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 with a leading edge (LE) and a trailing edge (TE), a chord extending between the LE and TE, and a quarter-chord location (QC) along the chord measured from the LE;
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL) and a plurality of blades arranged in one or more arrays, each of the blades having a root and the plurality of blades defining a maximum outer diameter (D), the unducted fan propulsor having a point (P) defined as one of:
(a) wherein the plurality of blades is arranged in a single array, the point P is located at an intersection of the CL and a line perpendicular to the CL that passes through a midpoint between edges at the root of one of the plurality of blades, and
(b) wherein the plurality of blades is arranged in a forward array and a rearward array, the point P is located at an intersection of the CL and midpoint between a rearward trailing edge (RTL) of the rearward array and leading edge (LE) of the forward array when a blade of the forward and rearward arrays 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) and at an angle θ as measured from a vector from the QC to the TE of the airfoil section to the line EOR, where, when viewed with the LE to the left of TE, a positive θ (1) increases in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and (2) increases in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, and
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.
2. The aircraft of claim 1 , wherein the P of the unducted fan propulsor is located in a second ellipse having a second major axis length (2MajAL) and a second minor axis length (2MinAL) with a second ellipse origin defined by EORL/D of 1.051 and θ of 228.8°, and where 2MajAL/D is 1.86 and 2MinAL/D is 1.56.
3. The aircraft of claim 1 , wherein the P of the unducted fan propulsor is located in a third ellipse having a third major axis length (3MajAL) and a third minor axis length (3MinAL) with a third ellipse origin defined by EORL/D of 0.870 and θ of 239.6°, where 3MajAL/D is 1.4 and 3MinAL/D is 0.9.
4. The aircraft of claim 1 , wherein the P of the unducted fan propulsor is located in a fourth ellipse having a fourth major axis length (4MajAL) and a fourth minor axis length (4MinAL) with a fourth ellipse origin defined by EORL/D of 0.763 and θ of 235.7°, and where 4MajAL/D is 0.94 and 4MinAL/D is 0.44.
5. The aircraft of claim 1 , wherein the unducted fan propulsor is undermounted to the airfoil with one or more intermediate structures.
6. The aircraft of claim 1 , wherein the P of the unducted fan propulsor is variable to accommodate different operating conditions.
7. An aircraft comprising:
a fuselage;
an airfoil extending from the fuselage, the airfoil having an airfoil section with a leading edge (LE) and a trailing edge (TE), a chord extending between the LE and TE, and a quarter-chord location (QC) along the chord measured from the LE;
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL) and a plurality of blades arranged in one or more arrays, each of the blades having a root and the plurality of blades defining a maximum outer diameter (D), the unducted fan propulsor having a point (P) defined as one of:
(a) wherein the plurality of blades is arranged in a single array, the point P is located at an intersection of the CL and a line perpendicular to the CL that passes through a midpoint between edges at the root of one of the plurality of blades, and
(b) wherein the plurality of blades is arranged in a forward array and a rearward array, the point P is located at an intersection of the CL and midpoint between a rearward trailing edge (RTL) of the rearward array and leading edge (LE) of the forward array when a blade of the forward and rearward arrays 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 and at an angle θ as measured from a vector from the QC to the TE of the airfoil section to the line R, where, when viewed with the LE to the left of TE, a positive θ (1) increases in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and (2) increases in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, and 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
.
7
6
4
*
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
.
7
6
4
*
sin
(
θ
)
+
0
.
1
9
1
4
6
*
cos
(
θ
)
)
1.96
*
sin
2
(
θ
)
+
0
.
7
2
2
5
*
cos
2
(
θ
)
<
0.
8. The aircraft of claim 7 , wherein:
0.254<RL/D<1.86 and θ is between 199° and 306°, and
the P of the unducted fan propulsor is defined by the following expressions:
R
L
D
+
(
0.52621
*
[
0.7205
*
sin
2
(
θ
)
-
0.352
*
cos
2
(
θ
)
+
0.7448
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
8
4
7
6
*
sin
(
θ
)
+
0
.
2
3
1
1
9
*
cos
(
θ
)
)
0
.
8
6
4
9
*
sin
2
(
θ
)
+
0
.
6
0
8
4
*
cos
2
(
θ
)
>
0
and
R
L
D
+
(
-
0.52621
*
[
0.7205
*
sin
2
(
θ
)
-
0.352
*
cos
2
(
θ
)
+
0.7448
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
8
4
7
6
*
sin
(
θ
)
+
0
.
2
3
1
1
9
*
cos
(
θ
)
)
0
.
8
6
4
9
*
sin
2
(
θ
)
+
0
.
6
0
8
4
*
cos
2
(
θ
)
<
0.
9. The aircraft of claim 7 , wherein:
0.369<RL/D<1.43 and θ is between 204° and 291°, and
the P of the unducted fan propulsor is defined by the following expressions:
R
L
D
+
(
0.09923
*
[
0.2964
*
sin
2
(
θ
)
-
0.36
*
cos
2
(
θ
)
+
0.66
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
3
6
7
5
*
sin
(
θ
)
+
0
.
