Astonishingly strange features on a car

[ian2144]

Fiddlemesticks said:

My wifes Sorento has a Barometer. Not a friggin clue why.

My Hilux Surf has Barometer as well, along with Altimeter, and compass. Just in case you get lost at the top of a mountain.

[kambites]

youngsyr said:

kambites said:

Strictly speaking the purpose of a spoiler is to reduce lift rather than add downforce. I'll admit that it's a rather arbitrary definition in practice though.

I suspect the airflow over the back of a 3-series probably hugs the rear window fairly well actually, putting that spoiler squarely in the airflow.

Rear spoilers on modern FWD hatchbacks rather amuse me - of course they're commonly known for lacking rear end grip.

I'm not an expert, but from what I've read, even with a fastback shaped car, the spoiler needs to be close to the roofline to have a significant effect:



This theory seems to be confirmed in reality. If you look at the BTCC cars, you can see that they don't have small lips on the boot, or low spoilers, they have funking great shelf panels very high up and close to the roof line.

Wings and spoilers are completely different things. Wings need to be in undisturbed air (so above the roof line is good), spoilers are simply there to break the airflow away from the body of the car (to spoil the air flow) and so need to split the air near to the body work. Hence the statement that spoilers reduce lift (by carefully managing the airflow over the rear of the car) and wings add downforce (using and aerofoil in clean air).

A spoiler will never reduce lift beyond neutral but can actually reduce drag. A wing will add drag but can apply significant actual downforce to the car.

Edited by kambites on Wednesday 10th December 08:17

[BAHN-STORMA]

Mark-C said:

How about "winglet" ?

I'm more of a breast man myself!

[RDM]

tuscan_thunder said:

911s, until the 1990s, had a rear wiper.......but no wash function.

My 2005 has this, don't know if they still do.

[youngsyr]

kambites said:

Wings and spoilers are completely different things. Wings need to be in undisturbed air (so above the roof line is good), spoilers are simply there to break the airflow away from the body of the car (to spoil the air flow) and so need to split the air near to the body work. Hence the statement that spoilers reduce lift (by carefully managing the airflow over the rear of the car) and wings add downforce (using and aerofoil in clean air).

A spoiler will never reduce lift beyond neutral but can actually reduce drag. A wing will add drag but can apply significant actual downforce to the car.

Hmmm, I think I need a crash course in aerodynamics (who'd have thought it with a car shaped like a brick!). Do you have any links to good sites that discuss it?

[kambites]

youngsyr said:

kambites said:

Wings and spoilers are completely different things. Wings need to be in undisturbed air (so above the roof line is good), spoilers are simply there to break the airflow away from the body of the car (to spoil the air flow) and so need to split the air near to the body work. Hence the statement that spoilers reduce lift (by carefully managing the airflow over the rear of the car) and wings add downforce (using and aerofoil in clean air).

A spoiler will never reduce lift beyond neutral but can actually reduce drag. A wing will add drag but can apply significant actual downforce to the car.

Hmmm, I think I need a crash course in aerodynamics (who'd have thought it with a car shaped like a brick!). Do you have any links to good sites that discuss it?

Not really. I did some basic fluid dynamics as part of my degree but to be honest, most of what I know about automotive aerodynamics comes from here, and as such is probably completely wrong.

ETA: You can get a reasonable amount of information by putting things like "spoiler" or "wing" into wikipedia. No guarantee that that is right either, of course, but it usually is.

Edited by kambites on Wednesday 10th December 12:22

[mat205125]

RDM said:

tuscan_thunder said:

911s, until the 1990s, had a rear wiper.......but no wash function.

My 2005 has this, don't know if they still do.

The angle of the 911 rear window is that shallow, that the wiper is there (i'd guess) to clear water from the window when it is raining.

On a normal hatchback or estate, the rear window is much more vertical, and the wash function is there primarily to combat the dirt and water sucked UP from the road, rather than the clean rain falling DOWN from the sky.

[pdV6]

anonymous said:

[redacted]

It's one of those things that is a legal requirement in the USA.
I guess more and more manufacturers are adding them as standard to avoid having to add them in the US market.

Even the Elise has one in the US, despite most fag packets not having opposable thumbs or the necessary intelligence to realise they want to escape from the luggage compartment...

[OJ]

kambites said:

Rear spoilers on modern FWD hatchbacks rather amuse me - of course they're commonly known for lacking rear end grip.

I experienced rear end lift in my bog standard 1.6 Focus going around a the curve of a Motorway-Motorway sliproad at... some speed once. I was on a slightly trailing throttle but I didn't expect it. Luckily I felt it coming and got back on the power before it came around big time.

