In-Flight Investigation of Large Airplane Flying Qualities for Approach and Landing

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Report Number: AFWAL-TR-81-3118
Author(s): Weingarten, Norman C., Chalk, Charles R.
Corporate Author(s): CALSPAN
Laboratory: Flight Dynamics Laboratory
Date of Publication: 1981-09
Pages: 485
Contract: F33615-79-C-3618
DoD Project: 2403
DoD Task: 240305
Identifier: ADA120202

A study of the handling qualities of large airplanes in the approach and landing flight phase was performed. An in-flight simulation experiment utilizing the USAF-AFWAL/Calspan Total In-flight Simulator was carried out to gather data for the analysis effort. A one-million pound statically unstable airplane model was used as a baseline about which variations were made. The primary variables were relative pilot position with respect to center of rotation, command path time delays and phase shifts, augmentation schemes and levels of augmentation. Both longitudinal and lateral-directional characteristics were investigated. The experiment design, conduct of the experiment, and analysis of the data are described. Results are presented in the form of pilot ratings, pilot comments and various analysis techniques. The results indicate that the approach and landing task with very large airplanes is a fairly low bandwidth task. Low equivalent short-period frequencies and relatively long time delays can be tolerated. As the pilot position is moved aft towards and then behind the center of rotation, pilot ratings are degraded. A multiloop analysis of pitch attitude and altitude control gave insight into this pilot position phenomenon. Altitude loop bandwidth correlated well with pilot ratings. The control problem experienced by the pilots, when flying the airplane while seated behind the center of rotation, tended to occur at low altitude when they were using visual cues of rate of sink and altitude. These aft pilot position configurations, similar to the space shuttle orbiter, also lack the initial normal acceleration cue from pitch acceleration that the other conventional large airplane configurations possess. A direct lift controller improved final flight path control of the shuttle-like configurations. Lateral acceleration levels that are achievable in very large airplanes degrade pilot ratings as predicted by the lateral acceleration parameter.

Provenance: University of Colorado Colorado Springs, Kraemer Family Library

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