How narrow could Asphalttretboot be before it is impractical?

[AustraliaDan]

Varna Torso is an interesting vehicle.

Varna 24

varna 24 - Varna 24

varna 24 Ce n'est certainement pas une construction amateur, mais d'un grand Amateur de VPH, Georgi Georgiev. Toutefois, je pense que les détails glanés aujourd

velorizontal.1fr1.net

Similarly Asphalttretboot is very interesting, no idlers for example.

I want you to consider how narrow could an Asphalttretboot be before it is no longer practical for turning corners on a road for example.

Also the task of closing the rear end is of concern.

The narrowness is appealing, I can fit inside 37cm at the hip which is narrow. Snoek is 68cm wide, a ~45cm width velo could be very fast?

I have been doing some calculations but they only can take me so far. There are some clever minds here that I hope to pick.

Also can anyone recommend a pre-loadable velomobile universal joint (without slack) for sale that I can purchase for this project?

 

[einrad]

Hi Dan,
it might make sense to explain the meaning of your expression "universal joint".
I have no idea what you mean...
Best regards, Harald

 

[Cars10]

Where you want to ride it: daily use or battle mountain only?

 

[Niko]

Universal Joint => Kardangelenk

 

[einrad]

Danke Niko,
Das kannte ich nicht und eine Suche für so einen allgemeinen Begriff hab ich für nicht aussichtsreich gehalten.
Wieder was gelernt...
Gruß, Harald

 

[Ralsch]

Comparing the Asphalttretboot with the Varna 24 is .... "interesting"?!

I started to reply, but in the end it doesnt make much sense to go into details.
A 40cm wide Asphalttretboot will be as fast as a Varna 24 - which is build 5 meters wide (sorry for the rough estimation, my FEM-Computer is just busy calculating the meaning of life, the universe and everything ).

The concept of the Asphalttretboot is more for fun riding to decelerate yourself and adding a universal ball joint transmission steals further power.

At something like 25km/h top speed, the width doesn't make any difference in drag, it just slows you further down (if this is even possible) in corners.

 

[Niko]

adding a universal ball joint transmission steals further power.

I think they are intending to use the universal joint for steering, not for power transmission?

 

[BastlerWilly]

I want you to consider how narrow could an Asphalttretboot be before it is no longer practical for turning corners on a road for example.

The "Camping-Velomobil" and the "Meufl-Velomobil" are about 80cm wide and able for everyday use. Maybe around 70cm would be possible. But if you build it as narrow as a Varna it will tip over in every corner or at the first gust of wind.

 

[TimB]

I think they are intending to use the universal joint for steering, not for power transmission?

Dann könnte man das Tillergelenk von velomobiel.nl kaufen oder nachbauen.

and able for everyday use

Das halte ich nur für eine eingeschränkte Definition von Alltagsgebrauch gültig.

Vor allem ist kein Asphalttretboot schnell, solange vorne das unverkleidete lenkende Laufrad die Luft verwirbelt, bevor sie überhaupt zur Karosse gelangt.
Und der Antriebsstrang muss natürlich am Fahrer vorbei, wenn man die Asphalttretbootkonstruktion nur schmäler machen möchte. 45 cm sind so nicht machbar. Ich denke, daß @AustraliaDan etwas vorschwebt, was er noch nicht in Worte fassen kann.

Gruß,

Tim

 

[AustraliaDan]

Where you want to ride it: daily use or battle mountain only?

Riding on 60km per hour roads with cars to work and grocery shopping.

The universal joint is for steering.

I drew some pictures to visualize some possible layouts.

Using excel I compared the width of layouts.

 

[berry]

Wenn es möglichst schmal und dabei maximal kippstabil sein soll, könnte man über ein zweites Vorderrad nachdenken.

 

[AustraliaDan]

If you want it to be as narrow as possible and have maximum stability against tipping, you could consider a second front wheel.

Not enough space up front for a second wheel.
However I did have an idea, trail can move the contact patch laterally increasing stability in a turn.
More trail = A wider effective track width

There is not enough space at the front for a second wheel. However, I had an idea that the caster could shift the contact patch laterally, increasing stability in a corner. More trail = A wider effective track width

 

[schlawag]

Varna Torso is an interesting vehicle.

extremely beautiful (ce truc est vachement beau)! date 2014...

 

[BastlerWilly]

move the contact patch laterally increasing stability in a turn.

But decreasing stability at lateral wind. Maybe you need to build a test vehicle with adjustable trail to find a compromise.

 

[tieflieger]

That single front wheel outside the fairing, is not good for aerodynamics. As is the square back. Google windresistance of square shapes. There is a Julian Edgar who has several interesting Youtube video's about car aerodynamics. There is a lot to learn from those. A rectangle is better that a Parachute, but nowhere near a Varna. Aerodrag is the Rear frontal surface multiplied by the Factor. A Milan is at about 0,07. The Varna perhaps even better. The original has a drivetrain like your 3 from the left, that is the least intrusive. The Camping Velomobile is similar.

As in testing by Ben Parke, just fitting a small camera on the shell of a milan increases drag by 10 watt's. Not huge but its about 9% extra, just cause the camera is aerodynamicaly so poor.

It would take way longer than i'm willing to take, to explain why one is such a great shape, and the other way less. Try to educate yourself a bit better on vehicle aerodynamics.

