h a l f b a k e r yOn the one hand, true. On the other hand, bollocks.
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NASCAR vehicles have roof flaps that flip up when the car spins past 90 degrees of the direction of travel. This avoids the reverse aerodynamics of the body from picking the car up and flinging it into the stands.
I propose forward-facing flaps that flip out from the rear quarter panels and back
end of the roof whenever the ABS system engages. Active ABS pretty much means the braking conditions aren't optimal anyway. The added drag would help slow the vehicle and get it back under control. When the ABS disengages, the flaps would fold back in for normal operation.
Sbarro Robur
http://perso.club-i.../Sbarroroburgb.html
'Brakes are ventilated disks, assisted by an ... air brake !' [angel, Nov 20 2001, last modified Oct 21 2004]
(?) Gyrocars
http://www.dself.de...yrocars/gyrocar.htm
[angel, Nov 30 2001, last modified Oct 21 2004]
Mercedes-Benz 300SLR
http://dhost.info/t...00slr/55300slr.html
The upper two photos show the version with the air brake [Ned_Ludd, Feb 20 2008]
Knight Rider
http://en.wikipedia.org/wiki/Knight_Rider
[jhomrighaus, Feb 20 2008]
[link]
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and the flaps successfully clipping that pedestrian you were braking so hard to avoid |
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We're not talking wings here [bristolz]! If the flaps get 'em, the car would have anyway. |
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Ok, okay . . . well, how much area were you talking about extending? |
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The NASCAR flaps are 8" (high) by 20" (wide), so that would be a place to start. I figure a private automobile could dedicate more surface area to flaps than a NASCAR car can, so maybe they can be lower in profile. |
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Since it's just you and me, want to get together at StarGaps and discuss this over coffee? |
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Those roof flaps are, as you said, to adjust the car's aerodynamics, not to add much in the way of braking. Without a full-blown parachute, aerobraking won't make much of a difference. You'd be better off with some kind of system that releases a heavy concrete anchor onto the road, attached to the car with a chain... |
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The StarGaps in Barnes and GapBucks? |
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The cars that Porsche raced at Le Mans in the fifties had retractable air brakes. |
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UnaBubba: I always thought if a motorcyclist needed to stop suddenly, he could always just open his jacket and stretch it out like a sail. You could manufacture special jackets with extra cloth that deployed in an emergency. Also handy if you ride your moped off a cliff. |
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I rode my roomie's motorcycle a bit in college and whenever I would put my chest on the gas tank JohnnyRacer style and ride at incredible speeds then raise my chest a la the chest sail you've been discussing [here's the point, finally-->] my ears would hurt from the force and I would feel all discombobulated. Did I just have a shitty helmet that let too much air in or do you other guys just deal with the pain in pursuit of ever more efficient air-braking? |
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Acoustic guitars act as brakes also, catching the air inside them, seeing as how they're hollow and all, even more so if a string snaps while you're playing it and wraps itself around a road-sign, causing your bike to make a sharp left off the mountain at 150 miles an hour sideways and 500 feet straight down. |
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Let's just say I was in a bit of a pickle... |
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And I didn't want a pickle. |
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"Did not make" as in "didn't fall down" or as in "Motorcycle, cheap. Slightly used. Bring your own dustpan." |
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My father told me about a friend's son, who went biking after having a long discussion with his friend Jack Daniels, who told him that he didn't need leathers...Busted, skidded along the road, broke his leg and sanded six inches off the femur. |
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My eyes watered for a week. |
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It's off my topic, but who wants to post "Gyroscopes for motorcycles"? |
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Motorcycles already have gyroscopes; the wheels. |
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(Still off my topic) Yes but their axis is pointed in the wrong direction to take advantage of procession to keep the vehicle upright which is the point of someone else's idea. |
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Also off your topic, see link for stuff on gyroscopically stabilized cars. |
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(Still off my topic) Why? |
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Thought you might be interested. It mentions using the gyro to control leaning. (Feel free to delete this lot.) |
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(Still off my topic) Ah, yes. Very interesting. |
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Incidentally, 'precession'. |
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Thanks [angel]. I'll leave the error and your annotation. |
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Ok, you've convinced me to modify the 2003 car I just bought. I'm willing to hacksaw the roof, and use hydraulics to push it vertical for aerodynamic breaking. |
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Its 6 foot by 5 ( 30 sq feet ? ) so at 80 mph when I deploy the 30 sq foot brake how much deceleration will
I experience, and how much quicker will my stopping distance be? Its 312 feet currently. |
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Also, if I dont go totally vertical with it, couldnt the
resulting downforce be benifical for breaking?
( especially if it was centered closer to rear wheels which normally do little braking in panic situation ) |
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If I knew, I'd tell you. Unfortunately though, I haven't yet got that far into AS Physics. Come back in June and I'll have it sorted. Probably. |
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There's an easy way to find out. Someone with a convertible that closes/opens electrically get their car up to 80mph and open the roof. |
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the new porshe that is out has a retractable wing. it come out when it is going at high speed. |
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for the downforce to be optimised, just place some wings angled downwards over the rear spoiler and front spoiler, which give the car extra downforce when it is needed. extra downforce increaces the weight of the car, and thus enable the force on the tyres and road to ge increaces, resulting in a shortened breaking distance. this effect works to a lesser extent at low speeds (30 mph). but if you drive over the limit like me, then the aerodynamic effect would be greater, sure, you would stop in a longer time than 30 mph, but you would stop faster than someone else at 50 mph without the wings. |
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alternativly, angle the wings upward, and fly over the object you wish to avoid. |
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Oooh oooh ooh! I had a similar idea last night! I should have known that it'd have already been thought of, and checked in here. |
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I don't think it'd have much use on your average soccermommobile, but for cars that actually do use their aerodynamics, it'd probably come in handy. In racing, being able to be the last one to begin decelerating into a corner, means that you gain a tiny bit on your competitors on each curve. By creating even a slight increase in the rate of deceleration, and keeping a high rate of speed longer than everyone else, you could win the race. I like. |
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I once transported an airplane wing on top of a car. I lashed it down on the roof rack with one end projecting forward about as far as the front bumper. The drag on the car was great because this wing interfered with air going over the car. The pressure on the underside of this wing would also take weight off the wheels to some degree. Perhaps a scheme in which a rigid panel would project forward would serve as an aero brake for cars. It would be most effective on sports or sporty cars where more of the air goes over the car. |
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I designed airbrakes for my luge board....I like this idea - even if it added little to braking, it would be a visual alert that things were changing ahead of you - have lights underneath them. |
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The Mclaren F1 (Tho road car not the race car) has a roof flap the extends to the vertical position under braking to help slow the car. |
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The Bugatti Veyron also has an air-brake, said to apply the same amount of braking force as an ordinary saloon car's wheel brakes. |
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Mercedes-Benz 300SLR, Stirling Moss in the 1955 Mille Miglia, if I'm not mistaken. |
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Aerobraking was one of the features installed on the car KITT on the television show Knight Rider back in 1986(link), this is an old idea to be sure. |
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only worthy at high speed, and you may want to use it before ABS kick in |
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