The high strength and great deformability of copper-based single-crystal shape memory alloys (SCSMAs) permits the storage of mechanical energy at densities far greater than ordinary materials - up to 50 times more than steel springs. Nine percent recoverable strain at nearly constant stress enables the construction of simple machines that produce constant acceleration. One such application is a spring mechanism that can be human-transported and release sufficient mechanical energy for a soldier to carry heavy loads or jump onto a building. This paper presents one method of using SCSMA for the storage and use of mechanical energy.