 

[AustraliaDan]

That single front wheel outside the fairing, is not good for aerodynamics. As is the square back. Google windresistance of square shapes. There is a Julian Edgar who has several interesting Youtube video's about car aerodynamics. There is a lot to learn from those. A rectangle is better that a Parachute, but nowhere near a Varna. Aerodrag is the Rear frontal surface multiplied by the Factor. A Milan is at about 0,07. The Varna perhaps even better. The original has a drivetrain like your 3 from the left, that is the least intrusive. The Camping Velomobile is similar.

As in testing by Ben Parke, just fitting a small camera on the shell of a milan increases drag by 10 watt's. Not huge but its about 9% extra, just cause the camera is aerodynamicaly so poor.

It would take way longer than i'm willing to take, to explain why one is such a great shape, and the other way less. Try to educate yourself a bit better on vehicle aerodynamics.

Thank you for your reply, it sounds like you have some ideas.

With regard to aerodynamics I figure a laminar flow body coupled with <0.3m^2 frontal area and canopy for street worthiness should be satisfactory for my commuting speed.

My questions are more relating to the optimizing/narrowing of the Asphalttretboot layout. More people here are familiar with this layout and some have even built a version of it.

 

[Beinarbeit]

Call me stupid, but I don't get the intention behind the idea(?) That is, which characteristic(s) of the Asphalttretboot are actually you after?
Super-small turning radius?
Side-by-side tandem (probably not, if we look at your sketches)?
Delta configuration?

If you want to commute reasonably fast with a bit of shopping, almost any modernish velomobile would do. And probably way better than what you have in mind.

If you mainly want to haul stuff around and don't care that much for speed, a quad should do fine (maybe have a look at @BuS velomo 's threads about the Velomo/Katanga quads; practicality to the max, if you want).

Or is it more about the project itself, like, building a wonky contraption yourself? Don't get me wrong -this would be a totally valid reason as well (just a completely different one).

PS: Not meaning to derail this thread by pretending I knew better than you what want. Just trying to clarify, so people (me, for example) have a better idea what to make of the whole thing and how to answer/discuss ...

 

[AustraliaDan]

Call me stupid, but I don't get the intention behind the idea(?) That is, which characteristic(s) of the Asphalttretboot are actually you after?
Super-small turning radius?
Side-by-side tandem (probably not, if we look at your sketches)?
Delta configuration?

If you want to commute reasonably fast with a bit of shopping, almost any modernish velomobile would do. And probably way better than what you have in mind.

If you mainly want to haul stuff around and don't care that much for speed, a quad should do fine (maybe have a look at @BuS velomo 's threads about the Velomo/Katanga quads; practicality to the max, if you want).

Or is it more about the project itself, like, building a wonky contraption yourself? Don't get me wrong -this would be a totally valid reason as well (just a completely different one).

PS: Not meaning to derail this thread by pretending I knew better than you what want. Just trying to clarify, so people (me, for example) have a better idea what to make of the whole thing and how to answer/discuss ...

I am interested to go faster than current velomobiles can go while still being road worthy.
For this I have to optimize frontal area with cornering g-force.

To optimize narrowness and cornering g-force I arrived on Asphhalttretboot layout because
1) The rear two wheels don't turn, narrower.
2) A rear wheel is driven so more weight % can be on those wheels increasing effective track width without losing traction, narrower.
3) Simplest chain line, lowest seat height.
4) The shape can fit inside a laminar flow body, faster.

Unfortunately for years I have been obsessed with designing a vehicle, it is a curse.

 

[flowi]

@AustraliaDan I assume you want to use only pedal power, no assist.

>a ~45cm width velo could be very fast?

Yes. Reducing frontal area ("narrow") will help a lot getting faster. Basically halving the area will half the air drag (but NOT double the speed). The extremely fast battle mountain bikes are designed to wrap as close as possible around an athlete they picked in advance.

But the square front and rear ends of that bath tub will have a drag resistance of a truck which will be slowing down more than what you gain with narrowing.

Do you understand the theory regarding how fast you can go with a certain pedal power. So the cycle rolling resistance Crr, the drag resistance Cd, etc. And how to make a design aerodynamic to reduce Cd.

If not, we can give some pointers.
If you think you understand the theory, maybe you can explain how much power you think is needed to bring that bath tub up to speed, and why.

 

[AustraliaDan]

@AustraliaDan I assume you want to use only pedal power, no assist.

>a ~45cm width velo could be very fast?

Yes. Reducing frontal area ("narrow") will help a lot getting faster. Basically halving the area will half the air drag (but NOT double the speed). The extremely fast battle mountain bikes are designed to wrap as close as possible around an athlete they picked in advance.

But the square front and rear ends of that bath tub will have a drag resistance of a truck which will be slowing down more than what you gain with narrowing.

Do you understand the theory regarding how fast you can go with a certain pedal power. So the cycle rolling resistance Crr, the drag resistance Cd, etc. And how to make a design aerodynamic to reduce Cd.

If not, we can give some pointers.
If you think you understand the theory, maybe you can explain how much power you think is needed to bring that bath tub up to speed, and why.

Hello thank you for your reply.

Regarding the aerodynamic shell, it would feature a laminar flow body designed as small as possible while having a head bubble similar to varna 24. The challenge is closing the tail at the rear without excessive length. I have read that 17 degrees is the maximum angle to prevent separation.

I have a general understanding of aerodynamics of streamlined HPV that I have read over the years.