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Old 02-08-2012, 12:53 PM   #11 (permalink)
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On the plus side, if he just has to run into the corner store for a moment, he can hop off his bike and leave it standing on the sidewalk

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Old 02-08-2012, 02:33 PM   #12 (permalink)
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If he just has to run into the corner store for a moment, he can "charge" it at home
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e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

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Old 02-02-2013, 05:01 PM   #13 (permalink)
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Quote:
Originally Posted by Old Tele man View Post
...shades of the WWI Gnome engines! -- "snap" turn one direction but NOT the other (ha,ha).
Thought I would revive this thread.

In the bike the flywheel is rotating on the same axis as the frame. In the plane the axis was 90 degrees to the frame. It was the torque of the 350 pound rotating engine that allowed the plane to turn so quickly in one drection versus the opposite direction. The Fokker Dr1 could do a Flat turn, basically spinning on the axis of the engine with the rudder alone.

Spin a flywheel on a dinner plate, you can move it around easily while it is spinning vertically on the plate. You can even lift the plate rapidly until the flywheel is airborne and let it land on the plate, still spinning.

The flywheel resists changes in its plane of rotation more than any other.

That is why if horzontal or vertical It would resist leaning in either direction and allow the bike to stand vertically.

The rotary fighters of WW1 were wicked to fly. With engines weighing almost a third of the total weight of the plane and gobs of torque, they were inherently unstable and killed more pilots in training than combat. They would do 6 g turns and make pilots black out if they were not careful. Not bad for fabric, wood, and wires.

A horizontal spinning flywheel in a vehicle would also tend to make the vehicle stay level when encountering bumps or things like railroad tracks.

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Old 02-02-2013, 08:18 PM   #14 (permalink)
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One very big problem with the bike is it looks like there is NO freewheel between the wheel and flywheel. That means the flywheel STOPS when the bike stops. And it makes it VERY hard to accellerate unless you have already slowed down. You have to time the traffic lights and can not stop at stop signs.
Notice in the second video he cut out the start from a stop.

There needs to be a way to allow the flywheel to float at zero RPM until the first slowdown and to coast at high RPM at a stop. I also think it needs to be isolated from interference inside the wheel, though that will disrupt dynamics a lot versus the center of mass like his design.
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Old 07-17-2013, 06:04 PM   #15 (permalink)
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To counteract some of the gyroscopic effects have 2 rotors spin up but in opposite directions. To make the CVT infinitely variable so it can be used from a stop insert a planetary gear set or power split device if you will. Look up IVT transmissions.
I was thinking of rigging up something like this in the trunk of my 2010 Prius working on the back wheels. The idea would be it would absorb the excess regen that the battery can't take and would supplement the acceleration when speeding up. This would allow those heavier on the brakes to capture more of the kinetric energy and the round trip efficiency would likely exceed the HV battery roundtrip efficiency. I'm also thinking about compressing nitrogen with a hydraulic gen/motor set up like Citroen in France are doing. For now it's just an idea.
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Old 07-18-2013, 12:55 AM   #16 (permalink)
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It may be better, if more expensive, to connect the flywheel to a motor/generator and feed the energy in and out electrically, even at the size of storage required in an HPV.

That is how the Williams (F1 initially but now commercialized) and Porsche (which I think is using Williams' technology) work. The flywheel can then be sealed in a vacuum with magnetic bearings, the losses reduced and the flywheel run at higher speed.

I did find on the web (somewhere) reference to a university project where they had built prototypes that were about the size of a large coffee can. It didn't look to be too far beyond DIY either.

There was a Chrysler Sports Car Prototype (Le Mans) a decade or two ago that ran flywheel storage (with an LNG fuelled gas turbine). (It never raced.) That might be worth investigating to see how the gyroscopic effects were handled. The Chrysler Patriot - I think Reynard were involved on the engineering side.

Actually, given the power requirements in an HPV, chemical cell batteries are probably lighter and easier.

Last edited by Occasionally6; 07-18-2013 at 01:01 AM..
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Old 07-18-2013, 03:14 PM   #17 (permalink)
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Color me dubious.

We all know, or should know, that it takes energy to propel a vehicle - any vehicle. So all energy stored in the flywheel is a product of the rider since there is no other source. If the rider doesn't initiate the pedaling, there's no energy stored. Even the downhill runs are ultimately a product of the rider - you have to expel 'human' energy to reach the top of the hill. Or if you expect to utilize the flywheel to assist uphill jaunts, then you MUST first input that energy into the flywheel BEFORE it can be extracted. There's no free lunch.

But more importantly, you need to consider the ADDITIONAL losses associated with the increased rolling resistance, and the added frictional losses in the rotating hardware - and lets not forget, the NuVinci CVP hub he's using is not very efficient (about 70% IIRC) and adds an additional 5.4 lbs to the total mass - in addition to the 15 lb flywheel. There's no shortage of 'flywheel' assisted bicycle patents.

We have spent decades pursuing efficient HPV's. The only way to improve upon it, is to lose weight, improve aerodynamics and make the gearing & tires more efficient. Bolting-on an additional 25lbs of mass & increased friction is not only counter productive, but an enormous waste of what precious little wattage the typical human is capable of.
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Old 07-19-2013, 04:12 PM   #18 (permalink)
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Kenny, nobody said the energy from the flywheel was free. Its sole purpose is to store braking energy which would normally be wasted as heat.

Yes, adding all of that complexity would only hinder long distance biking, but may be worth its extra weight when catching and releasing energy in stop and go city traffic.

It's exactly the same as in hybrid cars: Motor/generators, batteries, fancy electronics do pay off in traffic, but not in steady highway driving.
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e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

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Piwoslaw's Peugeot 307sw modding thread

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Old 07-19-2013, 08:20 PM   #19 (permalink)
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Quote:
Originally Posted by Piwoslaw View Post
It's exactly the same as in hybrid cars: Motor/generators, batteries, fancy electronics do pay off in traffic, ...
I disagree - your motors & batteries are a secondary, independent source. The bike rider has no secondary source,.. only his/her legs. So where do think the energy comes from to resupply the energy used from the flywheel for multiple stops?

Quote:
Originally Posted by Piwoslaw View Post
Yes, adding all of that complexity would only hinder long distance biking, but may be worth its extra weight when catching and releasing energy in stop and go city traffic.
Prudent cyclists time 'lights' to minimize stopping - I do it daily... and have been for 50+ years.
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Old 07-20-2013, 12:07 AM   #20 (permalink)
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I agree; you really try to avoid braking on a bike so the opportunities for energy capture are limited.

You might presumably use the flywheel as a power booster for acceleration after waiting at a light but, other than as a way of bypassing a power limit on electric motors for bicycles, I think electrical assistance with an externally charged battery will be superior.

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