DETAILED ACTION
Continuation Reissue Application
The instant reissue application is a continuation reissue of earlier reissue Application No. 17/338,276 and, thus, is a second application for reissue of US Patent No. 10,309,346 B2. See MPEP 1451, 35 USC 251(b), and 37 CFR 1.177.
Earlier reissue Application No. 17/338,276 was concluded with the issuance of US Reissued Patent No. RE49,778 E on January 2, 2024.
Maintenance Fees
MPEP 2504 explains that, for maintenance fees due on or after January 16, 2018, separate maintenance fees must be paid in:
Each reissued patent in force on (i.e., issued before) the maintenance fee due date. This includes all reissued patents that replace the same original patent.
An original patent that is not surrendered because one or more applications for reissue of that original patent are still pending on the maintenance fee due date.
USPTO records show that the four-year maintenance fee has been timely filed and, thus, maintenance fee payments are up to date for original US Patent No. 10,309,346 B2. No maintenance fee is yet due for US Reissued Patent No. RE49,778 E.
Status of Submission
This Office action is responsive to the amendment filed on October 10, 2025, which has been entered with the exception of the proposed replacement drawing sheets (see explanation below).
Claims Subject to Examination
New reissue claims 27-41 and 43-50 are subject to examination. Patent claims 1-26 and reissue claim 42 have been canceled.
Proposed Replacement Drawing Sheets
The proposed replacement drawing sheets filed on October 10, 2025 are approved only as proposed drawing corrections. They are not approved as replacement drawing sheets because they do not comply with 37 CFR 1.84(l).
Formal drawings incorporating the approved corrections are required.
Application Data Sheet
The corrected Application Data Sheet (ADS) filed on October 10, 2025 corrects the defects in the original ADS filed on December 21, 2023.
Filing Receipt
A Corrected Filing Receipt was issued on October 17, 2025 showing the correct Domestic Benefit data for this application.
Consent of Assignee
This application is objected to under 37 CFR 1.172(a) as lacking the written consent of all assignees owning an undivided interest in the patent. The consent of the assignee must be in compliance with 37 CFR 1.172. See MPEP 1410.01.
The consent of assignee (i.e., Form PTO/AIA /53) filed in the instant application on December 21, 2023 is a copy of the consent of assignee filed in parent reissue Application No. 17/338,276 on June 3, 2021. Such a copy of the assignee consent is only acceptable if the continuation reissue application corrects an error for which consent was made in the parent reissue application. That is, such a copy of the assignee consent is only acceptable if it gives consent for an error that was (a) identified in the parent reissue application (e.g., in the reissue oath/declaration filed in the parent reissue application), and (b) corrected in the continuation reissue application. See MPEP 1451, subsection II.
In this case, applicant has failed to explain why the filing of the copy of the reissue declaration from the parent reissue application is sufficient to ensure that an error is correctly identified by the continuation reissue application. See MPEP 1451, subsection II. Thus, applicant has failed to establish that consent was made in the parent reissue application for the error now corrected in the continuation reissue application.
A proper assent of the assignee in compliance with 37 CFR 1.172 and 3.73 is required in reply to this Office action.
Reissue Oath/Declaration
The reissue declaration filed on December 21, 2023 is defective because it fails to specifically and properly identify at least one error which is relied upon to support the reissue application. See 37 CFR 1.175 and MPEP 1414-1414.01.
As required by 37 CFR 1.175(a), the reissue oath/declaration must specifically identify at least one error pursuant to 35 U.S.C. 251 being relied upon as the basis for reissue. In identifying the error, it is sufficient that the reissue oath/declaration identify a single word, phrase, or expression in the specification or in an original claim, and how it renders the original patent wholly or partly inoperative or invalid. It is not sufficient to merely state that applicant seeks to broaden or narrow the scope of a patent claim. Further, a statement in the reissue oath/declaration of “…failure to include a claim directed to…” and then reciting all the limitations of a newly added claim would not be considered a sufficient error statement because applicant has not pointed out what the other claims lacked that the newly added claim has, or vice versa.
The reissue declaration (i.e., Form PTO/AIA /05) filed in the instant application on December 21, 2023 is a copy of the reissue declaration filed in parent reissue Application No. 17/338,276 on June 3, 2021.
Where a continuation reissue application is filed with a copy of the reissue oath/declaration from the parent reissue application, and the parent reissue application is not abandoned, the copy of the reissue oath/declaration is improper under 35 U.S.C. 251 unless it is accompanied by a statement explaining compliance with 37 CFR 1.175(f)(2). If the same error corrected in the parent reissue application is also being corrected in the continuation reissue application, but the error is being corrected in a different way, a statement is needed to explain compliance with 37 CFR 1.175(f)(2). See MPEP 1414, subsection II(D). In this case, applicant has failed to explain why the filing of the copy of the reissue declaration from the parent reissue application is sufficient to ensure that an error is correctly identified by the continuation reissue application. See MPEP 1451, subsection II(B).
Claim Construction
During examination, the pending claims are normally interpreted according to the broadest reasonable interpretation standard (hereinafter, the “BRI standard”). That is, claims are given their broadest reasonable interpretation consistent with the specification, and limitations in the specification are not read into the claims. See MPEP 2111 et seq.
