Aerodynamic aspects of an old GoOne 3 velomobile

[freebeard]

Fingers of wake turbulence, clutching at anything rear facing.


https://ppembzparts.com/i-30499205-m...-2003-208.html

[beate]

My feeling is that the back plate of the 3 might be sightly too large. And some of these VMs actually have large holes in the back plate (mine has only small ones). See pics in #1 of this thread.

[freebeard]

Mercedes-Benz and Morelli favor a mesh


ecomodder.com/forum/showthread.php/morellis-fluid-tail

hot rodders and tuners favor speed holes


i.kinja-img.com/gawker-media/image/upload/s--gTJzCMBK--/pyzuedkopejzd2eihqoc.jpg

[beate]

New openings in the back - easier in heat, neutral reagarding aerodynamics.



new front wheels - improved brakes, better cooling, fewer spokes, carbon wheel disks still in production. And Wheel fences in te front. Still cardboard, and still only in the front because i want to to learn about optimizing the outlet of the air behind the wheel. I am going to saturate the cardboard with epoxy and thus turn it into some kindo of "micarta".

[kach22i]

I wonder if you could fit a couple of small 12V cooling fans in those openings for flow at lower speeds.

[aerohead]

I'm still struggling with the original 'shape' of the the trike:
* the belly should all be on the same plane.
* the belly should not slant upwards towards the rear by more than approximately 3-degrees.
* the lower body, behind the front wheels should not have a reflexed surface at all.
*the lower body should just have a 'cambered' contour, like a fish, dolphin, falcon, the 'same' width as the upper portion of the body.
* the 'loose' fit of the canopy, compared to the body suggests that there would be some unwanted interference drag all around the gap, as well as the exterior surface.
*the volume of the wheelhouses seem 'enormous' compared the needs for 'wheel-flop' of the steering.
*if the front wheels cannot be enclosed, the wheel-arch-to-tire gap should be the absolute minimum.
* the wheels should be completely covered with shallow, convex, 'MOON'-esque wheel covers.
* a one-piece, slip-on, quick-release truncated boat-tail, would be the single-most effective streamlining addition you could make.
------------------------------------------------------------------------------------
In your apartment, a 'sculptor's' armature, covered in a slightly undersized papier mache ( wet newsprint and laundry starch ) 'buck', could be fiber-glassed to it's final dimension.
Once cured, and soaked in the bathtub, the 'buck' would dissolve enough to allow the composite shell to release, leaving you with only the featherweight fiberglass shell ( all the mods to my Honda CRX were fabricated this way ).
* if you use epoxy resin, you'd still need to ventilate your apartment, as with polyester resin, but there'd be no 'odor' and no upset to your neighbors.
--------------------------------------------------------------------------------------
you may not get to Cd 0.11, but you'd get a lot closer.
just some thoughts.

[beate]

Originally Posted by aerohead

I'm still struggling with the original 'shape' of the the trike:
* the belly should all be on the same plane.
* the belly should not slant upwards towards the rear by more than approximately 3-degrees.
* the lower body, behind the front wheels should not have a reflexed surface at all.
*the lower body should just have a 'cambered' contour, like a fish, dolphin, falcon, the 'same' width as the upper portion of the body.
* the 'loose' fit of the canopy, compared to the body suggests that there would be some unwanted interference drag all around the gap, as well as the exterior surface.

All true. But luckily the canopy in its present state is already an improvement. Which does not mean that i am not thinking about further improving it.

*the volume of the wheelhouses seem 'enormous' compared the needs for 'wheel-flop' of the steering.

But the wheels actually do touch the inner walls.

*if the front wheels cannot be enclosed, the wheel-arch-to-tire gap should be the absolute minimum.

AFAIK, there should be a different shape in the upper half of the wheel streamlining the vortex coming out of the wheel box. Learning on that is one of the reasons why i left out that area for now and concentrate on the front part of the wheel box before i do the back part.

* the wheels should be completely covered with shallow, convex, 'MOON'-esque wheel covers.

As the old ones made of fabric are worn, they will be replaced but such discs. The manufacturer is in summer holidays...

* a one-piece, slip-on, quick-release truncated boat-tail, would be the single-most effective streamlining addition you could make.

I still do not understand why my attempts failed - and i have to improve the stiffness of the velomobile in order to make a better one like the tail made by the other guy.

* if you use epoxy resin, you'd still need to ventilate your apartment, as with polyester resin, but there'd be no 'odor' and no upset to your neighbors.

I am currently doing my 1st attempts with epoxy - soaking the cardboard covers added into the wheel boxes with epoxy. Tomorow i'll see if that idea works. They actually do close the gaps to the wheels as far as possible. And if that works i can continue toward the back and also into the interior of the wheel box and take away unnecessary volume.

[The Toecutter]

Originally Posted by beate

As the old ones made of fabric are worn, they will be replaced but such discs. The manufacturer is in summer holidays...

You can make your own with coroplast and zip ties to hold you over. It can be done in less than an afternoon of work for about 15 Euros of materials, and the benefits are significant. That by itself is liable to reduce overall aero drag by 10% or more versus an uncovered spoked wheel.

https://www.instructables.com/Aerody...For-your-Bike/

I still do not understand why my attempts failed - and i have to improve the stiffness of the velomobile in order to make a better one like the tail made by the other guy.

Is it possible that the rear wheel is flexing and deforming over bumps and in corners? I had that issue with my custom build. The solution was to widen the rear wheel well housing enough to where there was no scrub when the wheel leaned.

[beate]

That's what's happening. Well, not quite - the wheel itself is stiff. It is definitely the swing arm and evenven the back part of the body. My solution was exactly the same as Yours (see above), but i also had to shorten the back a bit because it was too narrow.

Which means i will need to work on the stiffness issue before new attempts with the back are meaningful. BTW: a well known problem with these bikes.

[freebeard]

If it's in the monocoque and not the connections, possibly some telltales, like thin easily deformable wire or something, that would stretch and not rebound if the mounting points move relative to each other. Or not.