Trimmable tail kit rudder

Patent metadata

Field	Value
Publication number	US-11067371-B2
Application number	US-201916361322-A
Country	US
Kind code	B2
Filing date	Mar 22, 2019
Priority date	Mar 22, 2019
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A tail kit assembly of a guided munition having a tail kit base connected to a trailing end of a projectile body. The tail kit base is rotatable relative to the projectile body. A trimmable rudder has forward and rearward ends. The forward end is pivotally coupled to the tail kit base, such that the trimmable rudder can, relative to the tail kit base, between retracted and extended orientations. An actuator is fixed between the tail kit base and the rearward end of the trimmable rudder. The actuator is electrically coupled to an onboard guidance system that controls actuation of the actuator to pivot the trimmable rudder between the retracted orientation and the extended orientation.

First claim

What is claimed:

1. A tail kit assembly, the tail kit assembly comprising:
a tail kit base configured to be connected to a trailing end of a projectile body, the tail kit base being rotatable about a longitudinal axis relative to the projectile body when deployed;
at least one strake being coupled to and radially extending from the tail kit base such that each strake has an edge shaped in a helical manner;
at least one trimmable rudder having forward and rearward ends, the forward end being flexibly coupled to the tail kit base and the rearward end being a rearward free end, such that the at least one trimmable rudder is movable, relative to the tail kit base, between a retracted orientation and an extended orientation; and
at least one actuator being fixed between the tail kit base and the rearward free end of each of the at least one trimmable rudder,
the at least one actuator configured to be electrically coupled to a guidance system of the projectile body, the guidance system controllably activating each of the at least one actuator to independently bias the rearward free end of the at least one trimmable rudder between the retracted orientation and the extended orientation.

2. The tail kit assembly according to claim 1 , wherein the at least one actuator is a synthetic muscle that is electrically activated by the guidance system to bias the corresponding rearward free end of the at least one trimmable rudder to the extended orientation in which the rearward free end of the at least one trimmable rudder is radially biased away from the tail kit base, and, when inactivated, the synthetic muscle is retracted and received within a cavity formed in a lower surface a pocket in the tail kit base and the at least one trimmable rudder is retracted into the pocket in the tail kit base.

3. The tail kit assembly according to claim 2 , wherein when each of the at least one trimmable rudders is received within a respective pocket in the surface of the tail kit base, an exterior surface of the trimmable rudder is uniform with an outer surface of the tail kit base.

4. The tail kit assembly according to claim 1 , wherein the edge shaped in a helical manner of the at least one strake communicates with an airflow to rotate the tail kit base in a direction counter to a direction of rotation of the projectile body when deployed.

5. The tail kit assembly according to claim 4 , wherein the at least one strake reduces drag and provides a differential rotational speed between a rotational speed of the tail kit base and a rotational speed of the projectile body, the differential rotational speed being between 10,000 to 20,000 RPM, and the at least one actuator is configured to be modulated between 50 to 200 Hz to independently actuate the at least one trimmable rudder to facilitate variable course correction matched to a current airspeed of a munition.

6. The tail kit assembly according to claim 4 , wherein the at least one strake comprises four orthogonal strakes.

7. The tail kit assembly according to claim 4 , wherein the at least one strake is coupled to a separate actuator that adjustably biases the edge of each strake that is shaped in a helical manner into the airstream as a function of air speed to maintain a fixed differential rotational speed between the tail kit base and the projectile body during flight.

8. The tail kit assembly according to claim 1 , wherein the at least one trimmable rudder comprises four trimmable rudders and each of the trimmable rudders is configured to be independently biased to the extended orientation during rotation of the tail kit base when each trimmable rudder is oriented in a position correlating to a desired course correction when deployed.

9. The tail kit assembly according to claim 1 , wherein the at least one trimmable rudder comprises a plurality of trimmable rudders and each of the plurality of trimmable rudders is configured to be controllably biased independent of each other by a corresponding one of a plurality of actuators.

10. The tail kit assembly according to claim 9 , wherein each of the plurality of actuators being synthetic muscle that when deactivated and activated is configured to bias the corresponding rearward free end of a trimmable rudder between the retracted and the extended orientations at a frequency of 200 Hz.

11. The tail kit assembly according to claim 1 , further comprising a plurality of strakes being connected to the tail kit base, the plurality of strakes reduce the spin of the tail kit base from 20,000 RPM to between 0 to 12,000 RPM when deployed.

12. The tail kit assembly according to claim 11 , wherein the at least one trimmable rudder, in the retracted orientation, is configured to be received in the tail kit base such that an exterior surface of the at least one trimmable rudder is entirely flush with an outer surface of the tail kit base, and the plurality of strakes are coupled to at least one actuator that variably biases an edge of each of the plurality of strakes that is shaped in a helical manner into the airstream such that an interaction of the strake with the airstream is adjustable.

13. The tail kit assembly according to claim 12 , wherein the plurality of strakes is variably biased into the airstream as a function of airspeed of the munition such that a fixed differential rotational speed between the tail kit base and the projectile body is maintained during flight.

14. The tail kit assembly according to claim 1 , wherein each of the at least one trimmable rudders is formed as a hinged flap in an outer surface of the tail kit base.

15. The tail kit assembly according to claim 14 , wherein the at least one trimmable rudder comprises four hinged flaps, each of the four hinged flaps being independently moved by a corresponding actuator to the extended orientation during rotation of the tail kit base when that flap is aligned in a position correlating to a desired course correction of the munition.

16. The tail kit assembly according to claim 2 , wherein the synthetic muscle is comprised of a carbon fiber material.

17. A method of guiding a munition having a tail kit assembly, the method comprising:
mounting at least one trimmable rudder and at least one strake having an edge shaped in a helical manner on the tail kit assembly;
providing the munition to an ordnance and firing the munition such that a body of the munition rotates about a longitudinal axis at a first rotational speed;
de-spinning the tail kit assembly with the at least one strake such that the tail kit assembly rotates about the longitudinal axis at a second rotational speed relative to the munition body;
receiving, with a guidance control system, signals which either signify a course correction of a current trajectory of the munition is necessary or unnecessary;
if the received signals signify the course correction is necessary, controlling an actuator per each at least one trimmable rudder, with the guidance control system, to adjust an orientation of a rearward free end of the at least one trimmable rudder between a retracted orientation and an extended orientation to correct the current trajectory of the munition; and
if the received signals signify a course correction is unnecessary, maintaining, with the guidance control system, the orientation of the at least one trimmable rudder between the retracted orientation and the extended orientation to maintain the current trajectory of the munition.

18. The method of guiding a munition according to claim 17 , further comprising:
de-spinning the tail kit assembly with the at least on

Assignees

• Bae Sys Inf & Elect Sys Integ

Inventors

• Choiniere Michael J
• Stockwell Jason T

Classifications

• F42B10/64 Primary

  of fins · CPC title

• F42B10/26

  using spin (F42B10/04, F42B10/12, F42B10/14, F42B10/24, F42B14/02 take precedence) · CPC title

• F42B10/20 Primary

  deployed by combustion gas pressure, or by pneumatic or hydraulic forces · CPC title

• F42B10/60

  Steering arrangements (F42B19/01 takes precedence) · CPC title

• F42B10/62

  Steering by movement of flight surfaces · CPC title