Prosecution Insights
Last updated: October 04, 2026
Application No. 18/188,805

ELECTRICALLY DRIVEN DUCTED FAN ENGINE

Final Rejection §103
Filed
Mar 23, 2023
Priority
Mar 25, 2022 — EU 22164586.4
Examiner
PRUITT, JUSTIN A
Art Unit
3745
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Lilium Eaircraft GmbH
OA Round
4 (Final)
62%
Grant Probability
Moderate
5-6
OA Rounds
0m
Est. Remaining
77%
With Interview

Examiner Intelligence

Grants 62% of resolved cases
62%
Career Allowance Rate
167 granted / 270 resolved
-8.1% vs TC avg
Strong +15% interview lift
Without
With
+15.4%
Interview Lift
resolved cases with interview
Typical timeline
3y 1m
Avg Prosecution
29 currently pending
Career history
308
Total Applications
across all art units

Statute-Specific Performance

§101
0.8%
-39.2% vs TC avg
§103
54.3%
+14.3% vs TC avg
§102
21.1%
-18.9% vs TC avg
§112
22.6%
-17.4% vs TC avg
Black line = Tech Center average estimate • Based on career data from 270 resolved cases

Office Action

§103
Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Response to Amendment The amendment submitted 05/18/2026 has been entered. Claims 1, 5-11, and 13-24 remain pending. Claims 2-4 and 12 have been cancelled. The amendments to the claims have overcome the objection to the claims made in Non-Final Rejection mailed 03/18/2026 and those objections are hereby withdrawn. The amendments to the claims have overcome each and every rejection made under 35 USC 112 and those rejections are hereby withdrawn. Response to Arguments Applicant's arguments filed 05/18/2026 have been fully considered and were found persuasive. However, the amendments to the claims have changed the scope of the claims necessitating new grounds of rejection. Please see new grounds of rejection below. Claim Rejections - 35 USC § 103 In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. Claim(s) 1, 5, 13, 15, and 24 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 11387693 to Hennig in view of US 11434819 to Murugappan in further view of US 8602348 to Bryant. (a) Regarding claim 1: (i) Hennig discloses an aircraft (100, Figs 1a-b) comprising a fuselage (102, Fig 1b); at least one pair of wings (primary and canard wings 104/106, Figs 1a-b); and at least one electrically driven ducted fan engine (ducted fans 108/110, Figs 1a) pivotably mounted to one of the wings (ducted fan engines mounted to and pivot with primary and canard wings 104/106 between vertical and horizontal configurations, Fig 1a), the at least one electrically driven ducted fan engine including: a housing (duct chamber 210) with an inner housing wall (inner wall of duct chamber 210, Figs 2a-3b), defining a substantially cylindrical inner space (inner space of duct chamber 210, Figs 2a-3b) and a longitudinal axis (axis of rotation of thrust assembly 212, Fig 3a-4a); an inlet opening provided in the housing (portion of duct chamber 210 upstream of thrust assembly 212, Figs 3a-4a); a rotor (fan assembly 404, Fig 4a) with a multitude of rotor blades (fan blades 412, Fig 4a) positioned in an inner space of the housing downstream of the inlet opening with respect to the longitudinal axis of the ducted fan engine (Figs 3a-b); an electrical motor (406, Fig 4a) configured to rotate the multitude of rotor blades (Col 6 Lns 23-24); a stator assembly (stator 410, Fig 4a) with a multitude of guide vanes (stator blades 414, Fig 4a) extending from a radially central region of the inner space to the inner housing wall (Figs 3a-4a), wherein the stator assembly is fixedly arranged in the inner space of the housing downstream of the rotor with respect to the longitudinal axis of the ducted fan engine (Figs 3a-3b); and an exhaust opening (downstream opening downstream of thrust assembly 212, Figs 3a-3b) provided in the housing downstream of the stator assembly with respect to the longitudinal axis of the ducted fan engine (Figs 3a-3b); (ii) Hennig does not explicitly disclose wherein an acoustic liner is provided to the housing. (iii) Murugappan is also in the field of acoustic liners (see title) and teaches: a housing (fan casing portion 122 and transcowl portion 124, Fig 1), wherein an acoustic liner (100) is provided to the housing (acoustic liners 100 may be positioned … aft of a fan casing portion 122 and/or transcowl portion 124, Col 6 Lns 22-24, Fig 1). (iv) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the housing as disclosed by Hennig with the above aforementioned acoustic liner as taught by Murugappan for the purpose of suppressing, damping, or attenuating noise (Col 6 Lns 25-36). (v) Hennig as modified by Marugappan does not