An air inlet for a flight vehicle engine includes at least one fin, at least partially upstream of a throat of the engine. The fin protrudes into a flow channel, extending beyond a boundary layer into the main airstream in the inlet. The fin causes mixing in the flow, bringing high-momentum flow into areas of the flow channel containing low-momentum flow by aggregating the boundary layer and causing it to lift from the surface. The fin may have a width and/or height that varies along its length in the flow direction, which may allow it to shape the flow around it in predictable ways, without resulting in excessive drag.

Systems and methods for expanding an operating speed range of a high speed flight vehicle include providing an engine with an inlet air duct, and positioning a heat exchanger in the inlet air duct to cool at least a portion of duct air flow associated with an engine core. Additionally or alternatively, a nozzle assembly includes a cowl fluidly communicating with the engine and having a cowl internal surface defining a cowl orifice, and a plug defines a primary thrust surface. The plug is supported relative to the cowl so that a portion of the primary thrust surface is disposed within the cowl orifice to define a throat therebetween. An actuator is coupled to at least one of the cowl or the plug, and is configured to generate relative movement between the cowl and the plug, thereby to modify the throat.

An aerospace vehicle including: a body, wherein the body is configured to generate heat during operation; a coating disposed over at least a portion of the body, the coating being configured to shift a frequency of at least one wavelength of the heat generated by the body from a first frequency to a second frequency having higher transmissivity relative to a neighboring medium surrounding the body as compared to the first frequency.

A dual flow path exhaust assembly for use with a combined turbofan and ramjet engine includes a turbofan engine exhaust duct, a ramjet engine exhaust duct, a combined outlet, and door configured to move between an open position and a closed position to selectively isolate the turbofan engine exhaust duct from the combined outlet.

An assembly for an aircraft propulsion system includes a variable area inlet with a fixed structure and a moveable structure. The variable area inlet is configured to open and close an airflow inlet passage into the aircraft propulsion system. The moveable structure is configured to move axially along a centerline between an aft position and a forward position. The moveable structure includes an inlet lip structure and a deflector. When the moveable structure is in the aft position, the airflow inlet passage is closed, and the deflector is at least partially recessed into the fixed structure. When the moveable structure is in the forward position, the airflow inlet passage is opened axially between an aft end of the inlet lip structure and a forward end of the fixed structure, and a forward end of the deflector is disposed axially at the forward end of the fixed structure.

A high efficiency hydrogen fuel system for an aircraft at high altitude which utilizes compressors to compress air to a sufficiently high pressure for the fuel cell. Liquid hydrogen is compressed and then utilized in heat exchangers to cool the compressed air, maintaining the air at a temperature low enough for the fuel cell. The hydrogen is also used to cool the fuel cell as it is also depressurized prior to its entry in the fuel cell cycle. A water condensation system allows for water removal from the airstream to reduce impacts to the atmosphere. The hydrogen fuel system may be used with VTOL aircraft, which may allow them to fly at higher elevations. The hydrogen fuel system may be used with other subsonic and supersonic aircraft, such as with asymmetric wing aircraft.

An inlet duct for use with an engine is presented. The invention includes a duct structure, at least one spike disposed along an interior surface of the duct structure, and an inlet throat formed by one or more apexes disposed along an equal number of spikes. The inlet throat corresponds to the minimum cross-sectional area through which airflow passes as otherwise allowed by the maximal obstruction formed by the apex(es) within the duct structure. Each spike is bounded by a longitudinal ridge and a lateral ridge along an upper end and a base along a lower end. The longitudinal ridge and the lateral ridge intersect at the apex. In preferred embodiments, the longitudinal ridge is at least partially non-linear so as to properly conform to the interior surface of the duct structure. The portion of each spike upstream of the inlet throat functions primarily as a supersonic diffuser. The portion of each spike downstream of the inlet throat functions primarily as a subsonic diffuser. Airflow is isentropically compressed and then expanded within the inlet duct so that greater-than-subsonic flow at an input end is reduced to subsonic flow at an output end.

A high efficiency hydrogen fuel system for an aircraft at high altitude which utilizes compressors to compress air to a sufficiently high pressure for the fuel cell. Liquid hydrogen is compressed and then utilized in heat exchangers to cool the compressed air, maintaining the air at a temperature low enough for the fuel cell. The hydrogen is also used to cool the fuel cell as it is also depressurized prior to its entry in the fuel cell cycle. A water condensation system allows for water removal from the airstream to reduce impacts to the atmosphere. The hydrogen fuel system may be used with VTOL aircraft, which may allow them to fly at higher elevations. The hydrogen fuel system may be used with other subsonic and supersonic aircraft, such as with asymmetric wing aircraft.

A ramjet including: a combustion area having an air inlet and an exhaust outlet; and a fuel cell in fluid communication with the air inlet and a fuel supply of the ramjet, wherein the fuel cell is in thermal communication with the combustion area.

An inlet duct for use with an engine is presented. The invention includes a duct structure, at least one spike disposed along an interior surface of the duct structure, and an inlet throat formed by one or more apexes disposed along an equal number of spikes. The inlet throat corresponds to the minimum cross-sectional area through which airflow passes as otherwise allowed by the maximal obstruction formed by the apex(es) within the duct structure. Each spike is bounded by a longitudinal ridge and a lateral ridge along an upper end and a base. The ridges intersect at the apex. A portion of each spike upstream of the inlet throat functions primarily as a supersonic diffuser and downstream as a subsonic diffuser. Airflow is isentropically compressed and then expanded within the inlet duct so that greater-than-subsonic flow at an input end is reduced to subsonic flow at an output end.