Abstract: Portable solar heater structure comprising a substantially rectangular frame having a back with openings therethrough for permitting air to be drawn into the solar heater, a layer of insulating material in contact with the back, a plurality of cup-shaped solar collectors open toward the front of the solar heater structure positioned adjacent the insulating material, a cover over the front of the solar heater having openings therein adjacent the top thereof through which air heated by the solar heater is passed and a passage between the openings in the back and cover of the solar heater through which relatively cool air is drawn through the openings in the back over the collectors to be heated for subsequent withdrawal through the openings in the cover.

Abstract: A sprocket designed to drive chains in power transmission systems, which is characterized by a tooth profile having clearance, loading, and topping curves tailored to a selected chain barrel diameter and chain pitch, a selected pressure angle compatible with minimum stress on each engaged tooth of the sprocket, and a continuously curving tooth profile also contributing to the minimizing of stresses.