WhiteBlue wrote:
It looks like you have lost me somewhere along the way. The continuous 100kW model that I calculated is equivalent to intermittent breaking with 333kW.
I agree that the mass based on the available data is not acceptable but the data will be 5 years old by the time the systems are supposed to be used. It is very conceivable that the weight will have been reduced by that time to 50%. If not they simply will have to build a smaller 2MJ system or use a different kind of energy storage if that is better suited.
Maybe you have lost a little bit sight of the facts we have agreed on WB.
IIRC we have agreed that a F1 car brakes for ~12 sec per 75 sec lap (you later mentioned 80 sec laps, but this does not matter).
You devised a system to harvest 100kW/s or 100KJ over a period (braking) of 12 sec, this makes 1200 kW/s or 1,2 MJ our/your aim was 4 MJ IIRC. No?
If you use your stored energy and release it over the rest of an (let`s stick with 75 sec) lap.
This means you have 63 sec time, and could spend ~19kW extra.
(19kW x 63 s = 1197 kW/s)
So for a power advantage of ~20kW you are carrying ~150 kg extra.
Sure you can perhaps use you energy as a "boost button" activating 120-160kW extra to make a strategic move (overtake), but you did not wanted to use KERS this way.
You wanted proper dual torque mode.
If you still wonder, where it got wrong with your calc, I think this is the answer:
WhiteBlue wrote:
We plan to send 2x4MJ of energy through the cells in a period of 80s which is equivalent to 4MJ in 40s. Lets keep that in mind
We need to charge and discharge 4 MJ in 80s. That means 8 MJ in 80 s. That is the same as charging 4 MJ only in 40s, or charging 1MJ in 10 s. Our effective power for the charge is 100 kJ/s or 100 kW. 100 kW is the same as 100 kVA
How much simpler you need it?
You have 100kW/s charge rate and 12s per lap where you brake --> 1200kW/s = 1,2 MJ
unless you want to brake for 40s per lap, in which case my non KERS 450kW car with 490kg weight will beat you even more easy.
BTW, I thought they where talking about an 120kW KERS, as far as the max power goes.
That´s something we just have created here, but, unless you will brake for much longer, you wont be able to harvest and store your 4 MJ during 12 sec braking per lap.
If you want to harvest 4MJ during 12 sec you will need 333kW/s and for this you would need ~3.3 times the battery capacity (~440kg just for batteries).
On another note:
If we look at the Brembo data we can see, that we have ~1000kW/s which we could harvest during braking. Now if we consider your proposed brake balance of 60/40 front/rear, we would be able to harvest 400kW/s only at the rear axle.
So there is not really the need for AWKERS.
Sure you will loose the traction advantage, but you save yourself a lot of hassle.
Maybe a hydraulic/pneumatic KERS is not that bad after all.
Merry Christmas WB