/tech/ - Technology

I remember reading children's books published in the 70's and 80's about cars and a lot of them touched on flywheels. I had to ask my dad about them because I never saw them mentioned anywhere but these old books.
They're probably not in cars because gas is relatively cheap. That's probably why I only saw them mentioned in 70's era books, during the energy crisis.
I do see them talked about more recently so it looks like interest in flywheels is increasing.

>>10754
They were a thing in Formula1 car racing, very briefly.
There also were buses that were powered by that, those were called Gyrobus.

Flywheels are limited in capacity to hold energy by material limitations. There are still people researching to improve fly-wheels although those are more like magnetically levitating rings now. The ultimate fly wheel is a stream of magnetic particles in a giant linear accelerator that loops back onto if self.

Today super capacitors have enough power to service many applications that used to be flywheel territory. If you could have a bicycle with a fly wheel power-storage (or capacitor bank) that would allow you to go up and down hills while you only have to push the peddles hard enough for the average power consumption, that would be awesome. (I'm assuming that's what your picture shows)

>>10756
>(I'm assuming that's what your picture shows)
It's a kinetic energy recovery system, not some kind of motor. When you hit the breaks it recovers some of your momentum and stores its energy in the spinning flywheel. Then when you want to start moving again you can release this energy (which you already created previously by pedaling) back into the wheels. You can't get out more than you've already put in, and significantly less due to energy lost from friction.

>>10757
>It's a kinetic energy recovery system
I know, and if you think along these lines a little further, you can go towards making it a buffer system that smooths out the load variation as you drive up and down hills. And in the ideal case you would peddle with constant intensity supplying the average amount of energy needed through the entire track, and your would not feel the ups and down anymore.

Magnetic bearings and vacuum housings for flywheels have allowed them to become so efficient now that they are actually competitive with large battery and capacitor banks. There's a big flywheel facility at a power station near New York that handles load balancing.

>>10759
>Magnetic bearings and vacuum housings for flywheels have allowed them to become so efficient now
Do you really need a vacuum chambered fly wheel for something like OPs bike ?

>>10757
>It's a kinetic energy recovery system,
I think you need an electric transmission, that uses a motor/generator for decent efficiency, because a mechanical transmission only gets about 15% of the original energy back, unless of course you can change gearing ratios.

>>10766
This guy says ~15% was about the energy efficiency he got using batteries as well.

>>10776
true he did indeed say that, but wouldn't you want more efficiency if you could get it ? electrically coupled fly wheels get way higher efficiency, and if you are willing to compromise on torque just a little bit you can get an electric link for the same cost as a mechanical one.

>>10755
>They're probably not in cars because gas is relatively cheap.
Speak for yourself burger king. In other parts of the world fuel can be very expensive, e.g. Japan. That's why Japanese cars, even super cars like NSX and GTR, have relatively small engines. Nips do everything they can to squeeze as much performance as they can while saving fuel. They even experimented with completely different engine designs like the rotary engines used in Mazdas. So lack of motivation is not the reason.

>>10780
So, why didn't Japanese car makers include flywheels ?

>>10781
>So, why didn't Japanese car makers include flywheels?
Because they cost more than they save?
>[_] Miracle technology everybody is too dumb to use
>[X] You don't have all the facts and there is a catch somewhere

>>10782
hey i was just asking a honest question

>Because they cost more than they save?
No that can't be it, there were short range buses that were powered by flywheels, which essentially used them like batteries. For a car to recover breaking energy you'd need a tiny fraction of the capacity.

there has to be something else that prevents their use that is not so obvious. Like maybe gyroscopic properties that made the car handling weird or something.

>>10783
>there were short range buses that were powered by flywheels
Ok. There are also cars that run on wood. Just because it's possible doesn't mean it's a good idea.

It's worth noting that many electric cars and hybrids have regenerative braking. You just reverse the motors and turn them into generators while braking. Then you get a nice boost of energy when you accelerate after the corner. The Porsche 918 was famous for being one of the first road cars to do that. The mechanical flywheel thing doesn't seem that useful though.

There's a bit of history about Formula 1 trying to use flywheels here
https://en.wikipedia.org/wiki/Regenerative_brake#Use_in_motor_sport
My interpretation is they are only really useful for countering turbo lag in racing and even then it was not really worth the extra weight and complexity.

And like I say, if there was any fuel efficiency gains to be had then Japan at least has more than enough ingenuity and motivation to make it work.

>hey i was just asking a honest question
*baka**

>>10784
>It's worth noting that many electric cars and hybrids have regenerative braking. You just reverse the motors and turn them into generators while braking. Then you get a nice boost of energy.
Batteries can't handle enough current, they can only capture between 10% and 25% of braking energy. Electric super capacitors should be able to capture enough energy for stop and go regenerative braking. However Flywheels can handle truly enormous power spikes at high efficiency in a very compact size, this tech will probably make a comeback.

>>10783
>Like maybe gyroscopic properties that made the car handling weird or something.
That actually is a problem and why flywheels are more common on vehicles that don't turn a lot. You need a flywheel mounted in gimbals to be able to overcome its inertia and make large directional changes when storing really large amounts of energy.