An exception to the BRI standard occurs when the applicant acts as their own lexicographer. For this exception to apply, the applicant must clearly set forth a special definition of a claim term in the specification that differs from the plain and ordinary meaning it would otherwise possess. See MPEP 2111.01, subsection IV.
Another exception or special case occurs when a claim recites a means-plus-function limitation that must be interpreted in accordance with 35 USC 112 ¶ 6, or 35 USC 112(f). See MPEP 2181. According to the guidance provided by Williamson v. Citrix Online, LLC, 792 F.3d 1339 (Fed. Cir. 2015) (en banc), 35 USC 112 ¶ 6 applies when the claim term fails to recite (i) sufficiently definite structure, and/or (ii) sufficient structure for performing the claimed function.
The following claim terms/limitations are construed by the examiner to aid in reexamination:
Claim Term:
Bead
Examiner’s Construction:
A continuous line or deposit of applied material
Examiner’s Explanation:
The term “bead” is used in applicant’s specification and claims in a manner consistent with the following ordinary meaning of the term “bead”: a line of continuously applied ductile material, such as solder or caulking compound.1 Applicant’s “bead” is not a solder or caulking compound, but it is a line of continuously applied ductile material. Further, the term “bead” is used in applicant’s specification and claims in a manner similar to (but not exactly the same as) the following ordinary meaning of the term “bead”: (in welding) a continuous deposit of fused metal, either straight (stringer bead) or zigzag (weave bead).2 Applicant’s “bead” is not a welded bead per se, but it is a continuous deposit of material that fuses to adjacent beads of material.
Claim Term:
Eddy current (or eddy)
Examiner’s Construction:
A reverse flow of fluid that (i) is produced by the fluid’s interaction with an obstacle, and (ii) creates a rotary/whirling/swirling motion in the fluid downstream of the obstacle
Examiner’s Explanation:
The term “eddy current” is used in applicant’s specification and claims in a manner consistent with the following ordinary meanings of the term “eddy”:
a current at variance with the main current in a stream of liquid or gas, especially one having a rotary or whirling motion.3
a movement in a stream of air, water, or other fluid in which the current doubles back on itself causing a miniature whirlwind or whirlpool.4
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is naturally observed behind large emergent rocks in swift-flowing rivers.5
The term “eddy current” is used in applicant’s specification and claims in a manner distinct from the disclosure of a “vortex flow” or “swirling flow” in applicant’s specification. The port wall surface pattern or geometric shape is described in applicant’s specification as both (i) forming a rifling pattern that induces a “vortex flow” or “swirling flow” of oxidizer and fuel gas around the center port axis line to provide more thorough mixing of the oxidizer and fuel gas and more thorough combustion (see col. 1, ll. 24-35; col. 7, ll. 43-49; col. 8, ll. 37-48; col. 11, ll. 56-60; col. 15, ll. 19-30), and (ii) causing the mixture of fuel gas and oxidizer to continually “trip” over the ribs of the undulating port wall surface pattern and create an “eddy current” or a consistent, circular “eddy current flow” that contributes to more thorough combustion and higher specific impulse (see col. 13, l. 62 to col. 14, l. 14). Thus, the disclosed “vortex flow” or “swirling flow” is flow revolving (spiraling) around the center port axis line, but the disclosed “eddy current” is circular flow in a space/area along the port wall immediately downstream of a rib or undulation in the port wall.
The term “eddy current” is not used in applicant’s specification and claims in a manner consistent with the following ordinary meanings of the term “eddy current”:
an electric current in a conducting material that results from induction by a moving or varying magnetic field.6
an electric current induced in a massive conductor, such as the core of an electromagnet, transformer, etc, by an alternating magnetic field.7
Effective Filing Date
The examiner has reviewed the disclosures of the applications to which priority is claimed in order to determine whether such applications provide support in the manner required by 35 USC 112(a) for the subject matter claimed in the instant application. The examiner finds that prior Application Nos. 12/052,934 and 15/262,661 and prior Provisional Application No. 60/896,296 fail to provide support in the manner required by 35 USC 112(a) for at least the following subject matter recited in claims 27-41 and 43-50 of the instant application:
“the boundary wall has a pattern of undulations that is configured to induce an eddy current in a fluid flowing through the combustion port” (claim 27, ll. 5-7; claim 39, ll. 4-6).
“the fuel grain material comprises between 80% and 95% by mass of the hybrid rocket fuel material and between 5% and 20% by mass of the metallic material” (claims 35 and 47).
Prior Application No. 15/262,661 discloses a rifling pattern that induces a “vortex flow” or “swirling flow” revolving (spiraling) around the center port axis line, but it fails to disclose an “eddy current” in the form of a circular flow in a space/area along the port wall immediately downstream of a rib/undulation in the port wall.
Further, the examiner finds that prior Application No. 12/052,934 and prior Provisional Application No. 60/896,296 fail to provide support in the manner required by 35 USC 112(a) for at least the following subject matter recited in the claims of the instant application:
“the fuel grain material comprises a mixture of a hybrid rocket fuel material and a metallic material” (claims 34 and 46).
“in which an end of each fuel grain section is bonded to an end of an adjacent fuel grain section to form the fuel grain assembly” (claims 37 and 49).
Accordingly, the effective filing date of claims 27-41 and 43-50 of the instant application is January 11, 2018, i.e., the filing date of US Patent No. 10,309,346 B2 for which reissue is sought.
