Northrop Grumman Systems Corporation

Kyle M Rahrig

Barnaby S Wainfan

Geoffrey S Sommer

Jonathon J Linch

An extremely quiet short take-off and landing (STOL) aircraft includes: two wings, wherein each wing comprises an engine system; a fuselage structurally connected to each wing; and a ducted fan thruster positioned on the fuselage in an orientation that is rotated relative to the typical orientation on a helicopter. An extremely quiet STOL aircraft includes: two wings, wherein each wing comprises an engine system; a fuselage structurally connected to each wing; channel shrouds surrounding at least one of the engine systems; and a ducted fan thruster positioned on the fuselage. An extremely quiet STOL aircraft includes: two wings, wherein each wing comprises an engine system, the engine system comprising two engine dual packs; a fuselage structurally connected to each wing; and a ducted fan thruster positioned on the fuselage.

Extremely quiet short take-off and landing (STOL) aircraft

An aircraft has a small high-speed propeller used during take-off, climbing and landing maneuvers, and a large collapsible or foldable propeller used for loitering. The large collapsible or foldable propeller is kept in a folded configuration during take-offs and landings to minimize drag and to avoid ground strikes. During loitering operations, the large collapsible propeller is unfolded and used at a lower rotational speed than the smaller high-speed propeller to permit efficient and quite loitering. During loitering operations, the smaller high-speed propeller may be disengaged so as to spin freely or held in a non-rotational position. One or more foldable propellers may be paired with at least one conventional propeller. The propellers may be arranged as twin tractor, tractor-pusher, or nearly any other type of layout on the fuselage or wings, or on pods of the fuselage or wings.

Collapsible large diameter propeller for quiet aircraft

A propeller includes a hub coaxially surrounding a longitudinal axis. A ring shroud coaxially surrounds the longitudinal axis and is spaced radially from the hub. At least one propeller blade is fixedly attached to both the hub and ring shroud and extends radially therebetween for mutual rotation therewith. At least one stub blade has a first stub end radially spaced from a second stub end. The first stub end is fixedly attached to a selected one of the hub and ring shroud. The second stub end is cantilevered from the first stub end and is radially interposed between the first stub end and the selected one of the hub and ring shroud.

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El Segundo, CA, United States of America

Kyle M Rahrig