Hybrid propulsion engines for aircraft

1. A hybrid propulsion engine for an aircraft, the hybrid propulsion engine comprising:

a propulsor;

a gas turbine engine to drive the propulsor during a first mode of operation, the gas turbine engine having a core air intake;

an electric motor to drive the propulsor during a second mode of operation;

an overrunning clutch disposed between the gas turbine engine and the electric motor; and

a damper disposed in the core air intake of the gas turbine engine to block airflow through the core air intake during the second mode of operation.

2. The hybrid propulsion engine of claim 1 , wherein the damper is operable between an open state that allows airflow through the core air intake and a closed state that blocks airflow through the core air intake.

3. The hybrid propulsion engine of claim 1 , wherein the core air intake is defined by an outer radial wall and an inner radial wall, and wherein the damper includes a plurality of vanes between the outer radial wall and the inner radial wall.

4. The hybrid propulsion engine of claim 3 , wherein the damper includes an actuator to rotate the vanes.

5. The hybrid propulsion engine of claim 3 , wherein the vanes are rotatable about axes extending radially from a center axis of the core air intake.

6. The hybrid propulsion engine of claim 3 , wherein, in a closed state, the vanes overlap in an axial direction such that the vanes block airflow through the core air intake.

7. The hybrid propulsion engine of claim 1 , wherein the propulsor is a fan, and wherein the gas turbine engine and the fan form a turbofan engine.

8. The hybrid propulsion engine of claim 1 , wherein the propulsor is a propeller, and wherein the gas turbine engine and the propeller form a turboprop engine.

9. A hybrid propulsion engine for an aircraft, the hybrid propulsion engine comprising:

a propulsor;

a gas turbine engine to drive the propulsor during a first mode of operation, the gas turbine engine having a core air intake defined by an outer radial wall and an inner radial wall;

an electric motor to drive the propulsor during a second mode of operation; and

a damper disposed in the core air intake of the gas turbine engine to block airflow through the core air intake during the second mode of operation, the damper including:

a plurality of vanes between the outer radial wall and the inner radial wall;

an actuation ring disposed around the outer radial wall;

a plurality of arms coupled between respective ones of the vanes and the actuation ring; and

an actuator to rotate the actuation ring to rotate the vanes simultaneously.

10. A method comprising:

receiving, at a controller, an input signal requesting to change a state of a damper from an open state to a closed state, the damper being disposed in a core air intake of a gas turbine engine, the gas turbine engine being part of a hybrid propulsion engine including an electric motor, a propulsor, and an overrunning clutch disposed between the gas turbine engine and the electric motor, the gas turbine engine to drive the propulsor during a first mode of operation, the electric motor to drive the propulsor during a second mode of operation;

determining, via the controller, whether one or more state-change parameters are satisfied; and

sending, via the controller, a command signal to move the damper from the open state to the closed state based on the determination that the one or more state-change parameters are satisfied, wherein, in the closed state, the damper is to block airflow through the core air intake during the second mode of operation.

11. The method of claim 10 , wherein the controller is to send the command signal while the hybrid propulsion engine is operating in the second mode of operation.

12. The method of claim 10 , wherein the input signal is a first input signal and the command signal is a first command signal, the method further including:

receiving, at the controller, a second input signal requesting to change the state of the damper from the closed state to the open state; and

while the hybrid propulsion engine is operating in the second mode of operation, sending, via the controller, a second command signal to move the damper from the closed state to the open state.

13. The method of claim 12 , further including, after the damper is moved to the open state, sending, via the controller, a third command signal to start the gas turbine engine to switch the hybrid propulsion engine from the second mode of operation to the first mode of operation.

14. The method of claim 10 , wherein the command signal is a first command signal, further including:

sending, via the controller, a second command signal to move the damper to a partially open state between the closed state and the open state; and

while the hybrid propulsion engine is operating in the second mode of operation, sending, via the controller, a third command signal to start the gas turbine engine to at least one of produce heat or provide power to one or more aircraft systems.

15. The method of claim 10 , wherein the damper includes a plurality of vanes disposed in the core air intake, and wherein the command signal is to activate an actuator to rotate the vanes from an open position in which the vanes allow airflow through the core air intake to a closed position in which the vanes block airflow through the core air intake.

16. The method of claim 10 , wherein the one or more state-change parameters include at least one of a temperature of the gas turbine engine or a revolutions-per-minute (RPM) of the gas turbine engine.

17. An aircraft comprising:

a hybrid propulsion engine including:

a propulsor;

a gas turbine engine operatively coupled to the propulsor, the gas turbine engine having a compressor and a core air intake to direct air into the compressor, the gas turbine engine to drive the propulsor during a first mode of operation;

an electric motor operatively coupled to the propulsor, the electric motor to drive the propulsor during a second mode of operation;

an overrunning clutch disposed between the gas turbine engine and the electric motor; and

a damper disposed in the core air intake, the damper operable between an open state to allow airflow into the compressor during the first mode of operation and a closed state to block airflow into the compressor during the second mode of operation.

18. The aircraft of claim 17 , wherein the core air intake is defined by an outer radial wall and an inner radial wall, and wherein the damper includes a plurality of vanes between the outer radial wall and the inner radial wall.

19. The aircraft of claim 18 , wherein the vanes are rotatable between an open position that allows airflow between the vanes and a closed position that blocks airflow between the vanes.

20. The aircraft of claim 18 , wherein the damper includes an actuator to rotate the vanes simultaneously.