peddled art car

Re: peddled art car

Postby JRoyale » Mon Aug 11, 2008 2:49 pm

capjbadger wrote:I think what I really need at this point is the fine print regs the the BLM gave us since that's where the DMV says these rules are coming from.
I want to see their definition on "Human Powered", and if it's not clear there, then at least I can email them.


Actually, we're no longer referring to the BLM when we restrict driving at the event, tho' some of the older stuff out there might still mention it.

The event is a pedestrian and bicycle event not because of the BLM but because Larry sez so.

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Re: peddled art car

Postby capjbadger » Mon Aug 11, 2008 4:03 pm

JRoyale wrote:
capjbadger wrote:I think what I really need at this point is the fine print regs the the BLM gave us since that's where the DMV says these rules are coming from.
I want to see their definition on "Human Powered", and if it's not clear there, then at least I can email them.


Actually, we're no longer referring to the BLM when we restrict driving at the event, tho' some of the older stuff out there might still mention it.

The event is a pedestrian and bicycle event not because of the BLM but because Larry sez so.

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Ok, so then what is the definition of "human powered" as far as the DMV approval goes?
For (silly) example, if the Contessa was somehow pedal powered, would it need DMV approval?

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Re: peddled art car

Postby JRoyale » Mon Aug 11, 2008 5:30 pm

capjbadger wrote:Ok, so then what is the definition of "human powered" as far as the DMV approval goes?
For (silly) example, if the Contessa was somehow pedal powered, would it need DMV approval?

Badger


Human power would be the only source of power is humans. And yes, if you want to push or pedal the Contessa around the playa with humans, you don't need a license.

And I didn't completely follow the sub thread on flywheels, but we really don't care as long as it's small. But if you're talking about a huge flywheel that you charge up over hours using human power, then you need to talk to us first and let us know what you're doing.
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Postby gyre » Mon Aug 11, 2008 5:45 pm

I think that was more of a joke or random contraptioneering.
Flywheel drive has only proven successful with relatively low mass very high speed flywheels so far.
I think powering one of those would be extremely complex with human power.

I think if anyone can pull this off, the dmv ought to encourage them.
It will either be an incredible feat of engineering that will startle the world, or the most amazing social persuasion for a group effort since the standing stones were built, or maybe both.

Ask LeChat how much power it takes to run an mv around the playa by hand.
He knows, since he did it last year.

Too much to be practical.
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Postby LeChatNoir » Mon Aug 11, 2008 7:31 pm

gyre wrote:Too much to be practical.


But not too much to be un-fun.

I suspect that the thing would be more efficient without the flywheel actually, but its much more fun to look at and play with like it is.

And yeah... I don' t have any winning lottery tickets hidden anywhere after all. So the 15 foot flywheel idea was sort of 70% in jest. The one I've already got is almost more than I can manage.

Incidently, I was approached by someone who wanted me to spearhead an enormous mass transit vehicle that was human powered with a titanic flywheel. If I wanted to burn out and die I'd take them up on it.

Maybe I'll think about it.
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Postby LeChatNoir » Mon Aug 11, 2008 7:42 pm

And by the way…I should add here that I worked back and forth with JRoyale last year.  He was a really big help when working out the details of The Contraption needing a license or not.  He’s got my appreciation for both that and responding to questions here on eplaya.
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Postby JRoyale » Mon Aug 11, 2008 11:27 pm

gyre wrote:I think if anyone can pull this off, the dmv ought to encourage them.


We probably would... we just need to know so we can avoid any unpleasantness on the playa.

And we also have a concern about safety. Not so much the particular details but that design and build team understand what they're doing so they don't create something that hurts a bunch of random people.
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Postby Elliot » Tue Aug 12, 2008 7:21 am

We probably would... we just need to know so we can avoid any unpleasantness on the playa.

And we also have a concern about safety. Not so much the particular details but that design and build team understand what they're doing so they don't create something that hurts a bunch of random people.


Very sensible.
Over in the parallell universe of Kinetic Sculpture Racing, which is a human-power sport, we had a debate last year over "stored energy" -- to be unleashed when needed, such as on a steep climb or thru a mud pit. Electric power transmission (and any capacitors or batteries in that system) was one concern. But the biggie was flywheels -- the accumulation of energy (from human power) in a large whirling spinning mass that some "Rube Goldberg" (like me) has fabricated out of scrap metal and concrete in his back yard. The overwhelming majority was opposed to this idea. A valid technical excercise, but too bloody dangerous.
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Postby gyre » Tue Aug 12, 2008 3:19 pm

State of the art seems to be carbon fibre flywheels.
Besides strength, when they fail they are supposed to disintegrate totally.
Just like the lightweight air tanks, this makes them easy to contain and relatively safe.

