(under subclass 4) Aeronautical machines having provision for sustentation in part or entirely by aerodynamic action on airfoils in fixed relation to the machines, having also provision for the sustention by the reaction to the downward movement of restricted masses or jets by air or other fluid, the forward propulsion of the machines may also be derived from movement of the same or similar masses or jets of air or other fluid.
SEE OR SEARCH THIS CLASS, SUBCLASS:
15, for fluid propelled aircraft.
23, for aeronautical machines sustained solely by fluid reaction.
29, for lighter-than-air craft partially sustained by fluid reaction.
73+, for fluid propulsion and sustention devices, per se.
