h a l f b a k e r yCompound disinterest.
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Sometimes regular brakes don't cut it. Sometimes the emergency brake doesn't cut it. Sometimes, you need the Extreme Emergency Brake.
With a quick twist and pull of the EE Brake, the wheels of the car are jettisonned to the sides, severed by explosive bolts, and the body of the car slams to the ground,
on top of the giant flattened panel attached to the bottom of the car; made out of a steel panel coated an inch thick with the same rubber as the tire, trimmed so excess doesn't show, this provides an extreme source of friction.
The car grinds to a halt with a giant rubbery squeal, much like scuffing a giant shoe. You, with your human body able to withstand several G's without harm, climb out safely. Sure, you need new wheels and tires, but you are safe, and hopefully have insurance.
The original
The_20_22EE_22_20Brake
[DesertFox, Apr 12 2006]
[link]
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I've got to hand it to you for extreme, but my bet is it would flip and end over end down the road. |
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//...emergency brake doesn't cut it.//
Those make better brakes for parking on hills than emergencies. I fried mine to a state of permanent "on" one time while "testing" it out on a long, smooth country road. |
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Could also make for an interesting "Ben Hur" moment. |
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I was told that the San Francisco cablecars have three ways of stopping:
- they can let go of the cable
- they can brake the wheels
- the brakeman can release a rake-like device which digs into the road surface.
The last option usually results in derailment, but is more effective than mere rubber. |
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probably better to simply eject the rear wheels and keep the fronts. This should reduce the tendency to flip or spin. |
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why not shift into first and ride it out? better to rear end someone than to flip, crash, burn, and die. |
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v4.0 fire explosive retro-rocket-cannons. This also could clear the road ahead... |
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Actually that's very similar to an earlier version. |
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The problem with skidding, even if its on rubber, is that you no longer have control of the car. One of the things that they teach you in the better driving schools is that when you go into a skid the best thing to do is release the brake so that the wheels can absorb the energy of the vehicle in motion. |
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v5.0 pinch a piece of antimatter out the rear to create a gravity well *just* strong enough to alter spacetime that, relative to the object in front of you, you are no longer moving. Cleanup might be nasty. |
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Friction doesn't depend on surface area, so why bother with the enormous rubber plate? What you need to increase friction is downforce, so perhaps you could have an emergency-deployed spoiler, tuned for maximum... um, drop. |
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I'm with [normzone]. Plus, even if it does work, you're undergoing massive deceleration; unless you're plunging over a cliff, how is this different from crashing and decelerating via the crumple zones? |
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Finally, there's a law of decreasing returns in place here; the larger the surface area, the lower the pressure. Locking up small wheels will skid you to a halt; locking up massively wide wheels will stop you with a shorter skid. However, as the area increases, so the benefit decreases until a huge thick rubber plate may not be worthwhile. Fit big wheels with wide tyres instead; they'll improve the handling and you might not get into the situation in the first place. |
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[Loris] I'm glad you said that. Friction is not dependant on surface are, IF the two objects are considered (relatively) smooth, and flat, and ALSO unbreakeable. |
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If they aren't, things are different. |
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1) The rubber would actually catch on the road better with a giant rubberized plate because a small piece of rubber would wear off in milliseconds. |
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2) The giant rubber pad would provide stability; maximum ground surface area (normzone, listen up) provides maximum stability.This rubber plate, with the ejection of the wheels, LOWERS the center of gravity by a bit, adding even more stability. |
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3) [Loris] As I stated above, the friction-area thing only works for perfect solids. In reality, things compress, tear, stretch, and so on. In the real world (vs. theoretical) friction is like 2 hooks; objects grab on to each other and don't want to let go. More hooks = more friction More area = more places for hooks (or hook-ups, as parts of the objects grab onto each other). |
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I'll bun this becuase it is ludicrous and halfbaked and has tyres shooting off with explosive bolts. Bravo. |
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However, as Jscotty points out, the whole skidding thing is why it is halfbaked. Correct braking, without wheel lock, transfers the kinetic energy from the forward motion of the car onto the brake pads & shoes. The proposed brake pad will be the sole conduit for the transferral of energy and you will solely rely on the material contact. That's not good... |
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Sure, it lowers the centre of gravity slightly. However, it also applies massive force on the bottom of the car, in the opposite direction to the direction of travel. This force, multiplied by the vertical distance between the centre of gravity and the ground, gives you a torque (or moment, the two are the same). This will tend to rotate the car so that the back end lifts. When this happens, the centre of gravity will rise and the torque will increase, causing the car to flip end over end down the road. |
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What you've got is an unstable situation. In theory it might work, the whole thing sliding to a halt. In practice, the slightest upward impulse is going to flip you over, because the forces you're playing with are so large. Unless your road is utterly, mathematically, theoretically flat you're stuffed. |
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Ditch the explosive tires, too much danger of killing someone. Imagine a big pile up with many cars involved tires flying everywhere. Getting your tires and rims back would be like a bad sock hop.
Cover the skid plate with 3" to 4" of tire type rubber, then replace part of the suspention with the air ride like in a low rider, in a fast stop sensors drop the car in to contact with the pad, and like ABS it pulses the contact between full and reduced till you stop, once the car realizes you stopped the bags reinflate and off you drive.
Down side if it ever wore out like things do on cars that would be a pain, all the sudden BOOMM scrraaaape...now really have to drag your car home. |
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I believe this was inadvertently attempted here in the states by the Ford motor comany by means of Firestone tires and their own "Explorer" model. But perhaps with some less than satisfactory results. |
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Actually, what I said above was, of course, incorrect - even on a mathematically flat road, there's still a strong net overturning moment, so you'll flip whether there are imperfections in the surface or not. |
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And as for friction being "like hooks" in real life, well, no, not quite. It's more like lots of spikes. Having more area gives you more spikes and hence more grip. However, you've only got the weight of the car to push the spikes into the road surface; the more spikes, the less strongly each individual spike will grip. Having twice as much surface area will give you more grip, but not twice as much grip. |
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Yes, but in reality, 100 little spikes is a lot less likely to tear up the opposing object as compared to one giant spike. |
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The giant spike would tear a hole through the other object, creating less friction. |
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I know of the friction - area law; scientific laws tend to deal with ideals. I'm trying to focus on the "It wont wear away as fast as a 1cmx1cm patch of rubber, and won't tear up the road" part. |
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How often do cars burst tyres through excessive wear when performing an emergency stop? |
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How are you going to avoid flipping the car? It's a direct physical consequence of the rate of deceleration being too high. |
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//Friction doesn't depend on surface area// bullshit. |
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Friction doesn't depend on bullshit?
How come halfbakers' cars stop almost instantaneously then? |
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// How come halfbakers' cars stop almost instantaneously then?// |
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Must have hit a custard filled speedbump, duh! |
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