Abstract: A thermal management system for an aircraft and method of using same are provided. The system includes a fuel reservoir, a fuel recirculation loop, a fuel mixing valve, and a control module. The fuel recirculation loop includes a fuel recirculation tank, heat exchanger that transfers waste thermal energy to the fuel, and another heat exchanger that transfers waste thermal energy out of the heated fuel. The fuel recirculation loop supplies heated fuel to a combustion engine and is configured to return a portion of the heated fuel to the recirculation tank via a return line. The fuel mixing valve fluidly couples the fuel reservoir and the fuel recirculation tank to provide a mixture of the two fuel sources based on the temperature of the heated fuel. The thermal management system increases an aircraft thermal endurance over that which can be attained by a single tank fuel flow topology.

Abstract: A selectively self-locking actuator includes a threaded shaft having a first threaded portion and a second threaded portion. The first threaded portion includes a semicircular ball screw threadform and the second threaded portion includes a power screw threadform. The actuator further includes a ball nut mated to the first threaded portion, a split nut selectively mated with the second threaded portion, and a nut coupler plate configured to secure the ball nut and split nut at a fixed distance from each other. The split nut includes at least a first split nut portion and a second split portion each mated to a spring and a driver. The spring is configured to bias the first split nut portion and the second split nut portion either radially inward or radially outward with respect to the threaded shaft, and wherein the driver is configured to selectively oppose the bias of the spring.

Abstract: Precision ballistic airdrop of packages from an aircraft comprises entering the estimated wind field in the drop zone into a CPU aboard the packages; computing a transition altitude for each of the packages based on the wind field and the order in which each package is released, each package having a predetermined release order; programming the computed transition altitude into each of the packages; releasing each of the packages in the predetermined order; comparing a pressure altitude to the transition altitude in the CPU of each package; jettisoning the drogue chute and deploying the main chute for each of the packages when the pressure altitude is less than or equal to the transition altitude; and descending each of the packages under its main chute, wherein the wind field affects the flight of some of the packages more than others based on the selection of the transition altitude for each package.

Abstract: A selectively self-locking actuator includes a threaded shaft having a first threaded portion and a second threaded portion. The first threaded portion includes a semicircular ball screw threadform and the second threaded portion includes a power screw threadform. The actuator further includes a ball nut mated to the first threaded portion, a split nut selectively mated with the second threaded portion, and a nut coupler plate configured to secure the ball nut and split nut at a fixed distance from each other. The split nut includes at least a first split nut portion and a second split portion each mated to a spring and a driver. The spring is configured to bias the first split nut portion and the second split nut portion either radially inward or radially outward with respect to the threaded shaft, and wherein the driver is configured to selectively oppose the bias of the spring.

Abstract: A method of configuring a wing velocity profile includes segmenting a complete wingbeat cycle into a set of quarter-strokes including a first quarter-stroke, a second quarter-stroke, a third quarter-stroke, and a fourth quarter-stroke. The method further includes generating time-varying quarter-stroke wing position commands for each of a first and second wing planforms to produce wing flapping trajectories that generate non-zero, cycle averaged wing lift and drag and alter a cycle average center of pressure of each of the first and the second wing planforms relative to the aircraft. The wing position commands include velocities and positions with temporally symmetric and asymmetric quarter-stroke components for the first wing planform and the second wing planform. The first wing planform and the second wing planform produce controlled six-degrees-of freedom vehicle motion without using actuators in excess of the first actuator and the second actuator.

Abstract: A method of controlling wing position and velocity for a flapping wing air vehicle provides six-degrees-of-freedom movement for the aircraft through a split-cycle constant-period frequency modulation with wing bias method that generates time-varying upstroke and downstroke wing position commands for wing planforms to produce nonharmonic wing flapping trajectories that generate non-zero, cycle averaged wing drag and alter the location of the cycle-averaged center of pressure of the wings relative to the center of gravity of the aircraft to cause horizontal translation forces, rolling moments and pitching moments of the aircraft.

Abstract: A method, computer usable medium including a program, and a system for braking a vehicle during brake failure. The method and computer usable medium include the steps of determining a brake force lost corresponding to a failed brake, and determining a brake force reserve corresponding to at least one non-failed brake. At least one commanded brake force is determined based on the brake force lost and the brake force reserve. Then at least one command brake force is applied to the at least one non-failed brake wherein at least one of an undesired yaw moment and a yaw moment rate of change are limited to predetermined values. The system includes a plurality of brake assemblies wherein a commanded brake force is applied to at least one non-failed brake.