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adjustable aerodynamics
enables cars aerodynamics to be changed at different speeds to maximise the engine efficiency | |
i've recently noticed that most cars have permanent spoilers on the backs of them. And that when driving along at high speeds these (like in the notorious TT incidents) have been proven to dramatically help to keep the cars on the road. But these spoilers actually reduce the speed of the car at lower
speeds and therefore, can really reduce the effieiency of the car at low speeds. I have also recently seen a few concepts whereby the spoilers are adjustable, so that at high speeds the angle can be increased (depending on the speed), and at low speed the spoiler might not need to be used at all. Pneumatics or hydraulics are used to lift and lower the spoilers (which are pivoted by one side on the rear of the vehicle).
Why not make the air vents or front spoilers (that bring air to the engine and keep the car firm on the road) adjustable. So when the engine is working hard on the freeway, the air vents can take in more air, to cool the engine, and the aerodynamics could also be adjusted like the spoilers, to maximise the engine efficiency and potential.
(?) Automobile wind turbine patent
http://164.195.100....um.htm&r=0&f=S&l=50
This link is to the US Patent database server script. If it doesn't work, go to the patent database and look up patent number 5287004. [Dog Ed, Jun 21 2001, last modified Oct 17 2004]
Aircraft piezoelectric applications
http://www.icase.ed...hive/v8n2/art1.html
Not quite what I was thinking of, but might provide grist for your mill. [Dog Ed, Jun 21 2001, last modified Oct 17 2004]
Brian's Riceboy Page
http://www.riceboypage.com/
'Riceboy' means people who put 'go-fast crap' on their cars... [StarChaser, Jun 21 2001, last modified Oct 17 2004]
[link]
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Like a Porsche 911 or Boxster, you mean? The 911 one comes up at 75 I think, to give more downforce at higher speeds (unlike the one on my old 911 which is permanently fixed). [sorry couldn't help dropping that one in there]. Like the idea of being able to change the angle as well though. Just need a computer to continually trim it.
Air vents on the front don't keep the car on the road though (unless it has a groundforce effect underside like the Ferrari F50). Mostly, the front spoiler is there to force the air to go over the car instead, increasing the Bernoulli effect and increasing the downforce. |
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not to mention that, for a spoiler to actually provide an appreciable amount of downforce or, rather, less up-lift, the car must be travelling at speeds that will easily net you a ticket and possibly get you your license suspended. pretty much every car on the road today with a spoiler has it for looks alone. if you want to make the car more aerodynamic, getting rid of the side view mirrors would be a big start, and reducing the frontal (or projected area) is a good second step. the front air dam prevents air from travelling underneath the car and causing it to lift off the ground. the spoiler helps to break up the airflow above the car to further reduce the bernoulli effect as mentioned by goff. the reason the beetle has one, is that it's cross-section is sufficiently wing-shaped and it's ability to lift off of the ground at speed is increased as a result, so the spoiler breaks up the airflow over the top of the car to reduce the lift potential. |
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This is more like it, hover_dude. There are some cool areas of development you might check out. At least one manufacturer of piezoelectric fibers is experimenting with electrically deformable airfoils for aircraft; the piezo fibers are embedded in a stiffly flexible sheet and the whole sheet flexes when a current is applied. There is also a patent registered for wind-turbine generating devices to be mounted at the front of a car and in the spoiler; the inventor claims that the turbines will not only generate electricity but will also work to increase aerodynamics. |
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What notorious TT incident? Isn't the 'Notorious TT' a rapper? |
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Dog Ed: What happens if those piezo-aircraft get struck by
lightning while in flight? Large-scale cramp in all the
control surfaces, a stall, and then a nice plummet to the
ground? |
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PotatoStew: I don't know. "Flight 605 was stricken by severe cramps due to flying too soon after eating..." |
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Maybe if they get the piezo
material baked we can make the
entire car dynamically
aerodynamically modifiable. |
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Just for the record, I hope I
never say "dynamically
aerodynamically modifiable" again. |
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is hover dude talking about the crashes that the Audi TT's drivers experienced when it first came out.
The TT's side view is alot like the beetle, and due to this a spoiler was needed to keep the TT's back on the road. |
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i heard about one owner in germany who was driving on the autobahn on the way back from buying his TT, and the car lost control, skidded round and wrapped round a tree.
he died. |
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so audi called all the cars back and fitted spoilers |
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I think you refer correctly, krea. The TT was what you might call a 'bit tail happy'. As is my 911, except because the engines out the back behind the rear axel, it tends to act more like a pendulum than anything else, so back off in the corner and your pirouettting like Nureyev on speed... |
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[UnaB]: Yes, that and suspension geometry. Mainly weight distribution, though. A car with a light front end and heavy rear will initially understeer (go straight when you want to turn) but when it it eventually starts turning it oversteers (back end tries to overtake front end). My Triumph Herald, Vitesse and Spitfire did the same thing when I backed off in a corner, but for the other reason. |
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[UnaBubba] Yes, mostly, but I don't find the understeer that bad - it's quite easy to balance the steer against the throttle on a dry road. And those massive rear tyres still provide quite a lot of grip. The spoiler certainly won't provide any sort of downforce unless your doing over about 80Mph, and I don't go round too many corners at that speed.
In the wet I just drive as if there were black-ice all over the road. It's the low risk option. |
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goff>The TT was what you might call a 'bit tail happy'. As is my 911, |
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unabubba> Porsches have been doing that since the 356 was released (at least all of the rear-engined Porsches I've ever been in or driven) I've not driven a 928 to see whether it was also prone to the 'demon-possessed understeer" |
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Um, isn't "tail happy" the exact opposite of understeer? I'd call a car that tended to fishtail "tail happy" -- that's oversteer. |
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Yes TickelMe (may I call you TickleMe - it's just the best first name I've ever come across). What UnaBubba is saying is that the 911 tends to understeer slightly on the turn in, but as you go through the corner (and apply the power) then oversteer is definitely it's bent. In other words, it can actually take quite alot to get the tail to go in the first place (unlike, say, a TVR) but if it does...whooaaa watch out. These things bite. |
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I think the car techno's call the Porsche 911 tendency to leave the road tailfirst "high polar moment effect." The new ones with PSM (Porsche Stability Management) are dramatically easier to maintain control in. |
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Ford produced a concept car that had a pop up spoiler once it reached a certain speed. They never made it tho. |
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The Mitsubishi 300GT has a spoiler that deploys at speed. Not sure if it's counterpart (the Dodge Stealth) has the same feature... |
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[steve degroof]: The continuously variable shape car is a very cool notion. I don't know if nitinol has enough stiffness to maintain the shape, though. Plus, isn't nitinols memory based on thermal changes? It would be hard to change the temperature to a network of nitinol "muscles' on a large enough, or granular enough scale to make it work, methinks. |
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why not rig up the tilting spoiler to steering input etc. to increase df/ reduce lift when cornering? Ok, only useful on the race track, but intriguing none the less. |
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And the new Lamborghini has extra vents that open over a certain speed/engine compartment temp. But I'll let you off that one as I think it wasn't released until after this idea. |
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Porsche Carreras have a spoiler that raises up at speeds over something like 50 mph. Jim Hall's Chaparral race cars had adjustable spoilers until they were banned- he replaced them with a fan that sucked air from under the car, which was successful until that idea was banned (actually, they used another interpretation of the "no movable airfoil" rule that banned his previous cars.) I really don't believe airfoils are effective at legal speeds in the US or most parts of Europe. A really effective aerodynamic shape for a vehicle would look something like a tadpole- a rounded snout to part the air gently, and a tapered tail to allow the air to return without creating a partial vacuum behind the vehicle. (Remove the spoilers from a mid-70s Camaro, and you have a near-ideal shape- if it goes backwards... ) Buckminster Fuller's Dymaxion car was also a good example of the ideal teardrop shape. |
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Heh. You could call this product "One Minute Rice." |
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Underpowered import car jokes aside, I like the idea of variable aerodynamics on cars that might actually make use of them. As the variable spoiler is already well baked, what about an aircraft style air-brake for emergency highspeed stops? |
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There's only a certain amount of force that tires will take before they start to slide. And after they begin sliding, it takes longer to stop. So why not make use of the massive forces that fastly moving air has against a blunt object to assist in the braking? Now, I'm not suggesting a drager-style drogue chute, but just something that might pop up like the spoiler on the 911. Now, it might not provide that much stopping power in addition to the brake. However, a few extra feet of leeway could mean the difference between disaster and merely a pair of flapspotted tires. Moreso, could this be applied to racing? Braking faster than your opponent, even by a small amount, can all add up. |
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Ideas? Comments? Should I go create a new batch and stick this baby in the oven to see if it comes out? |
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Spoilers are no good. If you want
traction it is far better to create a
vacuum under the car. It's a marketing
thing. |
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This is so baked. And for your information, spoilers are good. Where do you think Formula One cars derive the majority of their downforce from? Ground-effect downforce is better however, but it's more difficult to achieve than using a spoiler. And yes, on most production cars, spoilers are only for cosmetic value, but ground-effect. And the TT didn't crash cos it didn't have a spoiler, it crashed because the suspension was set up badly. |
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Spoilers that pop up on braking are called, oddly enough, "air brakes", and are used most notably on the Mercedes-McClaren SLR. But that car postdates this idea, I think--not that airbrakes themselves are a new idea, but their actual use is fairly new. |
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If spoilers and ram air intakes are bad, then why do WRC Subarus have them? There is something to be said for getting intake air from outside the engine compartment so you have more cold dense air. And it's definately good to have stability at high speeds, although I don't think spoilers help that much with regular highway driving. |
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[Rasberry], the Subaru WRX is a somewhat special case. The scoop on the hood is not an air intake, but instead the duct for the turbo's intercooler. The intake air comes from an entirely different location, and the hood scoop serves only to pass air over the intercooler element. |
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The spoiler/wing, on the other hand, is largely due to the WRX's rally car heritage. Being purpose built for racing, plenty of work has been put into the aerodynamics of the vehicle--and with the work done, why not sell it to the consumers too? After all, rally cars are supposed to (required to in many respects) closely resemble their road counterparts. |
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Anyway, most people don't give spoilers and wings enough credit when it comes to low speed effects. True, the downforce generated is directly proportional to speed, but vehicles do not have to be traveling exceptionally fast to derive some benefit--taking the rally racing example, it's unusual to exceed 150 km/h, but all modern rally cars are equipped with numerous wings, spoilers, and the like. Even if it's not generating significant downforce, a well designed wing can reduce drag, and more importantly wings and spoilers can eliminate aerodynamic /lift/, which many cars suffer. |
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Under vehicle suction is generally
banned in car races. That's why it's not
used. 5th - at least while flow remains
laminar, lift is proportional to speed
squared. |
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F1 cars and pro drag racers also tend to have large air scoops right on top of the engine. These people definately know what they're doing. Is it possible that this design is good for horsepower, or is it only the result of some regulations. I would think that just by scooping up cold air from outside the engine bay would help. |
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