Aerodynamic aspects of an old GoOne 3 velomobile

[beate]

Please let me point to some boundary conditions with such a back:

- it must be easily removable for maintenance
- i need a solution for the back light because i often drive in the night. And that light must remain attached to the old back of the VM.
- the angle of the back of the fairing and the back to the canopy is pretty steep. An even transition is not possible:



The longer variant seemed to have been slightly faster, but that was not consistent.

[kach22i]

Originally Posted by beate

Please let me point to some boundary conditions with such a back:

- it must be easily removable for maintenance...........

Makes sense, I personally would lean towards a key locking device because strong jolts from pothole bumps can unlatch things in a hurray.

Paddle latch (flush recesses stainless steel marine grade), rotary latch, or cam latch?

These images posted of a gas powered GoOne3 back a month ago, show what a mess of things can be done when aerodynamics is NOT considered.

Post #922
https://ecomodder.com/forum/showthre...-35653-93.html

Originally Posted by kach22i

So close, if only they finished off the aft section properly.

The Aurora Project: A Human-Hybrid Lithium Rocket Trike!
https://diesel-bike.com/Aurora/aurora.html

I found the images you posted on 1/25/22 shown below to be exhilarating.

https://ecomodder.com/forum/showthre...-35653-97.html

Originally Posted by beate

...............
BTW: here the two sucessors of the GoOne 3 - the larger one is its direct descendent:

Is there a "lane presence" rational (like the Aptera below) for going horizontal as well as a vertical orientation at the tail?

Dec 2020
Aptera is taking orders for its solar-electric three-wheeled EV
https://www.slashgear.com/aptera-is-...d-ev-07649983/


A simple conical tail might be best aerodynamically, but rear wheels and safety lights could be incorporated and not tacked on later as afterthoughts if done right in my opinion.

Then of course there are cross-winds and stability issues one must contend with.

Knowing the center of mass/ center of gravity, wheel loading and center of side force (side acting as a sail) must be imagined or designed for.

The extra height of a rear fin could be a welcomed safety feature if topped off with a strobe light, or could spin you around like a top.

https://www.quora.com/Do-horizontal-stabilizers-move

[beate]

Well, the Aptera is two seated and accordingly pretty wide. For an aerodynamic back it might be easier to narrow it horizontally - the vehicle becomes a lot shorter and a lot less prone to side winds (which, btw, is indeed a problem on some velomobiles including the two successors of my vehicle (the Evolution and the Evo-R)).

Furthermore those shapes need to be free standing, i.e. sufficiently distant from the road in order to be effective. That will lead directly to the shape of vehicles like the aptera.

But in the picture of the motorized GoOne You can quite clearly see a major main problem when You want to extend it with some kind of tail: the steep downward angle of the contour.

Another issue might probably be that of outlets for the air from the interior of the vehicle, especially when the canopy is fully open or missing entirely.

[freebeard]

You can quite clearly see a major main problem when You want to extend it with some kind of tail: the steep downward angle of the contour.

One possibility might be a counterflow cabin air circulation that puts an intake behind the problematic contour. The best example I forget the name of, but here's the X-47


https://www.globalsecurity.org/milit...04-image65.jpg

[beate]

At a bicycles's speed?

[freebeard]

There is a floor set by Reynolds number, somewhere around walking speed, with the upper limit around 250 MPH. aerohead will have the citations.

Still can't remember the other example. It's a bubble canopy with a shark mouth air intake directly behind, rather than extended around the sides like the X-47. A NACA duct would be more efficient but lack the opportunity to revise the loft line.

[kach22i]

The canopy aft angle near the top is indeed too steep, that is where overlap of the tail cone would help to reshape.

Question, is that steep angle so the canopy can open better?

Below I found an example that is more literal.

Bike2c24
https://www.tuvie.com/bike2c24-for-streamlined-cycling/




I'll ask a second time, is more of a "lane presence" a preference? What I mean is the larger/louder the object is, the more likely someone will be aware of your presence and hopefully not run into you.

Freebeard; I think a larger cowl that forms an intake is a novel idea, and I like it. Careful venting of what air enters can be narrowed into an aft air-curtain I assume.

EDIT-1:

Another example that is not too far a stretch from the original craft (video in link).

Velomobile Aerodynamic Direction Indicator
https://www.pinterest.com/pin/22447698115511169/

[aerohead]

For typical passenger cars, subsonic critical Reynolds number would be achieved by 20-mph, the coefficient of drag would become fixed, and remain so until compressibility effects would arise in transonic flow, at around 250-mph, in standard air.
There are online sources for the Rn calculation, based upon structure length and velocity, at standard air.

[beate]

Originally Posted by kach22i

Question, is that steep angle so the canopy can open better?

I don't know but am unsure, just because of the last of Your examples, which is the smaller of the two successors of my bike. Anyway, it would be interesting to find out about the flow with my canopy in its present stage, wouldn't it?

I also would like to get an idea why the tail i built was so much less successful than the black one (which was reported to gain some 15-20% speed increase even in its raw version).

I'll ask a second time, is more of a "lane presence" a preference? What I mean is the larger/louder the object is, the more likely someone will be aware of your presence and hopefully not run into you.

to some degree, but i do not think the reduced size of the Evo-R below will matter much. Anyway, i have to live with the size of that velomobile. And it is actually VERY visible, mostly because of its color.

Freebeard; I think a larger cowl that forms an intake is a novel idea, and I like it. Careful venting of what air enters can be narrowed into an aft air-curtain I assume.

We just have the back light at the top as a boundary condition. What would happen if i opened the space in the top of the back like here:

Another example that is not too far a stretch from the original craft (video in link).

The VM you show is the GoOne Evo-R - the 2nd successor of my model. And the developer is exactly the person who hat raced the GoOne shown above (with the modified wheel boxes and the large hole in the top of the back). He did that upon his experience with the Go3 in races. The Evo R is one of the really fast and lightweight machines.

I simply cannot afford it. Especially the new version coming out that spring.

[kach22i]

First pass, sketched it up.

Purpose of tail-fins:

1. Lane Presence - to occupy full lane front to back, avoids crowding.

2. Safety - LED strips in cross pattern or round dots going to get noticed

3. Stabilization - I've never seen a dart without tailfins - just say'n

4. Strength - something more to crush than your spine, crumple zone.

I suppose with some imaginative thought a few more reasons will pop up, like easier to right the vehicle should it end up on it's side.

EDIT:

Small fish with spines say "stay away" even from a distance, which helps make up for their lack of largeness or size.

Bright colors that say "I'm poisonous" do much the same.

In my opinion, you want something that gets a little attention, and says stay away.

There is a danger on the road of creating a visual so mesmerizing that the driver of a car drives towards what they are starring at - a bad thing. This is why early experiments/practices of motorcycle riders wearing orange helmets and or road repair crew type vests ended so badly.