Aircraft with an unducted fan propulsor
The present disclosure is generally related to aircraft having one or more unducted fan propulsors at locations within specific regions relative to an airfoil, such as a wing or horizontal stabilizer. More specifically, the specific regions are located where there is a relatively higher pressure air flow beneath the wings or above a horizontal stabilizer. That higher pressure air flow can be utilized to provide increased thrust from the unducted fan propulsor.
1 . An aircraft comprising:
a fuselage;
an airfoil extending from the fuselage, the airfoil having an airfoil section defining a quarter-chord location (QC);
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein only one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D);
a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; and
a positioning line (R) having a length (RL) and extending from the QC to the point P of the unducted fan propulsor at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section when viewed looking from an outboard position towards an inboard position of the wing; wherein 0.07≤RL/D≤2.0 and θ is between 187° and 342°,
wherein the unducted fan propulsor includes:
a fan having the plurality of blades of the forward array or the rearward array coupled to a fan shaft having one or more fan bearings, each of the plurality of blades of the fan being rotatable about a pitch axis and extending from a fan hub; and
a fan actuation system disposed within the fan hub for rotating the plurality of blades about the pitch axis and having one or more radial thrust bearings, wherein the fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24, the fan actuation system length envelope being given by:
N
FB
×
D
FT
L
AXIAL
×
(
R
TB
N
FB
)
wherein N FB is a number of the plurality of blades of the fan, D FT is a fan tip diameter of the plurality of blades, R TB is a thrust bearing radius of the one or more radial thrust bearings, and L AXIAL is an axial length from a fan hub tip of the fan hub to the one or more fan bearings.
2 . The aircraft of claim 1 , wherein the fan actuation system includes a pressurized pneumatic chamber that is filled with a pressurized gas that biases the plurality of blades of the fan to a feather position.
3 . The aircraft of claim 1 , wherein the fan actuation system includes one or more counterweights for reducing inertial loading associated with rotation of the plurality of blades of the fan.
4 . The aircraft of claim 1 , wherein the unducted fan propulsor has a longitudinal centerline axis and includes a core inlet that is annular about the longitudinal centerline axis.
5 . The aircraft of claim 1 , wherein the fan actuation system includes a hydraulic system that supplies hydraulic fluid for rotating the plurality of blades of the fan about the pitch axis.
6 . The aircraft of claim 1 , wherein N FB is in a range of ten to sixteen, D FT is in a range of 120.0 inches to 192.0 inches, R TB is in a range of 10 inches to 27 inches, L AXIAL is given by A FH +A FB , A FH being a fan hub axial length from the fan hub tip to the pitch axis of the plurality of blades and A FB being a fan bearing axial length from the pitch axis of the plurality of blades to the one or more fan bearings, A FH is in a range of 25 inches to 85 inches, and A FB is in a range of 10 inches to 23 inches.
7 . The aircraft of claim 1 , wherein the fan actuation system has a fan actuation system axial length (A FAS ) defined from an axially forward-most surface of the fan actuation system to the pitch axis of the plurality of blades, A FAS being a maximum of 80% A FH .
8 . An aircraft comprising:
a fuselage;
an airfoil extending from the fuselage, the airfoil having an airfoil section defining an effective quarter chord point (QC);
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein only one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D);
a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; and
an ellipse origin positioning line (EOR) having a length (EORL) extending from the QC to an ellipse origin (OR) at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and measured positive in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, when viewed looking for an outboard position towards an inboard position; wherein the P of the unducted fan propulsor is located within a first ellipse having a first major axis length (1MajAL) and a first minor axis length (1MinAL) with a first ellipse origin defined by EORL/D of 0.938 and θ of 253.6°, and where 1MajAL/D is 2.8 and 1MinAL/D is 1.7,
wherein the unducted fan propulsor includes:
a fan having the plurality of blades of the forward array or the rearward array coupled to a fan shaft having one or more fan bearings, each of the plurality of blades of the fan being rotatable about a pitch axis and extending from a fan hub; and
a fan actuation system disposed within the fan hub for rotating the plurality of blades about the pitch axis and having one or more radial thrust bearings, wherein the fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24, the fan actuation system length envelope being given by:
N
FB
×
D
FT
L
AXIAL
×
(
R
TB
N
FB
)
wherein N FB is a number of the plurality of blades of the fan, D FT is a fan tip diameter of the plurality of blades, R TB is a thrust bearing radius of the one or more radial thrust bearings, and L AXIAL is an axial length from a fan hub tip of the fan hub to the one or more fan bearings.
9 . The aircraft of claim 8 , wherein the fan actuation system includes a pressurized pneumatic chamber that is filled with a pressurized gas that biases the plurality of blades of the fan to a feather position.
10 . The aircraft of claim 8 , wherein the fan actuation system includes one or more counterweights for reducing inertial loading associated with rotation of the plurality of blades of the fan.
11 . The aircraft of claim 8 , wherein the unducted fan propulsor has a longitudinal centerline axis and includes a core inlet that is annular about the longitudinal centerline axis.