At high speed especially with modest amounts of power, Aero becomes far more important than driven wheels. I suspect barely anyone drives a bog standard Focus in a manner that they might find out, but I have no doubt that's why there's a big lip spoiler on the Focus RS.

[kambites]

OJ said:

kambites said:

Rear spoilers on modern FWD hatchbacks rather amuse me - of course they're commonly known for lacking rear end grip.

I experienced rear end lift in my bog standard 1.6 Focus going around a the curve of a Motorway-Motorway sliproad at... some speed once. I was on a slightly trailing throttle but I didn't expect it. Luckily I felt it coming and got back on the power before it came around big time.

At high speed especially with modest amounts of power, Aero becomes far more important than driven wheels. I suspect barely anyone drives a bog standard Focus in a manner that they might find out, but I have no doubt that's why there's a big lip spoiler on the Focus RS.

Personally I have no doubt that the big lip spoiler on the RS is there because RS buyers expect a big lip spoiler. It certainly does nothing that a small lip spoiler wouldn't.

Edited by kambites on Wednesday 10th December 13:19

[Jgtv]

My GTV has a leaver under the wheel that raises and lowers the wheel by no more than millimeters. It is completely useless to man or beast, apart from the fact it can say it has adjustable stearing wheel.

[mat205125]

pdV6 said:

Even the Elise has one in the US, despite most fag packets not having opposable thumbs or the necessary intelligence to realise they want to escape from the luggage compartment...

Now THAT really is pointless

Car related, however not a feature on the car itself. Why do lifts in multistory car parks have braille on the buttons?

Retorical question

[OJ]

kambites said:

Personally I have no doubt that the big lip spoiler on the RS is there because RS buyers expect a big lip spoiler. It certainly does nothing that a small lip spoiler wouldn't.

Edited by kambites on Wednesday 10th December 13:19

But my car had a small lip spoiler!

[Alfanatic]

Speaking of spoilers, what about the kicked up tail on the Turbo Esprit?



According to an Evo article, the spoiler on the tail is there because Chappers insisted on it for looks and it had a negative effect on the car's aerodynamics... i.e. it is worse than useless! The lip on the top louvre above the rear window is there only to cancel the effect of the tail spoiler.

Also, has anyone mentioned the famously useless dart wing that was an option on the Countach? Apparently it did nothing but knock a dozen or so mph off the top speed.

Edited by Alfanatic on Wednesday 10th December 13:44

[kambites]

OJ said:

kambites said:

Personally I have no doubt that the big lip spoiler on the RS is there because RS buyers expect a big lip spoiler. It certainly does nothing that a small lip spoiler wouldn't.

Edited by kambites on Wednesday 10th December 13:19

But my car had a small lip spoiler!

In that case, maybe they should have sorted out the suspension. Any car will over-steer when you lift off in the right (wrong?) conditions but it shouldn't do it unpredictably.

[Zod]

mat205125 said:

Sport Coupe said:

BMW's ///M - Mode = The most pointless button !!!

It should be in that mode permanently, if you want a soft car with a bit of ooomph then by a 550i instead.

I'd argue that it is a way of having a nice gutsy cruiser with a lot of pace like a 550i for daily family use and commuting, and also a double hardcore snarling super saloon for when THAT road appears through the windscreen .... rationing the drug makes the hit all the more rewarding.

Even though I drive with the M button pressed much of the time, I still believe it is useful. I generally don't want the more aggressive throttle map, harder EDC settings and MDM traction mode around town. Having them available on a single button for the moment I hit the open road is very useful.

[Crusoe]

agree the feature is useful but maybe if it did the reverse. A button for lower power softer suspension mode that you could use in town or on the motorway so that it was in full sport spec as standard.

[youngsyr]

kambites said:

Personally I have no doubt that the big lip spoiler on the RS is there because RS buyers expect a big lip spoiler. It certainly does nothing that a small lip spoiler wouldn't.

I've heard people say the same about the Evo spoiler, but if you believe the marketing hype it does have an affect.

The standard Evo X has a low level spoiler, the uprated one has the larger spoiler more commonly associated with Evos...

[kambites]

youngsyr said:

kambites said:

Personally I have no doubt that the big lip spoiler on the RS is there because RS buyers expect a big lip spoiler. It certainly does nothing that a small lip spoiler wouldn't.

I've heard people say the same about the Evo spoiler, but if you believe the marketing hype it does have an affect.

The standard Evo X has a low level spoiler, the uprated one has the larger spoiler more commonly associated with Evos...

I don't know about the Evo, but I'd always assumed it was a proper wing. How is it mounted to the car? That's usually a good indication. If it's just bolted to the bodywork, it's for show; if it's bolted to something solid, it's probably actually doing something.

[minimoog]

Foot-operated parking brakes (yes I'm looking at you Mercedes).