System and method for aircraft thermal capacity prediction
A technique for identifying, projecting, displaying, and enhancing the thermal capacity for an aircraft is disclosed wherein the thermal capacity is defined as the amount of time or range the aircraft can continue until a thermal limit is exceeded.
1. A method of operating an aircraft, comprising the steps of:
a) establishing a mission projection for the aircraft;
b) flying the aircraft;
c) sensing data regarding a current state of the aircraft;
d) executing a prognostics model using the mission projection and the sensed data to estimate a duration until a thermal limit of the aircraft is exceeded, wherein the prognostics model outputs optimal thermal operation information comprising an alternative flight plan, wherein the alternative flight plan is displayed as trades between thermal capacity, system capabilities, fuel range, and aircraft speed;
e) communicating the estimated duration to an operator of the aircraft; and
f) changing an operating point of the aircraft based upon the estimated duration.
2. A method of operating an aircraft, comprising the steps of:
a) establishing a mission projection for the aircraft;
b) flying the aircraft;
c) sensing data regarding a current state of the aircraft;
d) executing a prognostics model using the mission projection and the sensed data to estimate a duration until a thermal limit of the aircraft is exceeded, wherein the prognostics model outputs optimal thermal operation information comprising data showing a relationship between heat rejected from the aircraft and predicted range of the aircraft;
e) communicating the estimated duration to an operator of the aircraft; and
f) changing an operating point of the aircraft based upon the estimated duration.
3. The method of claim 2 , wherein the optimal thermal operation information includes a Pareto front showing a best compromise between heat rejected from the aircraft and predicted range of the aircraft.
4. A method of operating an aircraft, comprising the steps of:
a) establishing a mission projection for the aircraft;
b) flying the aircraft;
c) sensing data regarding a current state of the aircraft, wherein the sensed data is selected from the group consisting of: altitude, speed, power level angle, ambient temperature, ambient pressure, fuel temperature, and fuel mass;
d) executing a prognostics model using the mission projection and the sensed data to estimate a duration until a thermal limit of the aircraft is exceeded;
e) communicating the estimated duration to an operator of the aircraft; and
f) changing an operating point of the aircraft based upon the estimated duration.
5. The method of claim 4 , wherein the mission projection comprises a model of an altitude the aircraft will be flown at for each time segment of a predefined mission.
6. The method of claim 4 , wherein the prognostics model models the aircraft's real-time thermal capacitance as a function of time based on dynamic internal and external boundary conditions.
7. The method of claim 4 , wherein the prognostics model comprises:
a boundary conditions block that accepts the sensed data and mission projection as inputs and creates a boundary conditions output;
an adaptive technique section that accepts the sensed data, the boundary conditions output, and a fuel temperature/fuel mass output as inputs and creates a corrective term as an output;
a heat transfer/fuel flow block that accepts the boundary conditions output and the fuel temperature/fuel mass output as inputs and creates a heat transfer/fuel flow output;
a summing block that sums the heat transfer/fuel flow output and the corrective term to create a sum output;
an integrator that integrates the sum output to create an integrator output; and
a fuel temperature/fuel mass block that accepts as an input the integrator output and produces the fuel temperature/fuel mass output.
8. The method of claim 7 , wherein the fuel temperature/fuel mass output is used to generate the estimated duration.
9. The method of claim 7 , wherein the boundary conditions output is selected from the group consisting of: solar loading, convection, and fuel flow rate.
10. The method of claim 7 , wherein the prognostics model is executed repeatedly at a first rate while the aircraft is flown.
11. The method of claim 10 , wherein the adaptive technique creates the corrective term at a second rate, wherein the second rate is slower than the first rate.
12. The method of claim 4 , wherein the operating point is selected from the group consisting of: altitude, speed, and fueling.
13. The method of claim 4 , wherein if the aircraft is not currently on the mission projection, the prognostics model estimates the duration by assuming that the operator will return the aircraft to the mission projection immediately.
14. The method of claim 4 , wherein the estimated duration comprises data selected from the group consisting of: distance, and time.
15. The method of claim 4 , wherein step (e) comprises creating a display visible to the operator, the display comprising:
a first non-numerical visual indicator communicating a current of net heat into or out of the aircraft;
a first numerical display communicating the estimated duration;
a second non-numerical visual indicator communicating an amount of fuel projected to be remaining when the aircraft lands; and
a second numerical display communicating a distance prior to landing that the aircraft will exceed the thermal limit.
16. The method of claim 4 , wherein the prognostics model outputs optimal thermal operation information for the aircraft.
17. The method of claim 16 , wherein the optimal thermal operation information comprises an alternative flight plan.
18. The method of claim 17 , wherein the alternative flight plan is displayed in real-time.
19. The method of claim 17 , wherein the alternative flight plan is displayed as Mach number and altitude.
20. The method of claim 4 , wherein steps (a), (d) and (e) are performed by a processing device selected from the group consisting of: a digital computer, a field-programmable gate array, a complex programmable logic device, a microprocessor, a digital signal processor, an analog computer, analog circuitry, and digital circuitry.
21. The method of claim 4 , wherein the mission projection is based on one or more factors selected from the group consisting of: time, range, mission segments, destination, geographical coordinates, or meteorological data.