0
8
9
1
*
cos
(
θ
)
)
0
.
4
9
*
sin
2
(
θ
)
+
0
.
2
0
2
5
*
cos
2
(
θ
)
>
0
and
R
L
D
+
(
-
0.09923
*
[
0.2964
*
sin
2
(
θ
)
-
0.36
*
cos
2
(
θ
)
+
0.66
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
3
6
7
5
*
sin
(
θ
)
+
0
.
0
8
9
1
*
cos
(
θ
)
)
0
.
4
9
*
sin
2
(
θ
)
+
0
.
2
0
2
5
*
cos
2
(
θ
)
<
0.
10. The aircraft of claim 7 , wherein:
0.477<RL/D<0.9455 and θ is between 211° and 274°, and
the P of the unducted fan propulsor is defined by the following expressions:
R
L
D
+
(
0.01069156
*
[
0.036
*
sin
2
(
θ
)
-
0.3485
*
cos
2
(
θ
)
+
0.5418
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
1
3
9
1
6
7
*
sin
(
θ
)
+
0
.
0
2
0
8
1
2
*
cos
(
θ
)
)
0
.
2
2
0
9
*
sin
2
(
θ
)
+
0
.
0
4
8
4
*
cos
2
(
θ
)
>
0
and
R
L
D
+
(
-
0.01069156
*
[
0.036
*
sin
2
(
θ
)
-
0.3485
*
cos
2
(
θ
)
+
0.5418
*
sin
(
θ
)
*
cos
(
θ
)
]
+
0
.
1
3
9
1
6
7
*
sin
(
θ
)
+
0
.
0
2
0
8
1
2
*
cos
(
θ
)
)
0
.
2
2
0
9
*
sin
2
(
θ
)
+
0
.
0
4
8
4
*
cos
2
(
θ
)
<
0.
11. The aircraft of claim 7 , wherein the unducted fan propulsor is undermounted to the airfoil with one or more intermediate structures.
12. The aircraft of claim 7 , wherein the P of the unducted fan propulsor is variable to accommodate different operating conditions.
13. An aircraft comprising:
a fuselage;
an airfoil extending from the fuselage, the airfoil having an airfoil section with a leading edge (LE) and a trailing edge (TE), a chord extending between the LE and TE, and a quarter-chord location (QC) along the chord measured from the LE;
an unducted fan propulsor mounted relative to the airfoil section on a high pressure side thereof, the unducted fan propulsor having a centerline (CL) and a plurality of blades arranged in one or more arrays, each of the blades having a root and the plurality of blades defining a maximum outer diameter (D), the unducted fan propulsor having a point (P) defined as one of:
(a) wherein the plurality of blades is arranged in a single array, the point P is located at an intersection of the CL and a line perpendicular to the CL that passes through a midpoint between edges at the root of one of the plurality of blades, and
(b) wherein the plurality of blades is arranged in a forward array and a rearward array, the point P is located at an intersection of the CL and midpoint between a rearward trailing edge (RTL) of the rearward array and leading edge (LE) of the forward array when a blade of the forward and rearward arrays 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 and at an angle θ as measured from a vector from the QC to the TE of the airfoil section to the line R, where, when viewed with the LE to the left of TE, a positive θ (1) increases in a counter-clockwise direction when the high pressure side of the airfoil section is below the airfoil section, and (2) increases in a clockwise direction when the high pressure side of the airfoil section is above the airfoil section, and
wherein RL/D≤2 and θ is between 187° and 342°.
14. The aircraft of claim 13 , wherein 0.15≤RL/D.
15. The aircraft of claim 13 , wherein 0.35≤RL/D, and preferably RL/D is about 0.72.
16. The aircraft of claim 13 , wherein θ is between 198° and 310°, and preferably between 205° and 285°.
17. The aircraft of claim 13 , wherein the unducted fan propulsor operates at a cruise flight Mach M 0 of between 0.5 and 0.9, preferably between 0.7 and 0.9, and more preferably between 0.75 and 0.9.
18. The aircraft of claim 13 , wherein the unducted fan propulsor has a dimensionless cruise fan net thrust parameter expressed as follows:
0
.
1
5
>
F
net
ρ
0
A
an
V
0
2
>
0
.
0
6
,
wherein F net is cruise fan net thrust, ρ 0 is ambient air density, V o is cruise flight velocity, and A an is annular cross-sectional area perpendicular to an axis of rotation of a rotor axis of rotation.
19. The aircraft of claim 13 , wherein the unducted fan propulsor is undermounted to the airfoil with one or more intermediate structures.
20. The aircraft of claim 13 , wherein the P of the unducted fan propulsor is variable to accommodate different operating conditions.
21. The aircraft of claim 1 , wherein the plurality of blades are arranged in two arrays, with the forward array being rotating and the rearward array being non-rotating.
22. The aircraft of claim 7 , wherein the plurality of blades are arranged in two arrays, with the forward array being rotating and the rearward array being non-rotating.
23. The aircraft of claim 13 , wherein the plurality of blades are arranged in two arrays, with the forward array being rotating and the rearward array being non-rotating.