teach wherein the at least one electrically driven ducted fan engine is configured to pivot relative to one of the wings. (vi) Bryant is also in the field of aircraft (see title) and teaches a wing (wing-structure 1, Fig 1) and at least one electrically driven ducted fan engine (propulsion units 2-5, Fig 1; Col 1 Lns 63-66), wherein the at least one electrically driven ducted fan engine is configured to pivot relative to the wing (Col 5 Lns 26-34). (vii) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the at least one electrically driven ducted fan engine as taught by the combined teachings of Hennig as modified by Marugappan to be pivotably mounted to one of the wings as taught by Bryant for the purpose of allowing for individual thrust vectoring to control forward/backward speeds as well as control yaw, pitch, and roll (Col 5 Lns 36-44). (d) Regarding claim 5: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 1. (ii) Hennig as modified by Murugappan as further modified by Bryant further teaches wherein the acoustic liner comprises a porous liner material (Murugappan: due to any or all of apertures 212, Figs 2A-2D; reticulations 400, Figs 4A-4E; pathways 502, Fig 5; and resonant spaces 207, Figs 6-8C/11B-12B). (e) Regarding claim 13: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 1. (ii) Murugappan further teaches: wherein the ducted fan engine has an inlet section (inner barrel 120, Fig 1), an interstage region (region between aft edge of casing portion 122 and unlabeled guide vanes, see Fig 1 and annotated Fig 1 below), a guide vane region (region taken up by guide vanes, see annotated Fig 1 below), and an exhaust region (region of transcowl portion 124 downstream of guide vanes, see annotated Fig 1 below; and/or core cowl portion 126, Fig 1); wherein the inlet section is defined as a region between an inlet opening (inlet 112, Fig 1) and the rotor (Fig 1); the interstage region is defined as a region between the rotor and the stator assembly (see annotated Fig 1 below); the guide vane region is defined as a region in a longitudinal section of the ducted fan engine in which the guide vanes extend to the inner housing wall (see annotated Fig 1 below); and the exhaust region is defined as a region between the stator assembly and the exhaust opening (as defined, see annotated Fig 1 below). PNG media_image1.png 305 380 media_image1.png Greyscale (f) Regarding claim 15: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 13. (ii) Hennig as modified by Murugappan as further modified by Bryant further teaches wherein the inlet section is devoid of acoustic liner (Murugappan: Fig 1). (g) Regarding claim 24: (i) Hennig as modified by Murugappan teaches the aircraft of claim 13. (ii) Hennig as modified by Murugappan further wherein the acoustic liner is provided to the housing in the interstage region, the guide vane region, and the exhaust region (Murugappan: Col 6 Lns 8-14/30-31, Fig 1). Claim(s) 6-10 and 17-23 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 11387693 to Hennig in view of US 11434819 to Murugappan in further view of US 8602348 to Bryant as applied to claim 5 above, and further in view of US 10107139 to Jones. (a) Regarding claim 6: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 5. (ii) Hennig as modified by Murugappan as further modified by Bryant further teaches wherein the porous liner material is tuned (Col 9 Lns 16-19) to at least partially absorb a sound emitted by the aircraft (Murugappan: Col 1 Lns 14-17) with respect to a porosity (Murugappan: Col 2 Lns 3-5; Col 8 Lns 18-38) and cavity thickness (Col 1 Ln 64 – Col 2 Ln 2; Col 8 Lns 6-27), wherein: the cavity thickness is defined as a thickness of a hole in the porous liner material (as defined). (iii) Hennig as modified by Murugappan as further modified by Bryant does not teach wherein the porous liner material is tuned to absorb a sound emitted by the aircraft with respect to a flow resistivity and tortuosity of the porous liner material, wherein: the flow resistivity is defined as a measure of the resistance to the passage of sound waves through the porous liner material; and the tortuosity is defined as a ratio of a path length through the porous linear material to a straight-line thickness of the porous liner material. (iv) Jones is also in the field of acoustic liners (see title) and teaches wherein a porous liner material (face sheet 210, Fig 2) is tuned to at least partially absorb a sound (Col 4 Lns 25-50/61-67; Col 7 Lns 57-63) emitted by an aircraft (Col 1 Lns 35-36) with respect to a porosity (Col 4 Lns 7-9; Col 7 Lns 57-63), cavity thickness (Col 3 Ln 65-67; Col 4 Lns 7-9/16-17; Col 7 Lns 50-51), flow resistivity (Col 7 Lns 57-63), and tortuosity (Col 4 Lns 61-67, Fig 3) of the porous liner material, wherein: the cavity thickness is defined as a thickness of a hole in the porous liner material (as defined); the flow resistivity is defined as a measure of the resistance to the passage of sound waves through the porous liner material (Col 7 Ln 60); and the tortuosity is defined as a ratio of a path length through the porous linear material to a straight-line thickness of the porous liner material (chamber path length greater than height, i.e. straight-line thickness; Col 4 Lns 61-67, Fig 3). