Half a croissant, on a plate, with a sign in front of it saying '50c'
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Dry ice afterburner

Safe. Explosive.
  [vote for,

I was pondering afterburners in the linked idea. I understand that in a jet engine, afterburners use waste heat captured in a structure after the main combustion chamber to facilitate vaporization of fuel and provide extra power.

It seems to me that one could use this to provide bursts of power for an automobile, provided that the waste heat were captured in metal associated with the exhaust, the exhaust exit point were fortified so that it could provide rocket-type thrust to the car, and precautions were taken to allow free flow of exhaust during the burst of speed - otherwise backpressure from the afterburner could prevent the free flow of exhaust and stop the main engine.

In rockets this is accomplished by adding more fuel. Fuel is volatile, and might burn if there is any oxygen left in the exhaust. Otherwise the volatile fuel burns after exiting the exhaust and reaching outside air which looks nifty but does not provide much thrust and catches things on fire.

One could add water and make a burst of steam. But it takes a lot of heat to boil water.

I propose this could be done with dry ice pellets. The pellets will quickly convert into a large amount of gas (read "explode") on contacting the heat retaining structures in the exhaust. There is no fire risk.

If there were a hinged valve which diverted exhaust during CO2 burst (pushed closed by burst back pressure and at the same time opening detour for exhaust), this would ensure normal function of the engine while CO2 was deployed.

bungston, Jul 07 2010

Steam Afterburner Steam_20afterburner
My inspiration [bungston, Jul 07 2010]

Thermite dry ice rocket Thermite_20dry_20ice_20rocket
More dry ice propulsion. [bungston, Jul 07 2010]

Junkyard Wars Jet construction http://www.qwizx.co...5/jettrike/jet.html
These images are a nice synopsis of the show. I learned a lot watching it. I had an idea that jet engines were more complicated than they are. This was a good show in that both constructions worked like they were supposed to, and the contest was close. [bungston, Jul 07 2010]


       It might work. But in my experience dry ice sits around for a while slowly sublimating (word of the day). I've never seen it vaporize anywhere near explosively... Also your understanding of afterburners seems to be slightly- how do I put this, wrong.
DIYMatt, Jul 08 2010


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