Apr 10, 2016
Todd Burch That's been around since the beginning of the Model S. It's how the rangers get into the back end screens. You don't have to do the Easter egg first.�
Apr 10, 2016
AWDtsla That's to enter service mode. And you can do some neat stuff in there. Chances of any of that being made public - near 0%.�
Apr 10, 2016
SageBrush Best to check my arithmetic, but 0 to 60 mph in 2.8 seconds is almost one G, so the filmed portion seems quite a bit less than ludicrous.
Can you post the speeds at exactly 2,3, and 4 seconds into the acceleration ? I don't know how to see individual frames.�
Apr 10, 2016
P85DEE Until I see and hear a little more, I'm not ready to fully commit one way on the other on this.
There is indication that it could be a hoax and there is indication that it could be on the up and up.
After thinking it over a little more, no matter how "compelling" the indication that it is straight up is, .... so far, for me, well while it's still not getting and "F" just yet, it's not getting more than a "C" to a "C minus" on the smell test right now. And I have a pretty keen sense of smell when it comes to things such as this.
They're going to have to give me a little bit more than "special sauce" here. And that name certainly didn't help with credibility.
I can't make a meal off of "sauce". I need a little more. Show me some numbers. vBox, dash gauges, give me something other than just some guy's moans and grunts of enthusiasm.�
Apr 10, 2016
omarsultan Got it - thx�
Apr 10, 2016
AWDtsla I didn't do timing, just power. Just slow it down to .25 in youtube.
FYI I have a power limited ideal quarter simulator for the Model S. If I plug in max acceleration as 1.67G and keep power the same, then I get slightly under 2.5s to 60. 1.67G's are held for ~.7s up to ~25mph, falling to 1G at ~1.2s and ~39mph. This seems to pass through the BS filter, as that guy would have to at least being doing some fancy integral math to get the two figures to BS about
�
Apr 10, 2016
JQ11 Within the comments on YouTube the owner of the Tesla responded to a question with - if it makes it to production it would be late summer. Also a week or so back on his Twitter feed he had a loaner Tesla for 3 days suggesting this wasn't just a software update - probably a new battery and or other terminal upgrades etc.�
Apr 10, 2016
SageBrush I downloaded the video and watched it with VLC 0.25x speed. That still leaves room for error but it was the best I could do for now
At 5:42, 13 mph
At 5:43, 35 mph
At 5:44, 51 mph
So over these two seconds,
the first second was 9.83 meters per second per second acceleration, equal to 1 G
the second second was 7.15 meters per second per second acceleration, equal to 0.73 G
Addendum:
I found frame by frame, and the video is encoded at 30 fps
Starting from 3 mph and advancing 15 frames (0.5 second) showed 16 mph, thus 1.2 G
I christen this "sedate roller coaster" speed ;-)�
Apr 10, 2016
yak-55 Sorry, a question so blatantly rhetorical didn't seem to deserve one, no ?�
Apr 10, 2016
Ben W It's possible they contrived this figure as the total acceleration felt by the driver, including the 1.0g downward pull from gravity. To get to 1.67g net, you need 1.0g downward + 1.34g horizontal acceleration. (Thank you Pythagoras.) This still stretches the limits of what ordinary road tires are capable of; I thought the traction limit was around 1.1g, but with super-sticky tires it might be possible. Sustained 1.34g forward acceleration would take you from 0-60mph in just a shade over 2 seconds. Wheee!!!
