CAMRAD II

CAMRAD II Papers

The technical papers summarized below describe details of the CAMRAD II physical models, and present results of applications of CAMRAD II to rotorcraft problems. The papers are available in Adobe pdf format.

List of publications regarding CAMRAD II, CAMRAD/JA, and CAMRAD (through January 2017): pdf file (548 Kb)

CAMRAD/JA documentation: Volume 1 (25.3Mb), Volume 2 (13Mb)

CAMRAD Plot and CAMRAD Draw: Java applications that produce two-dimensional and three-dimensional graphics respectively. Jar files (244 Kb) Macintosh applications (268 Kb)

 

CAMRAD II software description
images from CAMRAD II calculations
Johnson Aeronautics home page

 

Rotorcraft Aeromechanics Applications of a Comprehensive Analysis. Presented at Heli Japan 98: AHS International Meeting on Advanced Rotorcraft Technology and Disaster Relief, Japan, April 1998. pdf file (287 Kb)

Abstract: Results from the comprehensive analysis CAMRAD II are presented, illustrating recent developments in the aerodynamics and dynamics models, and demonstrating the technology that is needed for an adequate calculation of rotorcraft behavior. Calculations of rotor performance, airloads, structural loads, and stability are presented, including comparisons with experimental data.

 

Technology Drivers in the Development of CAMRAD II. Presented at the American Helicopter Society Aeromechanics Specialists Conference, San Francisco, California, January 1994. pdf file (154 Kb)

Abstract: Technology drivers in the development of the comprehensive helicopter analysis CAMRAD II are reviewed. The issues discussed include flexibility of configuration model and solution procedure; expandability; mathematical model of kinematics, dynamics, and response; transportability; ease of use and productivity; and demonstrated capability.

 

A General Free Wake Geometry Calculation For Wings and Rotors. Presented at the American Helicopter Society Forum, Fort Worth, Texas, May 1995. pdf file (271 Kb)

Abstract: A general free wake geometry calculation for wings and rotors is presented. The method, which has been implemented in CAMRAD II, gives good performance and airloads correlation at advance ratios of 0.05 and above, with reasonable computation speed. The wake geometry distortion can be calculated for multiple wings, multiple rotors, and non-identical blades; for all wake structures, including multiple rolled-up trailed vorticity and inboard sheets as well as tip vortices; using the same wake model as the induced velocity calculations; for transients as well as the trim solution. The theoretical approach is described. Results are presented for rotor airloads, flapping, and performance, including comparisons with a common wake geometry method and with measured data. Calculated wake geometries are shown for a nonrotating wing, a single rotor, multiple main rotors, and a wind turbine.

 

Rotorcraft Dynamics Models for a Comprehensive Analysis. Presented at the American Helicopter Society Forum, Washington, D.C., May 1998. pdf file (383 Kb)

Abstract: Recent developments of the dynamics models for the comprehensive analysis CAMRAD II are described, specifically advanced models of the geometry and material for the beam component, and a force balance method for calculating section loads. Calculations are compared with measurements for beams undergoing large deflection. Bearingless rotor stability and bending loads calculations are compared with the results from a full-scale wind tunnel test. With a reasonable number of beam elements representing the rotor blade, any large deflection effects are captured by the rigid body motion (which is always exact), and a second-order model of the beam element elastic motion is adequate. The deflection method gives unacceptable results for the structural loads in practical cases, and even with uniform blade properties. The force balance method described here gives good results for blade load, without requiring a large number of nodes.

 

Rotorcraft Aerodynamics Models for a Comprehensive Analysis. Presented at the American Helicopter Society Forum, Washington, D.C., May 1998. pdf file (397 Kb)

Abstract: Recent developments of the aerodynamics models for the comprehensive analysis CAMRAD II are described, particularly the unsteady aerodynamic models and dynamic stall models, and the free wake geometry calculation. Three models for the unsteady aerodynamic loads in attached flow are implemented: from incompressible thin-airfoil theory, from ONERA EDLIN, and from Leishman-Beddoes. Five dynamic stall models are implemented: from Johnson, Boeing, Leishman-Beddoes, ONERA EDLIN, and ONERA BH. A key feature of the implementation of these models is revisions allowing the retention of airfoil tables for static loads in all cases. Results are presented for a two-dimensional airfoil, a three-dimensional wing, and rotors. Extensions of the CAMRAD II free wake method to include hover and ground effect are described, including hover performance correlation.

 

Johnson Aeronautics, PO Box 1253, Palo Alto, CA 94302 USA