Propellerless aerial gun turrets that could fly straight up at 70 miles an hour, are proposed by a California aircraft inventor-as a novel means of air defense. Already his “flying mushrooms” have proved satisfactory in scale-model form and a full-scale demonstration is being planned. The top of the “mushroom” is a circular wing, its outer circumference the thin “trailing” edge. The “leading” edge surrounds a central hole, a conical pit into which air is drawn down by powerful blowers and then discharged radially over the upper surface of the wing. This creates lift just as it is created in a conventional airplane. Movable control vanes on the wing surface would prevent the craft from spinning and would facilitate maneuvering it. By proper manipulation it could be made to travel horizontally as well as vertically, dodging attacking aircraft. The stem of the “mushroom” would house a crew of three or four men and a battery of 37-millimeter or even larger guns, firing at the enemy through portholes in the armored wall. Efficiency claimed for the design is so high that an ordinary automobile engine could power the blower to lift the loaded aerial gun turret and its crew. For even higher efficiency the inventor, Charles H. Roberts, who is president of an aviation engine company at Burbank, Calif., has designed an air-cooled rotary engine with but three moving parts, the opposed pistons being connected rigidly by means of a Scotch yoke. The engine weighs about one pound per horsepower. Each cylinder has a pre-compression compartment where the fuel charge is compressed, similar to the operation of a displacement-type supercharger. The design is said to be practical up to 150-horsepower, above which the moving mass becomes unwieldy. A swarm of “flying mushrooms” could be shot into the air at the moment an air raid alarm is given, to flood the sky above any fortress or defense factory with antiaircraft shells. Each turret, too, could suspend wires that would form a dangerous fence against the invading planes. Mr. Roberts was an aerial gunner in the world war.