Then again, 1.67g of horizontal acceleration would take you from 0-60mph in about 1.64 seconds. And for reference, top fuel dragsters can go 0-100mph in 0.8 seconds, and 0-60mph in <0.5 seconds. Somehow I don't think this will be street-legal anytime soon�
Apr 10, 2016
AWDtsla LOL you always have 1G downard. No one would/should be referring to the vector of acceleration and gravity, that would be retarded. And no one said 1.67 continuous. See my post above. As for "street-legal", there's no law that limits torque.�
Apr 10, 2016
Ben W Hence my use of the word "contrived". Even 1.67g instantaneous is not possible with normal road tires; the traction limit is 1.1-1.2g for any commercially available road tires. You'd need your tires to physically melt on the road to provide higher traction that this, and I don't think _that_ would be street-legal�
Apr 10, 2016
AWDtsla How are you so sure? Because no ICE car has achieved this feat? Or because someone has done the appropriate coefficient of friction calculation? I do have one datapoint, and that is 1.1G's is NOT maxing out traction even with the MXM4's. Of course for rubber, the highest mu is achieved with some amount of longitudinal slip. If Model S's were achieving this small amount of slip through 60, we would all know.. Right now, the torque limits are pre-programmed. It's not like an ICE where the engine does what it can.�
Apr 10, 2016
Ben W Disable traction control in the Model S and you can spin the wheels all you want from 0-20mph. The electric motors have more than enough torque; the limiting factor is friction. If 1.67G's were physically possible with the S's tires, someone would have already done it and smashed the traction-controlled 0-60 times. Since no one has done it, the implication is that the wheels aren't capable of it, because the motors surely are.
Or you could google "tire road friction" and find countless empirical measurements around 1.0 for the maximum tire-road coefficient of friction, which directly corresponds to the maximum horizontal acceleration. (Coefficient of friction 1.0 -> 1.0g max acceleration.) Using very sticky tires, the P90DL has managed ~1.1g for fractions of a second, which is highly impressive. 1.67g is simply not in the realm of possibility for currently used road tire materials.�
Apr 10, 2016
AWDtsla The challenge is to hold torque at exactly the right slip ratio, not to light up the tires. This is much more complicated than turning off traction control.
But my tires are crap all seasons and I'm getting over 1G. A nice set of sticky summer rubber should significantly higher. By how much is the question.�
Apr 11, 2016
FlasherZ For what it's worth, I've heard from many individuals that Tesla is very firm about their NDA's. They control the release of information and it's definitely not done through bloggers and VC's, because they are concerned with the messaging that accompanies such a release. Based on my knowledge of how they approach information release, this wasn't a purposeful leak.
If that's true, then either a) this guy is indeed some kind of tester and just completely blasted his NDA, knowing that his friend was going to post a video blog entry about this, or b) he's just got simple ludicrous mode and oversold his rather excitable friend the easter egg in hopes of boosting his followers and ego.
My money's on b).�
Apr 11, 2016
Camera-Cruiser Single best explanation yet!
Also, based on Kevin Bacon's 6 degrees of separation theorem, couldn't someone who knows someone just call him? Or is this multi-page thread simply more fun?�
Apr 11, 2016
wk057 At the request of a few people I ruthlessly debunked the video in the comments section. The poster and the P85D owner both replied with nonsense, which I also debunked. Then the reply just turned to basically "Well it's a secret! You'll see!"
30 minutes later the video is no longer available. (Made private)
lol.�
Apr 11, 2016
Camera-Cruiser But, you ruined the funness.�
Apr 11, 2016
deonb I'm 2 degrees of separation from the Deli Lama. There is no way I can call him...�
Apr 11, 2016
DillyBop wk057... what did you say in the comments?! i'm dying to know.
saw this on this "Barnacules" dude's twitter just now...
Barnacules
@georgeisbusting Yeah, had to take it down. Can't comment on it though unfortunately.
4/11/16, 6:58 PM�
Apr 11, 2016
brianman Hey! I like the MXM4s. "Crap"? Disagree.�
Apr 11, 2016
eclipxe The bigger win here is that you're posting again on TMC�
Apr 11, 2016
brianman Preparer of divinely inspired sandwiches.�
Apr 11, 2016
msnow Well we had it...for about a week or two then it lost about a mile a week of rated range until it bottomed out at [email�protected]%. I don't see these two things as related since this included all 90D's not just P90D's.�
Apr 11, 2016
AWDtsla They're all-season tires. As in, they suck in all seasons. They are quiet and supposedly have rolling resistance, so I can see why a Tesla own may think they are "good".�
Apr 11, 2016
ChadS Stop on by; he will make you One with Everything.�
Apr 11, 2016
zzzzdoc I'm thinking this is an April Fool's joke, but hoping it isn't.
