A method for producing an ablative resin by carrying out a reduction reaction for the reduction of a compound of formula A, followed by a polymerization reaction, formula A being the following: ##STR00001##

A method for producing an ablative resin by carrying out a reduction reaction for the reduction of a compound of formula A, followed by a polymerization reaction, formula A being the following: ##STR00001##

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.

A vehicle includes a main body and a gas generator producing a gas stream. At least one fore conduit and tail conduit are fluidly coupled to the generator. First and second fore ejectors are fluidly coupled to the at least one fore conduit. At least one tail ejector is fluidly coupled to the at least one tail conduit. The fore ejectors respectively include an outlet structure out of which gas from the at least one fore conduit flows. The at least one tail ejector includes an outlet structure out of which gas from the at least one tail conduit flows. First and second primary airfoil elements have leading edges respectively located directly downstream of the first and second fore ejectors. At least one secondary airfoil element has a leading edge located directly downstream of the outlet structure of the at least one tail ejector.

A propulsion system coupled to a vehicle. The system includes an ejector having an outlet structure out of which propulsive fluid flows at a predetermined adjustable velocity. A control surface having a leading edge is located directly downstream of the outlet structure such that propulsive fluid from the ejector flows over the control surface.

A turbofan engine that includes a first flowpath, a second flowpath, a third flowpath, and a third flowpath exhaust nozzle is provided. The first flowpath is radially inboard of the second flowpath at a location upstream of a core section of the turbofan engine. The third flowpath is radially outboard of the second flowpath at the location upstream of the core section. The third flowpath exhaust nozzle defines a plurality of third flowpath exhaust exit ports through which gas traveling along the third flowpath may be discharged. An area or a geometry of each of the plurality of third flowpath exhaust exit ports is independently and selectively adjustable. A method for operating the turbofan engine includes independently and selectively adjusting an area or a geometry of at least one of the plurality of third flowpath exhaust exit ports to achieve a desired engine operation.

A nacelle for a gas turbine engine includes a ring shaped body defining a center axis and having a radially outward surface and a radially inward surface. An aft portion of the radially inward surface includes an axially extending convergent-divergent exit nozzle. An axially extending secondary duct passes through the nacelle in the convergent-divergent exit nozzle. The axially extending secondary duct includes an inlet at a convergent portion of the convergent-divergent exit nozzle and an outlet at a divergent portion of the convergent-divergent exit nozzle.

A system for enhancing the thrust produced by an aircraft propulsion element having a propulsion fluid outlet includes a shroud element having an inlet, an outlet and a diffusing section positioned between the shroud element inlet and shroud element outlet. The shroud element is coupled to the aircraft such that the diffusing section is positioned directly downstream of the propulsion fluid outlet. At least one actuator is operable to rotate the shroud element about a first transverse axis of the shroud element and a second transverse axis of the shroud element.

A servo valve for an actuator is described. The servo valve comprises a housing and a sleeve provided within the housing having a plurality of metering holes for communication with a cavity within. The servo valve further comprising a metering rod provided with metering members on a central rod for metering flow into and out of the cavity through the metering holes. The metering members comprise annular elements which are located axially on the central rod by an interference fit. The position of the metering members can be adjusted through using heat to thermally expand the metering member relative to the central rod to release the hold of the friction fit, allowing the metering member to be repositioned by being slid along the central rod.

A flow control device includes a first axially extending flow control surface, a second axially extending flow control surface radially offset from the first surface to define a gas flow path therebetween, the gas flow path having a downstream flow path exit, and a third axially extending flow control surface radially offset from the first surface and capable of axially translating with respect to the first and second surfaces for modifying the gas flow path and selectively closing the flow path exit. A turbofan engine includes a core flow passage, a fan bypass passage located radially outward from the core flow passage, a third stream bypass passage located radially outward from the fan bypass passage, and a flow control device that dynamically regulates the third stream bypass passage, allowing fluid flowing through the third stream bypass passage to provide thrust to the turbofan engine and reduce afterbody drag.