Manual Manipulation of Engine Throttles for Emergency Flight Control
Abstract: If normal aircraft flight controls are lost, emergency flight control may be attempted using only engines thrust. Collective thrust is used to control flightpath, and differential thrust is used to control bank angle. Flight test and simulation results on many airplanes have shown that pilot manipulation of throttles is usually adequate to maintain up-and-away flight, but is most often not capable of providing safe landings. There are techniques that will improve control and increase the chances of a survivable landing. This paper reviews the principles of throttles-only control (TOC), a history of accidents or incidents in which some or all flight controls were lost, manual TOC results for a wide range of airplanes from simulation and flight, and suggested techniques for flying with throttles only and making a survivable landing.
Cites background from "Manual Manipulation of Engine Throt..."
...The output, y1, is initially below the limit and both Equations (1) and (2) are false....
...Conditions 1 and 2 can be developed into equations analogous to Equations (1) and (2) with non-negative design parameters α2 and β2. min222 *)1( yy α+≤ (3) min2222 ** yTydt dy ≤∆β+ (4) It is worth noting that when Condition 1 is met (the variable is “close” to the limit) that the construction of Condition 2 can tB....
...The switches shown on the output of each limit regulator only connect to the Max and Min selector blocks when both bounding conditions are true—Equations (5) and (6) for the Max limit regulator and Equations (7) and (8) for the Min limit regulator....
...To determine the effectiveness of the conditionally active limit regulators on the engine response, three situations are evaluated: (1) a case where a transient limit regulator is necessary to ensure safe operation, (2) a case where a steadystate limit regulator is necessary to ensure safe operation, and (3) a case where a limit regulator becomes active unnecessarily during a transient....
...The discrete version of the maximum limit inequalities Equations (5) and (6) is listed below where e[k] refers to the error at the current time index and e[k-1] to the error at the previous time step. max11 *][ yke α≤ (9) ( ) T kekeke T ∆β − ≤−− ∆ * ]1[1 1 1 11 (10) Also, the designer may find it desirable to use a filtered version of e[k] to reduce noise....