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New Launch Mode - firmware 2.9.40
- Thread starter PatP
- Start date
Cyclone
Cyclonic Member ((.oO))
That and likely different target demographics. Those who are looking for extra edge in performance likely bought a P. Those who love the performance of the Tesla and are ok not getting the "fastest" likely won't have much use for launch mode. There are hose of us who do want it without "paying to play", but I would venture to say the majority who would really want it to actually use (beyond one-time "I did it") would already have the P-car.
Chasedrgc1223
Nearly Insane
As much as I'd love launch mode, I doubt it's coming for us just because I think Tesla wants to make the feature exclusive to performance models. However, what does keep me a little optimistic is the sport mode update we got in early April, making us the first non P model to get an acceleration mode selector. They did remove it eventually replacing it with Sport mode all the time.
Chasedrgc1223
Nearly Insane
Back in April they gave us a sport mode to play with, but after an update they got rid of it and made it always have the performance of sport mode. There used to be Normal and Sport, but now it's always sport.
Well, again why should it? By choosing the 85D, you chose to not go for and pay (the extra 20K USD) for performance (although the 85D is also extremely fast).
Future automobiles like the Model S will see a whole new world coming. It's just like a PC. Essentially you will probably get the whole HW stuff at time of purchase, the options however will have to be selected on top That's the way it should be.:biggrin:
Then they should have probably made it easier to use...
edit - option 3: To stop magazine reviewers from trying to brake-torque during tests.
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stopcrazypp
Well-Known Member
Technically, the car has as long as it wants to cross the 1 foot mark before timing starts.
stopcrazypp
Well-Known Member
The number is a rough estimate and will obviously will vary by car (since acceleration in that range and the circumference of wheels will vary), but ~0.3 seconds is a very good estimate that covers a wide range of cars. 1 foot is only 1/6-1/7 of a turn of the wheel. The acceleration within that range isn't going to vary that much.
One of the slowest cars ever tested by Edmunds (2011 Smart ed):
0-60 (sec): 22.4
0-60 with 1-ft Rollout (sec): 22.1
(difference 0.3 seconds)
http://www.edmunds.com/car-reviews/...2011-smart-fortwo-electric-drive-passion.html
Front tire: 155/60R15 (70.13 inch circumference: 1/5.84 turn for 12 inches)
P85D
0-60: 3.5
0-60 with 1 foot of rollout: 3.2
(difference 0.3 seconds)
http://www.edmunds.com/tesla/model-s/2015/road-test/
Front tire: 245/35R21 (87.19 inch circumference: 1/7.27 turn for 12 inches)
If you are talking about some hypothetical situation, I think it'll be unlikely to find a situation where a car's wheels are made to turn 1/6-1/7 of a turn and then stop there for long while just to make a big gap in the rollout number in an acceleration run. You might do that during parking a car in a tight spot, but not when you are trying to measure peak acceleration.
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Bill D
Member
The ~0.3 sec estimate makes sense because the math shows that accelerating at 1G, you'll reach 1 ft in 0.25 sec. BTW it also shows that you'll reach 5.5 MPH.
SomeJoe7777
Marginally-Known Member
1-foot rollout is nearly always stated for 0-60 times in the US because that matches the method used to measure the elapsed time you get on the drag strip.
Drag strip timing is done using the staging beams. The staging beams are two beams of light about 1" off the ground at the starting line, and they're about 6-8" apart. When you break a beam with your tires, that lights up a staging light on the tree. The first beam, called the pre-stage beam, is 6-8" behind the starting line. As you pull forward and your tires break this beam, the pre-staging light (topmost light on the tree) lights up. You continue to pull forward and break the 2nd beam, called the staging beam, which is at the starting line. When this beam is broken, the second light on the tree, the staging light, lights up.
When both cars are staged, then the tree sequences downward to the green light. Two separate times are recorded:
1. Reaction time (RT): The time from when the green light on the tree lights until the staging beam is unbroken.
2. Elapsed time (ET): The time from when the staging beam is unbroken until the car crosses the finish line, 1/4 mile down the track. At the finish line is a beam to stop the ET timer, and 66 feet before the finish line is another beam that helps measure the average speed of the car over the final 66 feet before the finish line (known as the trap speed).
Since the beams are about 1" off the ground, and your tire has only barely covered the staging beam at the start, the forward-aft section of your tires that are blocking the staging beams is about 12" long. Thus, your car needs to roll about 12" forward to un-break the staging beam and start the ET timer.
This is why manufacturer-stated 1/4 mile times and 0-60 times are almost always "with 1-foot rollout". The stated 1/4 mile time will match the ET on the drag strip, and the 0-60 time is stated using the same measurement method.
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benjiejr
Technogeekextraordinaire
Great description @SomeJoe7777. I'm new to drag stuff and I've tried to read up on this, but I feel like you summed it up nicely.
Walta
Member
My last champ car
99Shell Atlanta 1 - YouTube[/QUOTE]
Wow! Would LOVE to have my P90DL sound like that ... nasty.
99Shell Atlanta 1 - YouTube[/QUOTE]
Wow! Would LOVE to have my P90DL sound like that ... nasty.
SomeJoe7777
Marginally-Known Member
That's true for many types of electric motors, but not all.
The speed at which an AC induction motor makes max torque can actually be varied by adjusting the rotor resistance and/or the applied frequency. In a typical squirrel-cage induction motor, the rotor resistance is fixed, and for most motors without some type of inverter drive, the frequency is also fixed. This results in a max torque point that is a certain percentage of the motor's synchronous speed. In most 3-phase industrial AC induction motors, this is about 75% of the synchronous speed. Thus, torque at start is higher than typical operating torque, but not the highest torque that the motor can put out.
Most single-phase AC induction motors have very low starting torque because they can't develop a rotating magnetic field without tricks like split-phase windings or capacitor assistance. Typical residential air conditioning compressors use the latter.
In the Tesla, the rotor resistance is fixed, but the applied frequency and voltage is adjusted by the inverter to supply maximum torque at 0 RPM.
ArtInCT
Always Learning
BTW, Motor Trend's latest newsstand issue dated February 2015 has a 3 page Tesla P90D article. A must have for the P90D enthusiast.
Looks like their car is mostly optioned out, including 21" wheels and pano, and they still managed 10.9 @ 122.7 mph? hmmmm
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