Abstract: An aircraft having counter-rotating, ring-type wing rotors that are driven by engines located at the wing tips is disclosed. The aircraft incorporates large span, high aspect ratio wings that are configured in a joined-tip design to improve the structural characteristics of the wings. One of the wings counter-rotates inside the other wing to enable vertical take-off and landing. The wings may comprise elliptical shapes, each having upper and lower sections that are separated from each other.

Abstract: An aircraft having counter-rotating, ring-type wing rotors that are driven by engines located at the wing tips is disclosed. The aircraft incorporates large span, high aspect ratio wings that are configured in a joined-tip design to improve the structural characteristics of the wings. One of the wings counter-rotates inside the other wing to enable vertical take-off and landing. The wings may comprise elliptical shapes, each having upper and lower sections that are separated from each other.

Abstract: Seat structure is provided for supporting a person. An inflatable cushion is coupled to the seat structure in a position for bearing at least a part of the force exerted by the person when supported by the seat structure. A source of gas under pressure is provided for inflating the cushion. A control arrangement including a pressure sensor and a valve is coupled to the cushion and to the source for maintaining the pressure of the gas in the cushion at a given level. Also provided is a pressure release mechanism including an outlet and an outlet valve independent of the control arrangement for deflating the cushion to allow the force exerted by the person supported by the seat structure, when high acceleration forces are encountered, to be born primarily by the seat structure. In one embodiment, the pressure release mechanism is a flexible strap for compressing the cushion when the outlet valve is opened for increasing the rate of deflation.