Weight and balance computer apparatus for aircraft
First Claim
1. Apparatus for providing a measure of the gross weight of an aircraft having engines for providing propelling thrust therefor comprisinga. means responsive to an operating characteristic of the engines for providing a measure of the thrust thereof,b. means responsive to aerodynamic forces acting on said aircraft and said measure of thrust for providing a measure of a function of the angle of attack of said aircraft, andc. means responsive to said angle of attack function measure for providing an output measure of the gross weight of said aircraft.
1 Assignment
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Accused Products
Abstract
Aircraft weight and balance computer apparatus processes sensor outputs to generate an electrical signal that is proportional to aircraft gross weight at the time take-off thrust is initially applied to the aircraft on the runway and continually updates the weight signal when airborne to account for burn off of fuel or other weight loss and also provides a measure of the location of the aircraft center of gravity position. This is achieved by computing the aerodynamic forces on the aircraft in its longitudinal plane and the thrust generated by the engines and relating these computations to the corresponding acceleration components measured by a pair of linear accelerometers that are mounted orthogonally in this longitudinal plane.
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Citations
28 Claims
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1. Apparatus for providing a measure of the gross weight of an aircraft having engines for providing propelling thrust therefor comprising
a. means responsive to an operating characteristic of the engines for providing a measure of the thrust thereof, b. means responsive to aerodynamic forces acting on said aircraft and said measure of thrust for providing a measure of a function of the angle of attack of said aircraft, and c. means responsive to said angle of attack function measure for providing an output measure of the gross weight of said aircraft. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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12. The apparatus as set forth in claim 10 wherein said gross weight signal includes undesired high frequency components included in said angle of attack function signal, further including
a. means responsive to said gross weight signal for providing an output signal including only long term variations thereof b. means responsive to said long term weight signal and said gross weight signal including said high frequency components for providing a weight error signal, and c. means supplying said weight error signal to said weight measure providing means for reducing the effects of said high frequency components of said angle of attack measure in said aircraft gross weight signal. -
13. The apparatus as set forth in claim 1 further including means providing an output measure of the take-off weight of said aircraft comprising
a. means for providing a measure of the longitudinal acceleration of said aircraft, b. means responsive to said measure of the thrust of said aircraft and said longitudinal acceleration measure for providing a resultant measure of the take-off weight of the aircraft, c. switch means for substituting said resultant take-off weight measure for said angle of attack function measure to said weight measure providing means, and d. means responsive to a predetermined value of said engine operating characteristic for operating said switch means. -
14. The apparatus as set forth in claim 13 wherein said aircraft is equipped with brakes on the landing gear wheels, said apparatus further including
a. means responsive to release of said brakes for providing a corresponding signal, and b. logic means responsive to said predetermined value of said engine operating characteristic and said brake signal for operating said switch means. -
15. The apparatus as set forth in claim 12 further including means providing an output measure of the take-off weight of the aircraft comprising
a. means for providing a measure of the longitudinal acceleration of the aircraft, b. means responsive to said measure of thrust of said aircraft and said longitudinal acceleration measure for providing a resultant measure of the take-off weight of the aircraft. c. first switch means for substituting said resultant take-off weight measure for said angle of attack function measure to said weight measure providing means, d. second switch means for rendering said long term weight variation signal and said weight error signal ineffective and substituting thereofor the instantaneous value of said take-off weight signal, and e. means responsive to a predetermined value of said engine operating characteristic for operating both first and second switch means. -
16. The apparatus as set forth in claim 13 further including
a. timing means responsive to operation of said switch means for rendering said substitution of said take-off weight measure effective for only a short time period, on the order of one to five seconds, and for thereafter effectively clamping said take-off weight measure at the value then obtaining. -
17. The apparatus as set forth in claim 16 further including:
a. Further switch means responsive to an airborne condition of said aircraft for reinstating said angle of attack function measure to said weight measure providing means.
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18. The apparatus as set forth in claim 13 wherein said means for providing said resultant measure of take-off weight comprises computer means responsive to said measure of thrust and longitudinal acceleration for providing a measure proportional to take-off weight as a function of said signals in accordance with the equation ##EQU36## where WTO = aircraft take-off weight
ax = longitudinal acceleration of the aircraft g = gravity acceleration μ - RL = rolling friction of the aircraft
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19. Apparatus for providing a measure of the take-off weight of an aircraft comprising
a. means for providing a measure of an operating characteristic of the aircraft engines for providing a measure of the take-off thrust thereof, b. means for providing a measure of the longitudinal acceleration of the aircraft, c. means for providing a measure of the rolling friction of the aircraft, d. means responsive to said measures for providing an output measure of the take-off weight of said aircraft as a predetermined function of said signals, e. switch means for rendering said means responsive to said measures effective, and f. means responsive to a predetermined value of said engine operating characteristic for operating said switch means.
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22. Apparatus for providing a measure of the gross weight of an engine powered aircraft comprising
a. means responsive to an operating characteristic of each of the aircraft engines at the Mach number speed and static pressure environment of the aircraft for providing a signal corresponding to the thrust produced on the aircraft by each of the engines and means for summing all of said thrust signals for providing a resultant signal corresponding to the total thrust produced by all of the engines, b. means responsive to accelerations of the aircraft along mutually perpendicualr axes corresponding to the vertical and longitudinal axes of the aircraft and for providing signals corresponding thereto, c. means responsive to the Mach number speed of the aircraft and the static pressure environment of the aircraft for providing signals corresponding thereto, d. means responsive to the positions of aerodynamic surfaces of the aircraft affecting the lift and drag characteristics thereof, and e. computer means responsive to all of said signals for providing an output signal corresponding to the solution of the pair of equations ##EQU38## wherein W = the gross weight of the aircraft T = the total thrust of the engines ax = longitudinal acceleration of the aircraft az = normal acceleration of the aircraft M = the Mach number speed of the aircraft Ps = the static air pressure at the aircraft α - = the angle of attack of the aircraft
Cl = the coefficient of lift of the aircraft Cd = the coefficient of drag of the aircraft S = the wing area of the aircraft g = the gravity acceleration of the earth, said output signal corresponding to the simultaneous solution of said equations for said gross weight term W.
- = the angle of attack of the aircraft
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23. Apparatus for providing a measure of the position of the center of gravity of an aircraft having a main sustaining wing, wing flags, horizontal stabilizer and elevator, relative to the mean aerodynamic chord of said wing comprising
a. means for providing a signal proportional to the effective position of the horizontal stabilizer in producing a pitching movement on said aircraft, b. means for providing a signal proportional to a function of the horizontal and normal accelerations of the aircraft and the thrust-to-weight ratio of said aircraft, and c. means responsive to said signals for providing a signal proportional to the position of the center of gravity of the aircraft about which said pitching moment is effective.
Specification