Abstract: A variable cycle jet engine is provided with a mixing duct assembly which mixes core engine exhaust gas with bypass air when the engine is operating in a turbofan mode and which blocks flow from the core engine and isolates the core engine from the bypass flow when the engine is operating as a ramjet.

Abstract: Steam turbine nozzle blades and buckets are profiled in accordance with Tables I and II or multiples of the X,Y and R coordinates of the charts. The profiles of the nozzle blades impose a parabolic flow distribution at the throat and the buckets accommodate the incoming flow. The nozzle blades and buckets are over-cambered at their roots and tips to constrict flow from the roots and tips into the mid-regions of the blades and buckets. Improved aerodynamic efficiencies are obtained by directing the flow away from the end walls of the blades and buckets toward the efficient mid-region of the blades and buckets whereby flow velocity and angle leaving the nozzle has a non-linear distribution and the bucket velocity leaving angles are similarly non-linear.

Abstract: A combined turbofan and ramjet aircraft engine includes a forward bypass duct which allows the engine to operate more efficiently during the turbofan mode of operation. By mounting a ramjet preburner in the forward duct and isolating this duct from the turbofan bypass air, a transition from turbofan operation to ramjet operation can take place at lower flight Mach numbers without incurring pressure losses or blockage in the turbofan bypass air.

Abstract: An optical beam switching mechanism is used from switching a light beam between a plurality of light beam paths. A rhombic prism is mounted for rotation on an axis and is rotated between positions by a geneva mechanism. A plurality of microswitches are positioned to reposition the prism after rotation to a predetermined position. The geneva mechanism is driven by an electric motor and has an index wheel attached to a cradle supporting the prism which index wheel is rotated by a drive arm connected to the electric motor.

Abstract: A labyrinth seal system for reducing leakage flow of a compressible fluid between a rotating portion of a machine rotating relative to a stationary portion of the machine. A stator seal element is connected to the stationary portion of the machine and a rotor seal element is connected to the rotating portion of the machine. The rotor seal element defines a plurality of staggered cavities. Straight long teeth connected to the stator seal element define throttling clearances with the bottom walls of the staggered cavities of the rotor seal element, and short teeth connected to the stator seal element slanted upstream relative to the direction of leakage flow define throttling clearances with the rotor seal element. Undercuts can optionally be defined by the rotor seal element on the downstream side of the cavities. Optional straight teeth connected to the rotor seal element downstream of the cavities define throttling clearances with the stator seal element.