For a statewide school science competition in 1988, I obtained some sample nitinol springs and attempted to build a rotating engine powered by heat differential

For a statewide school science competition in 1988, I obtained some sample nitinol springs and attempted to build a rotating engine powered by heat differentials. Unfortunately the ones they sent me were very short so I had to make a reciprocating engine instead. I remember being very disappointed at the time, but seeing the prototypes McDonell Douglas made around then leads me to believe I was on the right track.