Standard clutch containment technology should be applicable up to a certain level.
I would think this would be quite self limiting for human power.
Add enough weight to store energy and you're not going far anyway.
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Postby Elliot » Tue Aug 12, 2008 3:59 pm

:D
A flywheel that turns to dust if its structural integrity is compromised? Kind'a like tempered window glass? That sounds like a good idea. But not for most of us shade-tree low-buck fabricators!

The KSR debate envisioned an other risk, beyond fragmentation of the flywheel: Namely that the axle bearings might fail and the axle twist off, leading to a runaway buzz-saw. Good Wyle E. Coyote cartoon image; bad in real life.
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Postby JRoyale » Tue Aug 12, 2008 11:18 pm

Elliot wrote::D
A flywheel that turns to dust if its structural integrity is compromised?


All that energy can't just magically disappear.
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Postby gyre » Wed Aug 13, 2008 12:00 am

I'm told that they disintegrate in a fundamentally different fashion, besides leaving no large pieces, which is fundamentally easier to contain.
It's like the difference between lighting powder spread out on the ground and the same powder contained in a shell.
The same power is involved, of course.

I think ballistic wraps for clutches have become quite good, and are particularly effective with this type of containment too.

I saw a viddy of one of the large fibre tanks pushed to failure and it sort of gave up all at once instead of starting to fail in one concentrated spot.
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Re: peddled art car

Postby capjbadger » Wed Aug 13, 2008 12:34 am

JRoyale wrote:
capjbadger wrote:Ok, so then what is the definition of "human powered" as far as the DMV approval goes?
For (silly) example, if the Contessa was somehow pedal powered, would it need DMV approval?

Badger


Human power would be the only source of power is humans. And yes, if you want to push or pedal the Contessa around the playa with humans, you don't need a license.

Cool. It's really nice to get info from the proverbial horse's mouth. :)

Elliot touches on another question that has been batted back and forth. Alternate forms of trasmission of human power.

I've been playing with the idea of converting my MV to be human powered, but the design make the usual pedal and chain power transmission setup next to impossible.
So the idea of pedaling a generator which is wired directly to a electric motor. No batteries. Is this still human powered as far as the DMV sees it?

Thanks again. All us crazy MV building geeks really appreciate the info you're giving us. :)

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Re: peddled art car

Postby JRoyale » Wed Aug 13, 2008 1:17 am

capjbadger wrote: Is this still human powered as far as the DMV sees it?

Thanks again. All us crazy MV building geeks really appreciate the info you're giving us. :)

Badger


So here's the deal. We want to make Burning Man better for everyone so as a general rule MVs that we think the average Burner thinks makes Burning Man better for everyone get licenses. MVs that are mostly for the convenience of their owner, well not so much.

So honestly, I'd much rather have a discussion about making cool "art cars" then about how to gut a Pirus and make it a shell you can put over a bicycle. And I'm an engineer by training, so I love all weird "contraptions" that people bring to the playa. I really do, cause deep down I'm a function over form kinda a guy. But here, for better or worse, the DMV is mostly looking for form over function. I mean, I'd personally love to hear all about your home built steam engine - but if it is powering a Chevy Nova and not "dragon" you're not getting a license.

And really, if you're going to spend the time and money to build a custom power train, how much harder is it to make it look like something that could get a license?

But to answer your specific question about powering an electric motor with pedals and no other power source. Technically the answer would be no... you've got a motor and that's what the Rangers are looking for. But, you are definitely living inside of what we are looking for when we talk about human power, so while I couldn't 100% guarantee we could make this work, I'd work pretty hard on your behalf to make it possible.

That said, something like this isn't something you talk to us about in August... think February.

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Postby Elliot » Wed Aug 13, 2008 7:58 am

:D
I'm very grateful for JR's thoughtful posts!

And indeed, this discussion belongs much earlier in the year. It works the same with Bonneville Land Speed Record cars. Thas is another hobby -- if that's the right word -- where unlimited innovation is encouraged. Builders are also strongly encouraged to submit their plans for evaluation before beginning construction. Saves a lot of last minute disappointment.

That said, this forum becomes an archive of information for future reference, so I'll mention a couple of things.

Electric power transmission has been used in Kinetic Sculpture Racing (a human power sport). The rider pedaled a generator, and an electric motor drove the wheel. With no storage device like battery or capacitor in between, this is considered 100% legitemate in KSR. The debate started when a racer incorporated several large capacitors to "smooth out the power flow" or some such. Direct electric tranmission of power is common in our society -- used in railroad locomotives, for one thing. But for human powered vehicles, it has proven terribly inefficient.

Hydraulic power transmission falls in the same category.

It is hard to beat the roller chain for efficient power transmission. But for some of us, difficulties arise when we need to turn the power around corners, more or less literally. The solutions can be simple and efficient, such as installing pedals crosswise in the vehicle. Or complex, such as running the power thru a series of U-joints -- as in the commercially manufactured Conference Bike.

