Accession Number:

ADA214295

Title:

An Examination of Helicopter Rotor Load Calculations

Descriptive Note:

Corporate Author:

ARMY AVIATION RESEARCH AND TECHNOLOGY ACTIVITY MOFFETT FIELD CA AEROFLIGHTDYNAMICS DIRECTORATE

Personal Author(s):

Report Date:

1988-01-01

Pagination or Media Count:

20.0

Abstract:

The structural response of three full-scale helicopter rotors has been examined. Airloads predicted by CAMRAD were compared by harmonics with test measurements. Flapwise bending moments were calculated from the CAMRAD airloads using three methods force integration, curvature, and a finite-difference method. The force-integration and curvature moments were calculated with the CAMRAD program itself however, the finite-difference method was calculated externally by a forced response program, Blade Response to Aerodynamic Loading BRAL. The BRAL analysis with measured airloads was shown to agree well with strain-gauge measurements on the CH-34 rotor in a wind tunnel. The CAMRADforce-integration bending moments were shown to accumulate error as the integration progressed from tip to root. The CAMRADcurvature moments agreed well with the finite-difference moments over most of the blade however, at regions of rapidly changing stiffness the agreement was poor. When applied to the BRAL solution, force integration was shown to give excellent results, provided the integration had a small step size. Shear forces calculated by CAMRAD and BRAL showed fair agreement. Keywords Aerodynamic loading Flight loads Rotor blades Dynamic loads. kt

Subject Categories:

  • Aircraft
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE