Method of optimizing sections of a tail boom for a rotary wing aircraft

Patent metadata

Field	Value
Publication number	US-10640206-B2
Application number	US-201715662335-A
Country	US
Kind code	B2
Filing date	Jul 28, 2017
Priority date	Jul 28, 2016
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A method of optimizing sections of a tail boom for a rotary wing aircraft, and also to a tail boom including such sections. The method comprises the step of creating a database characterizing standard sections for a tail boom that give precedence to minimizing a negative lift and/or to increasing a lateral force generated by the air stream from the main rotor of the aircraft flowing over the tail boom, a step of establishing looked-for aerodynamic and structural characteristics for said tail boom, and a step of defining the sections of the tail boom as a function of the standard sections and of the looked-for aerodynamic and structural characteristics. The tail boom as defined in this way optimizes the reduction in the negative lift and/or the increase in the lateral force generated by the air stream from the main rotor.

First claim

What is claimed is:

1. A method for producing a tail boom for a rotary wing aircraft having a main rotor and a fuselage, the tail boom to extend from the fuselage in a longitudinal direction, the tail boom to be constituted by successive sections with each section being defined in a plane perpendicular to the longitudinal direction by a chord between a leading edge and a trailing edge of the section and by a maximum thickness measured perpendicularly to the chord, the method comprising:
an optimization process for defining the sections of the tail boom, the optimization process including the steps of:
a step of performing studies, digital simulations, and/or tests for determining standard sections for the tail boom;
a step of creating a database characterizing the standard sections for the tail boom, the database having four types of standard sections for the tail boom, a first type of standard sections being symmetric and maximizing a lateral force of the tail boom, a second type of standard sections being asymmetric and maximizing the lateral force of the tail boom, a third type of standard sections being symmetric and minimizing a negative lift of the tail boom, and a fourth type of standard sections being asymmetric and minimizing the negative lift of the tail boom;
each standard section being defined by extreme characteristic points A0, A1, A2, A3, and by intermediate characteristic points A1, A2, A11, A12, A21, A22, A31, A32, the characteristic points being defined in a secondary reference frame attached to each standard section and defined by the directions of the chord and of the maximum thickness of the standard section, one unit along the abscissa axis or along the ordinate axis being equal to the chord, the extreme characteristic points A0, A1, A2, A3, belonging to an outline of the standard section, A0 being situated at the trailing edge and having coordinates (1,0), A2 being situated at the leading edge and having coordinates (0,0), the extreme characteristic points A1 and A3 forming the maximum thickness and having respective coordinates −t/(2.c) and t/(2.c), the intermediate characteristic points A01, A02, A11, A12, A21, A22, A31, A32 being construction points for constructing the outline of the standard section serving to define a direction of the outline of the section at each extreme characteristic point A0, A1, A2, A3;
a step of establishing looked-for aerodynamic and structural characteristics of the tail boom in terms of lateral force and negative lift generated by an air stream from the main rotor flowing over the tail boom;
a step of defining the sections of the tail boom as a function of the standard sections and of the looked-for aerodynamic and structural characteristics for the tail boom in order to give precedence to minimizing the negative lift and/or to maximizing the lateral force of the tail boom; and

the method further comprising providing the tail boom having the sections as defined per the optimization process.

2. The method according to claim 1 , wherein each standard section being further defined as a function of the ratio of the maximum thickness of the standard section divided by the chord of the standard section.

3. The method according to claim 2 , wherein for each standard section of the first type, the maximum thickness of the standard section is arranged downstream from the middle of the chord of the standard section in the flow direction of the air stream from the main rotor;
for each standard section of the second type, the maximum thickness of the standard section is arranged downstream from the middle of the chord of the standard section and in the proximity of the middle of the chord of the standard section; and
for each standard section of the third type and for each standard section of the fourth type, the maximum thickness of the standard section is arranged upstream from the middle of the chord of the standard section.

4. The method according to claim 1 , wherein the database comprises the following first table defining ranges for the characteristic points for standard sections of the first type:

t/c
value
uA1, uA3
vA01
uA02
uA11
vA12
vA21
uA22
uA31
vA32

50%
low
0.55
0.6
0.1
0.6
0.08
−0.08
0.6
0.1
−0.6

high
0.95
0.95
0.25
0.95
0.25
−0.25
0.95
0.25
−0.95

60%
low
0.55
0.6
0.1
0.6
0.08
−0.08
0.6
0.1
−0.6

high
0.95
0.95
0.25
0.95
0.25
−0.25
0.95
0.25
−0.95

70%
low
0.55
0.6
0.08
0.6
0.08
−0.08
0.6
0.08
−0.6

high
0.95
0.95
0.4
0.95
0.25
−0.25
0.95
0.4
−0.95

80%
low
0.55
0.6
0.1
0.6
0.08
−0.08
0.6
0.1
−0.6

high
0.95
0.95
0.25
0.95
0.25
−0.25
0.95
0.25
−0.95

90%-130%
low
0.55
0.6
0.1
0.6
0.08
−0.08
0.6
0.1
−0.6

high
0.99
0.95
0.25
0.95
0.25
−0.25
0.95
0.25
−0.95

Assignees

• Airbus Helicopters

Inventors

• Alfano David
• Legras Guillaume
• Leusink Debbie

Classifications

• B64C27/82 Primary

  characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft · CPC title

• B64C27/06

  with single rotor · CPC title

• G06F2113/28

  Fuselage, exterior or interior · CPC title

• B64F5/00

  Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title