Abstract: A projectile accelerator using reversed magnetic fields to accelerate a cylindrical projectile. The magnetic slingshot (MSA) includes an outer coil which produces a magnetic field within itself and a coaxial inner cylinder with breakable contacts, called a flux reverser. The magnetic field produced by the outer coil is suddenly reversed, trapping the original magnetic field within the flux reverser and storing magnetic energy in the form of magnetic flux lines that curve around the aft end of the projectile, which fits just inside the flux reverser. The stored magnetic field interacts with azimuthal currents, causing an accelerating force along the axis of the coil. A contact in the flux reverser opens aas the projectile passes, allowing the flux lines to closely trail the accelerating projectile and maintaining an imbalance in the accelerating force.