Listing of Prior Art
The following is a listing of the prior art cited in this Office action together with the shorthand reference used for each document (listed alphabetically):
“Chen et al.”
US Publication No. 2011/0203256 A1
“Fuller”
US Publication No. 2013/0042951 A1
“Gunners et al.”
US Patent No. 5,423,179
“Jones ‘479”
US Patent No. 9,453,479 B18
“Lou et al.”
US Patent No. 5,386,777
“Moriwaki et al.”
JP Publication No. 2011-1904 A (with translation)
“Mullaney”
US Patent No. 2,990,682
“Nissan”
JP Publication No. S46-39645 B1 (with translation)
“Schlueter”
WO Publication No. 2017/027198 A1
“Stark”
US Patent No. 3,423,943
“Stickler”
US Patent No. 5,529,648
“Whitmore et al. ‘256”
US Publication No. 2016/0194256 A1
“Whitmore et al. ‘892”
US Publication No. 2015/0322892 A1
Claim Rejections – 35 USC § 251
The following is a quotation of 35 U.S.C. 251:
(a) IN GENERAL.—Whenever any patent is, through error, deemed wholly or partly inoperative or invalid, by reason of a defective specification or drawing, or by reason of the patentee claiming more or less than he had a right to claim in the patent, the Director shall, on the surrender of such patent and the payment of the fee required by law, reissue the patent for the invention disclosed in the original patent, and in accordance with a new and amended application, for the unexpired part of the term of the original patent. No new matter shall be introduced into the application for reissue.
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(b) MULTIPLE REISSUED PATENTS.—The Director may issue several reissued patents for distinct and separate parts of the thing patented, upon demand of the applicant, and upon payment of the required fee for a reissue for each of such reissued patents.
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(c) APPLICABILITY OF THIS TITLE.—The provisions of this title relating to applications for patent shall be applicable to applications for reissue of a patent, except that application for reissue may be made and sworn to by the assignee of the entire interest if the application does not seek to enlarge the scope of the claims of the original patent or the application for the original patent was filed by the assignee of the entire interest.
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(d) REISSUE PATENT ENLARGING SCOPE OF CLAIMS. No reissued patent shall be granted enlarging the scope of the claims of the original patent unless applied for within two years from the grant of the original patent.
GROUND 1: Claims 27-41 and 43-50 are rejected under 35 U.S.C. 251 as being based upon a defective reissue oath/declaration. See 37 CFR 1.175. The nature of the defect(s) in the reissue oath/declaration is explained above.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
GROUND 2: Claims 27-38, 41, 43, 44, 48 and 50 are rejected under 35 U.S.C. 112(b) as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention.
The preamble of claim 27 states that the claim is directed to “A fuel grain section for a hybrid rocket”. Likewise, the body of claim 27 is directed to and only defines a fuel grain section (see fuel grain section 10 shown in Figs. 1-3), which is one of plural fuel grain sections that are stacked and joined to form a complete fuel grain (see complete fuel grain 40 in Figs. 4A-4B). However, the body of claim 27 recites “to form a fuel grain” (l. 2) and “through the fuel grain” (l. 3), which recitations are inconsistent with the claim being directed to only a fuel grain section (not a complete fuel grain). The examiner suggests changing “fuel grain” to “fuel grain section” at lines 2 and 3.
In claim 28, the recitation “The fuel grain section of claim 27, in which the fuel grain comprises an elongated fuel grain” is indefinite. As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. Further, the fuel grain section of claim 27 does not constitute a fuel grain (as implied by the language of claim 28). It appears that claim 28 should depend from claim 37 and define the fuel grain assembly of claim 37 as elongated.
In claim 29, the recitation “The fuel grain section of claim 27, in which the fuel grain comprises a generally cylindrical fuel grain” is indefinite. As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. In claim 29, the examiner suggests changing “fuel grain” to “fuel grain section” at lines 1 and 2.
In claim 30, the recitation “The fuel grain section of claim 27, in which the fuel grain is…” is indefinite. As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. In claim 30, the examiner suggests changing “fuel grain” to “fuel grain section” at line 1.
Claim 31 is indefinite because it appears to encompass broader subject matter than the claim from which it depends. Since a dependent claim, by definition, includes all of the limitations of the claim from which it depends, a dependent claim is rendered indefinite when it appears to negate or broaden a requirement of the claim from which it depends. In this case, claim 27 has been amended to require a pattern of undulations, but claim 31 recites undulations as only one of five alternative boundary wall textures.
In claim 32, the recitation “The fuel grain section of claim 27, in which the fuel grain is…” is indefinite. As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. In claim 32, the examiner suggests changing “fuel grain” to “fuel grain section” at line 1.
In claim 36, the recitation “The fuel grain section of claim 27, “comprising a thermally insulating material encasing the fuel grain section” is indefinite. As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. According to the patent specification, individual fuel grain sections are not wrapped/encased in a thermally insulating material. Rather, as shown in Fig. 5, a complete fuel grain 40 is wrapped/encased in a thermally insulating material 50. Thus, claim 36 does not conform to the description of the invention in the specification. Such inconsistency renders the claim indefinite, i.e., it is unclear if the claim requires a complete fuel grain (even though a complete fuel grain is not defined in the claim) that is encased in a thermally insulating material, or whether the claim requires only one fuel grain section encased in a thermally insulating material. If only one fuel grain section is required, the claims fail to accurately define the invention described in the specification. It appears that claim 36 should depend from claim 37 and define the fuel grain assembly of claim 37 as encased in a thermally insulating material.
