A prototype horizontal electromagnetic rail launcher has been demonstrated along with a corresponding theory. This system builds out of published work in augmented rail guns, but modifies this technology so that the motor can operate for seconds rather than milliseconds, and provide low acceleration (such as might be needed to launch an aircraft) rather than the extreme accelerations seen in the guns. The final system operates off of relatively low voltages (tens of volts), but with substantial currents. A lab bench prototype has been constructed and operated, demonstrating 13 Gs acceleration of a small 230-gram sled.
Recent breakthroughs in capacitor and MOSFET (metal-oxide-semiconductor field-effect transistor) technology, coupled with insights into the benefits that can be achieved with modified (or augmented) rail gun designs, allow a substantial shift in the operating regime of these guns. Instead of supplying 10,000 Gs for a few milliseconds to a small projectile, a few Gs of acceleration can be supplied to a large object for many seconds, allowing this technology to be used for launch assist and other applications.
This launcher operates off of relatively low-voltage dc power, yet can potentially accelerate a small aircraft at 2 to 3 Gs. The design, including both the rails and the power system, is inexpensive, simple, and rugged (as compared to linear synchronous or induction motors).
The rail motor allows low-voltage sources to be used to move potentially heavy objects. The negatives are that very high currents are required and sliding contacts are necessary, which wear down with use.
This work was done by Robert Cox, Robert Youngquist, and Stanley Starr of Kennedy Space Center. For further information, contact the Kennedy Innovative Partnerships Program Office at (321) 861-7158. Refer to KSC-13597.