A computing system for an unducted rotor engine with a variable pitch vane assembly in aerodynamic relationship with an unducted rotor assembly, including a sensor-based controller configured to execute a first set of operations and a model-based controller configured to execute a second set of operations. The first set of operations includes obtaining a first signal corresponding to a commanded low spool speed; obtaining a second signal indicative of a pitch angle corresponding to thrust output from the unducted rotor assembly and variable pitch vane assembly; generating a pitch feedback signal corresponding to a commanded adjustment to the pitch angle based at least on one or both of a variable blade pitch angle or a variable vane pitch angle. The second set of operations include obtaining a desired thrust output via a throttle input; determining, at least via a power management block, a commanded thrust output signal; receiving the commanded thrust output signal; and generating an output signal.

A propulsion system is provided, the propulsion system including a variable pitch rotor assembly including a plurality of blades coupled to a disk. The plurality of blades includes a first blade configured to articulate a first blade pitch separately from a second blade configured to articulate a second blade pitch. A vane assembly is positioned in aerodynamic relationship with the variable pitch rotor assembly. A core engine including a high speed spool and a low speed spool, wherein the low speed spool is operably coupled to the rotor assembly. One or more controllers is configured to execute operations. The operations include articulating the first blade of the rotor assembly, wherein articulating the first blade alters the first blade pitch, and articulating the second blade of the rotor assembly, wherein articulating the second blade alters the second blade pitch.

A method is provided of operating a single unducted rotor engine, the single unducted rotor engine comprising a single stage of unducted rotor blades. The method includes operating the single unducted rotor engine to define a flight speed, V.sub.0, in a length unit per second and an angular speed, n, in revolutions per second, the single stage of unducted rotor blades defining a diameter, D, in the length unit; wherein operating the single unducted rotor engine comprises operating the single unducted rotor engine to define an advance ratio greater than 3.8 while operating the single unducted rotor engine at a net efficiency of at least 0.8, the advance ratio defined by the equation V.sub.0/(nD).

A system for removing heat from an aircraft component includes: an aircraft component; a heat exchanger in proximity to the aircraft component and having an inlet, an outlet, and an internal surface coated with a catalyst; a source of hydrocarbon fuel in fluid communication with the inlet of the heat exchanger; a source of oxygen in fluid communication with the inlet of the heat exchanger; and a distribution system for receiving reformed hydrocarbon fuel from the heat exchanger. A method of removing heat from an aircraft component includes the steps of: providing a heat exchanger in proximity to an aircraft component, the heat exchanger being in fluid communication with a source of hydrocarbon fuel and a source of water and having an internal surface coated with a catalyst; introducing a hydrocarbon fuel into the heat exchanger; introducing oxygen into the heat exchanger; contacting the hydrocarbon fuel with the catalyst; and cracking the hydrocarbon fuel to form a reformed hydrocarbon fuel and remove heat from the aircraft component.

A system for removing heat from an aircraft component includes: an aircraft component; a heat exchanger in proximity to the aircraft component and having an inlet, an outlet, and an internal surface coated with a catalyst; a source of hydrocarbon fuel in fluid communication with the inlet of the heat exchanger; a source of oxygen in fluid communication with the inlet of the heat exchanger; and a distribution system for receiving reformed hydrocarbon fuel from the heat exchanger. A method of removing heat from an aircraft component includes the steps of: providing a heat exchanger in proximity to an aircraft component, the heat exchanger being in fluid communication with a source of hydrocarbon fuel and a source of water and having an internal surface coated with a catalyst; introducing a hydrocarbon fuel into the heat exchanger; introducing oxygen into the heat exchanger; contacting the hydrocarbon fuel with the catalyst; and cracking the hydrocarbon fuel to form a reformed hydrocarbon fuel and remove heat from the aircraft component.

A propulsion system is provided, the propulsion system including a rotor assembly configured to rotate relative to the engine centerline axis, and wherein one or more blades of the rotor assembly are configured to rotate along a blade pitch angle axis. A vane assembly is positioned in aerodynamic relationship with the rotor assembly. The vane assembly includes one or more vanes, wherein each vane includes a vane pitch angle. A controller is configured to execute operations, the operations including moving each blade to a reverse thrust position about its respective blade pitch axis, and adjusting each vane about its respective vane pitch axis when the plurality of blades is in the reverse thrust position to modify an amount of reverse thrust generated by the propulsion system.

An integrated heat shield which encloses a frame structure comprises a leading edge component, a left side component, a right side component, an optionally top component, an optional bottom component and an optional trailing edge subassembly, wherein the leading edge component and the left and right side components are directly, integrally co-cured on the frame structure while in a B-stage. The leading edge component and the left and right side components are shingle laminated to form ply angles to air flow. The leading edge component and the side components are scarf-jointed or step-jointed. The side components and trailing edge subassembly are also scarf jointed or step-jointed. The co-curing as well as the scarf or step joints makes the heat shield an integrated assembly. A method of manufacturing the integrated heat shield is further introduced.

An integrated heat shield which encloses a frame structure comprises a leading edge component, a left side component, a right side component, an optionally top component, an optional bottom component and an optional trailing edge subassembly, wherein the leading edge component and the left and right side components are directly, integrally co-cured on the frame structure while in a B-stage. The leading edge component and the left and right side components are shingle laminated to form ply angles to air flow. The leading edge component and the side components are scarf-jointed or step-jointed. The side components and trailing edge subassembly are also scarf jointed or step-jointed. The co-curing as well as the scarf or step joints makes the heat shield an integrated assembly. A method of manufacturing the integrated heat shield is further introduced.

An aircraft structure, comprising a heat shield including. The heat shield includes an interior; a skin enclosing the interior; a plurality of barriers attached in the interior to the skin, each of the barriers spaced to separate a plurality of thermal insulation layers disposed in the interior; and wherein the barriers suppress heat flow between the thermal insulation layers.

An aircraft structure, comprising a heat shield including. The heat shield includes an interior; a skin enclosing the interior; a plurality of barriers attached in the interior to the skin, each of the barriers spaced to separate a plurality of thermal insulation layers disposed in the interior; and wherein the barriers suppress heat flow between the thermal insulation layers.