Alright tech. heads...gyro powered cars!


Wicked_Sludge

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Me and a fellow co-worker got to BS'ing today and i was telling him about those little wind-up cars that have a heavy, gryo-powered wheel that you wind up on a special base then set them free. i remember these things would haul ass and go forever and we got to wondering if it would be possible to adapt the idea to a real car.

after some research...come to find out its far from an original idea. i guess starting back in the '50's, Switzerland toyed around with gyro-powered buses. since then the idea has been tried and modified a bunch of times. i guess nasa is still toying around with high efficiency systems...carbon fiber, magnetic bearings, spinning in a vacuum, ect. i guess there are some interruptible power supplies that are gryo powered.

so now for some numbers. some of this math is a little over my head (or maybe its just late and my contacts are bugging my eyes :nopityA:) but ive converted the energy contained in a gallon of gasoline into KWh per mile (assuming a 20% efficiency of my internal combustion engine in the escort...which i hope is reasonable). at 34 mpg, im using about 0.211 KWh/mile (this seems reasonable, since the EV ranger used about 0.461 KWh/mile). so to go 50 miles, i need about 12 KWh.

i tried to find a good formula for figuring the kinetic energy of a flywheel of x weight, speed, and diameter...but i gave up and used this little calculator instead:CLICKY

its really intended for smaller flywheels i think, but it works if you convert pounds to ounces and feet to inches. it gives two output readings "disk" and "ring". at the bottom it says depending on the flywheels design, its actual KE will be somewhere between these readings. i plugged in 6400 ounces (400lbs), 60 inches (5 feet) and 10,000 RPM then averaged the two outputs to get 42 joules...or 11.6KWh.

so what do you guys think? go out in the morning and plug the car in. a small electric motor starts the flywheel in motion. after a few minutes its doing 10k and your set for 50 miles of extremely torquey very quiet driving? one major downfall i see is that parking for long periods is like parking a vehicle that has a hole in the gas tank. the longer you wait, the less "juice" you have to get home with.
 


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Will

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I thought about trying that but the problem I saw was that turning could present a serious problem. If you spin up a kids gyro and wave it around it's very resistant to changes in direction. Put in a wheel that is hold tons of energy in it and you'll have the same kinds of problems on a grand scale. I could also see some horrifying accidents because there is no way to suddenly turn it off.
 

samsonitesamsonite

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To turn it off, all you would have to do is put a transmission of sorts into neutral and let it freewheel.
 

Jorley

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I thought about trying that but the problem I saw was that turning could present a serious problem. If you spin up a kids gyro and wave it around it's very resistant to changes in direction. Put in a wheel that is hold tons of energy in it and you'll have the same kinds of problems on a grand scale. I could also see some horrifying accidents because there is no way to suddenly turn it off.
Add speed and the resistance to change of direction is more is increased. The resistance to change in direction is why they are used in navigation, such as auto-pilots and rocket and missle giudance systems.
You would try to turn and the vehicle would what to continue going straight.
 

AllanD

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The two problems are precession and conservation of energy.

If I need to explain either to you then there is no point in discussing it.

AD
 

Wicked_Sludge

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i think the gyroscopic effects could be minimalized. 2 counter-rotating horizontally mounted gyros, for example, would have no effect on a cars lateral handling....or even 4 gyros - two for each plane.

applying the gryos power to the ground would probably be accomplished by electric motors rather than a mechanical link. there are multiple problems with a mechanical link. first off, the gryos speed is a set RPM (it cannot be sped up and slowed down to vary the speed of the vehicle)...this means you would need some sort of either CVT or viscous clutch (the latter would waste a lot of energy) to allow an unlimited range of vehicle speeds. the other problem comes from the 10,000 RPM input...it'd take a serious gearbox to be able to handle the constant speed and torque that big of a flywheel would produce.

the flywheel itself would contain either magnets or a coil and would spin inside the other to produce electricity, which would drive the traction motor. if a large coil isnt feasible, perhaps driving a generator directly off the flywheel.

allan, this is a tech discussion, if you arent going to add to the conversation (i dont know exactly what precession is and i dont see what conservation of energy has to do with this idea), then butt out. i posted so i could get more brains on the idea, maybe teach and probably be taught...not to give know-it-all-mightier-than-thou individuals another chance to belittle members on the boards. thanks.
 