I've always gotten the ludicrous speed reference as well as the plaid, but where does the insane speed reference come from in Spaceballs?�
Apr 11, 2016
GoTslaGo I think I'll have a sucker sandwich please...
Guess it's April fools on me!�
Apr 11, 2016
commasign Bubble burst.�
Apr 11, 2016
eclipxe Or Lawyers...�
Apr 11, 2016
Todd Burch It seemed pretty clear this was faked when he did a launch and threw himself back into his seat, and yet if you watch the background it looks like a gentle launch in a Toyota Corolla...�
Apr 11, 2016
EternalChampion At greater than 1.6 g(s), his jowls should have been flapping a little more.�
Apr 11, 2016
Jool I recall seeing that video popping up in my recommended videos feed.
Looked like click-bait to me. The fact that it was taken down just solidifies my stance on that.�
Apr 11, 2016
Andyw2100 His jowls were flapping plenty anyway. Too bad there was no truth coming out of them.�
Apr 11, 2016
Caligula I don't suppose screen shots were taken?�
Apr 11, 2016
Hugh Mannity Yeah that ^^�
Apr 11, 2016
wk057 Nothing rude. Just facts.
Don't get used to it. This is my quota for participation for the quarter. lol.
I did not think to screenshot anything. Wasn't that important to me.�
Apr 12, 2016
LuckyLuke My current P85D was a loaner vehicle (first registered May 2015) at a service center for about half a year before I bought it (December 2015). In February 2016 I was able to schedule the Ludi upgrade (for March 2016) with no questions asked.
Maybe I just slipped through, don't know... But I am a very happy P85DL owner now�
Apr 12, 2016
Kalud I saw the comments, they were pretty interesting. The whole video was clearly a fake.�
Apr 12, 2016
eclipxe Not going to speculate more but wonder if the refresh will tell us more...First look at the Tesla Model S with new front-end�
Apr 12, 2016
yo mama Sounds like secret sauce may have been debunked, but my P85D did prompt me for a software update this morning that would take 1.5 hours. We shall see what that has to offer later this evening.�
Apr 12, 2016
Kalud Most likely 2.16.17 (cowbells)�
Apr 12, 2016
Andyw2100 There's a reason they call you LuckyLuke!�
Apr 12, 2016
sorka The video has been removed. It's even gone from my youtube playback history. Clearly Tesla got pissed...as they should have been.�
Apr 12, 2016
bhzmark I'm not sure that the video coming down means Tesla was pissed.
At least two, maybe three, possible explanations for why it was taken down:
1) The whole thing was a prank and wk057 revealed that it must be a prank and not true, so since the deception couldn't be maintained they took it down, along with the debunking comments.
2) There is some truth to this, and there was some further additional mode (which is consistent with other things that I have read about even Ludi cars still being detuned/not-utilizing-their true capabilities). This guy was a friendly beta-tester or possibly hacker who found that mode. And Tesla either because of an NDA or some other threats, requested/demanded that they take it down.
3) Or possibly a hybrid of the two above: there is some untapped capability beyond Ludi. But these guys didn't have it -- they just bluffed and pretended that they did. And that still drew Tesla's attention although then I don't see how Tesla would have incentivized them to take it down. They could have realized there was no more fun to be had.�
Apr 12, 2016
ohmman So.. it was either fake, true, or somewhere in between?�
Apr 12, 2016
sorka I don't think there was any in-between. It was fake. Was the driver in on it? Maybe not. Maybe it was just placebo for him. Was the beta tester in on it? Perhaps or perhaps not. Maybe there is a special mode that pulls more than 1500 amps and that the smart fuse really is more than 1500 amps if the car decides to draw that power. In either case, this car wasn't so it was either a hoax or he entered the code wrong and throught he was in this special mode.