Claim 38 recites “A hybrid rocket engine comprising: the fuel grain section of claim 27” (ll. 1-2) and goes on to recite “a casing, in which the fuel grain section is housed within the casing” (l. 7). As explained above, claim 27 is directed only to a fuel grain section, not to a complete fuel grain. According to the patent specification, the fuel grain section of claim 27 is one of plural fuel grain sections that are stacked and joined to form a complete fuel grain (see complete fuel grain 40 in Figs. 4A-4B). Thus, the fuel grain section of claim 27 does not constitute a complete fuel grain of the hybrid rocket engine of claim 38. In other words, the hybrid rocket engine of claim 38 is not complete since such an engine is not disclosed as comprising only a single fuel grain section. Further, according to the specification, the hybrid rocket engine 70 shown in Fig. 6 has a motor case 60 in which the complete fuel grain is housed (not just a single fuel grain section). Thus, claim 38 is incomplete and does not conform to the description of the invention in the specification. Such incompleteness and inconsistency render the claim indefinite. It appears that claim 38 should depend from claim 37 and define the hybrid rocket engine as comprising the fuel grain assembly of claim 37, with the fuel grain assembly housed within the casing.
If claim 38 is amended to depend from claim 37, then claim 38 will need to be amended to clarify the term “the combustion port” (claim 38, ll. 3-4, 5 and 6) since claim 27 defines a combustion port of a single fuel grain section, and claim 37 defines plural fuel grain sections that are aligned to define a combustion port of the fuel grain assembly.
Claim 41 is indefinite because it appears to encompass broader subject matter than the claim from which it depends. Since a dependent claim, by definition, includes all of the limitations of the claim from which it depends, a dependent claim is rendered indefinite when it appears to negate or broaden a requirement of the claim from which it depends. In this case, claim 39 has been amended to require a pattern of undulations, but claim 41 recites undulations as only one of five alternative boundary wall textures.
In claim 43, the recitation “…the boundary wall defines alternating protrusions and depressions” is indefinite. Prior claim 39 has been amended to require a pattern of undulations. It is unclear whether (i) the pattern of undulations of claim 39 includes or is defined by the protrusions and depressions of claim 43, or (ii) the pattern of undulations of claim 39 are distinct from the protrusions and depressions of claim 43. This ambiguity renders claim 43 indefinite.
In claim 44, the recitation “The fuel grain section of claim 39, in which the fuel grain is…” is indefinite. Like claim 27, claim 39 is directed only to a fuel grain section, not to a complete fuel grain. In claim 44, the examiner suggests changing “fuel grain” to “fuel grain section” at line 1.
In claim 48, the recitation “The fuel grain section of claim 39, “comprising a thermally insulating material encasing the fuel grain section” is indefinite. As explained above, claim 39 is directed only to a fuel grain section, not to a complete fuel grain. According to the patent specification, individual fuel grain sections are not wrapped/encased in a thermally insulating material. Rather, as shown in Fig. 5, a complete fuel grain 40 is wrapped/encased in a thermally insulating material 50. Thus, claim 48 does not conform to the description of the invention in the specification. Such inconsistency renders the claim indefinite, i.e., it is unclear if the claim requires a complete fuel grain (even though a complete fuel grain is not defined in the claim) that is encased in a thermally insulating material, or whether the claim requires only one fuel grain section encased in a thermally insulating material. If only one fuel grain section is required, the claims fail to accurately define the invention described in the specification. It appears that claim 48 should depend from claim 49 and define the fuel grain assembly of claim 49 as encased in a thermally insulating material.
Claim 50 recites “A hybrid rocket engine comprising: the fuel grain section of claim 39” (ll. 1-2) and goes on to recite “a casing, in which the fuel grain section is housed within the casing” (l. 7). As explained above, claim 39 is directed only to a fuel grain section, not to a complete fuel grain. According to the patent specification, the fuel grain section of claim 39 is one of plural fuel grain sections that are stacked and joined to form a complete fuel grain (see complete fuel grain 40 in Figs. 4A-4B). Thus, the fuel grain section of claim 39 does not constitute a complete fuel grain of the hybrid rocket engine of claim 50. In other words, the hybrid rocket engine of claim 50 is not complete since such an engine is not disclosed as comprising only a single fuel grain section. Further, according to the specification, the hybrid rocket engine 70 shown in Fig. 6 has a motor case 60 in which the complete fuel grain is housed (not just a single fuel grain section). Thus, claim 50 is incomplete and does not conform to the description of the invention in the specification. Such incompleteness and inconsistency render the claim indefinite. It appears that claim 50 should depend from claim 49 and define the hybrid rocket engine as comprising the fuel grain assembly of claim 49, with the fuel grain assembly housed within the casing.
If claim 50 is amended to depend from claim 49, then claim 50 will need to be amended to clarify the term “the combustion port” (claim 50, ll. 3-4, 5 and 6) since claim 39 defines a combustion port of a single fuel grain section, and claim 50 defines plural fuel grain sections that are aligned to define a combustion port of the fuel grain assembly.
Claims 33-35 are included in the rejection because of their dependencies.
