AIRCRAFT WEIGHT AND CENTER OF GRAVITY INDICATOR SYSTEM

• US 3,701,279 A
• Filed: 02/08/1971
• Issued: 10/31/1972
• Est. Priority Date: 02/08/1971
• Status: Expired due to Term

• Current Assignee: Carl R. Harris, Dallas V. Soward, Robert B. Banks
• Original Assignee: Carl R. Harris, Dallas V. Soward, Robert B. Banks
• Inventors: Banks, Robert B., Harris, Carl R., Soward, Dallas V.
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US05/113,129
• Time in Patent Office: 631 Days
• Field of Search: 73/65 177/136
• US Class Current: 73/65.06
• CPC Class Codes: G01G 19/07 for weighing aircraft
• CPC Class Codes: G01M 1/125 of aircraft
• CPC Class Codes: G01M 1/127 during the flight

Abstract

After a discussion of the prior art techniques and apparatus for insuring that an aircraft is loaded correctly, such as loading charts, manifest forms, tipping alarms, and the like, an improved weight and balance system for aircraft is described for providing automated monitoring of aircraft loading. The system includes a plurality of transducers generating signals proportional to the forces acting on the landing gear of the aircraft. These signals are summed to obtain a signal proportional to the instantaneous gross weight of the aircraft. In addition, an analog computer derives from these signals a signal which is proportional to the aircraft'"'"''"'"'s instantaneous center of gravity moment. A display means provides for the continuous display of gross weight and center of gravity, in terms of percent MAC. In addition, the gross weight signal is applied to first and second function generators which develop therefrom signals corresponding to forward and aft center of gravity limits. Comparison is made in appropriate circuitry of the instantaneous center of gravity moment with the forward and aft CG limits, and an appropriate indication is made if either limit is exceeded during loading. An embodiment of the function generators and comparators is described in detail. A modification of the system to compensate for effects of fuel withdrawal upon center of gravity during flight is also described.

Claims

1. An apparatus for indicating when the center of gravity of an aircraft whose landing gear are in ground contact has shifted past acceptable limits thereof with respect to a fixed reference, comprising:

a. a plurality of transducer means, each of said transducer means being disposed to provide an output signal proportional to the force exerted on one landing gear of the aircraft, b. means summing said output signals from said plurality of transducer means to obtain a signal proportional to the aircraft'"'"''"'"'s gross weight, c. means computing from said output signals a signal proportional to the aircraft'"'"''"'"'s center of gravity moment with respect to said fixed reference, d. means deriving from said gross weight signal first and second signals corresponding to desired forward and aft limits of said center of gravity moment with respect to said fixed reference, and e. means providing an alarm indication whenever said center of gravity moment signal exceeds either said first signal or said second signal.

2. An apparatus as recited in claim 1, further including a display means comprising means for computing the aircraft'"'"''"'"'s instantaneous center of gravity from said center of gravity moment and said gross weight signals, and a display device for providing a visual indication of either said instantaneous center of gravity or said instantaneous gross weight.

3. An apparatus as recited in claim 1, wherein said computing means comprises:

a. means multiplying each of said output signals by a factor proportional to the distance of the corresponding landing gear from said fixed reference, and b. means summing said multiplied signals to obtain said center of gravity moment signal.

4. An apparatus as recited in claim 3, wherein said gross weight signal is supplied to said multiplying means in place of one of said transducer output signals.

5. An apparatus as recited in claim 3, wherein said computing means further includes attitude sensing means providing a signal proportional to the tilting deviation of said aircraft from a predetermined position, and means connecting said signal to said summing means along with said multiplied signals.

6. A system for determining whethEr or not an aircraft has been safely loaded, comprising:

a. sensor means providing a plurality of signals, each signal being proportional to the force exerted on a landing gear of the aircraft, b. means computing the aircraft'"'"''"'"'s actual center of gravity from said plurality of signals, c. means computing the aircraft'"'"''"'"'s gross weight from said plurality of signals, d. means comparing said actual center of gravity with a predetermined envelope of desired values thereof and providing an output signal when said actual center of gravity does not correspond to said envelope, said comparing means including means generating signals corresponding to forward and aft limits of said desired center of gravity envelope, said generating means including a first function generator providing an aft center of gravity limit corresponding to a predetermined threshold value thereof, and a second function generator deriving from said aircraft'"'"''"'"'s gross weight a forward center of gravity limit.

7. A system as recited in claim 6, wherein said sensor means comprises a plurality of transducer means, each transducer means being responsive to the shear deflection force exerted on one landing gear of the aircraft.

8. A system as recited in claim 6, wherein said second function generator derives said forward center of gravity limit Lcg according to the relation Lcg L2 - FTL3/GW.