Lightning GT - Page 3

dsacks6 · 06-18-2007, 02:39 PM

What i don't understand is how it has the same accleration time as the tesla with so much extra horsepower...... ???

TEG · 06-18-2007, 02:52 PM

Tesla is traction limited, so must they be...

Tesla has two speeds so they can rev the eMotor higher sooner (in 1st gear) to get to HP peak earlier.

Maybe that explains it.

dsacks6 · 06-18-2007, 03:27 PM

If they are traction limited, why don't they just throw on thicker/wider tires? or is it not as simple as that?

TEG · 06-18-2007, 04:11 PM

Quote:

Originally Posted by GreenSpeed

If they are traction limited, why don't they just throw on thicker/wider tires? or is it not as simple as that?

Tesla's latest blog talks about that...
Tesla Motors - feel
"Sure, the engineers could have specified steamroller-sized wheels and tires to put even more rubber on the road and inflate the lateral grip numbers for the magazine statistics. That would have compromised the Tesla Roadster’s tactile response, and created a car that tramlines over grooves in the pavement and thuds over bumps and potholes..."
(In other words, having too wide tires can compromise handling).
Also wider tires have more rolling resistance that could shorten the ("oh so important") max range.
Stickier tires are possibly more important (to 0-60) than width. But sticky tires tend to have short lifespan and higher rolling resistance.
You really don't see much in the way of street cars with sub 3 second 0-60 times. You just start to get to the limit of traction no matter how much power you have.
Dragsters do things like putting bleach on the tires right before the race. They also use super soft tires that expand dramatically as they slip. They are only useful for straight line acceleration. See how much the drag tires wrinkle and distort under such heavy acceleration:

Those drag tires expand to double their at-rest diameter when blasting down the 1/4 mile.

dsacks6 · 06-18-2007, 07:32 PM

Thanks for that TEG :)
Still confused....so is it like this: They need to find just the right size that is the best compromise of everything....
everything being, accleration, grip, feel/handling.
F1 cars have very wide tires and I think they still handl fantastically so how is that?
I don't really get the whole tactile response thing? So are they saying/admitting the car would do a lap on a race track faster if it had wider tires?

TEG · 06-18-2007, 09:00 PM

The roadster is trying to be a balanced vehicle that give excellent steering feel, excellent directional change stability (quick through a slalom), high efficiency, etc. Wider tires would help with some attributes, but would detract from others. Would you trade a little bit of dry traction in exchange for making the range shorter, steering harder, and less compliance over bumps? As they said on their blog they are resisting the temptation. Yes, F1 cars tend to have wide tires, but they replace them frequently, they are hard to steer, and comfort isn't a priority.

dsacks6 · 06-18-2007, 10:24 PM

That makes more sense, but that begs the question for me, how they manage on cars like an enzo or buggati veyron with such huge tires, to keep comfort, steering feel, etc.
I was hoping they would offer a track pack for the tesla roadster like they do for the elise, whether it would be used on the track or not.

WarpedOne · 06-19-2007, 01:20 AM

Quote:

Yes, F1 cars tend to have wide tires, but they replace them frequently, they are hard to steer, and comfort isn't a priority.

Not to mention that big fat rear wing. Without it, F1 car is almost undrivable.
You could put wider tires on TR, attach a big fat rear wing and get 3s 0-60 time.

At at least 4-times shorter range and half the top-speed.

Magic word: balance.

Quote:

... but that begs the question for me, how they manage on cars like an enzo or buggati veyron with such huge tires, to keep comfort, steering feel, etc.

Active susspension, mass dampers, ... but than again what comfort? What makes you believe a supercar is comfortable to drive?

dsacks6 · 06-19-2007, 01:44 AM

Exactly my point, why don't they put on wider tires onto the tesla or lotus elise for that matter, the only downside i see is worse range, harder steering(which can be cured with more power steering), and more bumpy ride.
Or they should atleast make it an option imho.

WarpedOne · 06-19-2007, 02:03 AM

Quote:

Or they should atleast make it an option imho.

Aftermarket tinkering can take care of that.

As I see it they are concentrating on one base model. They are a newcomer and have much to learn. They try to reduce the number of variables as much as they can and in this way maximize the quallity and performance of the product. Offering options on suspension / drivetrain means you are spreading available resources over much wider landscape resulting in overall lower quality.

Another point: wider tires are heavier => more unsprung weight

=:)