CONTINUAL TRANSFERENCE OF FUEL BETWEEN FUEL TANKS AT A RATE COMMENSURATE WITH FUEL BURN DURING CRUISE FLIGHT OPERATION TO MAINTAIN THE AIRCRAFT CENTER OF GRAVITY WITHIN A PRE-SELECTED AFT CENTER OF GRAVITY ENVELOPE

• US 20100044515A1
• Filed: 08/25/2008
• Published: 02/25/2010
• Est. Priority Date: 08/25/2008
• Status: Active Grant

• Current Assignee: Embraer S.A.
• Original Assignee: Embraer S.A.
• Inventors: Neto, Rubens Domecildes
• Granted Patent: US 8,226,040 B2
• Time in Patent Office: Days
• US Class Current: 244/135.C
• CPC Class Codes: B64C 17/10 Transferring fuel to adjust trim
• CPC Class Codes: G01M 1/127 during the flight

Abstract

Fuel transference between aircraft fuel tanks, disposed in different locations, is used to maintain the aircraft Center of Gravity close to the aft limit of the certified Center of Gravity versus weight envelope. Continuous fuel transfer decreases the control band thus enhancing aircraft performance.

Claims

1. On an aircraft, an onboard active center of gravity control system with continuous fuel transference between fuel tanks, comprising:

at least one variable flow control element that is fluid-coupled between said fuel tanks, said flow control element capable of providing a variable flow rate of fuel between said fuel tanks; and

an electronic controller coupled to electronically control said at least one flow control element, said electronic controller dynamically controlling said variable flow rate of fuel transfer between said tanks to optimize aircraft center of gravity.

2. The system of claim 1 wherein said electronic controller provides continual transference of fuel between said fuel tanks at a rate commensurate with fuel burn during cruise flight operation to maintain the aircraft center of gravity within a pre-selected aft center of gravity envelope.

3. The system of claim 1 further including sensors that sense aircraft mass distribution, and wherein said electronic controller is coupled to said sensors and estimates center of gravity at least in part in response to said sensed aircraft mass distribution.

4. The system of claim 1 wherein said electronic controller accesses data indicating distribution of fuel and non-fuel mass on the aircraft.

5. The system of claim 1 wherein said electronic controller schedules end-of-flight fuel transference to ensure main tank fuel content complies with fuel regulations for landing.

6. The system of claim 1 wherein said electronic controller controls said flow control element to remain on continually.

7. The system of claim 1 wherein said electronic controller selectively deactuates said flow control element.

8. The system of claim 1 wherein said electronic controller includes a Center of Gravity Estimation Box (CGEB) that receives and processes signals from sensors and inputs, said CGEB converting information in terms of Center of Gravity to fuel flow required to be transferred between fuel tanks continually.

9. The system of claim 8 wherein said flow control element comprises pumps and/or valves able to modulate the fuel flow according to the output of the CGEB to take the aircraft CG to the optimum position.

10. The system of claim 1 further including a plurality of fuel tanks disposed in different zones of the aircraft with communicating fuel lines able to transfer fuel between the tanks.

11. A method of providing continual transference of fuel between fuel tanks on board an aircraft at a rate commensurate with fuel burn during cruise flight operation, said method comprising:

sensing at least one flight parameter;

estimating current aircraft center of gravity at least in part in response to said sensed flight parameter and stored data; and

in response to said estimating, automatically actuating a variable flow element that is fluid-coupled between a main tank and an auxiliary tank to maintain aircraft center of gravity within a pre-selected aft center of gravity envelope during flight.

12. The method of claim 11 further wherein said sensing includes sensing aircraft mass distribution, and said estimating comprises estimating center of gravity at least in part in response to said sensed aircraft mass distribution.

13. The method of claim 11 wherein said stored data indicates distribution of fuel and non-fuel mass on the aircraft.

14. The method of claim 11 further including scheduling end-of-flight fuel transference to ensure main tank fuel content complies with fuel regulations for landing.

15. The method of claim 11 further includes controlling said variable flow element to remain on continually.

16. The method of claim 11 further including selectively deactuating said variable flow element.

17. The method of claim 11 further includes converting information in terms of Center of Gravity to fuel flow required to be transferred between fuel tanks.

18. The method of claim 17 further including modulating fuel flow to take the aircraft CG to the optimum position.

19. The method of claim 11 further including bidirectionally transferring fuel between a plurality of fuel tanks disposed in different zones of the aircraft.

20. A system for providing continual transference of fuel between fuel tanks on board an aircraft at a rate commensurate with fuel burn during cruise flight operation, said method comprising:

means for sensing at least one flight parameter;

means for estimating current aircraft center of gravity at least in part in response to said sensed flight parameter and stored data; and

means responsive to said estimating for automatically actuating a variable flow element that is fluid-coupled between a main tank and an auxiliary tank to maintain aircraft center of gravity within a pre-selected aft center of gravity envelope during flight.