But the KW snapshot showing the maximum KW reading at maximum acceleration on a nearly fully charged battery which isn't as high as my KW meter shows when supercharged to 90% proves this car wasn't running extra power.�
Apr 12, 2016
ecarfan The video seems bogus to me. Someone is desperate for attention.�
Apr 12, 2016
yo mama Damn you and your logic/math/science! I'm still downloading my update tonight with a dash of hope that it will reveal untold goodness, if for no other reason that it makes me happy.�
Apr 12, 2016
Andyw2100 You're forgetting the part of the video where the driver asks the other guy about traction control, and the other guy supposedly just disables it, and then a few seconds later pretty much instantly enables it again. While it may have been possible for Jason to have been able to disable and enable traction control on his hacked car, I don't know of too many other people who actually had their cars hacked, the display did not look hacked, and on top of all that, I wouldn't imagine, even if that car was hacked, the switching between traction control on and off would be as fast as it appeared to be in that video.
My point? It was a hoax that they were both in on.�
Apr 12, 2016
eyespii Seems odd for a guy with 650k+ subscribers on YouTube to purposefully be making hoax videos, especially since it didn't post on April 1. He's not exactly hurting for subs, and making fake videos isn't going to gain him new fans.
Although the whole thing is still fishy, a small part of me hopes that it's still coming, and tesla just asked him to take it down. After all, the ludicrous upgrade still says 10.9 quarter mile...�
Apr 13, 2016
Eximos I have been following him for a long time and i think its unlikely that they did a hoax like this, like you say he have way to many viewers to need anything like this. My guess is that his friend just broke some NDA and Tesla called him.
I guess time will show.�
Apr 13, 2016
sorka The only thing we know for sure is that MS wasn't putting out more than normal Ludicrous power. Who knows what who knew and whether placebo, intentions, or simply mistakes played a part in the video.�
Apr 13, 2016
rroyter This twitter account now says
"I have been advised to make no comments at this time. - Adam Schmidt (@KevlarCondom)"
Sounds like he did break some NDA...�
Apr 13, 2016
commasign I can confirm with 100% certainty that you are correct.�
Apr 13, 2016
FlasherZ ...or it's just the next scene in the show. Hate to say it, but I know Tesla is absolute in its clarity about NDA's, and if it is an NDA he broke, then he did it willfully, negligently, and bordering on maliciously. Very few people are that stupid.
The "use a code to enable" hasn't been Tesla's MO, either, based on what we've seen from other early releases.�
Apr 13, 2016
rroyter Earlier in the thread someone posted a link to one of his earlier tweets that specify 0-60 in 2.4s. This tweet is now deleted. Maybe it's just a show, but then why would he go and clean up like that now?�
Apr 13, 2016
mgboyes So with the latest firmware various people have noted that if you have a PxxD you can press and hold the T, enter performance as the password, and a menu appears allowing you to get your car to emulate lower performance models. This is apparently used by sales centers to give test drives where people can see what the different models feel like.
On mine (software update completed earlier) there are 70, 90, 70D, 90D, P90D, and Max options. The menu is a bit buggy (whenever you open it it says 70 and you have to selec another option and then go back to the one you want to be sure you've enabled it).
I suspect it's confirmation bias, but I swear that "max" feels even more aggressive and quicker than my car normally does.
Guess we need someone like @wk057 to enable this mode with logging and see what it does to the drivetrain, but it's possible that this is what MotorTrend were given for example.�
Apr 13, 2016
Naonak Can also confirm. After strict empirical analysis and studying tens of thousands of similar examples, it is without a doubt one of those three options.�
Apr 13, 2016
eclipxe Remember how a lot of folks were convinced there was no refresh. While I certainly doubt the facts presented in the video, I think its helpful to have an open mind.�
Apr 13, 2016
brianman I think you use the word "everyone" incorrectly. Also, this color doesn't look good on you.�
Apr 13, 2016
eclipxe Note taken. Edited to explain my point a bit more carefully.�
Apr 13, 2016
brianman Concur.�
Apr 13, 2016
Edmond The 'special sauce' was chili con carne on enchiladas...�
Apr 13, 2016
ecarfan Which is actually a "comment". Designed to publicize his "transgression".
Pure promotion.�
Apr 13, 2016
wk057 Performance Demo Mode does not *increase* performance. It can only be used to *decrease* performance.
See my posts on the topic from a while back when I first discovered it:
Chassis CAN Logging To ASCII Text Plus Graphing
You can see in the graph I posted soon after that the performance is quite literally identical in "Max" as it is to not messing with performance demo mode at all.
