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Side indicators

I don't recall seeing atopic about this.

I was never a big fan of the original side indicators as seen on the alpha: see two angles, here and here. I didn't particularly like the way they looked, but more than that, it looked like they would be tough to keep clean. However, one aspect about them that I did think seemed cool and "flashy" (pardon the pun), is that it was the curved line above the 'T' that illuminated. I can't finda picture of this, but it was on an old poster/pamphlet issued by Tesla.

However, I'm not a fan of the new design either. I first saw it when the first time the beta was on temporary display in the Bellevue store. I think that it looks kind of cheap and visually, it kind of sticks out to me in a bad way. In particulaly, I don't like the "plasticy" look about them. So at the time, I thought it was just some kind of beta placeholder for whatever the design would really be. However, seeing as all of the promotional images feature the same style, and the Model X also has the same style side lamps, I'm assuming they're here to stay.

What do you think?

My guess - they're staying. I agree about hard to clean but I am willing to live with that as long as they illuminate. I think it looks good with the illumination. Will it light up??

I have to see them in person. Judging from the images, I first thought I liked the original, more pronounced version better, but in the mean time I became used to the look of the more moderated version that is now on the Beta models. The original version may actually be a tad too showy on a classy car like this.

I think they are here to stay, and I think they are a concession to aerodynamics. A Cd value of .22 doesn't come for free. If they go so far as to retract the door handles (of course, for aerodynamics only, not showy at all! ;-) the least they can do is give the side indicators an integrated, aerodynamic design.

@Volker.Berlin

My ignorance is showing again. What is a Cd value?

@Liz,

Cd = Drag Coefficient

It essentially indicates the impact of wind resistance on the car. A lower value of Cd is a very aerodynamic vehicle with less impact from wind resistance. A Cd value of 0.22 is very good. The drag coefficient for a Prius is around 0.29.

Liz G, aerodynamic drag is calculated as Cd x A (drag coefficient times frontal area). You could call the Cd value the car's "slip-slide factor"... In other words, the car tries to disturb the surrounding air as little as possible, because disturbing air costs a lot of energy.

The Model S' .22 value is extremely low (i.e., good). For example, I presume that it is next to impossible to achieve a value like this with an ICE, which requires an exhaust. The exhaust disturbs quite a bit of air and increases the Cd value.

On the other hand, sports cars usually have surprisingly high Cd values. That's because they have enough power to overcome the increased aerodynamic drag, and are designed to optimize contact pressure rather than efficiency -- the air flow is used to keep the car firmly on the ground.

Here's an entire thread dedicated to this topic:
http://www.teslamotors.com/forum/forums/aerodynamics

@Volker.Berlin & @Schlermie

Grazie

Like Volker.Berlin says if the car produces any downforce (for handling) then that automatically increases Cd. That is why you see Formula 1 cars at the top of the list in the http://en.wikipedia.org/wiki/Automobile_drag_coefficient

That is why I'm thinking Model S Cd might be a bit too low. It probably doesn't produce any downforce at all, and being very sporty by nature it kinda should. Not that it matters much in ordinary driving, but it could hurt bad in Nürburgring.

AFAIK the new E-class coupe currently holds the record for the lowest Cd value of any mass produced passenger vehicle (not counting the Model S yet) at .24, together with its sister, the new B-class. I doubt that the E-class coupe has "not enough down force" to be a safety concern on regular highways. Given that the exhaust system, open radiator grill, and door handles all contribute to the Cd value, and the Model S does not have them, I'd assume that downforce on the Model S is in the same ballpark as that of the E-class coupe.

Timo, I agree that downforce wins races (b/c it allows for higher speeds in curves and turns), and lack of downforce is a serious problem in the Nordschleife. I'm just mentioning the comparison with the E-class coupe to state that the Model S' Cd value is very low, but not dangerously low either. The Mercedes is a nice example because it has a comparably low Cd value and is known for first-class passenger safety at the same time.

Liz, I forgot to mention why we care about the Cd value at all: Aerodynamic drag is practically irrelevant in city driving, but it is the single most important "range hog" at highway speeds. Lower Cd value means that range decreases less sharply at higher speeds.

@Volker.Berlin

Well that will be good for me since most of my driving is highway miles and I have a bit of a lead foot. :-)

Maybe a new index is called for--the Grip Coefficient (Cg). The downforce added to the weight of the car, at a particular speed (e.g., a 20% increase at 60MPH would be a .20 Cg).

Well, there is the coefficient of friction which would depend on the tires used... Combine it with the downward components of the forces on the mass. Force applied would usually just be gravity, but also downforce when at speed and things like banked tracks will change how the components of the forces are applied. If I'm not mistaken, the downforce generated by a shape depends on some variables so it couldn't (without losing accuracy) be simplified into a constant.

Obviously it would vary non-linearly with speed, but so does Cd. The idea is to quantify the trade-off (with e.g. the Roadster).

The designer said in a video that the side marker is a functional vent to relieve a high pressure that builds in the front wheel wells to reduce the drag, the fact that it's also a badge and side marker is just icing on the cake.

But is the vent still in the car? The Alphas' looked like it was there but only the badge remains in the Betas'. Or is it just hidden better?

The Cd of the GM EV1 is reported to have been 0.195.

cerjor, wow! Any sources? The Cd of the Model S has been extensively discussed and compared in this thread, maybe you want to add the EV1 there:
http://www.teslamotors.com/forum/forums/aerodynamics

@Volker.Berlin

http://en.wikipedia.org/wiki/Automobile_drag_coefficient
0.195 General Motors EV1 1996

I see it in quite a few places (0.19 or 0.195) but no official source in a few minutes of clicking.

I did find this interesting image though...
http://www.ev1.pair.com/charge_across_america/graphics_for_Charge/photos...
... from here ...
http://www.ev1.pair.com/charge_across_america/charge_html/faqs.html

These look fairly official but no mention of the coefficient...
http://avt.inel.gov/pdf/fsev/eva/genmot.pdf

Another interesting PDF...
http://www1.eere.energy.gov/vehiclesandfuels/avta/pdfs/fsev/sce_rpt/ev1_...
... which reports 0.19


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