2022 Tesla Model S Plaid First Look: Lord Helmet Approves

Motor Trend ^ | Sept. 23 2020 | Greg Fink

[edwinland]

You got it, except it was a Grumman C-2 Greyhound cargo turboprop, which is not quite as exciting but still a pretty unbelievable experience.

[alexander_busek]

F=MA has not been repealed — those 2 second sprints to 60 still suck up a lot of energy.

Accelerating to 60 mph in 2 seconds does NOT "suck up" more energy than accelerating to 60 mph in 2 HOURS.

Regards,

[Amberdawn]

A quarter horse can do it in 20 seconds for a whole lot less.

[ontap]

I have some of his stock....no way I can afford his car!!!!

[minnesota_bound]

It looks like a corolla.....

[minnesota_bound]

Imagine car crash at a race track. No fireball but a thousand AA batteries lethally flying at the crowd.

[xp38]

And no one will hear it coming. If you watch the vid embedded in the article of a lap at Laguna Seca it’s remarkably silent except for running over the rumble strips on the edge of corners.

[Svartalfiar]

It’s not mentioned in this article but the Tesla website claims it will do 9 second quarter miles. That’s Dodge Demon territory. Sub 2 second 0 to 60 is also in the realm of F1 cars.

Perfectly plausible, electric engines are much better than gas/diesel in direct performance. Much better torque, reaction time, and energy transfer. Acceleration is pretty much instantaneous, as there is almost no lag time between pedal and fuel pump/injection/firing/speeding up. It's just pedal -> more rpms.

The issues with electric vehicles are mostly in other areas like refuel time / ease, cost, weight/volume of energy storage, environmental impact of those batteries, and other stuff. The only kinda issue with electric engines and speed/acceleration is that high speeds mean high rpms on the moving parts. I don't really know why they don't put a transmission on any electric vic, as that should increase your range, if you can operate at low power for high speeds...?

[Mr. K]

May the Schwartz be with you

[Mr. K]

falling?

[Svartalfiar]

It was one of the most intense feelings of my life. The most memorable part of it was the fact that the acceleration was (or at least felt) perfectly constant. It did not feel like we were suddenly jerked from a standstill. If felt like a giant began to pull us and pulled firmly but oddly gently for a few seconds and then let us go.

Actually, you certainly were jerked.

Position is where you are.
Velocity is where you're going.
Acceleration is what pushes you back in your seat.
Jerk is what pushes you in your seat harder or softer.
Snap is the changing of how hard or soft you're pushed.
Crackle and Pop are just getting way deeper than almost anyone ever needs to go into this.

[Mr. K]

Actually you have to go to the third derivative for this.

Velocity is the first derivative of the change in position over time.

Acceleration is the second derivative, the change in velocity over time.

But if you were to immediately accelerate from zero To maximum velocity (Constant acceleration) It would probably snap your neck.

So the acceleration is actually Changing over time (third derivative) from zero to max acceleration.

I once had to implement a pretty cool math algorithm for changing the acceleration of a large factory cutting table.

If you didn’t ramp-up the acceleration slowly it would jolt the machine back and forth like crazy.

Thus endeth the math lesson for today that you thought you would never use from high school and college.

[EVO X]

I did the landing, but not the take off. This article describes both.

https://theaviationist.com/2009/10/27/flying-to-from-an-aircraft-carrier-with-a-c-2-greyhound/

[Svartalfiar]

F=MA has not been repealed — those 2 second sprints to 60 still suck up a lot of energy.

Accelerating to 60 mph in 2 seconds does NOT "suck up" more energy than accelerating to 60 mph in 2 HOURS.

Actually, the most fuel-efficient method of accelerating is at a good strong throttle without blasting it. You want to get to speed (top gear) as quickly as possible, without pushing your vehicle into too-high rpms. There's lots of factors that go into it, but yes, while heavy acceleration does use up more energy, it then uses less energy to maintain that speed, while your slow acceleration is still under more load to accelerate. Also, most engines have a certain engine speed at which they're most efficient (generally 2-3M rpm), and very slow or extra fast acceleration will fall outside of that range.

Electric engines are a little different, as there is much less power loss in operation. Power to speed is a pretty linear relation, so the speed of acceleration doesn't matter nearly as much.

The reason many mileage comparisons say conservative drivers are better than heavy drivers is that they ignore the other factors that affect it more - top speed, braking, etc. The acceleration is a tiny part of the actual details - the biggest factor in mileage is how much you brake - every time you brake you're 100% losing all that momentum you spent so much fuel to acquire.

[Svartalfiar]

But if you were to immediately accelerate from zero To maximum velocity (Constant acceleration) It would probably snap your neck.

So the acceleration is actually Changing over time (third derivative) from zero to max acceleration.

Correct, and for most physics problems, this factor is mostly ignored. Force is assumed to be constant, so the acceleration is treated as near-instantaneous. Of course it really isn't, but for a practical math perspective, it is.


I once had to implement a pretty cool math algorithm for changing the acceleration of a large factory cutting table.
If you didn’t ramp-up the acceleration slowly it would jolt the machine back and forth like crazy.

Yup. Jerk is the change in acceleration, and snap is the change in jerk. Dunno if you got that far into your maths, but jerk definitely would have been involved there!

[ProtectOurFreedom]

What you say is all correct...until your last statement “the biggest factor in mileage is how much you brake - every time you brake you’re 100% losing all that momentum you spent so much fuel to acquire.” While that is correct for internal combustion engines without energy storage, it isn’t true for EVs.

Tesla (and other EV makers) use regenerative braking where braking converts a lot of the kinetic energy to potential energy stored in the battery. That is the huge advantage of EVs, especially city buses, where it is constant start/stop all day long. It’s not much of an advantage for EVs outside towns and cities where you go long distances without braking.

[Mr. K]

It was pretty cool watching the math implemented in real life.

We even had to measure and take into consideration the natural frequency of various components.

[edwinland]

OK so using that taxonomy, there was hardly any snap. The feeling of pressure due to acceleration was completely constant.

[alexander_busek]

Actually, the most fuel-efficient method of accelerating is at a good strong throttle without blasting it.

My original statement was based solely on Physics - without any consideration of possible differences between various types of engines, etc.

From the point of view of Physics, the amount of energy needed to accelerate a mass (e.g., a metal slug floating through space) to a given velocity is independent of the amount of time needed to achieve that final velocity.

Regards,

[nascarnation]

You don’t need a race track.
Happens on the street.
Houses catching on fire from the flying exploding batteries.
https://www.foxnews.com/auto/oregon-tesla-crash-battery-cells-flying-homes