MAKG

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Basically, conservation of energy means you have to put ALL the energy you need to drive 50 miles into the gyroscope, even if it had no losses. If you did this with an electric motor, why not just drive the car 50 miles with it?

Precession is how gyroscopes behave when you tweak them just a little. They do not stay pointed in one direction, nor do they move in the direction tweaked. Instead, they move at right angles. This makes the axis wobble circularly. Try it with a child's top. This bears some repetition. It means that if you try to turn right, the gyroscope will try to flip you over nose over nuts.

You don't solve the constant-axis problem with two counterrotating gyroscopes. Each of the gyroscopes individually sees those forces. So, you rip them apart. This means your device is going to be EXTREMELY heavy, even in nonrotating parts. You'll do much better other ways.

There are also issues of safety. What happens in a collision? High kinetic energy rotating parts can be EXTREMELY dangerous. As an example, here's a nasty story about a jet turbine blade: http://www.iasa-intl.com/folders/belfast/AA763EngineFire-3.htm .
 

Wicked_Sludge

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i understand conservation of energy and again, i dont understand what it has to do with anything. obviously you cant create energy with a flywheel...just like you cant create energy with a battery pack in an electric car. a gyro is simply a mechanical energy storage device.

the advantage of "charging" a gyro vs charging a bank of batteries is that a gyro can be spun up in much less time (you can only force energy into a battery so quickly before it boils), and there is much less energy lost through heat than there is when fast charging a battery.

looking back to the gryo buses...it took a maximum of 3 minutes charge time to travel almost 4 miles at almost 40 miles an hour. thats a ratio of .45:1 charging to distance traveled. so to travel my original 50 miles, it would only take 37 minutes. and thats using 1950's technology. i can only imagine something modern would have even higher efficiency.

i understand what you mean by precession now. even ive played with one of those bike wheels with the pegs on either side. i suppose if there was no way to get around it, you could mount the flywheel inside a gimble, along with its coils/magnets.

releasing all that kinetic energy all at once (be it a vehicular accident, or failure of the disks themselves), would have to be worked on. any containment vessel would have to be light weight, and very strong to keep shrapnel from spraying all directions. i wonder: would hundreds of smaller...say CD sized...flywheels be safer, easier to contain, and provide the same amount of energy storage?
 

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all this smart people talk is making my head hurt
 

Southern3.0

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Basically, conservation of energy means you have to put ALL the energy you need to drive 50 miles into the gyroscope, even if it had no losses. If you did this with an electric motor, why not just drive the car 50 miles with it?

Precession is how gyroscopes behave when you tweak them just a little. They do not stay pointed in one direction, nor do they move in the direction tweaked. Instead, they move at right angles. This makes the axis wobble circularly. Try it with a child's top. This bears some repetition. It means that if you try to turn right, the gyroscope will try to flip you over nose over nuts.

You don't solve the constant-axis problem with two counterrotating gyroscopes. Each of the gyroscopes individually sees those forces. So, you rip them apart. This means your device is going to be EXTREMELY heavy, even in nonrotating parts. You'll do much better other ways.

There are also issues of safety. What happens in a collision? High kinetic energy rotating parts can be EXTREMELY dangerous. As an example, here's a nasty story about a jet turbine blade: http://www.iasa-intl.com/folders/belfast/AA763EngineFire-3.htm .
Same reson you have to have an SFI approve bellhousing in drag racing, Ive seen pics of clutches that shattered and cut through frame rails, nasty...

Even tho it dosnt seem veary practical its still a pretty cool consept, it would be fun to tinker around with. And now that I think about it I used to have toy cars that had a flyweel in them, you would push them fast and they would just keep going..
 