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porous liner material as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant to be tuned with respect to a porosity, cavity thickness, flow resistivity, and tortuosity of the porous liner material as taught by Jones for the purpose of tuning the porous liner material to have a desired acoustic absorption (Col 4 Lns 7-9), in particular tuning for specific frequencies (Col 4 Lns 25-50/61-67; Col 7 Lns 57-63), and reducing the overall height of the acoustic liner (Col 1 Lns 49-51). (b) Regarding claim 7: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 6. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the porosity of the porous liner material is in the range of 80 to 99% (Murugappan: Col 2 Lns 4-5) and the cavity thickness of the porous liner material is approximately one quarter of a wavelength of a sound emitted by the aircraft (Jones: Col 4 Lns 25-26). (c) Regarding claim 8: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 1. (ii) Hennig as modified by Murugappan as further modified by Bryant does not explicitly teach wherein the acoustic liner comprises a Helmholtz liner. (iii) Jones is also in the field of acoustic liners (see title) and teaches an acoustic liner (acoustic liner 200) comprising a Helmholtz liner (Col 4 Ln 36). (iv) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the acoustic liner as taught by Hennig as modified by Murugappan as further modified by Bryant to comprise a Helmholtz liner as taught by Jones for the purpose of providing an acoustic liner with reduced height that absorbs lower frequency noise in addition to higher frequencies (Col 3 Lns 38-42). (d) Regarding claim 9: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 8. (ii) Jones further teaches wherein the Helmholtz liners are tuned with respect to: a cavity thickness (Col 1 Ln 62 – Col 2 Ln 5; Col 5 Lns 2-4), porosity (Col 4 Lns 7-9; Col 7 Lns 57-63), plate thickness (Col 4 Lns 7-9), hole diameter (Col 4 Lns 7-9), and cavity depth (Col 3 Ln 65-67; Col 4 Lns 7-9/16-17; Col 7 Lns 50-51) of the Helmholtz liners, wherein: the plate thickness is defined as a thickness of the Helmholtz liner (as defined); the hole diameter is defined as a diameter of a hole in the Helmholtz liner (as defined); and the cavity depth is defined as a depth of a hole in the Helmholtz liner (as defined). (e) Regarding claim 10: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 8. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches: wherein the Helmholtz liner has a hole diameter in a range of 0.1 to 5 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), a cavity thickness in a range of one-twentieth to one-fourth of a wavelength of a sound emitted by the aircraft (Jones: Col 4 Lns 25-27). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones do not explicitly teach wherein a porosity is in a range of 2 to 10%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (f) Regarding claim 17: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness greater than about 41 mm (Jones: chamber length of 0.5” to 7” corresponding to a range of about 12.7-178 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.25 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 42 mm (Jones: chamber length 0.5” to 7” corresponding to a range of about 12.7-178 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 5%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (g) Regarding claim 18: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness in a range of about 35 to 41 mm (Jones: chamber length of 0.5” to 7” corresponding to a range of about 12.7-178 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.25 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 36 mm (Jones: chamber length 0.5” to 7” corresponding to a range of about 12.7-178 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 10%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (h) Regarding claim 19: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness in a range of about 25 to 35 mm (Jones: chamber length of 0.5” to 7” corresponding to a range of about 12.7-178 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.25 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 28.5 mm (Jones: chamber length 0.5” to 7” corresponding to a range of about 12.7-178 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 10%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (i) Regarding claim 20: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness in a range of about 20 to 25 mm (Jones: chamber length of 0.5” to 7” corresponding to a range of about 12.7-178 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.25 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 23.5 mm (Jones: chamber length 0.5” to 7” corresponding to a range of about 12.7-178 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 11.5%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (j) Regarding claim 21: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness in a range of about 15 to 20 mm (Jones: chamber length of 0.5” to 7” corresponding to a range of about 12.7-178 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.4 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 18 mm (Jones: chamber length 0.5” to 7” corresponding to a range of about 12.7-178 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 11.5%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (k) Regarding claim 22: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness in a range of about 10 to 15 mm (Jones: chamber length of 0.5” corresponding to about 12.7 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.4 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a cavity depth of about 15 mm (Jones: chamber length greater than 0.5” corresponding to about 12.7 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 13%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). (l) Regarding claim 23: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 9. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the Helmholtz liner has a thickness of about 10 mm (Jones: chamber length of 0.5” corresponding to about 12.7 mm for which the liner must be thicker than, Col 4 Lns 57-58), a plate thickness of about 0.5 mm (Murugappan: Col 1 Lns 66-67), a hole diameter of about 0.4 mm (Murugappan: Col 1 Ln 67 – Col 2 Ln 2), and a minimum cavity depth of about 10 mm (Jones: chamber length greater than 0.5” corresponding to about 12.7 mm, Col 4 Lns 57-58). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not explicitly teach a porosity of about 4.5%. (iv) Jones further teaches wherein the porosity controls the amount of acoustic absorption that will occur (Col 4 Lns 7-9) as well as affecting the resistance through the hole geometry (Col 7 Lns 60-61), thereby establishing porosity as a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). Claim(s) 11 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 11387693 to Hennig in view of US 11434819 to Murugappan in further view of US 8602348 to Bryant as evidenced by non-patent literature “Architectural performance assessment of an electric vertical take-off and landing (d-VTOL) aircraft based on a ducted vectored thrust concept” to Nathen. (a) Regarding claim 11: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 1. (ii) Hennig as modified by Murugappan as further modified by Bryant does not explicitly teach wherein the ducted fan engine has a diameter of 28 to 38 cm. (iii) Applicant has disclosed no criticality, nor any new or unexpected results, from sizing the ducted fan engine within the range claimed and the engine of the prior art would perform the same when sized within the claimed range. Merely reciting an inventions size does not distinguish the claimed invention over the prior art, see MPEP 2144.04(IV)(A). Additionally, ducted fan engines sized within the claimed range are well known in the art as evidenced by Nathen (Page 7 between Figure 2 and Table 1, fan shroud diameter is taught as 29.5 cm). (iv) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the ducted fan engine as taught by Hennig as modified by Murugappan as further modified by Bryant to be within a size range as claimed as an obvious matter of design choice arriving at a configuration well known in the art as evidenced by Nathen. Claim(s) 14 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 11387693 to Hennig in view of US 11434819 to Murugappan in further view of US 8602348 to Bryant as applied to claim 13 above, and further in view of US 20110167785 to