Toward a Better Understanding of Helicopter Stability Derivatives.
Abstract
An amended six-degree-of-freedom helicopter stability and control derivative model was developed in which body acceleration and control-rate derivatives were included in the Taylor series expansion. These additional derivatives were derived from consideration of the effects of the higher-order rotor-flapping dynamics, which are known to be inadequately represented in the conventional six-degree-of-freedom, quasi-static stability-derivative model. The amended model was found to be a substantial improvement over the conventional model, effectively doubling the usable bandwidth and providing a more accurate representation of the short-period and cross-axis characteristics. Further investigations assessed the applicability of the two stability-derivative model structures for flight-test parameter identification. Parameters were identified using simulation data generated from a higher-order base-line model having sixth-order rotor tip-path-plane dynamics. Three lower-order models were identified: one using the conventional stability-derivative model structure, a second using the amended six-degree-of-freedom model structure, and a third model having eight degrees of freedom that included a simplified rotor tip-path-plane tilt representation. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1982
- Accession Number
- ADA119412
Entities
People
- Raymond S. Hansen
Organizations
- Ames Research Center