Motors car aerodinamics question.

i know this is going to sound daft, but i think certain cars would be more aerodynamic if they were going in reverse..... i mean, imagine this peugeot 206 running in reverse, it looks like a drop of water, and IIRC drop shape is very aerodynamic....

what do you think?

PS: by the way, why do US cars look like they have the aerodynamic profile of a brick?

 

I've never heard of a teardrop shape being more aerodynamic with the widened rear facing first. Have you confused it with the super-efficient boxfish shape by defunct DaimlerChrysler Auto Group?

I think that's a very shallow generalization. Any car without a sport personality often won't receive a low-drag design. Most of the Lexus sedans and coupes that I've seen are highly efficient designs... Other examples include the Pontiac Solstice, Dodge Viper, Plymouth Prowler, Ford GT, Cheverolet Corvette, and other sport cars. If you want to see aerodynamically inefficient cars with respect to their curb weight (drag-to-weight ratio), take a look at the Mini Cooper and Smart ForTwo.

 

the fat part is facing forward for the shape to be efficient....

edit: and i was not generalizing, i was implying that i see more round-ish Euro made and marketed cars than US cars that have these huge front grills and square backs..... and square fronts.....

edit 2: http://www.triggasports.com.au/images/tech_aero_shapes.bmp

 

Correct.

I don't really have much more to add apart from that.

 

When performance is a priority, the car is made as aerodynamic as possible goddamn! someone's got a pink one
and these guys are nice aswell:

A teardrop is not the most aerodynamic shape! It is the resulting shape of an object that is weaker than the force present by a resistance, such as air or even a soft object passing through water - the most aerodynamic shape is a pointy at each end/rocket/spear/arrow shape, but when an ideal shape for a racing car is wanted, things like ferrari's, ultima's, koenigsegg, lambo, etc get made - and best of all would have to be these cars!

 

http://www.hackaday.com/2008/01/02/inexpensive-mpg-modding/

 

They don't have pure aerodynamics in mind. Cars are made to direct airflow over certain surfaces to create downforce, other air is moved about to direct it into and out of the engine, as well as to quell noise and all manner of other things.

Car aerodynamics aren't just a simple "make it a teardrop!" concept, that's an idealistic idea that doesn't work.

 

If you're hinting at Le Mans cars then that's a bit of a grey area. Designers used to be faced with the challenge of making the car as fast a possible for the Mulsanne straight (record of ~248mph). Then the ACO put in the chicanes and changed the rules regarding aero and now there is so much to make a car 'work' around La Sarthe that it boggles the mind how they do it.

Checkout http://www.mulsannescorner.com/ for a real indepth look at aerodynamics in Le Mans.

 

Not to mention it actually has to look good.

 

I was going to edit that in, but got cba.

 

a teardrop isn't ideal! I'll quote this what this guy said:

and this guy:

by "best of all" i think that guy meant "best for racing in terms of downforce, cooling, engine air intake, driver air intake, low turbulence & air resistance"

um, on re-reading my post, i think i may be a little narky here i just told off a security guard so i'm still a lil fired up i guess, oh well

 

The fastest racing cars are all about downforce. It's not about just pushing the air around the car in the fastest/easiest manner, but rather using the airflow to push down the car.

Take an F1 car. Not enough speed on the corner and you're gonna go straight. Because the car is so light and powerful, you need speed to press the car down and thus get friction. Thus Aerodynamics can mean totally different things depending on the car type and it's purpose.

 

The only reason for downforce is high speed grip - f1 or lemans - at low speeds, less grip is needed to turn the car, so less downforce is required for lower speed turns, which is why greater spolier angles will be used on tracks with more high speed corners, compared to a track that has more tight turns - gearing is another tuning issue, same for suspension, but those are off topic. Dragsters don't want to turn but they want to be able to have enough grip to control the car and heaps of grip to get the huge acceleration force to the road.

At low speeds, such as a victory lap, or a yellow flag condition, or following a pace car, or a warm-up lap where the f1 cars are darting around VERY sharply on cold tyres that have alot less grip so there's a greater chance of sliding, notice how the f1 cars don't slide off the track despite the low speed and the low grip from the cold tyres - they grip all too easily, as less force is required to turn a car when it's travelling at lower speeds.

