Accession Number:

ADA014301

Title:

The Effects of Stability Augmentation on the Gust Response of a STOL Aircraft during a Curved Manual Approach.

Descriptive Note:

Final rept. Jun 71-May 75,

Corporate Author:

AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OHIO

Personal Author(s):

Report Date:

1975-06-01

Pagination or Media Count:

228.0

Abstract:

The multiple precision approach paths which are possible with microwave landing systems pose new lateral separation problems for the simultaneous optimum curved approach trajectories. Separation criteria for these new multiple paths will be influenced by aircraft path tracking performance. Manually piloted STOL aircraft will be particularly sensitive to atmospheric turbulence during precision tracking. In this study a parametric variation of the open loop poles of a STOL aircraft was made using stability augmentation system SAS gains, and the gust response of the manually piloted aircraft was analyzed at points on an MLS approach path. The study was reduced to two quadratic optimal control problems for linear infinite time stochastic systems 1 to compute the SAS gains using a rate-model-in-the-performance-index pole placement algorithm, and 2 to calculate the pilot gains and system gust response using a quadratic optimal pilot model. Both the SAS and pilot gains calculation yielded reasonable low gains for all cases, and the four lateral-directional poles and the longitudinal short period poles could be placed accurately. The most significant improvement in lateral error was achieved by increasing roll stability. The variation in lateral path error with bank angle was also significant and the nature of the variation was strongly influenced by the specific augmented poles. There was a conflict between good conventional flying qualities and optimum gust response since increased dutch roll frequency yielded the greatest reduction in the objectionable lateral and directional mode cross coupling while increasing the lateral gust response error.

Subject Categories:

  • VSTOL
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE