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 .
Election/Restrictions
Applicant's election with traverse of group II in the reply filed on June 1st, 2026 is acknowledged. The traversal is on the ground(s) that “because there would not be a serious burden on the Office to search and examine all of the pending claims of the application together”. This is not found persuasive because a separate field of search is still required for each invention. Each group would require a different search query to accurately search the specific arrangements and features of the proprotor, proprotor system, and aircraft, even though the inventions are classified in the same area.
The requirement is still deemed proper and is therefore made FINAL.
Claims 1-3, 6-8, and 10-14 are withdrawn from further consideration pursuant to 37 CFR 1.142(b), as being drawn to a nonelected invention, there being no allowable generic or linking claim. Applicant timely traversed the restriction (election) requirement in the reply filed on June 1st, 2026.
Claim Objections
Claim 5 is objected to because of the following informalities:
Claim 5 should have a comma so that it reads in part, “The proprotor system of Claim 4, further comprising…”.
Appropriate correction is required.
Claim Rejections - 35 USC § 102
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 the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 4-5, 24, and 26-27 are rejected under 35 U.S.C. 102(a)(2) as being anticipated by Tigner et al., hereafter Tigner (US 20230271713).
Regarding Claim 4, Tigner discloses a proprotor system comprising;
a proprotor hub (paragraph 0006; Fig. 2); and
a proprotor blade root oriented along a proprotor blade feather axis (paragraph 0022; Fig. 2) orthogonally offset from a proprotor hub center defined by a proprotor hub centerline of the proprotor hub (Fig. 2; see below), wherein the proprotor hub centerline is perpendicular to the proprotor blade feather axis (Fig. 2; see below).
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Regarding Claim 5, Tigner discloses all the limitations of Claim 4 above. Tigner further discloses a feather axis bearing offset from the proprotor hub centerline (paragraph 0022; Fig. 2).
Regarding Claim 24, Tigner discloses all the limitations of Claim 4 above. Tigner further discloses further comprising a second and a third proprotor blade root (Fig. 2).
Regarding Claim 26, Tigner discloses all the limitations of Claim 4 above. Tigner further discloses wherein the proprotor system is configured to provide thrust to an aircraft (paragraph 0004).
Regarding Claim 27, Tigner discloses all the limitations of Claim 26 above. Tigner further discloses wherein the aircraft is an electric vertical and takeoff and landing vehicle (paragraph 0047).
Claim Rejections - 35 USC § 103
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.
Claims 20-21 and 23 are rejected under 35 U.S.C. 103 as being unpatentable over Tigner in view of Karem et al., hereafter Karem (US 20180334251).
Regarding Claim 20, Tigner teaches all the limitations of Claim 4 above. Tigner further teaches wherein the proprotor blade root is rigid (Claim 8).
However, Tigner fails to teach wherein the proprotor blade root is non-hinged in the proprotor system.
Karem teaches a proprotor system where the proprotor blade root is rigid and hingeless (abstract, paragraph 0090). Tigner and Karem are analogous prior art as they each relate to proprotor systems. Therefore, it would have been obvious to a person of ordinary skill in the art that the rigid proprotor taught by Tigner would be hingeless as well, as Karem teaches that rigid proprotors are well known in the art to be hingeless as well (Karem abstract, paragraph 0090).
Regarding Claim 21, Tigner teaches all the limitations of Claim 4 above.
However, Tigner fails to explicitly teach wherein the proprotor blade root is non- articulated in the proprotor system.
Tigner does teach that the proprotor blade root is rigid (Claim 8).
Karem teaches a proprotor system where the proprotor blades are rigid, and therefore non-articulated (abstract, paragraph 0029). Tigner and Karem are analogous prior art as they each relate to proprotor systems. Therefore, it would have been obvious to a person of ordinary skill in the art that the rigid proprotor taught by Tigner would be non-articulated, as Karem teaches that rigid proprotors are well known in the art to be non-articulated as well (Karem abstract, paragraph 0029).
Regarding Claim 23, Tigner teaches all the limitations of Claim 4 above.
However, Tigner fails to teach further comprising at least one hub bearing, wherein a non-airfoil diameter of the proprotor system is less than a hub bearing diameter of the hub bearing.
Karem teaches a proprotor system with hub bearings, where the non-airfoil diameter of the proprotor system is less than a hub bearing diameter, in order to support and allow rotation of the hub (paragraphs 0118,0119). Tigner and Karem are analogous prior art as they each relate to proprotor systems. Therefore, it would have been obvious to a person of ordinary skill in the art to have added the hub bearing taught by Karem to the proprotor system taught by Tigner, in order to support and allow rotation of the hub (Karem paragraphs 0118,0119).
Claim 25 is rejected under 35 U.S.C. 103 as being unpatentable over Tigner in view of Pawar et al., hereafter Pawar (US 20170015404).
Regarding Claim 25, Tigner teaches all the limitations of Claim 4 above.
However, Tigner fails to teach wherein the proprotor hub comprises a composite material.
Pawar teaches a proprotor system where the proprotor hub comprises a composite material (paragraphs 0013,0015). Tigner and Pawar are analogous prior art as they each relate to proprotor systems. Therefore, it would have been obvious to a person of ordinary skill in the art that the hub taught by Tigner could comprise a composite material as taught by Pawar, as Pawar teaches that such a material is well known in the art to be suitable for proprotor hubs (Pawar paragraphs 0013,0015).
Allowable Subject Matter
Claims 15-19 and 22 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Claim 15 would be allowable for disclosing the proprotor system of claim 4, wherein a proprotor blade feather axis-to- center of pressure angle between the proprotor blade feather axis and the proprotor hub center to a proprotor blade center of pressure axis is greater than ten degrees.
None of the known prior art, alone or in combination, teaches or contemplates such an angle. While prior art such as Tinger inherently has an angle between the feather axis and hub center to blade center of pressure axis, Tigner is completely silent as to the angle itself or the relationship between the two axes. None of the known prior art provides sufficient motivation to optimize the angle to arrive at Applicant’s claimed range. Therefore, the combination of features would be allowable.
Claims 16-19 would be allowable for similar reasons as Claim 15 above.
Claim 22 would be allowable for disclosing the proprotor system of claim 4, further comprising first and second feather axis bearings, wherein a non-thrust generating proprotor disk diameter is less than three times a distance from an outside edge of the first feather axis bearing to an outside edge of the second feather axis bearing.
None of the known prior art, alone or in combination, teaches or contemplates such an ratio. While prior art such as Tinger inherently has an ratio between the non-thrust generating proprotor disk diameter and the distance from the outside edge of the feather axis bearings, Tigner is completely silent as to the ratio itself or the relationship between the two distances. None of the known prior art provides sufficient motivation to optimize the ratio between the disk diameter and bearing outside edge distances to arrive at Applicant’s claimed range. Therefore, the combination of features would be allowable.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
Duncan (US 20100048069) teaches a proprotor system where the blade has a center of pressure that is forms an axis with the hub center, which forms an angle with a bearing axis.
Molter (US 20250229916) and Kieswetter (US 20170297677) each teaches a proprotor system with a bearing axis offset from a hub centerline axis.
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/JACKSON N GILLENWATERS/Examiner, Art Unit 3745
/NATHANIEL E WIEHE/Supervisory Patent Examiner, Art Unit 3745
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