DETAILED ACTION
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 7/25/2026 has been entered.
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 .
This is in response to the correspondence filed on 7/25/2026.
Claim Rejections - 35 USC § 112
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1, 10, 19, and their dependent claims, are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
In Claim 1 (and similarly in Claims 10 and 19): “the volumetric capacity of the cryogenic fuel tank is sized without accounting for the Alternate mission segment regulatory reserve requirements of the aircraft” does not appear to be supported by the Specification and is considered new matter. It is noted that while Figure 2 shows H2 as the fuel for the ”short, typical range mission” “Block mission”, it does not disclose how the tank was sized, Fig 2 shows the operation concept but does not indicate tank capacity; The specification paragraph [0032] appears to discuss sizing, “Smaller and lighter hydrogen tanks: hydrogen fuel is sized for the typical mission, resulting in much smaller and lighter tanks than if they were to be sized for the design long range mission plus reserves. A smaller hydrogen tank may have a better form factor and increase its weight efficiency”, but this paragraph also does not appear to support, inter alia, “without accounting for the Alternate mission segment regulatory reserve requirements”. Furthermore, claim 1 also includes the limitation “the designed volumetric capacity sizing of the at least one cryogenic fuel tank being smaller than a size that would be required for cryogenically fueling the aircraft to propel the aircraft for a mission that includes the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for Alternate segment; wherein the volumetric capacity of the cryogenic fuel tank is sized without accounting for the Alternate mission segment regulatory reserve requirements of the aircraft” which appears to indicate the capacity of the cryogenic fuel tank, although smaller than, could be up to a size sufficient to fly “the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for Alternate segment", which appears to account for reserves for Alternate segment and more.
Claim 10, and its dependent claims, are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 10: in “A method of operating an aircraft designed and configured to fly a design long range mission and a typical range mission, the method comprising:
configuring aircraft aerodynamic structure overall geometry and design weights as a function of both a design long range mission burning non-cryogenic fuel and a typical range mission, wherein the typical mission comprises a Block mission segment burning cryogenic fuel and an Alternate mission segment burning non-cryogenic fuel, wherein the typical range Block mission segment is shorter in distance than the design long range Block mission segment and the distance ratio between the typical range Block mission segment and the design long range Block mission segment is between 0.2 and 0.5 …”
It is not clear how when performing “a method for operating an aircraft”, an operator/pilot of the aircraft accomplishes, inter alia, “configuring aircraft aerodynamic structure overall geometry and design weights”, “provisioning at least one cryogenic fuel tank housed within the aircraft aerodynamic structure” “sizing cryogenic fuel storage capacity”, “provisioning plural non-cryogenic fuel tanks housed within the aircraft aerodynamic structure”.
Claim Rejections - 35 USC § 112
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.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1, 10, 19 and their dependent claims are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claims 1, 10 recites the limitation “the typical range Block mission segment” but it is unclear if it is the same as “a Block mission segment” in “the typical range mission comprises a Block mission segment” recited earlier in the claim. It is also unclear if “a Block” is the same block repeated multiple times later in the claim referring to both typical range and design range.
Claims 1, 10, 19 recite the limitation “the design long range Block mission segment”. There is insufficient antecedent basis for this limitation in the claim.
Claims 1, 10, 19, recite the limitation “the cryogenic fuel tank”. There is insufficient antecedent basis for this limitation in the claim.
Claims 1, 10, 19, recite the limitation “the non-cryogenic fuel tanks”. There is insufficient antecedent basis for this limitation in the claim.
Claims 1, 10, 19: in Claim 1 (and similarly in claims 10, 19) in “the designed volumetric capacity sizing of the at least one cryogenic fuel tank being smaller than a size that would be required for cryogenically fueling the aircraft to propel the aircraft for a mission that includes the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for Alternate segment”, it is unclear how much of “an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment”, and it is also unclear if the “plus reserves for Alternate segment” should be added to the portion of the design long range block mission segment in the calculation, and it is also unclear if “reserves for Alternate segment” refer to reserves for a typical range mission or a long range mission (fuel reserve requirements may be different based on the overall distance of the main route, or distance to Alternate airports, weather conditions etc).
Claim 10: in “sizing cryogenic fuel storage capacity of the at least one cryogenic fuel tank for a typical range Block mission segment”, it is unclear if “a typical range Block mission segment” is related to “the typical range Block mission segment” recited earlier in the claim (multiple times).
Claim 10: It is unclear if “a design long range mission” “a typical range mission” in “a design long range mission burning non-cryogenic fuel and a typical range mission” are different than “a design long range mission” “a typical range mission” in “configured to fly a design long range mission and a typical range mission” recited earlier in the claim
Claim 9 recites the limitation "the plurality of engines". There is insufficient antecedent basis for this limitation in the claim.
Claim 10 recites the limitation " the stored quantity of non-cryogenic fuel". There is insufficient antecedent basis for this limitation in the claim.
Above is a non-exhaustive list of 112 issues found within the claims, additional 112 issues may be present and not listed, Applicant’s assistance in identifying issues and addressing them is respectfully requested.
