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Carbon disk wheel DIY, pancake wheels

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Yanto View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2017 at 10:29pm
I think it is safe to assume in the  last couple of hundred years that a diamond configuration has been tried, do we see any form of transport apart from a Harrier VTOL or B52 bomber using a diamond configuration? 

This is the only thing i can think of with a near diamond config and only for stopping/low speeds and last year i watched a chap turning one around, it was horrible watching the side wheels scuffing.

Ian, retired.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 1:34pm
https://www.hemmings.com/blog/2010/08/10/gordon-v-gorgoni-streamlined-diamonds-an-ocean-apart/



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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 1:43pm
Over the last XXX years, do we see velomobiles as a common way of transport?   This is the same argument as the non-existence of diamond arrangements in 'common use'. Velos are not in common use, yet, you are not giving up on them.

It could be that for heavy 1-2 ton vehicles driven by internal combustion engines, the diamond, indeed, has no advantages. For these vehicles, aerodynamics does not matter much, either, just look at any Range Rover or Cherokee. For lightweight vehicles (200 kilos max) traveling at 50 kmh in the rain and cross-wind, alternative wheel arrangements might matter -- who knows. It could be that the parameter space has not been fully explored. What I do know so far from this forum is that riding in 30 kmh winds and rain in a velo is unanimously described as 'scary'. I wonder if there are hacks around it.

I am going to print scale models of shapes on my 3D printer, sand blast them, epoxy-coat, and blow on them from different directions. I can measure the wind speed at which they tip, move etc. I can test several 'standard' shapes as well. If anyone knows where to get .stl files for common velos, would be cool to compare them.
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runcyclexcski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 1:46pm
In that picture, the rig seems too tall? Taller than the cars it is following?

Scuffing is a problem, indeed. I am not sure how it was addressed in the vehicle I posted: both front and rear wheels turned?
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runcyclexcski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 1:56pm
Then there is this one.


http://www.diseno-art.com/encyclopedia/strange_vehicles/litestar_pulse.html

It's odd that, by design, 3 wheels out of 4 contact the ground. That may truly feel like riding on training wheels. I remember myself riding them at age 4.

Edited by runcyclexcski - 23 July 2017 at 1:57pm
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AlanGoodman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AlanGoodman Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 2:19pm
Concept vehicles that never really caught on...I think we know why but nothing stopping somebody building a velomobile in that configuration and trying it of course.
 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 2:35pm
The Pulse/lightstar (the airplane-shaped one) sold 350 copies. For a vehicle like that, I say, not bad :)
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runcyclexcski View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote runcyclexcski Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 5:33pm
Regarding crosswind vehicle stability... This is probably TMI, but I just found this Ph D thesis X Zhang.

https://www.ksp.kit.edu/download/1000047001

The intro reads very well. The motivation for the research sounds very relevant for his group:

"current developments in vehicle engineering have been showing a trend of faster, more energy efficient and more comfortable vehicles with a high capacity of passenger transportation. These trends require that the vehicle has a much better handling stability. However, the demands for light-weight constructions and higher driving velocities are in conflict with crosswind stability."

My spouse, a German scientist, indicated to me that KIT (Karlsuhe Institute of Technology) is a respected school. The Ph D adviser was this Prof:

https://www.itm.kit.edu/english/dynamik/Staff_1231.php

One researcher that the thesis cites a lot is this UK Prof:

http://www.birmingham.ac.uk/staff/profiles/civil/baker-chris.aspx

For example:

Ground vehicles in high cross winds part I: Steady aerodynamic forces
Ground vehicles in high cross winds part II: Nonsteady aerodynamic forces

http://www.sciencedirect.com/science/article/pii/0889974691800123

The PDFs are attainable through Sci-Hub.


Edited by runcyclexcski - 23 July 2017 at 6:07pm
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Yanto View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 7:03pm
Originally posted by runcyclexcski runcyclexcski wrote:

Over the last XXX years, do we see velomobiles as a common way of transport?   This is the same argument as the non-existence of diamond arrangements in 'common use'. Velos are not in common use, yet, you are not giving up on them.


I didn't explain myself, I meant your thoughts will not be original (you proved me correct), the reason we don't see the diamond set up is because there are no reasons for it to be better than wheels at 4 corners, if it was we would all be driving about in cars looking like them.

As for velomobiles being a common way of transport? Well since Mochet designed his there hasn't exactly been a groundswell of support for them.

Just because I and the other 0.0000757% (approx') of the uk population ride them will never make them popular, I don't ride mine to be popular, i ride it for fun and being different, if everybody had one I would have something else.

In your tests don't forget to have a simulated human blob sitting in each velomobile in the correct posture/position otherwise your tests will be meaningless.

Ian

PS, please don't think I'm having a go at you personally, you obviously have set yourself a challenge and I wish you luck in achieving that, but you seem to be stuck in a rut and becoming obsessed with side wind stability, but have you actually analysed when these conditions occur that would preclude riding? and what you are proposing is not new, has been tried and even I can see massive flaws to everyday usage that outweigh the benefit of being able to use it a few days a year more. 


Edited by Yanto - 23 July 2017 at 7:48pm
Ian, retired.
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Yanto View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 23 July 2017 at 7:33pm
Originally posted by runcyclexcski runcyclexcski wrote:

The Pulse/lightstar (the airplane-shaped one) sold 350 copies. For a vehicle like that, I say, not bad :)

You got in one, "For a vehicle like that, I say, not bad :)"  You think 29 a year is not bad? I would counter that and say in the USA between 1985 and 1990 I'm sure a lot more cars/motorcycles were sold than that. It is a freak borne of obsession and appealed to a very very small minority, which I'm sure was not in the builders business plan.
Ian, retired.
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