Chassis CAN Logging To ASCII Text Plus Graphing
(Took me an obscene amount of time to find these posts due to the hard-coded 20 post per page limit, and I'm reminded of why I don't come here anymore...)�
Apr 13, 2016
sorka If he had really violated the terms of an NDA, he wouldn't then be allowed to turn around and post that he was advised not to say anything. That in itself would most likely violate the terms.
Sounds like it's just the next step in an elaborate hoax.�
Apr 13, 2016
James Anders Yeah, I got your "secret sauce" right....�
Apr 13, 2016
Andyw2100 Or a step that he is taking to try in some way to save some face.
Perhaps somehow things went other than how the guys who made the video expected them to go, and pulling the video and making that statement is just part of the damage control.
But like Sorka and others, I don't believe Tesla was in any way involved in the video being pulled. Getting involved in any way with a video like that, and the guys who made it, would be beneath Tesla.�
Apr 14, 2016
mikeash I'm not sure about this "beneath Tesla" idea. This is the company that canceled a guy's car reservation just because he was a total jerk, after all. (Not that I'm particularly critical of that move, but it was rather petty.)�
Apr 14, 2016
RogerHScott This is precisely how we received our test drive. We were interested in the 90D, but the dealer only had a P90D available, so the salesperson just dialed it down to "90D", except at the very end when he turned it all the way back up so we could experience a Ludicrous launch�
Apr 14, 2016
RogerHScott Does Tesla employ even a single lawyer? If so, nothing is beneath them. I have seen small, otherwise-very-reasonable
companies behave like total jerks when they don't keep their lawyer on a short enough leash.�
Apr 14, 2016
AWDtsla Before or after it's "ready"?�
Apr 14, 2016
mgboyes Before In fact, without enabling max battery or launch mode. Anyway wk057 has already debunked the theory that Max power might be more than normal.�
Apr 14, 2016
ohmman They have an entire legal department. You can view jobs available for that department by filtering on their career page. It's not a small facet of the company.�
Apr 14, 2016
RogerHScott That was a rhetorical question.�
Apr 14, 2016
ecarfan Sometimes that is difficult to determine in plain text communication as opposed to face to face.�
Apr 25, 2016
notAmeenPerson I watched the video before it was taken down. I stumbled upon this article that came out a while ago. You'll notice that it uses the same secret sauce phrase. Perhaps the upgrade he was testing out was tuned for performance rather than an increase in range.
Temporarily increased inverter efficiency could mean more power from the batteries reaching the motors, subsequently resulting in a performance increase? I don't know I'm grasping at shadows.
Barnacules on Twitter�
Apr 25, 2016
whitex If they could increase the efficiency of the inverter, that would both - help range AND possibly allow higher top end power.�
Apr 25, 2016
tom66 Trip Chowdry needs to do some more research. Tesla's AC induction inverters already vary the frequency on the output. Since the AC induction motor is synchronous the output frequency of the inverter is related to the speed of the motor.
The inverter is already very efficient, around 90%. Getting higher than that with just software will be difficult. It might be possible, Tesla do tweak motor firmware almost weekly with software updates, but I'd be surprised if they could squeeze more than 1-2% more out of the current hardware. IOW, if there is a secret sauce upgrade it's either going to need better hardware or it's going to risk early hardware failure. Perhaps they could allow it only once every hour for 5 minutes or something, but I doubt you'll be using it all the time.�
Apr 25, 2016
FlasherZ That article was written amidst a flurry of conversation on forums as well. The conclusion was that they could tweak the algorithms to get a little bit more out of it, but anyone expecting a near-step-change difference was going to be disappointing. Physics is still physics.
"Secret sauce" is used in the business world far too much, I'm afraid, to link these two.�
Apr 25, 2016
R.S
While you are right, that inverters already switch output frequencies, you are not right.
