A sports swing training device is attachable to a sports striking-object, such as a golf club, tennis racket, or baseball bat, and uses multiple motion sensors, including accelerometers, gyroscopes and magnetometers, in conjunction with one or more microprocessors and device displays, to measure and display various swing metrics and to project flight patterns resulting from each swing. Swing data are displayed in graphic and/or indicia format, on the device's displays and are wirelessly transmitted to the displays of one or more external devices, such as smart phones or tablet computers. The projected flight patterns reveal flaws in the swing so as to promote corrective adjustments by the athlete.