A simulation evaluation of a four-engine jet transport using engine thrust modulation for flightpath control

In a number of instances, aircraft that have suffered in-flight damage to their airframe or control system were brought safely to the ground using unconventional means of control. The success in these cases depended greatly on the pilot having had some exposure to unconventional control strategies. Control strategies are considered for cases of aircraft with damage only to the primary control system, as well as cases in which the vertical tail is lost. The piloting strategies are developed using optimal control theory, which optimizes the control law for a desired maneuver and a chosen aircraft configuration. The results show that, despite the loss of the primary control system or of the vertical tail, control of the aircraft is often possible, although it requires the use of unconventional control strategies, in particular, of differential thrust. Especially in the case without a vertical tail, the maneuver in which adverse yaw induces a rolling moment opposite to the intended yaw direction is somewhat surprising and, initially, counterintuitive. Nomenclature= rolling moment coefficient, roll moment/ 1 2 ρV 2 ∞ Sb C m = pitching moment coefficient, pitch moment/ 1 2 ρV 2 ∞ Sc C n = yawing moment coefficient, yaw moment/ 1 2 ρV 2 ∞ Sb C Y = side force coefficient, side force/ 1 2 ρV 2 ∞ S c = mean aerodynamic chord H = weighting matrix (terminal) J = performance index K = Riccati matrix l = roll moment M = Mach number m = pitch moment n = yaw moment P = roll rate; positive when right wing moves down Q = pitch rate; positive when aircraft nose moves up Q = weighting matrix (tracking) R = yaw rate; positive when aircraft nose moves to right R = weighting matrix (control effort) r = desired state trajectory S = wing area s = command signal T = thrust U = forward velocity u = control vector V = side velocity; positive when aircraft moves to right V ∞ = flight speed W = downward velocity x = state vector α = angle of attack; positive when aircraft nose up β = sideslip angle; positive when aircraft moves to right δ A = aileron angle; positive when right aileron up δ E = elevator angle; positive when trailing edge up δ R = rudder angle; positive when trailing edge to left (negative yaw, but positive roll moment) = pitch angle; positive when aircraft nose up = bank angle; positive when left wing up = yaw angle; positive when aircraft nose points to right of flight path

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“…(3)(4)(5)(6)(7)(8), the solution of the optimal control law for a desired trajectory depends on the choice of weighting matrices H, Q, and R.…”

Section: Tracking Problem Formulationmentioning

confidence: 99%

Piloting Strategies for Controlling a Transport Aircraft After Vertical-Tail Loss

Bramesfeld

Maughmer

Willits

2006

Journal of Aircraft

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“…In this section we construct the stabilizing control law for the cascaded system that is comprised od the error dynamics (22) and the engine dynamics (9). To this end we assume that the engine dynamics is of full relative degree n, and therefore can be represented in the normal form without internal dynamic…”

Section: Control Designmentioning

confidence: 99%

“…9 The research on the PCA system continued at NASA Dryden and Ames Research Centers in simulations as well as in actual flight test for different flight platforms. 4 The objective of the PCA system is to provide a necessary thrust command for each engine for emergency flight control in response to pilots flightpath input, assuming that each engine can be controlled individually.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Control of a Transport Aircraft Using Differential Thrust

Stepanyan

Krishnakumar

Nguyen

2009

AIAA Guidance, Navigation, and Control Conference

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The paper presents an adaptive control technique for a damaged large transport aircraft subject to unknown atmospheric disturbances such as wind gust or turbulence. It is assumed that the damage results in vertical tail loss with no rudder authority, which is replaced with a differential thrust input. The proposed technique uses the adaptive prediction based control design in conjunction with the time scale separation principle, based on the singular perturbation theory. The application of later is necessitated by the fact that the engine response to a throttle command is substantially slow that the angular rate dynamics of the aircraft. It is shown that this control technique guarantees the stability of the closed-loop system and the tracking of a given reference model. The simulation example shows the benefits of the approach.

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“…In the case of rudder or vertical tail failure, the differential thrust control is an effective way to counteract the yawing moments induced by the stuck rudders and thus allow the aircraft to track heading angle commands [11]. A propulsioncontrolled aircraft (PCA) system has been developed by the NASA Dryden Research Center, and was first evaluated on a piloted B-720 simulation [12]. In this PCA system, differential thrust was used as an emergency substitute for failed control surfaces [13] such as vertical tail loss with no rudder authority or rudder runaway case [11,14].…”

Section: Introductionmentioning

confidence: 99%

A Hybrid Sensor Based Backstepping Control Approach with its application to Fault-Tolerant Flight Control

Sun

Visser

Chu

et al. 2013

AIAA Guidance, Navigation, and Control (GNC) Conference

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Recently, an incremental type sensor based backstepping (SBB) control approach, based on singular perturbation theory and Tikhonov's theorem, has been proposed. This Lyapunov function based method uses measurements of control variables and less model knowledge, and it is not susceptible to the model uncertainty caused by fault scenarios. In this paper, the SBB method has been implemented on a fixed wing aircraft with its focus on handling structural changes caused by damages.

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A simulation evaluation of a four-engine jet transport using engine thrust modulation for flightpath control

Abstract: The use of throttle control laws to provide adequate fying qualities for flightpath control in the event of a total loss of conventional flight control surface use was evaluated. The results are based on a simulation evaluation by transport re-

Cited by 22 publications

References 1 publication

Piloting Strategies for Controlling a Transport Aircraft After Vertical-Tail Loss

Piloting Strategies for Controlling a Transport Aircraft After Vertical-Tail Loss

Adaptive Control of a Transport Aircraft Using Differential Thrust

A Hybrid Sensor Based Backstepping Control Approach with its application to Fault-Tolerant Flight Control

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