Double Patenting – Nonstatutory
The nonstatutory double patenting rejection is based on a judicially created doctrine grounded in public policy (a policy reflected in the statute) so as to prevent the unjustified or improper timewise extension of the “right to exclude” granted by a patent and to prevent possible harassment by multiple assignees. A nonstatutory double patenting rejection is appropriate where the conflicting claims are not identical, but at least one examined application claim is not patentably distinct from the reference claim(s) because the examined application claim is either anticipated by, or would have been obvious over, the reference claim(s). See, e.g., In re Berg, 140 F.3d 1428, 46 USPQ2d 1226 (Fed. Cir. 1998); In re Goodman, 11 F.3d 1046, 29 USPQ2d 2010 (Fed. Cir. 1993); In re Longi, 759 F.2d 887, 225 USPQ 645 (Fed. Cir. 1985); In re Van Ornum, 686 F.2d 937, 214 USPQ 761 (CCPA 1982); In re Vogel, 422 F.2d 438, 164 USPQ 619 (CCPA 1970); In re Thorington, 418 F.2d 528, 163 USPQ 644 (CCPA 1969).
A timely filed terminal disclaimer in compliance with 37 CFR 1.321(c) or 1.321(d) may be used to overcome an actual or provisional rejection based on nonstatutory double patenting provided the reference application or patent either is shown to be commonly owned with the examined application, or claims an invention made as a result of activities undertaken within the scope of a joint research agreement. See MPEP § 717.02 for applications subject to examination under the first inventor to file provisions of the AIA as explained in MPEP § 2159. See MPEP § 2146 et seq. for applications not subject to examination under the first inventor to file provisions of the AIA . A terminal disclaimer must be signed in compliance with 37 CFR 1.321(b).
The filing of a terminal disclaimer by itself is not a complete reply to a nonstatutory double patenting (NSDP) rejection. A complete reply requires that the terminal disclaimer be accompanied by a reply requesting reconsideration of the prior Office action. Even where the NSDP rejection is provisional the reply must be complete. See MPEP § 804, subsection I.B.1. For a reply to a non-final Office action, see 37 CFR 1.111(a). For a reply to final Office action, see 37 CFR 1.113(c). A request for reconsideration while not provided for in 37 CFR 1.113(c) may be filed after final for consideration. See MPEP §§ 706.07(e) and 714.13.
The USPTO Internet website contains terminal disclaimer forms which may be used. Please visit www.uspto.gov/patent/patents-forms. The actual filing date of the application in which the form is filed determines what form (e.g., PTO/SB/25, PTO/SB/26, PTO/AIA /25, or PTO/AIA /26) should be used. A web-based eTerminal Disclaimer may be filled out completely online using web-screens. An eTerminal Disclaimer that meets all requirements is auto-processed and approved immediately upon submission. For more information about eTerminal Disclaimers, refer to www.uspto.gov/patents/apply/applying-online/eterminal-disclaimer.
GROUND 3: Claims 27, 31, 39, 41 and 43 are rejected on the ground of nonstatutory double patenting as being unpatentable over claims 30, 31, 41 and 43 of US Reissued Patent No. RE49,778 E.
Claims 27, 31, 39, 41 and 43 of the instant application define a fuel grain section structured in a similar fashion to that required by claims 30, 31, 41 and 43 of US Reissued Patent No. RE49,778 E. While the wording of the claims differs slightly, a boundary wall having a pattern of undulations (claims 27 and 39 of the instant application) is encompassed by a boundary wall textured with undulations and defining alternating protrusions and depressions (claims 30, 31, 41 and 43 of US Reissued Patent No. RE49,778 E). Further, while claims 27, 31, 39, 41 and 43 of the instant application omit some limitations required by claims 30, 31, 41 and 43 of US Reissued Patent No. RE49,778 E, the omission of limitations with the consequent loss of their functions is recognized to be within the level of ordinary skill in the art.
Accordingly, claims 27, 31, 39, 41 and 43 of the instant application are not patentably distinct from claims 30, 31, 41 and 43 of US Reissued Patent No. RE49,778 E.
Pertinent Prior Art
The following prior art is considered pertinent to applicant’s disclosure.
Stark discloses a fuel grain for a hybrid rocket, comprising multiple fuel grain sections 18 and multiple additional fuel grain sections 26 arranged in a stacked configuration, with the fuel grain sections 18 each having an opening 20 bounded by a boundary wall, with the additional fuel grain sections 26 each having an opening 28 bounded by a boundary wall, and with the openings 20, 28 defining a collective combustion port (or respective combustion ports) extending axially through the fuel grain. See Figs. 1-3; col. 3, ll. 9-42. The additional fuel grain sections 26 define shoulders 32 that induce a highly turbulent flow of fluid through the combustion port, including cross currents possessing an outward radial component, resulting in partial recirculation for better mixing of gaseous fuel and oxidizer and more efficient combustion. See Fig. 1; col. 1, l. 56 to col. 2, l. 21; col. 3, ll. 43-60. This highly turbulent flow (i.e., cross currents having an outward radial component, resulting in partial recirculation) is illustrated in Fig. 1 as a reverse flow of fluid that (i) is produced by the fluid’s interaction with each shoulder 32, and (ii) creates a rotary/whirling/ swirling motion in the fluid downstream of each shoulder 32. Thus, each of the shoulders 32 is configured to induce an “eddy”.
