Method and device for detecting degradation of performance of an aircraft
First Claim
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1. A method for detecting aircraft performance degradation comprising:
- (a) receiving the initial weight of the aircraft from an external source;
(b) computing a current weight of the aircraft based on the received initial weight;
(c) computing the drag of the aircraft based on the computed current weight;
(d) computing a theoretical drag, CXth, of the aircraft based on the value of the computed drag and the square value of the computed drag(e) comparing the computed theoretical drag to a current drag of the aircraft that is computed by a different formula;
(f) generating an indication of aircraft performance degradation based on the result of the comparison; and
(g) outputting said indication.
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Abstract
An aircraft performance degradation detection system may include information sources, a central unit connected to the information sources, and a warning device that is connected to the central unit. Using information received from the information sources, the central unit computes the current weight and drag of the aircraft and computes a theoretical drag based on the current weight. The current and theoretical drags are compared, and a determination is made regarding performance degradation based on the comparison.
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Citations
31 Claims
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1. A method for detecting aircraft performance degradation comprising:
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(a) receiving the initial weight of the aircraft from an external source; (b) computing a current weight of the aircraft based on the received initial weight; (c) computing the drag of the aircraft based on the computed current weight; (d) computing a theoretical drag, CXth, of the aircraft based on the value of the computed drag and the square value of the computed drag (e) comparing the computed theoretical drag to a current drag of the aircraft that is computed by a different formula; (f) generating an indication of aircraft performance degradation based on the result of the comparison; and (g) outputting said indication. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for detecting aircraft performance degradation comprising:
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receiving the initial weight of the aircraft from an external source; computing a current weight of the aircraft based on the received initial weight; computing a theoretical drag of the aircraft based on the computed current weight; computing the current drag, CXa/c, of the aircraft using the expression;
CXa/c=2.T/R.S.TAS2−
G,in which; R is a constant value, S represents the area of the flying surface of the aircraft, TAS is a computed airspeed, G is a value dependent on TAS, and T is a value of traction; comparing the computed theoretical drag to the computed current drag of the aircraft; and outputting an indication of aircraft performance degradation based on the result of the comparison. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
for which; CXa/c is the computed current drag of the aircraft, CXth is the computed theoretical drag of the aircraft, Δ
CX1, Δ
CX2, and Δ
CX3 are predetermined values of drag,Δ
CXa/c is a deviation of computed current drag between two different predetermined instants, andΔ
CXth is a deviation of computed theoretical drag between two different predetermined instants.
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23. The method of claim 15 further comprising:
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determining whether the aircraft is in cruising flight; and when the aircraft is in cruising flight; computing a theoretical cruising speed based on the computed current weight of the aircraft; measuring a current speed of the aircraft; comparing the measured current speed and the computed theoretical cruising speed; and outputting the indication of aircraft performance degradation based on the comparisons of;
(1) the computed theoretical drag to the computed current drag of the aircraft and (2) the measured current speed and the computed theoretical cruising speed.
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24. The method of claim 23, wherein the theoretical cruising speed is computed on the basis of the computed current weight of the aircraft, a measured altitude of the aircraft, and the deviation between a standard temperature and a measured temperature.
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25. The method of claim 23, wherein aircraft performance degradation is determined to exist if one of the following two conditions C and D is fulfilled:
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condition C;
CXa/c>
CXth+Δ
CX4 andIAS<
IASth−
Δ
IAS1, for a predetermined duration;condition D;
CXa/c>
CXth+Δ
CX4,IAS<
IASth−
Δ
IAS1, andΔ
CXa/c>
Δ
CXth+Δ
CX5for which; CXa/c is the computed current drag of the aircraft, CXth is the computed theoretical drag of the aircraft, Δ
CX4 and Δ
CX5 are predetermined values of drag,IAS is the measured current speed of the aircraft, IASth is the computed theoretical cruising speed, Δ
IAS1 is a predetermined deviation in speed,Δ
CXa/c is a deviation in computed current drag between two different predetermined instants, andΔ
CXth is a deviation in computed theoretical drag between two different predetermined instants.
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26. The method of claim 25, wherein aircraft performance degradation is determined to exist if one of the following two conditions E and F is fulfilled:
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condition E;
CXa/c>
CXth+Δ
CX6 andIAS<
IASth−
Δ
IAS2, for a predetermined duration;condition F;
CXa/c>
CXth+Δ
CX6,IAS<
IASth−
Δ
IAS2, andΔ
CXa/c>
Δ
CXth+Δ
CX7for which; Δ
CX6 and Δ
CX7 are predetermined values of drag,Δ
CX6 is less than Δ
CX4,Δ
IAS2 is a predetermined deviation of speed, andΔ
IAS2 is greater than Δ
IAS1.
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27. The method as claimed in claim 26, wherein if none of the conditions C, D, E, and F is fulfilled:
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a check is performed to verify whether one of the following two conditions G and H is fulfilled; condition G;
CXa/c>
CXth+Δ
CX8 andIAS<
IASth−
Δ
IAS3, for a predetermined duration,condition H;
CXa/c>
CXth+Δ
CX8,IAS<
IASth−
Δ
IAS3, andΔ
CXa/c>
Δ
CXth+Δ
CX9,for which; Δ
CX8 and Δ
CX9 are predetermined drag values,Δ
CX8 being less than Δ
CX6, andΔ
IAS3 is a predetermined deviation of speed, which is less than Δ
IAS1 and Δ
IAS2; andif one of the conditions G and H is fulfilled, a message indicating that the cruising speed is low is emitted.
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28. A device for detecting aircraft performance degradation comprising:
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a set of information sources; a first computer that computes a current weight of the aircraft based on the initial weight of the aircraft obtained from the set of information sources; a second computer that computes a value of aircraft drag based on the computed current weight and computes a theoretical drag, CXth, of the aircraft based on the computed value of drag and the square of the computed value of drag; a first comparator that compares the computed theoretical drag to a current drag of the aircraft that is computed by a different formula; and a warning indicator that indicates aircraft performance degradation based on the result of the comparison. - View Dependent Claims (29, 30, 31)
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Specification