UK Karting - Notice Board (4-Stroke Karting) : Re: didn't take long...

Notice Board (4-Stroke Karting)

Re: didn't take long...
Posted by 'itpro' on 23 May 2013 @ 01:12

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itproJoined: August 2001
Total Posts: 6
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Brian..... you understand that the flywheel is there to give inertia (momentum). Without that inertia, at low revs, the engine would not be able to continue its rotation to pass to the next 'tdc' moment. You also understand that, with a clutched motor or one on which you can select 'neutral', i.e., where the mass of the whole kart/car/bike can be disconnected from the engine, the flywheel is imporatnt or else, when 'de-clutched' or in neutral , the engine would stall through lack of inertia to keep it running.

However..... in the simplest of karts (the 100 direct drive) the 'flywheel' can be partially replaced with the forward mass of the kart 'takes the place of' the heavy flywheel in that, the mass of the kart is sufficient to keep the engine rotating even with a very small flywheel.

The Norton, DID have a neutral AND a clutch.... hence the effect of the flywheel was needed.

Again, in an engine that's designed to be smooth and comfortable (i.e., a road bike) a heavy flywheel is attractive. On a RACE bike, the smoothness and comfort is not SO important.

On a bike, with gears, the 'slowing' effects of the flywheel are greater in low gears than in high gears as the rate of acceleration (change) of the engine is faster in 1st than in 6th; thus the flywheel-effect that would be minimal in 6th, could be substantial in 1st.

With the Aixro, we are NOT talking about an engine that has a huge flywheel in the first place as the Rotor itself is quite a massive object in comparison to a crankshaft. The Rotor takes a lot of the 'duty' of a flywheel.

Secondly, we don't care about the smoothness in a race engine (so much) and thus the flywheel on an Aixro would be smaller than on a road going bike, anyway. The Aixro began it's life as a race engine, not a road engine.

Thirdly, the Aixro doesn't have gears, thus the rate of change of revs is slower than on the Norton in 1st gear.

Fourthly, Aixro racers don't care THAT much about smoothness from an already SPECTACULARLY smooth engine, anyway. A Wankel runs more smoothly than an Otto cycle engine by design (I know the Norton was a Wankel, too).

Finally, for 99% of the time, the Aixro will be running with 'clutch engaged' and thus the mass of the kart/driver will cover many of the duties of the Flywheel, anyway. All this will have been taken into account in the design of the Aixro and the flywheel will be small in comparison to a road going engine.

***********

The proper test would be to calculate the 'energy' needed to accelerate a flywheel from rev band X to Y in Z seconds and then to calculate the the quantity of energy needed to accelerate the engine from X to Y in Z seconds for the whole mass of the kart. We'll know how important the flywheel is to acceleration by comparing the energy consumed for each test.

I would contend that, for a fixed gear, no clutch, Race bred Wankel that the amount you could remove from the flywheel (and thus improve the performance) would be MINUSCULE. The figures will tell us! I don't have that level of engineering/mathematical skills to calculate those figures. I bet someone here does!

Ian

Message Thread:

didn't take long... by 'BrianP' (22 May 2013 @ 9:53)

Re: didn't take long... by 'itpro' (22 May 2013 @ 10:46)

Re: didn't take long... by 'kai' (22 May 2013 @ 11:45)

Re: didn't take long... by 'BrianP' (22 May 2013 @ 13:29)

Re: didn't take long... by 'itpro' << You are here!

Re: didn't take long... by 'BrianP' (23 May 2013 @ 7:39)

Re: didn't take long... by 'itpro' (23 May 2013 @ 11:17)

Re: didn't take long... P.S. by 'itpro' (23 May 2013 @ 11:18)

Re: didn't take long... P.S. by 'PaulMRotax' (23 May 2013 @ 12:35)

Re: didn't take long... by 'BrianP' (23 May 2013 @ 20:52)

Re: didn't take long... by 'itpro' (23 May 2013 @ 22:31)

Re: didn't take long... by 'BrianP' (24 May 2013 @ 10:06)

Re: didn't take long... by 'itpro' (24 May 2013 @ 12:34)

Re: didn't take long... by 'BrianP' (24 May 2013 @ 12:47)

Re: didn't take long... by 'd-i-y71' (24 May 2013 @ 13:09)

Re: didn't take long... by 'itpro' (24 May 2013 @ 16:55)

Re: didn't take long... by 'PaulMRotax' (24 May 2013 @ 17:46)

Re: didn't take long... by 'd-i-y71' (24 May 2013 @ 18:03)

Re: didn't take long... by 'd-i-y71' (24 May 2013 @ 17:54)

Re: didn't take long... by 'PaulMRotax' (25 May 2013 @ 13:53)

Re: didn't take long... by 'itpro' (24 May 2013 @ 16:44)

Re: didn't take long... by 'BrianP' (24 May 2013 @ 17:35)

Re: didn't take long... by 'hetherip' (24 May 2013 @ 20:37)

Re: didn't take long... by 'itpro' (25 May 2013 @ 0:28)

Re: didn't take long... by 'BrianP' (25 May 2013 @ 9:29)

Re: didn't take long... by 'itpro' (25 May 2013 @ 23:14)

Re: didn't take long... by 'BrianP' (26 May 2013 @ 7:01)

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