RE: Blistering new 0-62mph record dips under a second
Discussion
remedy said:
romac said:
tr3a said:
Katzenjammer said:
The Swiss German dialect of a couple of the team members is funny too.
I speak and understand German quite well. Here, I was grateful for the subtitling.nelly1 said:
GT9 said:
Talksteer said:
Let's do maths for a balls to the wall electric dragster.
You can get 60C LiPo batteries for drones. Let's assume we have 1000kg of them, the rest of the vehicle being 1000kg.
If the rated capacity is 175wh/kg so that is a max power of 10.5MW, let's make the drive train quite inefficient due to heat build-up so 8MW at the back wheel.
Let's assume that the peak acceleration of a top fuel dragster of 5.6gs is a limit for traction. I have an existing time step acceleration model in excel with a power curve for a Model 3 motor in it. I have put some sensible drag factors from an F1 car in it (though drag makes very little difference)
We have geared the dragster max power at about 175mph at which point power stays flat for a bit before tailing off.
Results
0-60 - 0.47s
0-100 - 0.79s
0-200 - 1.68s
0-300 - 3.4s
100m - 1.92s 219mph
200m - 2.82s 274mph
300m - 3.56s 307mph
400m - 4.30s 328mph
1000m - 8.01s 347mph
1609m - 11.54s 393.65mph
So our pretend car can beat the record Top Fuel times, this assumes that electric traction doesn't allow us to do even better on traction.
Is this car feasible?
The battery looks quite feasible especially given we aren't challenging energy density in a drag race. It's also a relatively big item to drop heat into for 5 seconds.
The motor is more of a challenge, the best motors are about 10kw/kg. This would mean we need an 800kg motor, however those rating are for minutes of operation if not hours depending on application. If we need 5 seconds between overhauls we might be able to push much higher currents through them.
As a scoping calc let's assume that we will dump 2MW into the motor. We have cooled it with dry ice to -80C and it stops working at 200C. Copper needs 3850j/kg to raise it 1 Kelvin so for our 5 second run we only need ~10kg of copper to absorb that heat.
In reality we will need a motor with a lot more than 10kg in the windings but it is indicative that if we only need the motor to last 5 seconds then we could probably hit the 40kw/kg that an existing dragster engine manages.
The area where I can't even make some scoping calcs would be in the power electronics. I have no idea what their life Vs overload capability is or whether for this extreme application we could even use something retro like valves or a commutator.
Why hasn't someone done this, massive cost and the fact that research and development here has little practical use on any other application.
The error is where you've said 175 Wh/kg.You can get 60C LiPo batteries for drones. Let's assume we have 1000kg of them, the rest of the vehicle being 1000kg.
If the rated capacity is 175wh/kg so that is a max power of 10.5MW, let's make the drive train quite inefficient due to heat build-up so 8MW at the back wheel.
Let's assume that the peak acceleration of a top fuel dragster of 5.6gs is a limit for traction. I have an existing time step acceleration model in excel with a power curve for a Model 3 motor in it. I have put some sensible drag factors from an F1 car in it (though drag makes very little difference)
We have geared the dragster max power at about 175mph at which point power stays flat for a bit before tailing off.
Results
0-60 - 0.47s
0-100 - 0.79s
0-200 - 1.68s
0-300 - 3.4s
100m - 1.92s 219mph
200m - 2.82s 274mph
300m - 3.56s 307mph
400m - 4.30s 328mph
1000m - 8.01s 347mph
1609m - 11.54s 393.65mph
So our pretend car can beat the record Top Fuel times, this assumes that electric traction doesn't allow us to do even better on traction.
Is this car feasible?
The battery looks quite feasible especially given we aren't challenging energy density in a drag race. It's also a relatively big item to drop heat into for 5 seconds.
The motor is more of a challenge, the best motors are about 10kw/kg. This would mean we need an 800kg motor, however those rating are for minutes of operation if not hours depending on application. If we need 5 seconds between overhauls we might be able to push much higher currents through them.
As a scoping calc let's assume that we will dump 2MW into the motor. We have cooled it with dry ice to -80C and it stops working at 200C. Copper needs 3850j/kg to raise it 1 Kelvin so for our 5 second run we only need ~10kg of copper to absorb that heat.
In reality we will need a motor with a lot more than 10kg in the windings but it is indicative that if we only need the motor to last 5 seconds then we could probably hit the 40kw/kg that an existing dragster engine manages.
The area where I can't even make some scoping calcs would be in the power electronics. I have no idea what their life Vs overload capability is or whether for this extreme application we could even use something retro like valves or a commutator.
