cyclopticgaze

A Jam Jar Jet Engine, Revisited

Mar 26, 2009

      A few years ago, I built a small jet engine in a jar.  It worked pretty well and snagged quite a bit of attention.  But after firing it up a handful of times, it has sat on the windowsill and collected dust.

     Now, with minimal prodding, I was cajoled into pulling the jet engine out of retirement for another burn.  So I cleared the cobwebs, blew off the dust, and once again fueled up the old jam jar jet engine.  

     I poured in a little methanol (just some of that el cheapo gas tank anti-water treatments) and cooled it off in the 'frige for about 30 minutes.  Then I put that baby on the kitchen counter.  (What?  Tile doesn't burn!)  Lit it up and BBBBRRAAAAPPPP, it burned orange and blue for a good 10 seconds.  Pretty good run!  I'd never had it burn that long.

     But I'm trying to show off here;  we can do better.  I twirled it around and covered the inner walls with fuel, hopefully filling the inside with fuel vapors.  Didn't look like it was going to run again until I stuffed the starting flame deep down in there and BBRRAAPPPPP we're going again!  . . . and going . . . aaaaaand going.  It was a beautiful show.

     15 seconds.  Not just orange and blue flames but green!  Oooh.

     30 seconds.  The flame sinks to the bottom of the jar and the tone gets lower and lower.

     60 seconds. . . . still going.

     Ok, everyone back up.  "Where's the fire extinguisher again?"

     TINK!  The glass jar breaks, shatters but stays put.  Show's over.  There's a slow flame burning up the inside of the jar as the unspent fuel burns away.

Only a few slivers of glass blew away from the jar, but cracks crept all across it.

     Minutes after the engine stopped burning, the jar was still far too hot to touch.  The dramatic temperature change was too much for the glass to handle.

Picking up the jar reveals that it's completely shattered.

     No worries:  we can rebuild!