Aircraft weight estimation
In an embodiment, a method for aircraft weight estimation is provided that includes determining a weight signal based on a dynamic pressure signal, a calibrated angle of attack signal, a lift coefficient signal, a load factor signal, and a wing surface area. In another embodiment, a method to estimate aircraft weight is provided that includes determining a weight based on historical flight data relating horizontal control surface position to dynamic pressure. In another embodiment, a system for continuously estimating aircraft weight during flight is provided that includes a pitot-static subsystem, an angle of attack indicator, an accelerometer, a controller configured to provide a weight signal, and a signal filter for filtering the weight signal to determine a stable aircraft weight.
1. A method for aircraft weight estimation, comprising:
providing a dynamic pressure signal from a pitot-static subsystem;
determining a calibrated angle of attack signal from an angle of attack indicator;
determining a lift coefficient signal based on the calibrated angle of attack signal and a Mach number;
providing a load factor signal from an accelerometer; and
determining a weight signal based on the dynamic pressure signal, the calibrated angle of attack signal, the lift coefficient signal, the load factor signal, and a wing surface area.
2. The method of claim 1 , wherein determining the lift coefficient is further based on a flap position.
3. The method of claim 1 , further comprising determining a time-averaged weight signal by averaging the weight signal over time.
4. The method of claim 1 , further comprising updating the lift coefficient based on one or more lookup tables.
5. A method for aircraft weight estimation, comprising:
measuring a horizontal control surface position with a sensor;
providing a dynamic pressure from a pitot-static subsystem;
determining a weight using historical flight data relating the horizontal control surface position to the dynamic pressure based on aircraft weight; and
repeating continuously during flight the steps of measuring the horizontal control surface position, providing the dynamic pressure, and determining the weight to provide a weight signal.
6. The method of claim 5 , further comprising filtering the weight signal by averaging the weight over time.
7. The method of claim 5 , further comprising determining an airspeed based on the dynamic pressure signal.
8. The method of claim 7 , further comprising determining a Mach number based on the airspeed and a temperature measured with a temperature sensing device.
9. The method of claim 8 , further comprising updating the weight based on the Mach number and an air density measured using the pitot-static subsystem.
10. The method of claim 9 , further comprising determining a center of gravity based on the weight signal and an amount of fuel onboard the aircraft.
11. The method of claim 10 , further comprising updating the weight signal based on the center of gravity.
12. A system for continuously estimating aircraft weight during flight, comprising:
a pitot-static subsystem for providing a dynamic pressure signal;
an angle of attack indicator for providing a calibrated angle of attack signal;
an accelerometer for providing a load factor signal;
a controller configured to provide a weight signal based on an initial weight, the dynamic pressure signal, the calibrated angle of attack signal, and the load factor signal; and
a signal filter for filtering the weight signal to determine a stable aircraft weight.
13. The system of claim 12 , further comprising a flap indicator to sense a flap position for updating the lift coefficient.
14. The system of claim 12 , further comprising a lift-coefficient-slope lookup table for determining the lift coefficient based on the calibrated angle of attack signal.
15. The system of claim 12 , further comprising an airspeed indicator for providing airspeed based on the dynamic pressure signal.
16. The system of claim 15 , further comprising a zero-degree angle-of-attack lift coefficient lookup table for determining the lift coefficient based on airspeed.
17. The system of claim 12 , further comprising a control surface sensor for sensing a control surface position and a trim table based on historical flight data relating the control surface position to the dynamic pressure signal for a range of weights.