Schlueter discloses a fuel grain for a rocket, comprising a fuel grain section 24 that includes a fuel grain structure 26 formed of fuel grain material, with the fuel grain structure 26 defining a combustion port 28 bounded by a boundary wall and extending axially through the fuel grain. See Fig. 1; ¶¶ 0028-0029. The fuel grain structure 26 is specially configured for better mixing of gaseous fuel and oxidizer and more efficient combustion. See ¶ 0027. In the embodiment shown in Fig. 4, the boundary wall of the combustion port 228 has a specially configured vortex-inducing port wall surface feature 232 in the form of a protuberance (i.e., protrusion, projection or rib) 240, which causes a reverse flow of fluid that (i) is produced by the fluid’s interaction with the protuberance 240, and (ii) creates a vortex (i.e., rotary/whirling/swirling motion) in the fluid downstream of the protuberance 240. See Fig. 4; ¶ 0036. Thus, the protuberance 240 is configured to produce an “eddy”. While only one protuberance 240 is shown in Fig. 4, a plurality of such protuberances can be axially spaced along the combustion port 228. See ¶ 0036 and the plural vortex-inducing features 232 in Fig. 1. In the alternative embodiment of Fig. 6, the boundary wall of the combustion port 428 has a specially configured vortex-inducing port wall surface feature 432 in the form of a helical protuberance 440, which causes a reverse flow of fluid that (i) is produced by the fluid’s interaction with the protuberance 440, and (ii) creates a vortex (i.e., rotary/whirling/swirling motion) in the fluid downstream of the protuberance 440. See Fig. 6; ¶ 0036. Thus, the helical protuberance 440 is configured to produce an “eddy”. As shown in Fig. 6, the helical protuberance 440 forms a series of axially spaced protrusions, projections or ribs.
Chen et al. teaches a hybrid rocket engine 1 comprising vortex generators 12 that extend inward into the combustion port defined in the fuel grain 2, with the vortex generators 12 constituting vanes 120. See Figs. 1-3; ¶¶ 0017-0022. The vortex generators 12 generate eddies in the fluid flow to enhance the mixing of the fuel and oxidizer and provide more efficient combustion. See the abstract (which mentions “eddies”); ¶¶ 0019, 0021, 0023. Thus, as a result of the vortex generators 12, the boundary wall of the combustion port is configured to induce eddies in a fluid flowing through the combustion port.
Nissan teaches a complete fuel grain (comprising stacked fuel grain sections 11a, 12a, 11b, 12b, 11c, 12c) that is incorporated into a hybrid rocket engine comprising (i) an oxidizer source 5 configured to provide a flow of an oxidizer 4 through the combustion port during operation of the hybrid rocket engine, (ii) a valve 7 configured to control the flow of the oxidizer 4 through the combustion port, (iii) a nozzle 15 in fluid communication with the combustion port, and (iv) a casing/shell (see Fig. 1) within which the complete fuel grain, the oxidizer source 5, and the valve 7 are housed, with the nozzle 15 extending beyond an end of the casing/shell. See Figs. 1-2(b); p. 2, l. 35 to p. 3, l. 28.9 Like Schlueter, Nissan teaches that the fuel grain structure has a boundary wall of the combustion port that is specially configured to provide protrusions, which create eddies (i.e., rotary/whirling/swirling motion) in the fluid downstream of the protrusions for better mixing of gaseous fuel and oxidizer and more efficient combustion. See Fig. 2(b); p. 2, ll. 25-34; p. 3, ll. 16-33.
Jones ‘479 teaches a plurality of fuel grain sections 10a, 10b, 10c, 10d that are stacked and joined using interlocking features 100a, 100b, 100c, 102a, 102b, 102c, 104b, 104c, 104d, 106b, 106c, 106d to form a complete fuel grain 40. See Figs. 5A-6; col. 4, ll. 22-27; col. 5, ll. 20-43. The fuel grain sections 10a, 10b, 10c, 10d are formed of ABS using FDM®. See Figs. 1-4; col. 4, ll. 9-22; col. 4, l. 41 to col. 5, l. 19. Each of the fuel grain sections 10a, 10b, 10c, 10d includes a plurality of successive flat layers that are built up to form the fuel grain section and to define a specially configured boundary wall surface 14 of the combustion port 16 within the fuel grain section, with the flat layers providing the boundary wall surface 14 with a dimpled (textured) surface pattern in the form of a series of projections and depressions (i.e., undulations) along the boundary wall surface 14 in order to increase the surface area for combustion and provide the fuel grain with an increased regression rate. See Figs. 1-3; col. 2, ll. 27-39; col. 3, ll. 19-37; col. 3, l. 58 to col. 4, l. 8; col. 6, ll. 25-28. See also the “predetermined pattern of peaks and valleys” recited in claims 1 and 13. This specially configured surface pattern persists as the fuel grain burns, i.e., when the boundary wall ablates due to combustion in the combustion port, a new surface of fuel grain material is exposed to the combustion port. See Figs. 9A-9C; col. 2, ll. 36-45; col. 3, ll. 34-44; col. 6, ll. 29-35. The complete fuel grain 40 is wrapped in a thermally insulating film 50. See Fig. 6; col. 5, ll. 44-55. The wrapped complete fuel grain 40, an oxidizer source 76 and a valve 78 are housed in a shell 72 of a hybrid rocket 70, and a nozzle 82 extends beyond the end of the shell 72. See Figs. 7-8; col. 5, l. 56 to col. 6, l. 5. Jones ‘479 explains that the boundary layer 65 is usually turbulent over a large portion of the length of the combustion port 46 of the complete fuel grain 40, a turbulent diffusion flame sheet 66 within the boundary layer 65 produces a flow of fuel gas that mixes with the oxidizer, and the increased surface area of the specially configured boundary wall surface 14 produces an increased regression rate and corresponding thrust impulse. See Fig. 8; col. 6, ll. 6-28.
