VARIABLE ENGINE-INLET BYPASS CONTROL SYSTEMS AND METHOD

1 . A system comprising:

a forward-facing airframe-inlet duct interoperably coupled to an inlet of an engine of an aircraft;

an air-mass-flow bypass door coupled to the forward-facing airframe-inlet duct and adjustable to allow a selected amount of air entering an inlet of the forward-facing airframe-inlet duct to bypass the inlet of the engine;

an air-pressure sensor arranged in the forward-facing airframe-inlet duct adjacent to the inlet of the engine;

wherein a measured value (“PT1”) from the air-pressure sensor is used to determine a degree to which the air-mass-flow bypass door is to be opened so as to optimize air-mass-flow intake to the engine and minimize spillage drag; and

wherein the determination comprises comparing PT1 to a free-stream ambient air-pressure value (“PT0”).

2 . (canceled)

3 . The system of claim 1 , wherein an increase in PT1 causes an amount of opening of the air-mass-flow bypass door to increase.

4 . The system of claim 1 , wherein a decrease in PT1 causes an amount of opening of the air-mass-flow bypass door to decrease.

5 . The system of claim 1 , wherein PT0 is calculated based on air data, the air data comprising outside ambient temperature, altitude, and airspeed.

6 . The system of claim 1 , wherein the air-mass-flow bypass door is tuned in accordance with operational parameters of the engine.

7 . The system of claim 1 , wherein, when the air-mass-flow bypass door is open, the selected amount of air reduces spillage drag relative to a condition in which the air-mass-flow bypass door is closed.

8 . (canceled)

9 . A system comprising:

a forward-facing airframe-inlet duct interoperably coupled to an inlet of an engine of an aircraft;

a spring-loaded air-mass-flow bypass door coupled to the forward-facing airframe-inlet duct and operable to allow a variable amount of air entering an inlet of the forward-facing airframe-inlet duct to bypass the inlet of the engine; and

wherein the variable amount of air optimizes engine air-mass-flow intake and minimizes spillage drag.

10 . (canceled)

11 . The system of claim 9 , wherein the spring-loaded air-mass-flow bypass door is coupled to a tuned spring that resists opening of the spring-loaded air-mass-flow bypass door.

12 . The system of claim 11 , wherein the spring-loaded air-mass-flow bypass door opens and closes responsive to air pressure on the spring-loaded air-mass-flow bypass door.

13 . (canceled)

14 . (canceled)

15 . The system of claim 9 , wherein the spring-loaded air-mass-flow bypass door is tuned in accordance with operational parameters of the engine.

16 . The system of claim 9 , wherein, when the spring-loaded air-mass-flow bypass door is open, the variable amount of air reduces spillage drag relative to a condition in which the spring-loaded air-mass-flow bypass door is closed.

17 . (canceled)

18 . A method comprising:

sensing an air-pressure value within a forward-facing airframe-inlet duct and adjacent to an inlet of an engine coupled to the forward-facing airframe-inlet duct;

comparing the sensed air-pressure value to a free-stream ambient air-pressure value;

responsive to the comparing, determining an optimal position of an air-mass-flow bypass door coupled to the forward-facing airframe-inlet duct

wherein the optimal position optimizes air-mass-flow intake to the engine and minimizes spillage drag; and

responsive to the determining, positioning the air-mass-flow bypass door to be in the optimal position.

19 . The method of claim 18 , wherein the optimal position results in a reduction of spillage drag.

20 . The method of claim 18 , wherein the comparing comprises calculating a ratio of the sensed air-pressure value to the free-stream ambient air-pressure value.