taper is symmetrical in plan, but asymmetrical in elevation. IOW The underbody plenum gets less taper that the top.

[beate]

have a look here, page 47 : https://www.aia.rwth-aachen.de/vlueb.../Vorlesung.pdf

Well, i acually found the corresponding study: https://d-nb.info/1071469363/34

That looks like an analytical solution of a rotational symmetric problem which does not seem to be a good approach on a velomobile (but a good one for a submarine).