Heating control system and method for unpressurized aircraft

1. A heating system for an unpressurized aircraft, said heating system comprising:

a first ram air source configured to provide ram air to a heat exchanger via a first valve;

a bleed air source from a turbine engine configured to provide bleed air to the heat exchanger via a second valve, wherein the heat exchanger uses the ram air to cool the bleed air;

an ejector fluidly coupled downstream of the heat exchanger to receive cooled bleed air from the heat exchanger;

a second ram air source configured to provide ram air to the ejector via a third valve, wherein the ejector mixes the second ram air source with the cooled bleed air;

a controller operatively connected to the first valve, the second valve, and the third valve;

a control panel operatively connected to the controller, comprising:

a heating enable switch,

wherein the heating enable switch comprises an on configuration and an off configuration; and

a temperature selection control,

wherein the temperature selection control is configured to receive a desired temperature range; and

the controller is configured to regulate air temperature in the unpressurized aircraft by controlling the first, second, and third valves based on the temperature selection control when the heating enable switch is in the on configuration.

2. The heating system of claim 1 , comprising a temperature sensor disposed in a duct downstream of the ejector, wherein the temperature sensor is configured to provide a duct air temperature value to the controller.

3. The heating system of claim 1 , comprising:

an occupied compartment within the unpressurized aircraft; and

a temperature sensor disposed in the occupied compartment, wherein the temperature sensor is configured to provide an occupied compartment air temperature value to the controller.

4. The heating system of claim 1 , wherein when the heating enable switch is in the off configuration, automatically positioning the first, second, and third valves via the controller based on predetermined criteria without considering the desired temperature range.

5. The heating system of claim 1 , wherein the temperature selection control comprises an outside air temperature input, wherein the outside air temperature input is selected from one of two outside air temperature ranges of temperatures.

6. The heating system of claim 1 , wherein controller is configured to independently control a position of the first valve, the second valve, and the third valve to each have one of the following positions: 1) a fully closed position; 2) a fully open position; 3) a partially open position; or, 4) a modulated position based on a duty cycle.

7. A method for heating an unpressurized aircraft, comprising:

receiving, via a controller, a desired air temperature from a control panel;

calculating, via the controller, a target duct air temperature based on the desired air temperature;

determining, via the controller, an actual duct air temperature via a duct air temperature sensor disposed in an air duct;

calculating a target modulation of one or more ram air valves based on a difference between the target duct air temperature and the actual duct air temperature;

modulating one or more of the ram air valves via the controller based on the target modulation;

introducing a bleed air from a turbine engine to a heat exchanger;

introducing a temperature control air from one of the one or more ram air valves to the heat exchanger for cooling the bleed air to provide a temperature-controlled air;

mixing the temperature-controlled air from the heat exchanger with an ejector ram air in an ejector; and

providing air from the ejector to an occupied compartment of the unpressurized aircraft via the air duct.

8. The method of claim 7 , further comprising:

calculating a target ejector ram air valve position based on a flight position and the desired air temperature;

determining a measured ejector ram air valve position from a position sensor;

determining an error term based on the difference between the target ejector ram air valve position and the measured ejector ram air valve position;

maintaining an ejector ram air valve position when the error term is less than a predetermined value; and

adjusting the ejector ram air valve position based on the error term when the error term is greater than the predetermined value.

9. The method of claim 7 , further comprising:

calculating a target occupied compartment temperature based on the desired air temperature;

determining a measured occupied compartment temperature from a compartment temperature sensor;

calculating an occupied compartment temperature error based on the difference between the target occupied compartment temperature and the measured occupied compartment temperature; and

providing the occupied compartment temperature error to the controller for determining the target duct air temperature.

10. The method of claim 7 , wherein when a heating enable switch is in an off configuration, automatically positioning the one or more ram air valves via the controller based on predetermined criteria without considering the desired air temperature.

11. The method of claim 8 , comprising:

determining a flight position; and

setting the target ejector ram air valve position to a predetermined angle that avoids conflict with a temperature control valve when the flight position is determined to be an in air flight position.

12. The method of claim 8 , comprising determining an engine fire status, wherein upon determining that there is an engine fire, directing an ejector ram air motor via the controller to position the ejector ram air valve in a fully closed position.

13. A method for heating an unpressurized aircraft, comprising:

providing a desired air temperature to a controller via a control panel;

calculating, via the controller, a target duct air temperature based on the desired air temperature;

determining, via the controller, an actual duct air temperature via a duct air temperature sensor;

determining a temperature error based on a difference between the actual duct air temperature and the target duct air temperature;

calculating a target ejector ram air valve position based on the temperature error;

determining a measured ejector ram air valve position from a position sensor;

determining a valve error based on the difference between the target ejector ram air valve position and the measured ejector ram air valve position;

maintaining a position of an ejector ram air valve when the valve error is less than a predetermined value; and

adjusting the position of the ejector ram air valve based on the valve error when the valve error is greater than the predetermined value.

14. The method of claim 13 , further comprising:

introducing a bleed air from a turbine engine and ambient air received from a first air inlet to a heat exchanger to provide a temperature-controller air;

receiving ambient air from a second air inlet via the ejector ram air valve to provide an ejector ram air;

mixing the temperature-controlled air from the heat exchanger with the ejector ram air in an ejector to provide a mixed air; and

providing the mixed air from the ejector to an occupied compartment of the unpressurized aircraft via a duct.

15. The method of claim 14 , further comprising:

controlling an amount of ambient air received from the first air inlet via a temperature control valve;

determining whether the unpressurized aircraft is on the ground;

opening fully the temperature control valve when the aircraft is on the ground; and

modulating the temperature control valve when the aircraft is in the air.

16. The method of claim 15 , wherein modulating the temperature control valve comprises adjusting a duty cycle of the temperature control valve.

17. The method of claim 15 , further comprising:

controlling an amount of bleed air received from a turbine engine via a bleed air valve; and

providing a heating enable switch,

wherein, when the heating enable switch is in an off configuration, automatically positioning the ejector ram air valve, the temperature control valve, and the bleed air valve via the controller based on predetermined criteria without considering the desired air temperature.

18. The method of claim 17 , wherein when the aircraft is in the air, setting the ejector ram air valve position to a predetermined angle that avoids conflict with the temperature control valve.

19. The method of claim 13 , further comprising:

calculating a target occupied compartment temperature based on the desired air temperature;

determining a measured occupied compartment temperature from a compartment temperature sensor;

calculating an occupied compartment temperature error based on the difference between the target occupied compartment temperature and the measured occupied compartment temperature; and

providing the occupied compartment temperature error to the controller for determining the target duct air temperature.

20. The method of claim 13 , comprising determining an engine fire status, wherein upon determining that there is an engine fire, directing an ejector ram air motor via the controller to position the ejector ram air valve in a fully closed position.