An IGBT has a fixed switching frequency and with that frequency it modulates lower frequencies. To give you an example, imagine one "I" would be a 10ms voltage peak of 100% and "." would be a 10ms voltage of 0%. Now you can go "I.I.I.I.I." which has the frequency of 100Hz, but you can also go "I..II.III.II.I.." which would be 6.25Hz. Both modulate sine signals, but also have other frequencies in them (think Fourier series), which actually reduces motor efficiency. If you switch faster, the inverter losses increase, but the motor losses decrease, if you switch not so fast the inverter losses decrease and the motor losses increase.
And another thing, an induction motor runs asynchronous to the inverter frequency. It only runs in sync, if it produces no torque. Induction can only happen if the magnetic field of the stator moves faster than the rotor. Because -B d/dt = rot E�
Apr 25, 2016
tom66 I am reasonably certain Tesla use variable switching frequency, as well as inverter frequency. The inverter harmonics seem to change, indicating this.
You are correct frequency is only proportional to speed when the motor is theoretically unloaded. Some slip is necessary to create torque.�
Apr 26, 2016
R.S That could very well be, it would also make sense, although it would not be necessary. It is also more complicated, because you never want one bridge to short, which could happen more easily, if you change the switching frequencies dynamically, since the IGBT takes some time to shut off. Its a very complex topic, especially if you also want to reduce the voltage with the inverter. I always wondered if you could let a Buck-Boost converter do the voltage at the DC-part and use the inverter just for modulating the sine wave, but I guess that would be too expensive.
But how do you know the inverter harmonics change? Just out of interest.�
May 1, 2016
AZ Desert Driver So some of you guys prowl with Ludicrous enabled super cars. Part of me wants that throbbing power...but the sane(er) part of me says that such power is fleeting. That after a week or month of jackrabbit starts, one would "grow up" and begin driving in traffic like a good neighbor. One might tap intoLudicrous on fewer and fewer occasions.
Don't know if this "maturing" happens, but if it does, does that mean the Ludicrous mode is a fleeting purchase? Should I invest my nickles into other - more durable - options?�
May 1, 2016
Andyw2100 I drove with "Insane" mode enabled all the time, and now drive with "Ludicrous" mode enabled all the time, as does my wife. I assure you she never comes close to making use of the power Ludicrous can provide, and I almost never do. (The exceptions for me would be if I'm showing the car off to someone, or trying to test something.) All that being said, it's nice to know the power is there if and when I want it.�
May 1, 2016
thnp Eearlier, when buying cars I've always used the argument: "it's nice to have that extra power at hand for passing other cars etc", and then bought a slightly larger engine than I actually required ... But with the Tesla... Even the base fulfills this requirement.... When I got my S85 and then my 70D I just couldn't get myself to even think about a P-version... The base models are just... Enough...
For me at least - but everyone is different!�
May 1, 2016
Jason S Sometimes the extra power is nice. You find yourself in the wrong lane, you didn't see the oncoming car when pulling out, etc. I would drive with the option always on if given the choice.
I wouldn't, however, use launch control on every chance. That's just looking for trouble.�
May 2, 2016
anxman This is accurate. Eventually the novelty wears off and you use it less and less. It's just fun and nice to use it when I'm in the mood but really serves no practical purpose.
Now that the 90D is so beefy, I don't see any reason to spring for the P.�
May 2, 2016
AZ Desert Driver I'm trying to configure my Model 3....I am thinking Dual motor, 70 kw battery( I want max range, even if primary trip is local, want option of range up to 250 miles...same as gas tank)
No air suspension, no P or L.
I think you just convinced me on P and L. ( base level will still be awesome)
Still soft on Air. Heard there are lots of problems that make this small feature too expensive. True?�
May 2, 2016
AZ Desert Driver Dummy question - I don't know what the difference is between: Insane, Ludicrous and Launch - they seem to be the same, just rotating names. True?�
May 2, 2016
thimel They are different. Insane mode comes with the dual motor cars that have the model number starting with P. They have a bigger rear motor than the non-P cars. Ludicrous is a $10,000 upgrade to those cars that provides improved fuse, contractors and software so about ten percent more power is available. This reduces 0-60 times by about 0.2 seconds.
Launch is used informally to mean flooring it from a stop. "Launch control" is a special series of accelerator and brake pedal presses that one can use to get a good launch. Most find that just mashing the pedal works fine.
