Rotor unloading apparatus and method
A method and apparatus for enabling high speed flight in a rotorcraft are disclosed. The method may include executing a flight with a rotorcraft. The flight may include a first portion and second portion ordered sequentially. During the first portion, the rotorcraft may be flown with the rotor exclusively in autorotation. Once sufficient airspeed is obtained, the flight may transition to the second portion. Wherein, substantially all of the weight of the rotorcraft may be supported by one or more fixed wing surfaces of the rotorcraft. Thus, during the second portion, the rotor may be completely unloaded. To keep the rotor stable by turning, the rotor may be powered during the second portion by an engine of the rotorcraft by way of a prerotation system.
1. A method enabling high speed flight in a rotorcraft, the method comprising:
selecting a rotorcraft comprising at least one engine, a rotor, and at least one fixed wing surface;
executing, by the rotorcraft, a flight comprising a first portion and a second portion;
flying, during the entire first portion, the rotorcraft with the rotor exclusively in autorotation;
flying, during at least a portion of the first portion, the rotorcraft with substantially all weight of the rotorcraft supported by the rotor;
flying, during the entire second portion, the rotorcraft with rotation of the rotor being powered at least partially by the at least one engine; and
flying, during at least a portion of the second portion, the rotorcraft with substantially all weight of the rotorcraft supported by the at least one fixed wing surface.
2. The method of claim 1 , further comprising decreasing, during the second portion, the rotational speed of the rotor.
3. The method of claim 1 , wherein the rotorcraft further comprises a prerotation system.
4. The method of claim 3 , further comprising prerotating, by the at least one engine via the prerotation system, the rotor prior to the executing of the flight.
5. The method of claim 4 , wherein the flying during the second portion comprises powering, by the at least one engine through the prerotation system, rotation of the rotor.
6. The method of claim 5 , further comprising decreasing, during the second portion, the rotational speed of the rotor.
7. The method of claim 6 , wherein the first portion precedes the second portion.
8. The method of claim 7 , wherein the flight further comprises a third portion following the second portion.
9. The method of claim 8 , further comprising flying, during the entire third portion, the rotorcraft with the rotor exclusively in autorotation.
10. The method of claim 9 , further comprising flying, during at least a portion of the third portion, the rotorcraft with substantially all weight of the rotorcraft supported by the rotor.
11. A method enabling high speed flight in a rotorcraft, the method comprising:
selecting a rotorcraft having a weight and comprising at least one engine, a rotor, and at least one fixed wing surface;
executing, by the rotorcraft, a flight having an initial portion in which the weight of the rotorcraft is substantially supported by autorotation;
obtaining, during the flight, a first airspeed sufficient for the at least one fixed wing surface to support the entire weight of the rotorcraft;
supporting, by the at least one fixed wing surface after the obtaining, substantially all weight of the rotorcraft; and
powering, by the at least one engine during the supporting, rotation of the rotor.
12. The method of claim 11 , further comprising obtaining, during the supporting and powering, a second airspeed, greater than the first airspeed.
13. The method of claim 12 , wherein the second airspeed is greater than 250 miles per hour.
14. The method of claim 11 , further comprising slowing, during the supporting, the rotational speed of the rotor.
15. The method of claim 11 , wherein the rotorcraft further comprises at least one control surface selected from the group consisting of a rudder, elevator, and aileron.
16. The method of claim 15 , further comprising controlling the flight, during the supporting and powering, using the at least one control surface.
17. The method of claim 11 , wherein the rotorcraft further comprises a prerotation system.
18. The method of claim 17 , further comprising prerotating the rotor, by the at least one engine through the prerotation system, prior to the executing of the flight.
19. The method of claim 18 , wherein the powering comprises urging rotation of the rotor, by the at least one engine, through the prerotation system.
20. A method comprising:
selecting a rotorcraft having a weight and comprising at least one engine, a prerotation system, a rotor, and at least one fixed wing surface;
prerotating the rotor, by the at least one engine, through the prerotation system;
executing, by the rotorcraft, after the prerotating, a flight comprising a first portion, second portion, and third portion, the first portion immediately preceding the second portion, the second portion immediately preceding the third portion;
flying, during the first portion, the rotorcraft with the rotor operating exclusively in autorotation;
flying, during the second portion, the rotorcraft with substantially all of the weight supported by the at least one fixed wing surface and rotation of the rotor being powered substantially exclusively by the at least one engine via the prerotation system;
decreasing, during the second portion, the rotational speed of the rotor;
flying, during the third portion, the rotorcraft with the rotor exclusively in autorotation; and
terminating simultaneously the flight and the third portion by landing the rotorcraft.