A projectile launcher includes an acceleration rail with an accelerator mounted on opposite sides of the rail. Each accelerator includes an elastomeric energy generator having an end that is held stationary, while another end is connected to a string. This string then passes over a series of pulleys and crosses over the rail into the other accelerator. Thus, both accelerators act on the same string. In operation, as the string is pulled back and engaged with the projectile on the acceleration rail, the elastomeric drives are stretched. Also, each series of pulleys effectively causes a velocity multiplication that enhances the momentum of the projectile when it is launched.