Piloted Simulation Handling Qualities Assessment of a Business Jet Fly-By-Wire Flight Control System

Abstract

A pilot-in-the-loop handling qualities assessment of fly-by-wire control laws for a business jet with a sidestick was conducted in a simulation environment. The control laws were optimized to meet Level 1 requirements for a comprehensive set of stability, handling qualities, and performance specifications. This piloted fixed-based simulation experiment evaluated the control laws using a series of handling qualities demonstration maneuvers, including pitch and roll capture and tracking tasks, as well as an offset landing task. Quantitative performance metrics were collected, in addition to pilot handling qualities ratings and comments. The results show Level 1 handling qualities for the roll tracking and landing tasks, and borderline Level 1 handling qualities for the pitch tracking task. In addition, the fly-by-wire control laws were rated as very predictable and pilots could be more aggressive with a higher level of precision than with the bare-airframe. Nomenclature α Angle-of-attack [deg, rad] q Dynamic pressure [psf] β Angle-of-sideslip [deg, rad] ∆u Perturbation controls ∆x Perturbation states δ elev Elevator deflection [deg] δ stk Stick input γ Flightpath angle [deg, rad] M Mass matrix ω Frequency [rad/sec] ω c Crossover frequency [rad/sec] ω T Task bandwidth [rad/sec] ω BW Aircraft attitude bandwidth [rad/sec] ω co Pilot cutoff frequency [rad/sec] φ Roll attitude [deg, rad] ψ β Dutch roll oscillations phasing angle [deg] τ Time delay [sec] Downloaded by CORNELL UNIVERSITY on July 30, 2015 | http://arc.aiaa.org | This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. AIAA SciTech θ Pitch attitude [deg, rad] K Gain KCAS ref Reference airspeed [kts] n z Normal acceleration [g] n z u, n z +u Normal acceleration plus speed error [g] p Roll rate [deg/sec, rad/sec] q Pitch rate [deg/sec, rad/sec] r Yaw rate [deg/sec, rad/sec] s Laplace variable t Time [sec] V M CA Minimum control speed [kts] V M O Maximum operating limit speed [kts] Y c Aircraft response Y p

Handling Qualities Flight Test Assessment of a Business Jet N zU P-β Fly-By-Wire Control System

“…The results of the sum-of-sines tracking task are consistent with those attained during a previous simulation testing of these control laws. 10 First, very similar performance was attained for the different flight conditions and loading configurations tested, showing good robustness of the control laws to changes in aircraft loading and consistent performance of the gain schedule across the flight envelope. Second, pitch performance was in the 45-60% range while roll performance was in the 65-85% range.…”

“…The control laws used in this study are based on those previously developed for a small business jet similar to a Cessna CitationJet CJ1 8,9 and tested in a simulation handling qualities evaluation. 10 The control laws are based on an architecture that is analogous to an explicit model following system, 16 implemented to provide an "n z u"-command 17 response type in the longitudinal axis (Section III.A) and a "p-β"-command 18,19 response type in the lateral/directional axes (Section III.B).…”

“…8,9 The control laws were tested in a fixed-based simulation environment. 10 The results from the simulation handling-qualities assessment showed overall Level 1 handling qualities, and the control laws were rated as very predictable and pilots could be more aggressive with a higher level of precision than with the bare-airframe. The control system optimization, conducted using the Control Designer's Unified Interface (CONDUIT R ), 11 was driven by a comprehensive set of specifications divided into two tiers: Tier 1 specifications were used to drive the optimization, and Tier 2 specifications were used to check many commonly used alternative requirements for the completed design.…”