Composite Spring Propulsion System

Expendable mine-hunting countermeasures require a propulsion system that is acoustically and magnetically quiet while being light in weight, reliable, and inexpensive. Proposed for development and demonstration is a composite spring energy storage device. Calculations show that a spring weighing only eight pounds can deliver 1/10 horsepower for three to five minutes to power a small vehicle. The spring concept provides high torque at low speeds to allow a quiet, low-speed propeller to be used. The proposed spring is made of relatively inexpensive, high-strength glass in a plastic matrix. The key to the spring is an efficient glass fiber braiding technique that provides sufficient interlaminar shear strength to allow the spring strip to develop its full potential strength in bending. The proposed project includes modeling of spring parameters, fabrication of a spring for test, and laboratory demonstration of its energy storage capacity.