Whitmore et al. ‘256 teaches a plurality of fuel grain sections 30a, 30b, 30c (or 31a, 31b, 31c, or 33a, 33b, 33c) that are stacked and joined to form a complete fuel grain 10. See Figs. 1, 2A and 4; ¶¶ 0029, 0034, 0037. The fuel grain sections have interlocking features 35 (or 62, 63) and are also secured (bonded) end to end using ABS cement in order to form an air-tight connection. See Figs. 1 and 4; ¶¶ 0029, 0037-0038. The fuel grain sections are formed of ABS using FDM®. See ¶¶ 0008-0009, 0015, 0029, 0031. Each fuel grain section includes a plurality of successive flat layers 50 that are built up to form the fuel grain section and to define the combustion port within the fuel grain section (the combustion ports of the fuel grain sections collectively defining a combustion port 20 of the complete fuel grain). See ¶¶ 0008, 0015, 0029, 0035. As shown in Fig. 2B, the flat layers 50 provide the boundary wall of the combustion port with a textured surface pattern, i.e., a series of projections and depressions defining undulations. See ¶ 0033, which explains that the combustion port of the complete fuel grain is helical and produces helical flow to increase the nominal surface skin friction.
Whitmore et al. ‘892 teaches a hybrid rocket 10 including a first fuel grain section 20 (defining a housing of an ignition system 12) and a second fuel grain section 34. See Figs. 1-3B; ¶¶ 0030-0032, 0040. As illustrated in Figs. 2 and 3A, the first and second fuel grain sections 20, 34 are formed in one piece to define a complete fuel grain. The fuel grain sections 20, 34 are formed of ABS using FDM®. See ¶¶ 0011, 0030, 0032, 0040. The fuel grain section 20 includes a plurality of successive flat layers 18 that are built up to form the fuel grain section and to define the boundary wall surface 14 of the combustion port 48 within the fuel grain section, with the flat layers 18 defining ridges 16 and a series of projections 92 and recesses 94 (i.e., undulations) along the boundary wall of the combustion port 48. See Figs. 5-6; ¶¶ 0030, 0040-0042. Since the fuel grain section 34 is formed in one piece with and of the same fuel grain material as the fuel grain section 20, the skilled artisan would appreciate that the fuel grain section 34 can also be formed using FDM® to produce the plural flat layers 18 defining the ridges 16 and the projections 92 and recesses 94 along the boundary wall of its combustion port. Whitmore et al. ‘892 explains that:
The ridges 16 and the projections 92, 94 are formed as a result of ABS possessing a very unique electro-mechanical property such that FDM® results in a distinctive surface structure that is different than the surface of a monolithically fabricated (e.g., a molded or machined) ABS structure. See ¶¶ 0040-0042.
Due to the unique structure of ABS formed by FDM®, as material from the boundary wall surface 14 of the combustion port 48 is consumed or removed (ablates) through combustion, a newly exposed internal surface maintains similar surface characteristics or surface roughness. See ¶ 0041.
Fuller teaches a fuel grain section 128 made of a fuel grain material 208 comprising acrylonitrile butadiene styrene (ABS) and a metallic powder. See Figs. 1 and 4; ¶¶ 0048, 0072, 0089-0090. The fuel grain section 128 has a combustion port 210 with a relatively complex shape. See Fig. 4; ¶¶ 0044, 0049, 0071-0074. Fuller’s port shape can induce turbulence in the fluid flow. See ¶ 0049. A plurality of fuel grain sections are stacked to form a complete fuel grain. See ¶¶ 0024, 0078. Fuller further teaches the use of fused deposition modeling (FDM®)10 for forming a fuel grain having a combustion port with a complex shape. See ¶¶ 0051, 0053. Fuller explains that, in FDM®, a plastic is melted, a bead of molten plastic material is extruded through a moving nozzle, a trail of the extruded material solidifies behind the nozzle to form a substantially two-dimensional first layer, and the process is repeated to build up successive layers until a three-dimensional object is formed. See ¶¶ 0051, 0053.
Moriwaki et al. teaches a complete fuel grain 3 that is incorporated into a hybrid rocket engine comprising (i) an oxidizer source (see Figs. 4(A) and 6(A)) configured to provide a flow of an oxidizer through the combustion port 5 during operation of the hybrid rocket engine, (ii) a valve (see ¶¶ 0026, 0028) configured to control the flow of the oxidizer through the combustion port 5, (iii) a nozzle 4 in fluid communication with the combustion port, and (iv) a casing/shell 2 within which the complete fuel grain 3 is housed, with the nozzle 4 extending beyond an end of the casing/shell 2. See Figs. 1-6; ¶¶ 0002, 0026, 0028.11 The fuel grain structure has a boundary wall of the combustion port that is specially configured to provide protrusions 10a, 10b (see Fig. 1), 13 (see Fig. 2) or undulations 15 (see Fig. 4), which create turbulence in the fluid for better mixing of gaseous fuel and oxidizer and more efficient combustion. See Figs. 1-2 and 4; ¶¶ 0005-0013, 0018-0019, 0027, 0029-0035, 0040-0043. While plural combustion ports 5 are shown in Fig. 4, the fuel grain 3 can have a single combustion port 5. See ¶ 0044.
