This is for high speed car chases. Fast moving cars need oxygen to burn gas. I propose that a compressed gas bomb could be deployed so as to remove the oxygen necessary for internal combustion, killing to car engine. Any non-oxygen gas could be used for this: CO2 or N2 for example. The bomb would be deployed in front of the speeding car, perhaps launched there from a cannon or placed ahead and remotely deployed like a roadside bomb. The air intake of the car would not get enough oxygen or so I assert. When the engine died, the driver would not lose control of the car, making it a safer way of stopping than spikes / tire destruction, physical restraint.
The driver himself has a supply of oxygen in the vehicle cab air and so would not be put at great risk by the gas cloud. In the event that the driver did have a lack of oxygen and passed out, he would be rescued by pursuing law enforcement personnel.-- bungston, Aug 24 2009 Insert reserve compressed oxygen tank to thwart inert gasses of policefolk. May also help cure drunkenness before driving.-- daseva, Aug 24 2009 Number numbers numbers.
Car is doing, say, 100mph. Let's assume that it can coast quite happily for 10 seconds after the engine cuts out, before it has slowed down sufficiently for the police to intervene (say, to 50mph). That means it will have to travel for about 300 metres through the gas cloud. If the cloud is any smaller, the car will coast through it, come out the other side doing 50+mph and then restart.
So, we need to create a hemisphere of gas 300m in diameter. That's about 7 million cubic metres of gas. If we use, say, nitrogen, that is 7,000 TONS of gas.
Therefore, it seems pointless to worry about the other problems inherent in rapidly displacing a 300m hemisphere of air.
Always, always do a little sum before posting.-- MaxwellBuchanan, Aug 24 2009 I assumed one could not restart a car coasting at 50 mph. Can it be done? Assume an automatic transmission.-- bungston, Aug 24 2009 the tranny will automatically move into top gear when the engine's rpm drops way down *and* the clutch will unlock... so I don't think an auto tranny car can be bump-started at all unless you've hotwired the engine computer.-- FlyingToaster, Aug 25 2009 the Mythbusters once tried attaching CO2-extinguishers to the front of a speeding car, to stop the motor through lack of oxgen... a less than successful venture. And if the baddy makes his getaway in a Prius...-- loonquawl, Aug 25 2009 If the baddy makes his getaway in a Prius, you should have no problem jogging after him, opening the driver's side door, and hauling him out of his seat before he ever gets a chance to get up to speed.-- kaz, Aug 25 2009 "...I don't think an auto tranny car can be bump-started..." Shift the car into neutral, start it, shift back into drive.-- phoenix, Aug 25 2009 Why would an automatic transmission 'de-clutch' at speed? While the engine is still coupled to the wheels, it is kept spinning at high rpm.
Only when the car's speed drops so low that the engine approaches idle rpm will the drive disengage.
If this were not the case, automatic transmission cars would have no engine braking whatsoever.
Does your engine rpm drop to idle when you lift off at 50MPH?
All that aside, rather than try to asphyxiate the engine, why not try to poisin it?
Modern vehicles with catalytic converters and Llambda sensors are certainly sensetive to fuel additives. Is there perhaps a gas or vapourised fluid which could upset the system enough to stop or severely slow the engine?-- Twizz, Aug 25 2009 /poison it/ I was thinking of something like cyanide, which poisons oxidative respiration. I worry that anything which could poison combustion would be very tough on the driver.
Re fuel/air explosive - I imagine that tanks get things like these dropped on them. Does it kill the engine?-- bungston, Aug 25 2009 // why not try to poisin it//sp. "poisson" Yes, drop loads of fish on them.-- AbsintheWithoutLeave, Aug 25 2009 Ok twizz, i'll answer your questions....
Very basic description: With an automatic transmission you dont have a direct engagement between the engine and the trans. they connect through a stall converter, this is essentially two sets of propellers next to each other submerged in trans fluid. when the engine spins, it circulates the liquid and the liquid makes the second set of blades turn. however it is mostly a one way transfer, an example of this is say you are driving at 40mph and you turn off the engine while in gear, two things happen, 1. the car slows down from tire friction and the inefficiency of most transmissions to turn frictionless, and 2. the engine stops cold. so here you are gliding along in drive at 40mph but the engine isnt spinning. thats why you cant push start an automatic, i've tried just for spite at 30mph being pushed and it wont engage. you have to shift to neutral carefully (dont want it in park at 50mph trust me it make a horrendous noise!) and turn the key for the starter. then put in drive again-- Arcanus, Jan 29 2010 arcanus that is completely wrong. Reason why you cannot roll start a slush box has to do with the the position of the oil pump inside the transmission. Due to the need for hydraulic pressure to engage the bands on the planetary gear set even if the selector is placed in D the 1-R band will not be actuated. Without this band (or another gear range) selected the engine receives no torque from the drive wheels. All you have done by taking it out of park is disable the locking action of the transmission. It is still in neutral and will not be able to be put into any gear until there is pressure in the control circuit which will not happen until the torque converter and oil pump are spun (by the engine). There are designs that include a front and a rear pump allowing a fail safe operation and there are other obscure exceptions to this rule but it holds true for 99% of all automatic transmissions.-- WcW, Jan 30 2010 Did you let off a gas bomb somewhere and then approximate it here?-- rcarty, Jan 30 2010 random, halfbakery