- Login or Register
No account yet? Sign up
That's quite interesting. If I correctly understand what you're saying, they are adding said fuel to prevent the wheels from locking? If that's the case, wouldn't it be easier/more efficient to decrease the load on the MGU-K by some sort of PWM control signal? Don't know for sure if electronics would allow it or if it would be better, just asking.gruntguru wrote:Fuel would only be added (wasted) when the power available from braking the rear wheels is less than the power required to "motor" the crankshaft + 120 kW (max MGUK harvest).
I completely agree with the last two reasons for not doing this, this is what I was also thinking. Another thing about the first sentence of your post, isnt it always the case that when a F1 car brakes (so full pedal braking, not lift and coast) it almost always generates 120kW at the rear brakes/axle? Such that this situation almost never occures?gruntguru wrote:Fuel would only be added (wasted) when the power available from braking the rear wheels is less than the power required to "motor" the crankshaft + 120 kW (max MGUK harvest). Even then, fuel would only be added during braking if the full 120 kW available from MGUK to the ES was deemed "high priority" and the race fuel allowance was "low priority".
Using fuel in this way (purely to charge the battery) is much less efficient than fuel used at max power:
1. The thermal efficiency at circa 120 kW crankshaft will be much lower.
2. Inefficiencies in the "GUK harvest - ES charging - ES discharging - MUK drive to wheels" cycle will further reduce the fuel energy -> wheel energy conversion efficiency.
It does matter during the race if the 100 kg race limit is in play and the strategists need to decide in which modes to reduce fuel. They would obviously reduce fuel in the modes that will have least effect on lap time.Cold Fussion wrote:Surely the efficiency in this case would be measured against the potentially extra mgu-k harvesting vs the weight of having to carry the excess fuel. Whether or not the engine is only operating at 25% TE instead of 40% in this mode doesn't really matter, it will just swing the balance one way or the other.
No - not to prevent locking - to increase harvesting.alexx_88 wrote:That's quite interesting. If I correctly understand what you're saying, they are adding said fuel to prevent the wheels from locking? If that's the case, wouldn't it be easier/more efficient to decrease the load on the MGU-K by some sort of PWM control signal? Don't know for sure if electronics would allow it or if it would be better, just asking.gruntguru wrote:Fuel would only be added (wasted) when the power available from braking the rear wheels is less than the power required to "motor" the crankshaft + 120 kW (max MGUK harvest).
Yes so adding fuel purely to drive the GUK would be rare - especially during the race. More likely during qualy.bergie88 wrote:I completely agree with the last two reasons for not doing this, this is what I was also thinking. Another thing about the first sentence of your post, isnt it always the case that when a F1 car brakes (so full pedal braking, not lift and coast) it almost always generates 120kW at the rear brakes/axle? Such that this situation almost never occures?gruntguru wrote:Fuel would only be added (wasted) when the power available from braking the rear wheels is less than the power required to "motor" the crankshaft + 120 kW (max MGUK harvest). Even then, fuel would only be added during braking if the full 120 kW available from MGUK to the ES was deemed "high priority" and the race fuel allowance was "low priority".
Using fuel in this way (purely to charge the battery) is much less efficient than fuel used at max power:
1. The thermal efficiency at circa 120 kW crankshaft will be much lower.
2. Inefficiencies in the "GUK harvest - ES charging - ES discharging - MUK drive to wheels" cycle will further reduce the fuel energy -> wheel energy conversion efficiency.
it occurs for many seconds/lapbergie88 wrote: ......isnt it always the case that when a F1 car brakes (so full pedal braking, not lift and coast) it almost always generates 120kW at the rear brakes/axle? Such that this situation almost never occures?
Yes. Wuzak just made a great post in the "Honda Power Unit" threat where he uses data from Brembo to show that at Monza only around 700kJ, so 0.7MJ, is recovered during braking by the MGU-K. Do you think it is beneficial in this case to burn extra fuel (at a lower TE as gruntguru indicated), regenerate it by the MGU-K, store it in the battery and than use it again by the MGU-K to fill this up to 2MJ?Tommy Cookers wrote:it occurs for many seconds/lapbergie88 wrote: ......isnt it always the case that when a F1 car brakes (so full pedal braking, not lift and coast) it almost always generates 120kW at the rear brakes/axle? Such that this situation almost never occures?
either where trail-braking is attractive already or making trail-braking more valuable and so attractive
there seems to be a lot of engine noise on the overrun (it's hard to believe they are zero-fuelled)
or are we saying that people are not using their 2MJ or 4 MJ lap entitlements ?