Hope this helps.�
May 2, 2016
cheshire cat would like to see more on "air" too�
May 2, 2016
sorka Same up to 45 MPH and then 10% more power from 45+ and up.�
May 3, 2016
AZ Desert Driver Very good answer. Thanks.
This clears up why "over the air upgrade" won't get Ludicrous mode running. The car has to be built with those fuses...which don't come over the air. You just saved me $10,000 (in parts) plus more $ in fines/crashes from reverting to my teenage impulses.�
May 3, 2016
P85DBeast Whats next? the P100D+ And i bet the 0-60 is going to be about 2.3 Seconds and after that an even faster car! with a 0-60 of about 1.0 Second is that when Tesla's gonna stop b/c the Lamborghini and Bugatti might get jealous..... but heck they probably are already jealous!!�
May 3, 2016
R.S Without changing the tires, or doing some aerodynamic miracles, the lateral acceleration seems to have its maximum at 1.1g, for the Model S. So the minimal time to get to 60 mph, would be 2.486 seconds. The power needed to do that must be higher than 637 kW (854hp), based on a 2.2 ton Model S. If you increase power even more, without changing the rest, you just get faster to speeds above 60mph, but the 0-60 time stays unchanged.�
May 3, 2016
AZ Desert Driver I have spent my career as an engineer - specializing in material science. Many degrees, many hours in research labs. Your calculations SOUND fully reasonable. I've never been exposed to that flavor of physics. Can you illuminate how you got to these amazing figures? i.e. - how 1.1 g can be obtained - even with sticky tires. How 854 hp can't accelerate faster, just increase top speed. I am not doubting you. I've just never been exposed to these types of calculations.�
May 3, 2016
R.S For the 1.1g, thats something you might have to ask another material scientist, maybe even someone who deals with aerodynamics. If I'd had to guess its just the friction coefficient. But from acceleration data, we can see that its around 1.1g, it could be higher, but it sounds reasonable for a performance oriented car.
The power calculation, thats pretty easy. For that, we just need basic physics and my field of expertise, rotating electrical machines. As most know the typical electrical machine, has a flat torque curve from zero, but what many don't know is that at the point of maximum power, that changes and it becomes something like a flat power curve. So the torque curve goes down with the the increase of rotational speed/rpm. There is one point, where torque and power it at its maximum. If we would plot torque and power, over the rpm, its the point where at higher rpm the toque decreases, while at lower rpm the power decreases.
Maybe we need to clarify what torque exactly is. Torque is force times radiant and it can be geared up, or down. Thats one of the reasons why talking about motor toque in EVs is rather pointless. In the end the torque is transmitted to the road, as force. If the force is higher than the nominal force of the car, times the friction coefficient, the wheel slips.
So to get the fastest to 60mph, with a given friction coefficient, at minimal power. We just need to gear the car that way that we have the point of maximum power and toque at 60mph, because we have no multiple gear transmission, where we could switch the transmission ratio.
That way we have 1.1g of acceleration up until 60mph, which gives us the minimal time from 0-60, 2.486s. If we want to go lower, we need a higher friction coefficient.
Now we calculate the power. 1.1g times 2.2 tons, gives us the force needed, 23.74 kN. And since power is force times speed, we have 60mph*23.74kN, which is 637kW. Thats the minimal power needed. If we have more power, we could either leave the gearing the same, which would result in spinning wheels, but a higher acceleration at high speeds, or we gear up and set the point of maximum power at a higher rpm, which has basically the same effect. It would still accelerate slower than the lower geared car, but top speed would increase.�
May 3, 2016
AZ Desert Driver Thanks ...1.1 g just seems too much. 850 hp is not enough to accelerate? Nothing calculated, just gut feel. Thanks for the calculations - and explanations. My feelings have been trumped by science.�
May 3, 2016
brianman How quickly? Hasn't happened to me for the 2012 P85 or the 2014 P85D yet.�
May 3, 2016
Denarius Agreed, I've been launching daily since 2013.�
May 3, 2016
sorka Just FYI, a bunch of us with vbox and pbox accelerometers do record 1.1Gs from about 17 MPH to 35 MPH.�
May 3, 2016
LargeHamCollider This does seem to violate the laws of friction, theoretical maximum mu value is unity which means theoretical max acceleration is 1g. But that is between surfaces where the applied force is perpendicular to the two parallel surfaces which are in contact with one another. IRL tires deform and fill small fissures in the road creating patches of contact where the applied force is not perpendicular to the two surfaces (like the teeth in gears but on a smaller scale and with smaller angles) creating an effective coefficient of friction greater than 1 and allowing accelerations greater than 1g to occur.