MAKG

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releasing all that kinetic energy all at once (be it a vehicular accident, or failure of the disks themselves), would have to be worked on. any containment vessel would have to be light weight, and very strong to keep shrapnel from spraying all directions. i wonder: would hundreds of smaller...say CD sized...flywheels be safer, easier to contain, and provide the same amount of energy storage?
This makes it FAR less efficient. Kinetic energy of a rotating disk rises proportionally to mass, and proportionally to the SQUARE of the radius. That means, to get the same energy with more disks, you need to dramatically increase the weight of the device. Efficiency suggests a single large radius disk, heavy enough to withstand the shearing forces (which will be nasty).

It's not that these things are impossible. It's that they are impractical. You won't be able to do what you want without making a car that outweighs an Abrams tank. And if the goal is fuel mileage, that's failure.
 

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i still think if a bus carrying 60 passengers could travel 4 miles on nothing but a giant flywheel with 50's technology...that you could make a 2,000lb (base weight before the flywheel) car go further. is it impractical? maybe. but americans drive many an impractical vehicle. H2 anyone?

but if my math is correct on my first post...the flywheel need only weight 400lbs. thats about the weight of the motor and transmission you will be removing. granted it will be slightly heavier after adding a few hundred pounds of electric motors/ wiring/ scatter sheild, ect. but that doesnt seem all that far fetched to me. the biggest problem i see so far is countering the gyroscopic forces. i think mounting the device on a gimble could work, but then you need a 5ft dia. area for the thing to turn in, plus space for a scatter sheild.
 

MAKG

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I think you're dramatically underestimating the material you're going to need for this.

Take a look at that 767 failure I posted. That was a turbine blade, which isn't really all that different from what you are proposing (except it's a bit smaller). Parts of it were thrown more than 1/2 mile. The part embedded in the engine blew apart the first engine, blasted all the way through the airframe, wings and the other engine. What set this off? A stuck valve oil-starved a bearing, and the bearing seized and failed. Not too hard a failure to imagine in your application. A small shield like a skid plate isn't going to do a dang thing. You might as well make it out of paper.

And mounting it in a gymbal means you have to make THREE frames, each one capable of taking the full force of the gyroscope around a turn.

Gyroscopes also work quite nicely on aircraft and in orbit, but take very unkindly to being jarred by potholes, let alone collisions.

Making this thing anything less than a nasty deathtrap is going to require orders of magnitude more weight than you are estimating.
 

Wicked_Sludge

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mmm, touche...so lets just say we make it unsafe :tease:
 

Will

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I don't think any shield will protect you.

I'm not a math whiz or anything. But say you need to store 50hp-hours in this flywheel--that would mean 25hp for 2 hours or 12.5hp for 4 hours, for example. So 50hp is 67kw.

Doing some conversions it appears to me that your 50hp/hr flywheel is packing the energy of 100# of tnt. A 155mm artillery shell packs only 15# of TNT. So you are riding around with a kinetic force, not a potential one, equal to 6.7 artillery shells. If that flywheel comes apart--bodies for blocks. I think it would be easy for it not to come apart--that's not the accident I had in mind. I had just the flywheel coming free or a person getting tangled in it. If anything happens, there is no way to suddenly turn it off. If you could gimbal it you could not get any energy out of it. The moment you apply a force it isn't gimballed anymore.

That flywheel is absolutely thrumming with energy. My Lister diesel has 2 24" open flywheels--probably 50# each. It only spins 600rpm--has nowhere near the energy required for what you are thinking. It's damn scary to run it. If you got tangled with it it would ball you up like a bad fishing cast even after the fuel was cut and never even blink.

I've no doubt a bus or anything could go a few miles. No question. But it doesn't mean anything. A bus is massive and much more forgiving. It traveled only minutes and how fast? It might have needed only a couple of horsepower hours. The energy stored in the wheel would not have been anything close to the amount needed to be stored for a 40 mile commute in a commercially competitive auto.

But there's no reason not to build a scale model and use a small flywheel to test out the practicality.
 


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