Mullaney teaches a complete fuel grain 15 (comprising stacked fuel grain sections 17, 18) that is incorporated into a hybrid rocket engine comprising (i) an oxidizer source 11 configured to provide a flow of an oxidizer through the combustion port 16 during operation of the hybrid rocket engine, (ii) a nozzle 12 in fluid communication with the combustion port 16, and (iii) a casing/shell 10 within which the complete fuel grain 15 is housed, with the nozzle 12 extending beyond an end of the casing/shell 10. See Figs. 1-2; col. 1, l. 46 to col. 2, l. 13; col. 2, ll. 14-35. The fuel grain structure has a boundary wall of the combustion port 16 that is specially configured to provide protrusions, which create turbulence in the fluid for better mixing of gaseous fuel and oxidizer and more efficient combustion. See Figs. 1-2; col. 1, ll. 11-14 and 27-37; col. 2, ll. 2-13 and 35-60.
Lou et al. teaches (i) a fuel grain comprising a polymeric binder (i.e., PVA) and a metallic fuel material (e.g., aluminum), (ii) that the proportions of the polymeric binder and the metallic fuel material may vary, and (iii) the proportion of metallic fuel material will generally fall within the range of about 10% to about 40% on a weight basis. See col. 1, l. 55-60; col. 7, ll. 3-41.
Gunners et al. teaches a fuel grain structure in which the boundary wall of the combustion port is provided with lands (i.e., ribs or projections) in order to produce vortices downstream of the lands.
Stickler teaches a fuel grain structure in which the boundary wall of the combustion port has a surface that is specially configured to create depressions, voids or bumps that continuously roughen the surface in order to produce a higher burn rate.
Allowable Subject Matter
Claims 27-41 and 43-50 contain allowable subject matter because the prior art fails to teach a fuel grain section, as defined in independent claims 27 and 39, including a boundary wall having a pattern of undulations that is configured to induce an eddy current in the fluid flowing through the combustion port.
In order for claims 27-41 and 43-50 to be allowed, applicant must overcome the rejections under 35 USC 251 and 35 USC 112(b), and the double patenting rejection.
Response to Arguments
Applicant’s arguments filed on October 10, 2025 have been fully considered.
Applicant requests that the objection to the consent of the assignee be held in abeyance. This does not constitute a proper response since reissue applicants must comply with all reissue statutes and regulations.
Applicant requests that the objection to the reissue declaration and the rejection under 35 USC 251 be held in abeyance. This does not constitute a proper response since reissue applicants must comply with all reissue statutes and regulations.
Applicant argues that the prior rejection under 35 USC 112(a) has been overcome by the claim amendments. The examiner concurs.
With respect to the rejection under 35 USC 112(b):
Applicant argues that the phrase “eddy current” would be understood by one of ordinary skill in the art based on applicant’s specification. This argument is persuasive.
Applicant argues that the remaining findings of indefiniteness have been overcome by the claim amendments. The examiner disagrees for the reasons given above.
Applicant argues that the prior rejections under 35 USC 103 have been overcome by the claim amendments. The examiner concurs.
Applicant requests that the double patenting rejection be held in abeyance. This does not constitute a proper and complete response since all outstanding rejections must be addressed.
With respect to the prior objections to the specification:
Applicant argues that the phrase “eddy current” would be understood by one of ordinary skill in the art based on applicant’s specification. This argument is persuasive.
Applicant argues that the remaining objections have been overcome by the amendments to the specification. The examiner concurs.
Applicant argues that the objections to the drawings have been overcome by the replacement drawing sheets. While the proposed changes overcome the objections, the replacement drawing sheets do not constitute proper formal drawings for the reason explained above.
Final Action
Applicant’s amendment necessitated the new/modified grounds of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP 706.07(a).
Response Period
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action.
Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
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.
Amendments in Reissue Applications
Applicant is notified that any subsequent amendment to the specification, claims or drawings must comply with 37 CFR 1.173(b)-(g).
Failure to fully comply with 37 CFR 1.173(b)-(g) will generally result in a notification to applicant that an amendment before final rejection is not completely responsive. Such an amendment after final rejection will not be entered.
Disclosure Obligations
Applicant is reminded of the continuing obligation under 37 CFR 1.178(b), to timely apprise the Office of any prior or concurrent proceed-ing in which the patent for which reissue is sought is or was involved. These proceedings would include interferences, reissues, reexaminations, and litigation. Applicant is further reminded of the continuing obligation under 37 CFR 1.56, to timely apprise the Office of any information which is mate-rial to patentability of the claims under consideration in this reissue appli-cation. These obligations rest with each individual associated with the filing and prosecution of this application for reissue. See also MPEP 1404, 1442.01 and 1442.04.
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/PETER C ENGLISH/Reexamination Specialist, Art Unit 3993