 

i was talking about standard production cars.... i think if you make the car as aerodynamic as possible you can have higher MPG (look at what they did to the 78MPG lupo and the Bluemotion modified VW cars that do like 74MPG).... instead of making big ass boxes that travel like they have a parachute behind them....

http://www.volkswagen.com/vwcms_pub...almaster/en2/models/polo/polo_bluemotion.html

edit: BTW look at the shape of the aptera.

 

bloody thread drift!

Well for maximising fuel economy, the last thing you want is extra downforce, well maybe just a touch for med/high speed safety and that's it (people that really want fuel efficiency don't go over 100kmh/60mph anyway, and notice that economical cars handle like a boat at high speed for many reasons) and you don't want drag - having a big boot like that does create drag, but if they streamline the car for maximum aerodynamics, it would mean 2 changes in particular:
a low roof, and a sloping rear = 2 main problems: small boot, not much headroom so the seating posistion won't be upright, so the big boot is worth the little bit extra drag - they can afford to streamline the front, especially as some extra nose helps with safety aswell.

These are things that economical/practical a-b car buyers don't want: they want to go shopping, to work, and a little going out. They want to do it cheaply & easily, so they want upright seats for ease of driving & parking, a small/economical car, a decent sized boot even tho the car is small - meet these demands for good sales amongst the large quantity of value concious buyers.

No-one is in the market for a economical car, that is too low to give a decent view in peak hour traffic, too hard to park in busy parking lots, and has too small of a boot to take shopping - a ferrari fits this description, except for the economical/cheap part. Small boot is not a problem for a ferrari cos no-one would leave their ferrari in a shopping centre car park anyway, no-one wants to take a ferrrari into crazy/frenzy peak hour traffic. So the ferrari caters to it's niche market well = good sales amongst it's high cost/low quantity market.

So in the end, like all company decisions, it comes down to what will make the most money.

 

Actually a droplet shape is the most perfect aerodynamical shape in nature - which obviously is the reason why raindrops take on this form when falling towards the earth. Obviously, and as has been pointed out several times in this thread, one cannot simply make a car droplet shaped without also taking into consideration such things as downforce and handling. Whether or not the end result looks good is in the eye of the beholder.

Peugeot actually did a concept model with a very distinct teardrop shape. They called it the Peugeot 4002, and it looks like this: http://www.automobilemag.com/auto_shows/2003_fms_4002/index.html

 

I'm getting sick of repeating myself It's like i'm in the bloody plane on a conveyor thread or something.

What will fly further, a "normal" arrow, or an arrow shaped like a friken teardrop

 

I did read this the first time you posted it, though I forgot to comment upon it.

Obviously you are referring to the Sears-Haack body shape, which is regarded as the perfect aerodynamic shape. This is true, and I suppose I should have phrased myself differently. I was referring to the most perfect shape found in nature, which is a droplet shaped object. Well, at least as far as I know.

Edit: Suddenly I remembered that I completely forgot to think about birds while making this statement.

 

Mini Cooper's CD is 0.33 which isn't that bad, probably about average.
A 2006 Chevrolet Corvette Z06, is 0.28

 

a teardrop being thought to be a perfect natural effecient shape is jsut a misconception - it is just the result of an object being forced through a dense medium, eg:

a drop of water, falling due to the huge force of gravity through air, and as the speed increases, so does the air resistance, forming a teardrop shape - note the shape of teardrops during a heavy downpour = higher speed/air resistance - they are alot more like the shape of the most aerodynamic things, such as skinny birds, jet planes, rockets, arrows, spears, etc...


And cars like the mini have the great advantage of a small frontal cross sectional area - imagine how aerodynamic a mini would be if it was pointy, something like a little lotus elise - that car has heaps of downforce working against it's cd, but if you smoothly block the integral front spoiler, and smoothly remove the rear spoier, allthough the handling would suffer, it would be a damn slippery little car!