One solution we use all the time in KSR, is to run a bicycle chain in a twist. If the distance from hub to hub is at least a couple of feet, you can twist it 90 degrees.

About dispersement of energy in a carbon fiber flywheel explosion, I would expect a lot of that energy to convert to... A HUGE BANG! :lol:
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Postby gyre » Wed Aug 13, 2008 9:08 am

It depends on the power.
High speed flywheels, that is 40,000 to 100,000 rpm, are usually being designed very small for vehicles so there is low mass and high momentum.
The safer designs seem to use hoops or spiraled fibre that begins to fail slowly before catastrophic failure, allowing shutdown.

Separation of the entire wheel from it's mount is considered a higher risk.
Rotating cases are another approach to containing that.
There are other proposals such as multiple, very small diameter wheels and so on.
Most of these issues have been dealt with except cost.
Completely impractical for long term storage on a normal car now.
Some research is being done in short term storage for braking use.

I was looking for some pictures I found of total destructive testing but I can't find them.
They were nasty looking but most of the mass did not separate and the damage was not severe for the power involved.

A great deal of energy can be dissipated if the time period is not too abrupt and shrapnel can be contained.
Conversion to heat is one solution, a longer moment being ideal.
The speed of conversion of energy has a lot to do with the result.
Air resistance alone can absorb a lot of the energy in a lightweight wheel after failure.

Some proposals for cars involve unrealistic power storage ambitions that would be difficult to contain cheaply, but those power ratings are not realistic anyway.

Some of these are in use for UPS and as solar batteries, using magnetic bearings and a vacuum container.
Weight not being an issue, proper containment is not at issue for that.
It is all very intriguing, but not practical yet.

I would expect anything used for human power would be a low speed flywheel and if large enough to be useful, would be too heavy to be practical.
There are some fomulae for calculating size, speed and potential power.

The electric system I am working with used to have a very powerful nicad system, which blew up during charging.
The destruction was quite impressive.
Anything storing power can be dangerous.
I can assure you that if I use nicads, they will have a clutch shield over them, probably open on the bottom.

I would like to have a superconducting storage ring to use as a battery, but weight and cost issues again crop up.
Rats!

Oh, as perfect as the ring is, if the superconductivity fails, you have catastrophic failure even with that, resulting in a white quench if you're lucky.
A black quench if you're not, as the field dissipates all that energy.
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Postby LeChatNoir » Wed Aug 13, 2008 9:15 am

When I was a kid I was putting around up in the mountains in my old 4x4 Toyota pickup. I had it in 4Low, easing down a very VERY steep grade. After nearing the bottom and beginning to plane out just a bit, I decided it’d be fun just zoom down the rest of the way and ride it out like a roller coaster... down slope and up the next grade.

Prior to this moment I did not ever need to think about how fast the clutch would be spinning as the truck picked up speed in low range.

I pushed in the clutch peddle and got started on what would soon thereafter become an important lesson.

As the truck coasted up to 25mph or so, the clutch ramped up to an incredible whine followed immediately by a loud *BANG*.

End putting around for the day.

When we towed it back home and pulled the transmission that evening, it was full of what used to be the clutch plate but was now a bunch of brown, fibery dust.
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Postby JRoyale » Wed Aug 13, 2008 9:17 am

Elliot wrote: About dispersement of energy in a carbon fiber flywheel explosion, I would expect a lot of that energy to convert to... A HUGE BANG! :lol:


And I love a HUGE BANG as much as most people, if not more, but this gets back the whole "let's try not to hurt random people" interest the DMV has.
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Postby LeChatNoir » Wed Aug 13, 2008 9:26 am

On a side note, I’ve read about some catastrophic industrial flywheel failures before and they are rarely uneventful and usually dangerously impressive. Blowing out sides of buildings and rolling for great distances without much mind to what’s in their path.

One reason why, even with the engine on it, I’m still running the Contraption flywheel so far under its safe limit is that it’d be just so damn unnerving to sit atop of the thing going 1200rpm. Even if it was balanced enough to spin that fast safely (which its not), 250 is fast enough, thanks.
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Postby gyre » Wed Aug 13, 2008 9:46 am

I'm definitely in favor of safety anywhere rapid release of energy is a risk.
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Postby Elliot » Wed Aug 13, 2008 10:28 am

:D
..."let's try not to hurt random people"

I, for one, certainly agree with this.

Methinks we have allowed this thread to develop into two separate discussions: one practical and Playa-related, and one more hypothetical or scientific.

JR's contributions to the Playa-related discussion is much appreciated. And I do have plans for a motorized MV one of these days.

Meanwhile, here is one of my pedal-powered ones -- seen on the Playa in 2006. Yep, same one as in my avatar.

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