A propulsion system includes a first compressor in fluid communication with a fluid source. A first conduit is coupled to the first compressor, and a heat exchanger is in fluid communication with the first compressor via the first conduit. A second conduit is positioned proximal to the heat exchanger. A combustor is in fluid communication with the heat exchanger via the second conduit and is configured to generate a high-temperature gas stream. A third conduit is coupled to the combustor, and a first thrust augmentation device is in fluid communication with the combustor via the third conduit. The heat exchanger is positioned within the gas stream generated by the combustor.

A propulsion system coupled to a vehicle. The system includes a convex surface, a diffusing structure coupled to the convex surface, and at least one conduit coupled to the convex surface. The conduit is configured to introduce to the convex surface a primary fluid produced by the vehicle. The system further includes an intake structure coupled to the convex surface and configured to introduce to the diffusing structure a secondary fluid accessible to the vehicle. The diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid and secondary fluid.

An ignition system for a jet includes a squib. A solid propellant gas generator is ignitable by the squib and produces hot gas. An insulated hot gas accumulator is provided for storing the hot gas. A three-way hot gas valve is in fluid communication with the jet, the solid propellant gas generator, and the insulated hot gas accumulator. The three-way hot gas valve has a first condition establishing a first flow path from the solid propellant gas generator to the jet, a second condition establishing a second flow path from the solid propellant gas generator to the insulated hot gas accumulator, and a third condition establishing a third flow path from the insulated hot gas accumulator to the jet.

A propulsion system includes a fan, a gear, a turbine configured to drive the gear to, in turn, drive the fan. The turbine has an exit point, and a diameter (D.sub.t) is defined at the exit point. A nacelle surrounds a core engine housing. The fan is configured to deliver air into a bypass duct defined between the nacelle and the core engine housing. A core engine exhaust nozzle is provided downstream of the exit point. A downstream most point of the core engine exhaust nozzle is defined at a distance from the exit point. A ratio of the distance to the diameter is greater than or equal to about 0.90.

A propulsion system includes a fan, a gear, a turbine configured to drive the gear to, in turn, drive the fan. The turbine has an exit point, and a diameter (D.sub.t) is defined at the exit point. A nacelle surrounds a core engine housing. The fan is configured to deliver air into a bypass duct defined between the nacelle and the core engine housing. A core engine exhaust nozzle is provided downstream of the exit point. A downstream most point of the core engine exhaust nozzle is defined at a distance from the exit point. A ratio of the distance to the diameter is greater than or equal to about 0.90.

Attitude of a vehicle may be controlled using movable mass. The movable mass may move inside a vehicle or its outline, outside of the vehicle or its outline, inside-to-outside and/or outside-to-inside of the vehicle or its outline, or any combination thereof. The movable mass may be a solid, liquid, and/or gas. When the center-of-mass of the vehicle is moved relative to the line-of-action of applied forces such as thrust, drag, or lift, a torque can be generated for attitude control or for other purposes as a matter of design choice. In the case of external movable masses that extend from the vehicle or its outline, when operating in endoatmospheric flight, or general travel through a fluid, aerodynamic forces from the atmosphere or general fluid forces may further be leveraged to control the attitude of the vehicle (e.g., aerodynamic flaps).

During a method for forming a structural panel, a core structure is formed that includes a plurality of corrugated ribbons and a plurality of walls. Each of the corrugated ribbons is laterally between a respective adjacent pair of the walls. Each of the corrugated ribbons includes a plurality of baffles and a plurality of porous septums. Each of the porous septums is longitudinally between a respective adjacent pair of the baffles. The forming of the core structure includes bonding a first of the walls to a first of the corrugated ribbons and subsequently bonding a second of the walls to the first of the corrugated ribbons. The core structure is bonded to a first skin. The core structure is bonded to a second skin. The core structure is vertically between the first skin and the second skin, and the first skin is configured with a plurality of perforations.

A compression molding assembly for molding a honeycomb core, including a plurality of cells defined by a plurality of walls, of a blocker door is provided. The compression molding assembly includes a ram plate comprising a plurality of openings defined therethrough and a plurality of core inserts coupled to the ram plate such that the plurality of core inserts are configured to form the honeycomb core of the blocker door. Each core insert is removably coupled with a respective opening of the plurality of openings such that each core insert is configured to form a respective cell of the plurality of cells.

A compression molding assembly for molding a honeycomb core, including a plurality of cells defined by a plurality of walls, of a blocker door is provided. The compression molding assembly includes a ram plate comprising a plurality of openings defined therethrough and a plurality of core inserts coupled to the ram plate such that the plurality of core inserts are configured to form the honeycomb core of the blocker door. Each core insert is removably coupled with a respective opening of the plurality of openings such that each core insert is configured to form a respective cell of the plurality of cells.

An exhaust system for a rotary wing aircraft includes a diffuser located at an airframe of the rotary wing aircraft and operably connected to an engine of the rotary wing aircraft, and a chimney extending upwardly from a diffuser wall. A door is movably positioned at the diffuser to selectively direct an engine exhaust flow through the diffuser or through the chimney. A rotary wing aircraft includes an airframe, a rotor system positioned at the airframe and rotatable about a rotor axis, and an engine operably connected to the rotor system to drive rotation of the rotor system. The aircraft includes an engine exhaust system including a diffuser positioned at the airframe and operably connected to the engine, a chimney extending upwardly from a diffuser wall, and a door positioned at the diffuser to selectively direct an engine exhaust flow through the diffuser or through the chimney.