Analytical Methods


CAMRAD II is the most widely used and most extensively validated rotorcraft comprehensive analysis, licensed to industry and research laboratories throughout the world. A comprehensive analysis calculates rotor performance, blade and hub and control loads, airframe vibration, aircraft flight dynamics, and aeroelastic stability in a single computer program, for all rotor and aircraft configurations. CAMRAD II supports all phases of rotorcraft design, testing, and evaluation, including research, conceptual design, detailed design, wind tunnel and flight testing, and in-service support. Computation times range from minutes to hours on a desktop computer, depending on the complexity of the system to be analyzed. CAMRAD II capabilities and accuracy have been demonstrated through extensive correlation with test data and applications to conventional and new rotorcraft configurations in over 300 papers and reports.

CAMRAD II is particularly well suited to a wide variety of rotorcraft and flexible aircraft, including designs with wing-rotor or wing-propeller interactions. If the aircraft may be represented with airfoil tables, lifting lines, beams, and joints, then CAMRAD II can perform accurate prediction of the performance, loads, vibration, response, and stability. In addition to its own extensively-validated aerodynamic models, CAMRAD II can be used as the structural analysis engine for coupling with high-fidelity CFD. The trim task finds the equilibrium solution (constant or periodic) for a steady state operating condition. The transient task integrates the equations in time for a prescribed excitation. The flutter task obtains and analyzes differential equations, linearized about trim, perhaps with quasistatic reduction for a stability derivative model.

CAMRAD II uses a building block approach to achieve flexibility in modeling of the dynamic and aerodynamic configuration. Hence, it can model the true geometry of a rotorcraft, including multiple load paths (such as a swashplate and control system, lag dampers, tension/torsion straps, and bearingless rotors); vibration control devices (such as pendulum absorbers or active control); arbitrary elastic axis and arbitrary hinge order; drooped and swept tips; and dissimilar blades. CAMRAD II provides a powerful analysis capability, including advanced rotor aerodynamics; rigorous kinematics and dynamics (with consistent structural loads and dynamic response, and general interfaces between aerodynamic and structural dynamic components); and general transient solutions. For ease of use, a shell is provided to build typical rotorcraft and rotor models, while the core input capability always gives complete flexibility to define and revise the model. The shell constructs the input for an arbitrary one-rotor or multi-rotor helicopter or tiltrotor; in free flight or a wind tunnel; with N-bladed rotors having articulated, hingeless, teetering, gimballed, or bearingless root configurations, including a swashplate model. The aerodynamic model includes a sophisticated wake analysis to calculate the rotor nonuniform induced-velocities, using rigid, prescribed, or free wake geometry. A range of components and modeling options makes it a practical engineering tool, allowing the best balance of efficiency and accuracy to be found for a particular problem. CAMRAD II offers a common tool among organizations, and a design for growth that makes it an appropriate platform for future developments, for continuing access to new technology.

CAMRAD II is offered for sale, and consulting services are also available. For projects with short development timelines, where your aeromechanics analysis capabilities require assistance, or where company priorities do not justify the investment in developing in-house aeromechanics expertise, engaging Stark/AMI for consulting services may be the best solution. CAMRAD II was developed by Dr. Wayne Johnson of Johnson Aeronautics, and is marketed and distributed by Analytical Methods, a division of Stark Aerospace, Inc., under a joint agreement. Full support of the software is provided, including installation, training, maintenance, and applications. Contact Stark/AMI for further information regarding CAMRAD II.