Airfoil Shaped Tail Boom

• US 20120280079A1
• Filed: 07/20/2012
• Published: 11/08/2012
• Est. Priority Date: 09/20/2010
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Brand, Albert G., Narramore, Jimmy, Harse, James H., Lanigan, Brendan P.
• Granted Patent: US 8,840,058 B2
• Time in Patent Office: Days
• US Class Current: 244/17.19
• CPC Class Codes: B64C 2027/8245 using air jets
• CPC Class Codes: B64C 27/82 characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft

Abstract

A system and method to control fuselage torque of an aircraft. The system includes a tail boom having a first surface that creates a high-pressure region in a downward rotorwash and a second surface that creates a low-pressure region in the downward rotorwash. The difference in pressure regions creates a lateral force that opposes the fuselage torque.

Claims

1. A rotary aircraft, comprising:

a fuselage;

an engine carried by the fuselage;

a main rotor rotatably attached to the engine; and

a tail boom attached to and extending from the fuselage, the tail boom having;

a body having a first side surface and an opposing second side surface, the first side surface being contoured to act as a pressure surface of an airfoil and the second side surface being contoured to act as a suction surface of an airfoil;

wherein the engine rotates the main rotor, thereby creating rotorwash and a fuselage torque;

wherein the rotorwash flows around the first side surface and the second side surface of the tail boom, resulting in a high-pressure region forming near the first side surface and resulting in a low-pressure region forming near the second side surface; and

wherein the pressure difference between the high-pressure region and the low-pressure region causes the tail boom to move towards the low-pressure region, resulting in a lateral force opposing the fuselage torque.

2. The rotary aircraft according to claim 1, the body of the tail boom further comprising:

a leading edge; and

a trailing edge, having;

a rounded corner; and

a sharp edge;

wherein both the first surface and the second surface extend from the leading edge to the trailing edge;

wherein the rounded corner joins the second surface to the trailing edge; and

wherein the sharp edge joins the first surface to the trailing edge.

3. The rotary aircraft according to claim 2, the sharp edge comprising:

a first linear surface; and

a second linear surface;

wherein the first linear surface is oriented at an angle relative to the second linear surface.

4. The rotary aircraft according to claim 3, wherein the angle is about 90 degrees.

5. The rotary aircraft according to claim 1, wherein the tail boom is rotatably attached to the fuselage.

6. The rotary aircraft according to claim 1, further comprising:

an anti-torque system attached to the tail boom.

7. The rotary aircraft according to claim 6, wherein the anti-torque system is a tail rotor.

8. The rotary aircraft according to claim 6, wherein the anti-torque system is a strake.

9. The rotary aircraft according to claim 1, further comprising:

a flap pivotally attached to the tail boom.

10. The rotary aircraft according to claim 1, wherein an angle of attack of the tail boom with respect to the rotorwash is approximately six degrees.

11. A rotary aircraft, comprising:

a fuselage;

a main rotor;

a tail boom attached to and extending from the fuselage, the tail boom having;

a leading edge;

a tailing edge; and

a pressure surface and a suction surface, both extending from the leading edge to the trailing edge; and

a tail rotor attached to the tail boom;

wherein the tail boom creates a high-pressure region and a low-pressure region in the rotorwash flowing therearound, which in turn creates a lateral force in a direction opposing a fuselage torque during flight.

12. The rotary aircraft of claim 11, the trailing edge comprising:

a rounded corner; and

a sharp edge;

wherein the rounded corner joins the second surface to the trailing edge; and

wherein the sharp edge joins the first surface to the trailing edge.

13. The rotary aircraft of claim 12, the sharp edge comprising:

a first linear surface; and

a second linear surface;

wherein the first linear surface is oriented at an angle relative to the second linear surface.

14. The rotary aircraft of claim 13, wherein the angle is about 90 degrees.

15. The rotary aircraft of claim 11, wherein the tail boom is rotatably attached to the fuselage.

16. The rotary aircraft of claim 11, further comprising:

a flow control device attached to the tail boom.

17. The rotary aircraft of claim 11, further comprising:

a flap pivotally attached to the tail boom.

18. A method to control fuselage torque of a rotary aircraft, comprising:

providing a tail boom attached to a fuselage of the rotary aircraft;

creating a high-pressure region in a downward rotorwash along a first surface of the tail boom; and

creating a low-pressure region in the downward rotorwash along a second surface of the tail boom;

wherein the differences in low-pressure and high-pressure regions causes the tail boom to move in a lateral direction opposing the fuselage torque.

19. The method of claim 18, further comprising:

supplementing the lateral directional movement of the tail boom with an anti-torque system.

20. The method of claim 18, further comprising:

manipulating the rotorwash directional flow around the tail boom with a flap pivotally coupled to the tail boom.