Why hasn't someone done this, massive cost and the fact that research and development here has little practical use on any other application.
That defines energy density, not power density.
Power density of li-ion is much lower at around 1 kW/kg.
The instantaneous power required to accelerate the car is 4.5 kW/ton per g per mph.
You also need a bit more to overcome rolling resistance and drag.
That's heading towards 10 MW/ton of vehicle mass at the top end of the run.
Li-ion is not the right technology for this as you are talking many tons of batteries to deliver many MW.
Supercapacitors would push the power density up by at least an order of magnitude.
The other issue is voltage, even at 800V you would need a 10,000 amp DC link.
This task would require medium voltage, which then pushes you into the realms of different types of components and insulation systems.
The reason it hasn't been done is it's extremely challenging...
Talksteer and GT9 have done some wonderful work here even if it may have caused more questions. Thank you to both.
GT9 said:
The error is where you've said 175 Wh/kg.
That defines energy density, not power density.
Power density of li-ion is much lower at around 1 kW/kg.
The instantaneous power required to accelerate the car is 4.5 kW/ton per g per mph.
You also need a bit more to overcome rolling resistance and drag.
That's heading towards 10 MW/ton of vehicle mass at the top end of the run.
Li-ion is not the right technology for this as you are talking many tons of batteries to deliver many MW.
Supercapacitors would push the power density up by at least an order of magnitude.
The other issue is voltage, even at 800V you would need a 10,000 amp DC link.
This task would require medium voltage, which then pushes you into the realms of different types of components and insulation systems.
The reason it hasn't been done is it's extremely challenging...
The power density is based on the availablity of batteries with a 60C (and beyond) discharge rating. The C rating means that at peak discharge they are discharging at a rate at which they will fully discharge in 1 minute.That defines energy density, not power density.
Power density of li-ion is much lower at around 1 kW/kg.
The instantaneous power required to accelerate the car is 4.5 kW/ton per g per mph.
You also need a bit more to overcome rolling resistance and drag.
That's heading towards 10 MW/ton of vehicle mass at the top end of the run.
Li-ion is not the right technology for this as you are talking many tons of batteries to deliver many MW.
Supercapacitors would push the power density up by at least an order of magnitude.
The other issue is voltage, even at 800V you would need a 10,000 amp DC link.
This task would require medium voltage, which then pushes you into the realms of different types of components and insulation systems.
The reason it hasn't been done is it's extremely challenging...
Therefore to workout the discharge rate you need to times the energy density by the C rating.
Ergo 175*60=10.5kw/kg this is for a LiPo battery not a regular NMC battery in an EV.
TGCOTF-dewey said:
Have you missed out tyre Mu somewhere. A topfuel dragster is half the weight of your theoretical car.
I'm not saying you're wrong, but I can't see how doubling the mass, even with the power increase, drops the accel times given TF cars appear close to, if not at, traction limited.
I made an arbitrary assumption that tyres will be sized to provide the requisite traction. If said dragster is twice the weight of a top fuel dragster we could fit a tyre with twice the contact patch.I'm not saying you're wrong, but I can't see how doubling the mass, even with the power increase, drops the accel times given TF cars appear close to, if not at, traction limited.
If we lower the weight to match current cars we could get by with half the horsepower. The driver and their safety cell won't half in size but my estimates on weight were finger in the air anyway.
The point was with existing electric technology we could likely go about as fast as today's top fuel cars if we have similar attitudes to component lifespans.
PHZero said:
E63eeeeee... said:
PHZero said:
pycraft said:
0-60 in under a second; range 12 metres. It's the ultimate EV. 
It's possible that a male driver may have managed to get a quicker time. Perhaps not though.
ManyMotors said:
A top fueler hits 60 in 0.4, 100 in 0.9 and 300 in less than 4.0. But you can't run it in your driveway.
Says who?https://m.youtube.com/watch?v=TkWTcUqqnmI
Google [bot] said:
ManyMotors said:
A top fueler hits 60 in 0.4, 100 in 0.9 and 300 in less than 4.0. But you can't run it in your driveway.
Says who?https://m.youtube.com/watch?v=TkWTcUqqnmI
ManyMotors said:
A top fueler hits 60 in 0.4, 100 in 0.9 and 300 in less than 4.0. But you can't run it in your driveway.
300 in less than 3https://www.dragzine.com/news/mike-salinas-makes-h...
Coatesy351 said:
I missed this. Thank you! And......WOW!Gassing Station | General Gassing | Top of Page | What's New | My Stuff