Interesting point. Perhaps there are times when the most efficient strategy to conserve ES charge is to use intermittent cylinder fuelling with late ignition and produce highly energetic blowdown pulses to keep the turbine spooled?Tommy Cookers wrote:there seems to be a lot of engine noise on the overrun (it's hard to believe they are zero-fuelled)
Such that all the energy in the ES can be used to propel the car with the MGU-K instead of powering the compressor with the MGU-H? Could be yes.gruntguru wrote:Interesting point. Perhaps there are times when the most efficient strategy to conserve ES charge is to use intermittent cylinder fuelling with late ignition and produce highly energetic blowdown pulses to keep the turbine spooled?Tommy Cookers wrote:there seems to be a lot of engine noise on the overrun (it's hard to believe they are zero-fuelled)
Well yes - not at the same moment but keeping the max energy in the ES for when the car does need propulsion.bergie88 wrote:Such that all the energy in the ES can be used to propel the car with the MGU-K instead of powering the compressor with the MGU-H? Could be yes.gruntguru wrote:Interesting point. Perhaps there are times when the most efficient strategy to conserve ES charge is to use intermittent cylinder fuelling with late ignition and produce highly energetic blowdown pulses to keep the turbine spooled?Tommy Cookers wrote:there seems to be a lot of engine noise on the overrun (it's hard to believe they are zero-fuelled)
When the Formula 1 engine "overweight" is
Sebastian Vettel's former motor engineer explains what he means: this residual energy we get through the so-called 'overloading' of the engine. What is that? We use fuel to generate electricity. And how are you? When accelerating you do not need all of the engine power. You have too much torque with these engines. The driver drives in the initial stage of acceleration only half or three-quarter throttle. This gives us a leeway for energy production. Instead now according to inject less fuel, to restrict the torque, we burn more fuel. The excess power produced there is not invested in additional propulsion. This extra torque that we do not use for driving, is used to make the MGU-K run as a generator. With this power, the battery is charged. "
The same is done at the end of the straight line in the phases in which the driver takes his foot off the accelerator, but is not yet on the brake. Taffin clarified: "But it is more efficient to tap the energy in the partial load range." The new rules allow. "We can with the new motors save energy, whenever we want. The driver does not necessarily have it stand on the brakes, as was the case with the old Kers. The only limitations relate to the amount of energy that can may store and retrieve. "
This is a form of traction control, nothing more nothing less. Off course without the feedback control loop which makes it possibly illegal.When the Formula 1 engine "overweight" is
Sebastian Vettel's former motor engineer explains what he means: this residual energy we get through the so-called 'overloading' of the engine. What is that? We use fuel to generate electricity. And how are you? When accelerating you do not need all of the engine power. You have too much torque with these engines. The driver drives in the initial stage of acceleration only half or three-quarter throttle. This gives us a leeway for energy production. Instead now according to inject less fuel, to restrict the torque, we burn more fuel. The excess power produced there is not invested in additional propulsion. This extra torque that we do not use for driving, is used to make the MGU-K run as a generator. With this power, the battery is charged. "
If it is constant then it isn't traction control, it could only be deemed in my view as TC if they would have an open loop control that would vary the mgu-k harvesting (probably based off vehicle velocity) while the driver remained on full throttle.bergie88 wrote:This is a form of traction control, nothing more nothing less. Off course without the feedback control loop which makes it possibly illegal.When the Formula 1 engine "overweight" is
Sebastian Vettel's former motor engineer explains what he means: this residual energy we get through the so-called 'overloading' of the engine. What is that? We use fuel to generate electricity. And how are you? When accelerating you do not need all of the engine power. You have too much torque with these engines. The driver drives in the initial stage of acceleration only half or three-quarter throttle. This gives us a leeway for energy production. Instead now according to inject less fuel, to restrict the torque, we burn more fuel. The excess power produced there is not invested in additional propulsion. This extra torque that we do not use for driving, is used to make the MGU-K run as a generator. With this power, the battery is charged. "