Moore. (a) Regarding claim 14: (i) Hennig as modified by Murugappan as further modified by Bryant teaches the aircraft of claim 13. (ii) Hennig as modified by Murugappan as further modified by Bryant further teach wherein the acoustic liner is applied to the housing in at least two of the interstage region, the guide vane region, and the exhaust region (Col 6 Lns 8-14/30-31, Fig 1); a plate thickness is defined as a thickness of the acoustic liner (as defined); a hole diameter is defined as a diameter of a hole in the acoustic liner (as defined); and a cavity depth is defined as a depth of a hole in the acoustic liner (as defined). (iii) Hennig as modified by Murugappan as further modified by Bryant do not teach wherein at least one acoustic property of the acoustic liner is different between the at least two regions, the at least one acoustic property of the acoustic liner being selected from the group consisting of porosity, plate thickness, hole diameter, and cavity depth. (iv) Moore is also in the field of turbofans (see title) and teaches an acoustic liner (honeycomb core 137a, facesheet 137b, and second facesheet 137d; Par 0074) wherein a cavity depth varies over an axial length of a turbofan (Par 0074) and further that different acoustic liners in different locations may vary in porosity, plate thickness, hole diameter, and cavity depth (Par 0074). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the at least two regions as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant to have at least one differing acoustic property as taught by Moore for the purpose of tailoring the acoustic liner of differing regions to the differing needs of the differing regions, e.g. differing gas temperatures and spectral noise signatures (Par 0074). Claim(s) 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 11387693 to Hennig in view of US 11434819 to Murugappan in further view of US 8602348 to Bryant in even further view of US 10107139 to Jones as applied to claim 6 above, and further in view of US 9290274 to Roach. (a) Regarding claim 16: (i) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones teaches the aircraft of claim 6. (ii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones further teaches wherein the porous liner material has a cover plate thickness of about 1mm (Murugappan: Col 8 Lns 8-10) and a hole diameter of about 2mm (Murugappan: Col 8 Lns 18-20). (iii) Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones does not teach wherein the porous liner material has a porosity of about 0.9233, a tortuosity of 1.455, and a cover plate porosity of about 15%. (iv) Roach is also in the field of acoustic liners (see title) and teaches wherein porosity and tortuosity affect which frequencies of sound that are attenuated (Col 3 Lns 55-58), thereby making each a result effective variable. Routine optimization of a result effective variable requires only ordinary skill in the art, see MPEP 2144.05(II). (v) It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to have modified the porosities and tortuosity as taught by the combined teachings of Hennig as modified by Murugappan as further modified by Bryant as even further modified by Jones to be within the claimed range through routine optimization of a result effective variable, see MPEP 2144.05(II). Conclusion Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. Any inquiry concerning this communication or earlier communications from the examiner should be directed to Justin A Pruitt whose telephone number is (571)272-8383. The examiner can normally be reached T-F 8:30am - 6:30pm. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Nathaniel Wiehe can be reached at (571) 272-8648. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /JUSTIN A PRUITT/Examiner, Art Unit 3745 /NATHANIEL E WIEHE/Supervisory Patent Examiner, Art Unit 3745
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Prosecution Timeline

Show 6 earlier events
Jan 05, 2026
Request for Continued Examination
Mar 04, 2026
Response after Non-Final Action
Mar 18, 2026
Non-Final Rejection mailed — §103
Apr 09, 2026
Interview Requested
Apr 17, 2026
Applicant Interview (Telephonic)
Apr 17, 2026
Examiner Interview Summary
May 18, 2026
Response Filed
Sep 01, 2026
Final Rejection mailed — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

5-6
Expected OA Rounds
62%
Grant Probability
77%
With Interview (+15.4%)
3y 1m (~0m remaining)
Median Time to Grant
High
PTA Risk
Based on 270 resolved cases by this examiner. Grant probability derived from career allowance rate.

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