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Car Thrust Reversers 2

 Use energy stored in high-pressure tanks to help you stop.
 
(+2, -2) 		  [vote for,
against]

This is a variation of Ford's idea to compress gas as a means to store up braking energy to use for later kick-ass acceleration.

You have braking and/or the engine maintain (with compressors) two tanks at 5000 psi, stored in the trunk.

When you brake hard, that 5000 psi is vented forward, through tubes to give you backward thrust, helping you stop quickly.

—lumpy, Mar 10 2002

(?) FInd Lumpy's Car http://bz.pair.com/fun/lumpysCar.jpg
[bristolz, Mar 10 2002]

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       How much would this assembly weigh?
—phoenix, Mar 10 2002
   

       Bristolz! How did you put such a thing together so fast??? hahahahhaa.   

       You must think I'm quite a fanatic. :)
—lumpy, Mar 10 2002
   

       [bristolz] Brilliant picture - far more entertaining than lumpy's last couple of ideas.
—cp, Mar 10 2002
   

       cp: Not that I'm trying to be entertaining, but let's see you do better. At least I submit ideas.
—lumpy, Mar 10 2002
   

       Fair enough. "I may not know much about ideas, but I know what I like."
—cp, Mar 10 2002
   

       Lumpy - With all that clobber, you'd probably be better using your braking system as the engine, & the engine as a brake.
—stupop, Mar 11 2002
   

       [bristolz] Nice trees in the background too. I'm worried about how much free time you seem to have...
—hippo, Mar 11 2002
   

       phipo... It's not a free-time issue. She's just that fast.
—waugsqueke, Mar 11 2002
   

       UnaBubba: If Ford can do it, why can't I? Maybe you'd just have a pressure release valve when a rear-end impact is sensed so you don't have carbon-fiber shrapnel.
—lumpy, Mar 11 2002
   

       For those who like numbers, I've done some math, for 60 mph to 0 stopping..   

       -For an average car, 600 lbs additional backward thrust results in stopping distance reduction of 21% dry, 34% wet, 52% on snow.   

       -For an average car, 1200 lbs additional backward thrust results in stopping distance reduction of 35% dry, 51% wet, 68% on snow.   

       (body air-drag neglected & no ABS)
—lumpy, Mar 11 2002
   

       What about just a big, rubber foot that extends down to the ground in emergency stopping situations?
—RayfordSteele, Mar 12 2002
   

       hippo: you worry too much.
—bristolz, Mar 14 2002
   

       at 5000 psi, how big would a tank have to be significantly reduce the stopping distance of a vehicle?   

       say producing 600 lbs thrust for 10 seconds?
—ferd77, Sep 07 2002
   

       Goodness, Bristolz, I expected a bloke for some reason (no offence) - quite the artist, aren't we?
—NickTheGreat, Sep 09 2002
   

       Nice idea, using jet thrust to stop a car to get over the 1G braking limit. You need reaction mass to generate thrust however. Air is too low density, vent 5000psi of air and you waste all the energy. Now, use that air pressure to blow 100kg of water forward at 300m/s and you can stop the car in less than a second. Similar to my tiresome exposition in "Catapult to Work".   

       Other ideas for reaction mass: * Front seat passenger (Noble Sacrifice feature) * Contents of glove box * Contents of petrol tank* Whole front of car forward of bulkhead   

       BTW much better way to store that sort of energy for a single use is chemical, as explosive. So this idea is asymptoting towards an explosive charge that blows the front of the car forwards. Combine with serious airbags and you might get 5G decceleration for what's left. Unfortunately the poor pedestrian/other vehicle/elk gets hit by the front of your vehicle travelling at 200 mph.
—shameless_self_reference, Sep 09 2002
   

       // an explosive charge that blows the front of the car forwards //   

       Reactive armour is Baked ..... you could eject the entire engine block forward using pyrotechnic gas generators, it's a significant proportion of the vehicle's mass. Use explosive bolts to detach the engine mountings, then fire the thrusters. Orica make suitable pyrotechnic actuators. Only provides thrust along the centre of the vehicle so tricky if you're cornering.   

       NB: conservation of momentum means that if you're stopping the car by this method, the engine is going to fly forward a LOT faster than the vehicle was initially travelling. That's a good argument for liquid as reaction mass - although consider the damage produced by an EOD water disruptor unit .....   

       Hmmm.
—8th of 7, Sep 10 2002
   

       Pyrotechnic actuators, those sound like serious toys for serious boys.   

       Disruptors' useful action is at extremely short range (<1 metre?). Water ejected at 200m/s or so has a natural tendency to break up into droplets and disperse into an aerosol. Can't think offhand though where there is an example of this.   

       The requirement for a large water reservoir could be met by caravanettes/mobile homes, but then the coupling between chassis the bodywork in them may not be strong enough for 5g.   

       One consideration: this device has to be capable of variable impluse. You don't want to end up going backwards at 50mph cause you stopped from only 20mph rather than 70mph. If you're using pyrotechnics, you need a fast acting vent valve to dissipate the gas once you've stopped, or a shutoff on the water jet.
—shameless_self_reference, Sep 10 2002
   

       RayfordSteel; you-da-man.
—wst, Apr 30 2003
   

       [Bris], one day' I'm gonna offer you an air ticket to come and teach my kids how to draw.
—FloridaManatee, May 01 2003
   

       First class?
—bristolz, May 01 2003
   


 

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