Drag radials actually form a temporary chemical bond with the road allowing accelerations greater than 3g to occur.�
May 4, 2016
R.S Just to add some additional information, for those interested how fast an EV (one fixed gear) with a certain power and friction coefficient could accelerate.
The discussed problem was the simplest one, we reach the point of maximum power at 60mph, but we could also assume that we have a friction coefficient of 1.1, but only 500kW. That would be a bit more complicated, but sill solvable.
To get the maximum acceleration, we need to use all the force we can, without slipping.
So we just calculate the speed until we can do that. In our example, 500kW, 2.2 tons and 1.1g, v = 500 kW /( 2200kg * 1.1*9.81m/s^2)
= 21.06 m/s
Now we need the time until we get there t = 21.06 m/s / (1.1 * 9.81 m/s^2) = 1.95s
After we get the time to the point of maximum acceleration, it gets a bit tricky and there are multiple solutions. In my opinion the easies way is using the correlation between energy and power. Power is energy d/dt. In our case we just assume that the power stays constant after that point and we don't have to dial back because of increased proximity and skin effect losses.
So we just need the additional energy needed, to have a car moving at 60mph, or 26.82 m/s , over a car moving at 21.06 m/s.
W = {1/2 * m * (Vend)^2} - {1/2 * m * (Vstart)^2} = 0.5 * 2,200kg * (Vend^2 - Vstart^2) = 303kJ
Now we divide that by 500kW and we get 0.61 seconds. We add both times and we get to 2.558s
So not really a lot less, although we reduced our power by about 25%. If we reduce power by 50%, to 319kW we still get a pretty decent 3.1 seconds. Even with just 200hp, less than a quarter of our original calculation, we still end up with less than 5.6 seconds. If we, on the other hand increase our friction coefficient against infinity, we still can't get less than 5.27 seconds with 200hp. Because thats the time it takes to "fill up" the car's energy from 0 to 791MJ with 150kW.
In realty its always a bit lower, since there are also rotation masses, especially the wheels, which also take up lots of energy to speed up and of course some reaction time, be it your brains switching frequency, or that of a microcontiolller, IGB, CPU or something like that.
You can easily do these calculations with excel, its interesting to see what effect power and friction have on 0-60, 0-100, or 0-155mph times. If you want, cow can also add aerodynamic drag, which I left out, or a reducing power curve.�
May 9, 2016
AZ Desert Driver thanks all- for the clarifying formulas. now that you have revealed, they seem obvious.�
May 9, 2016
Laserbrain Just for comparison: a Porsche 918 Spyder does 0-60 in 2.2 seconds (0-120 in 6.7 and 0-180 in 17.5 seconds), a rolling start (5-60) in 2.4 seconds, a quartermile in 9.8 seconds and goes around the Ring in less than 7 minutes. 1.24g acceleration.�
May 9, 2016
RogerHScott Have you ever actually been in one of these situations without Ludicrous enabled and found the "basic" 90D power insufficient?
As a (mere
As I commented in some other thread a while back, after my first drive in my brand-new 90D I told my wife I only then realized the true
reason that "Ludicrous speed" is called that: the idea that you'd need anything more than what the 90D can do is, just, "ludicrous".�
May 9, 2016
MikeC How can the 5-60 time be greater than the 0-60 time?�
May 9, 2016
Johan ICE engines do better from stand still starts. They revv up and "load" a lot of kinetic energy in the drive train that is released on to the wheels as the clutch engages.�
Không có nhận xét nào:
Đăng nhận xét