Does a Light Weight Flywheel give you more power?

[TRex]

Nik forget the Maths son... it\'s proven Torque will be reduced.. not on paper with a pen but on actually engine dyno\'s and testing!
 Besides it\'s common sense anyway!

[nikp]

Torque is not reduced! Explain how torque will be reduced please - i\'d love to know! If i put a brick on top of the engine too, will that reduce torque as well?

[nikp]

Also, have a read of this article. This is the second time i will have posted up an article by this guy. He explains this very clearly, and very sensibly. At no time does he mention that torque is the overiding control involved in lightened flywheels: it\'s mass (or rotation mass to be precise)

http://www.pumaracing.co.uk/flywheel.htm

[Jit]

Ant ...im  not sur tbh as my engine was such a bodge that it really could be a TII flywheel and cw in there...

[onelastpost]

WTF? :wiggle :Hammer

[nikp]

WTF? :wiggle :Hammer

Wrong thread! :p

[onelastpost]

Wrong thread! :p

oops!!:guinness

[TRex]

Nik I think you lost me with that babble in that link..  As far as I could see there, as I had a scroll through that link and could find nothing about \'Torque\'!
 Unless you could prove otherwise!
 
 Not going in to too many details as I could go on for ages to prove it or even have a brief surf on the net here to show you more information!

 For now I will use your \'maths equation\'.. (which is not fully correct either)
 It\'s like this actually...  
Torque = Force x Radius   (force in this instance will be \'weight\')(flywheel weight)

 Actually I won\'t use science as yet to confuse, I\'ll keep it simple for everyone to understand without the silly maths calculations, as it\'s common sense to see if you understand how \'Torque\' is produced, you will see by reducing any one of \'Force or Radius\', Torque will be reduced!!!!!!!!

 (First you must understand how Torque is achieved..)

  I attached a small illustration of a common use of Torque.. Looking at the picture, if you move the position(reduce) the Force line, naturally less \'torque\' will be had!
 Again if you missed it, less/reduced force(weight), less \'Torque\'...

[nikp]

Right, ok. This could get complicated - and your mention of you getting confused may not help. As you may get lost. Rotational physics does take some explaining, and can be difficult to understand. As you\'re finding it. It\'s fascinating stuff.

As far as I could see there, as I had a scroll through that link and could find nothing about \'Torque\'!

That\'s what i said - there is no mention of torque. Torque is not effected by reduction in weight of a flywheel. It\'s all about the reduction inthe moment of enertia which allows something to be accelerated quicker. You really need to understand what is written in that link to be able to understand what reducing the weight of a flywheel does. I\'m afraid it is all about the mathematcis involved. The problem is, i understand it. You have to understand what he is writing about, to fully appreciate the physics involved in lightened flywheels.

Reducing the weight of a flywheel reduces the moment of inertia. That is the important thing here. Moment of inertia is reduced. That is why you reduce the mass from the outside edges of the flywheel if at all possible (Or at least, as from from the centre as possible). Moment of inertia is the sum of the mass times the radius of that mass squared (mr^2).

Yes, Torque is force times radius. However, my point was torque is the rotational equivalent of force = mass times acceleration. In rotational terms, force is torque. Mass is the moment of inertia, and acceleration is rotational acceleration. Reducing the moment of inertia has no play on the torque, it increases the rotational acceleration.

Yes, your picture is correct. However, you seem to misunderstand what is generating what!

Hmmmm.....this is difficult for me to put in simple terms. Ok, how about a theoretical ones here. If we have an engine developing 1000Nm of torque, and stick a really really large flywheel on it, so that that engine can only just begin to turn that flywheel, how much torque does that engine have? 1000Nm still. It\'s just having a lot more difficulty in turning that engine.

[TRex]

Ahhh correct... (your last statement)

 The \'Motor/engine\' will still be knocking out 1000Nm of Torque, \'But\' the transfer of the Torque or energy to the flywheel and then out will be greatly reduced....  
 
 A good example is Steam engines and electric motors which tend to produce maximum torque close to zero rpm, with the torque diminishing as rotational speed rises....  (but this is another example story..lol)

 One more example is a Classic DC wound Motor.  By varying the field current(\'FORCE/WEIGHT\'), it is possible to alter the speed/torque ratio of the motor...  :Thumbs-up

[nikp]

The \'Motor/engine\' will still be knocking out 1000Nm of Torque, \'But\' the transfer of the Torque or energy to the flywheel and then out will be greatly reduced....

Ah....I see where you\'re going wrong. Yes, i can see how you\'re coming up with this conclusion. It would appear like that, wouldn\'t it?

In fact, the engine is still producing the exact same torque. Nothing has changed. however, if we then add another flywheel to the same output shaft, is the torque reduced? No. It\'s just that the engines ability to accelerate the combined flywheels has been reduced - the two will accelerate even more slowly.

Lets put this in forward motion terms, instead of rotational terms - it\'s easier to understand. We have a car. It weighs X kg. It can accerlate by Y m/s/s. If we double X (Similar to doubling the weight of the flywheel, but not quite - it\'s due to that pesky moment of inertia thing again!) Y will be halved (We shall be ignoring frictional forces of course). This has had no effect of the torque (or power which is directly linked to torque). The force pushing the car forward is unchanged. It just has more mass to accelerate, and therefore cannot do it as quickly.

[TRex]

Yes it will have more \'force\' pushing the car not \'torque\'.. it\'s different..

 Have a think about the \'Electric motor\' example...  

 Nik don\'t dissappear on this mate, I\'ve got to run off and pay some bills(work..lol)

[onelastpost]

A heavier flywheel will reduce the effect of the torque.

I think this statement says it all - for me anyway!!

I reckon you guys are both saying exactly the same thing!

[nikp]

Pah! Work, it\'s overated!

In my example i gave, it is essentially the same one as the flywheel issue, but in a forward motion sense as opposed to a rotational sense.

Force will not change in my example, and nor will torque in an engine. It\'s the acceleration that will.

In the elctric motor example, if you had an ordinary run of the mill electric motor, and attached a large automotive flywheel to it, yes it won\'t turn. However, this is not because the motor is not generating any torque. It is still generating torque. It just cannot generate enough torque to turn the wheel. Now, before you jump on and say \'Aha! See, no torque on output\'. I would say two things. Firstly, where has that torque gone? When you lose torque from flywheel to wheels, it is lost through noise and heat energy, which includes friction. There very, very little of it there. In theory, the motor will be able to accelerate the flywheel round, but we all know that it won\'t be able to.

I strongly advise you to read that article, that details exactly how lightened flywheels work. Study the article, and understand it. It\'s very important.

[nikp]

I think this statement says it all - for me anyway!!

I reckon you guys are both saying exactly the same thing!

No. Perhaps i should clarify: it will reduce the perceived torque. No change will occur. It will appear that torque has been reduced, but in fact it will remain constant (at any given rpm of course)