Nitinol Memory Metal Heat Engine - Nitinol Wire Stirling Engine

This fully assembled Memory Metal Heat Engine demonstrates the conversion of heat energy into mechanical energy. This simple Nitinol Wire Heat Engine is constructed of a boomerang shaped clear acrylic holder with two high quality cast aluminum pulleys. The pulleys feature ball bearing construction for fluid movement. Simply immerse the leading edge of the smaller pulley into an 45 - 90 Degree Celsius water bath, give the larger wheel a gentle spin and watch it fly! These engines will work in either direction. This engine really moves, easily topping 500 RPM! ----SPECIFICATIONS---- Overall Length: 8" / 20cm Thickness: @ 1" / 25mm Weight: 4 oz. Minimum Operating Temperature (Starting Temperature May be Higher): 45 Deg. C Maximum Operating Temperature: 90 Deg. C ----CONCEPT---- This ingenious memory metal engine exploits a property of the Nitinol metal alloy that makes it want to return to the shape it was originally formed in when produced. This property of Nitinol alloy is known as the "memory effect". Nitinol wire is produced in straight lengths at a temperature of @600 Degrees Celsius. After it is allowed to cool, it is manually deformed and joined into a closed loop and positioned around the pulleys. When submerged into hot water (@ 80 Degrees C), the Nitinol wire tries to return to its original straight shape. The Nitinol exerts torque on the lower (smaller) wheel as it tries (in vein) to return to its original shape. This torque spins the lower wheel, and more Nitinol is drawn into the hot water. The other side of the loop is cooled by the air which momentarily relaxes the wire as it passes around the smaller pulley. The process will repeat as long as the water remains warm enough.