We show experimentally that properly selected chord-wise flexibility can have a significant effect on the propulsive efficiency of two-dimensional flapping (heaving and pithing) foils, up to a 36% increase, compared to the efficiency of a rigid foil, with small loss in thrust. Two different foil kinematics are employed in the experiments: the first using simple harmonic heave and pitch motions;...

This paper will discuss Air Force Research Laboratory (AFRL) Propulsion Directorate’s theoretical and computational results regarding trajectory simulations, qualitative analyses and parametric studies of a 25-cm focal diameter Laser Ramjet (X-25LR) using Optimal Trajectories by Implicit Simulation (OTIS). OTIS has been used to produce an optimized trajectory simulation of a laser ramjet’s flig...

Abstract. We present an analytical model for assessing the aerodynamic performance of a wind turbine rotor through different parametrization classical blade element momentum (BEM) model. The is named Radially Independent Actuator Disc (RIAD) model, and it establishes relationship between local thrust loading power, known as local-thrust coefficient local-power respectively. has direct physical ...

In this paper, some results are provided for minimum time roll about velocity vector maneuvering with thrust-vectoring and aerodynamic control in effect. The mathematical model for attitude motions of the aircraft is developed. First order necessary conditions for optimality using Pontryagen principle is applied, and the existence of an extreme family of solutions for the maneuver is shown. Mul...

Three blade-geometry optimization models derived along with assumptions from the blade element momentum (BEM) approach are studied by using a steady BEM code to improve small horizontal-axis rotor of three blades that has been previously used in experiments. The base linear-radially varying chord length and pitch angle, while other noted as Burton, Implicit Hansen due their references character...

In this paper, some results are provided for minimum time roll about velocity vector maneuvering with thrust-vectoring and aerodynamic control in effect. The mathematical model for attitude motions of the aircraft is developed. First order necessary conditions for optimality using Pontryagen principle is applied, and the existence of an extreme family of solutions for the maneuver is shown. Mul...

The Electromagnetic Aircraft Launch System (EMALS) is being developed utilizing electrical and electronic technologies. EMALS is emerging in order to replace the existing steam catapult on naval carriers. Recently, the double-sided linear launcher has drawn increasing attention of researchers. This paper presents the design and analysis of the Linear Hybrid Reluctance Motor (LHRM). This new mot...

In this paper, we present a detailed dynamic and aerodynamic model of a quadrotor that can be used for path planning and control design of high performance, complex and aggressive manoeuvres without the need for iterative learning techniques. The accepted nonlinear dynamic quadrotor model is based on a thrust and torque model with constant thrust and torque coefficients derived from static thru...

This paper proposes a thrust estimation scheme for marine propellers in four-quadrant operations. To calculate the thrust and torque coefficients of screw propeller in four-quadrant, a Chebyshev fit expression of the propeller properties in four-quadrant for surface vessel is given, and then it is changed into an ordinary polynomial expression. These expressions are suitable for calculating the...