Heating Control System and Method for Unpressurized Aircraft

A method for heating an unpressurized aircraft includes receiving a desired air temperature, calculating a target duct air temperature based on the desired air temperature, determining an actual duct air temperature via a duct air temperature sensor, 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 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.