12 . The aircraft of claim 8 , wherein the fan actuation system includes a hydraulic system that supplies hydraulic fluid for rotating the plurality of blades of the fan about the pitch axis.
13 . The aircraft of claim 8 , wherein N FB is in a range of ten to sixteen, D FT is in a range of 120.0 inches to 192.0 inches, R TB is in a range of 10 inches to 27 inches, L AXIAL is given by A FH +A FB , A FH being a fan hub axial length from the fan hub tip to the pitch axis of the plurality of blades and A FB being a fan bearing axial length from the pitch axis of the plurality of blades to the one or more fan bearings, A FH is in a range of 25 inches to 85 inches, and A FB is in a range of 10 inches to 23 inches.
14 . The aircraft of claim 8 , wherein the fan actuation system has a fan actuation system axial length (A FAS ) defined from an axially forward-most surface of the fan actuation system to the pitch axis of the plurality of blades, A FAS being a maximum of 80% A FH .
15 . An aircraft comprising:
a fuselage;
an airfoil extending from the fuselage, the airfoil having an airfoil section defining an effective quarter-chord point (QC);
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL), a plurality of blades arranged in a forward array and a plurality of blades arranged in a rearward array, wherein one of the forward and rearward array of blades are rotating blades and the rotating blades define a maximum outer diameter (D);
a point (P) located at an intersection of the CL and a line HP perpendicular to the CL that passes through an axial midpoint between a rearward trailing edge at a root of a blade of the rearward array and a forward leading edge at a root of a blade of the forward array when the forward leading edge and rearward trailing edge of the respective blades are aligned with each other; and
a positioning line (R) having a length (RL) and extending from the QC to the point P of the unducted fan propulsor at an angle θ measured positive in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and measured positive in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, when viewed looking from an outboard position towards an inboard position (e.g. the fuselage) OR when viewed with the LE to the left of the TE; wherein 0.065<RL/D<1.98 and θ is between 187° and 340°; and wherein RL/D and θ of the P of the unducted fan propulsor adhere to the following expressions:
R
L
D
+
(
1.4161
*
[
1.88978
*
sin
2
(
θ
)
-
0.0875
*
cos
2
(
θ
)
+
0.477
*
sin
(
θ
)
*
cos
(
θ
)
]
+
1.764
*
sin
(
θ
)
+
0
.
1
9
1
4
6
*
cos
(
θ
)
)
1.96
*
sin
2
(
θ
)
+
0
.
7
2
2
5
*
cos
2
(
θ
)
>
0
and
R
L
D
+
(
-
1.4161
*
[
1.88978
*
sin
2
(
θ
)
-
0.0875
*
cos
2
(
θ
)
+
0.477
*
sin
(
θ
)
*
cos
(
θ
)
]
+
1.764
*
sin
(
θ
)
+
0
.
1
9
1
4
6
*
cos
(
θ
)
)
1.96
*
sin
2
(
θ
)
+
0
.
7
2
2
5
*
cos
2
(
θ
)
<
0
wherein the unducted fan propulsor includes:
a fan having the plurality of blades of the forward array or the rearward array coupled to a fan shaft having one or more fan bearings, each of the plurality of blades of the fan being rotatable about a pitch axis and extending from a fan hub; and
a fan actuation system disposed within the fan hub for rotating the plurality of blades about the pitch axis and having one or more radial thrust bearings, wherein the fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24, the fan actuation system length envelope being given by:
N
FB
×
D
FT
L
AXIAL
×
(
R
TB
N
FB
)
wherein N FB is a number of the plurality of blades of the fan, D FT is a fan tip diameter of the plurality of blades, R TB is a thrust bearing radius of the one or more radial thrust bearings, and L AXIAL is an axial length from a fan hub tip of the fan hub to the one or more fan bearings.
16 . The aircraft of claim 15 , wherein the fan actuation system includes a pressurized pneumatic chamber that is filled with a pressurized gas that biases the plurality of blades of the fan to a feather position.
17 . The aircraft of claim 15 , wherein the fan actuation system includes one or more counterweights for reducing inertial loading associated with rotation of the plurality of blades of the fan.
18 . The aircraft of claim 15 , wherein the unducted fan propulsor has a longitudinal centerline axis and includes a core inlet that is annular about the longitudinal centerline axis.
19 . The aircraft of claim 15 , wherein the fan actuation system includes a hydraulic system that supplies hydraulic fluid for rotating the plurality of blades of the fan about the pitch axis.
20 . The aircraft of claim 15 , wherein N FB is in a range of ten to sixteen, D FT is in a range of 120.0 inches to 192.0 inches, R TB is in a range of 10 inches to 27 inches, L AXIAL is given by A FH +A FB , A FH being a fan hub axial length from the fan hub tip to the pitch axis of the plurality of blades and A FB being a fan bearing axial length from the pitch axis of the plurality of blades to the one or more fan bearings, A FH is in a range of 25 inches to 85 inches, and A FB is in a range of 10 inches to 23 inches.