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-2, 4, 6-7, 9-10, 13-17, 19-21 are rejected under 35 U.S.C. 103 as being unpatentable over Swann 20220316410 in view of Kamath 20150321767, Kawai 20160076461 and Schwarzer 20110101166
Regarding claim 1, Swann teaches:
An aircraft (Title; aircraft (abstract); aircraft propulsion system enters air [0011]) comprising:
an aerodynamic structure having an overall geometry and design weights (inter alia, aircraft (Abstract) has fuselage) configured to fly (aircraft propulsion system enters air [0011]) at least a design long range mission (a long range [0003]) burning non-cryogenic fuel (“an engine system capable of producing thrust by: an engine system capable of producing thrust by: [0008] (i) combusting hydrocarbon fuel; (i) combusting hydrocarbon fuel” [0007-0008]) and a typical range mission, wherein the typical range mission comprises a Block mission segment (flights not requiring a long range [0003]) burning cryogenic fuel (the aircraft propulsion system is capable of burning cryogenic fuel [0004, 0006, 0026, 0091], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]) and an Alternate mission segment (Alternate is known in the art as part of mission planning) burning non-cryogenic fuel (In accordance with the present invention, a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, [0055]), wherein the typical range Block mission segment is shorter in distance than the design long range Block mission segment (flights not requiring a long range [0003]) and the distance ratio between the typical range Block mission and the design long range Block mission segment is between 0.2 and 0.5 ( Swann teaches “For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; Swann is silent about a ratio of typical range mission to design long range mission is between 0.2 and 0.5. However, “the ratio between the typical range mission and the design long range mission” was recognized as a result-effective variable, i.e., a variable which achieves a recognized result, in the prior art, in this case the ratio of typical range mission to design long range mission is between 0.2 and 0.5 depending on sizing and capacity ratios between the different tanks, such that the determination of the optimum or workable ranges of said variable, in this case the ratio between the quantity of the different types of fuel that would allow flights with ranges between 0.2 to 0.5 of the design long range mission, may have been characterized as routine experimentation; it is noted that the claimed range of 0.2 to 0.5 discussed above is not further supported by in the application with any indication that the claimed range leads to any unexpected results. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B). Where the general conditions of a claim are disclosed in the prior art, in this case adjusting the fuel capacities on a flight -by-flight or seasonal basis [0092], it has been held that the discovery of optimum or workable ranges, in this case a range ratio between 0.2 and 0.5, by experimentation requiring only routine skill in the art, in this case the ability to adjust capacities, would have been an obvious extension of prior art teachings. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); MPEP 2144.05(II)(A).
engines carried by the aerodynamic structure capable of burning non-cryogenic fuel and cryogenic fuel (“An aircraft propulsion system includes a hydrocarbon fuel store, a hydrogen fuel store, an engine system capable of producing thrust by combusting hydrocarbon fuel and/or combusting or oxidising hydrogen fuel”, abstract)
at least one cryogenic fuel tank housed within the aircraft the aerodynamic structure (“An aircraft propulsion system includes […] a hydrogen fuel store”, abstract; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), the at least one cryogenic fuel tank having a volumetric capacity sized to store sufficient cryogenic fuel to fuel the engines to propel the aircraft for the typical range Block mission segment, excluding reserves for the Alternate mission segment (““For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003]), the designed volumetric capacity sizing of the at least one cryogenic fuel tank being smaller than a size that would be required for cryogenically fueling the aircraft to propel the aircraft for a mission that includes the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for Alternate segment (Dual-fuel aircraft have therefore been proposed which use both hydrogen fuel and hydrocarbon fuel (typically kerosene) in order to allow the range of an aircraft to be extended beyond that achievable using hydrogen fuel alone [0003], and it is noted that [0003] as a whole teaches the relationship between tank size and range, and presents pros and cons to be considered when the different types of fuels are used; and “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092] “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], and reserves are known in the art to be used to reach alternates and/or give the flight crew options during the flight); wherein the volumetric capacity of the cryogenic fuel tank is sized without accounting for the Alternate mission segment regulatory reserve requirements of the aircraft (Also see rejection under 112a; Swann teaches “x, 1−x of the total fuel energy flow rate Ė being represented by the hydrocarbon and hydrogen fuel energy flow rates respectively […] a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, rather than the aircraft's entire store of hydrocarbon being completely exhausted, so that the fraction x may be varied between zero and unity during any part of a flight mission, rather than only during the first portion of the flight mission. In the case of an aircraft which can in principle be powered solely by hydrogen, a relatively small store of hydrocarbon fuel may be carried on board, so that hydrocarbon or a combination of hydrocarbon and hydrogen may be combusted during parts of a flight mission in order to reduce total RF and/or ERF (or more generally climate warming impact) caused by the flight mission. Such an aircraft requires an engine system capable of utilising hydrocarbon fuel, and a combination of hydrocarbon fuel and hydrogen fuel, as well as hydrogen fuel alone” [0055]);
plural non-cryogenic fuel tanks housed within the aircraft aerodynamic structure (“An aircraft propulsion system includes a hydrocarbon fuel store”, abstract; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), the plural non-cryogenic fuel tanks configured to store a quantity of non-cryogenic fuel as a secondary fuel source for the aircraft (“An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]”;), for the purposes of Pure non- cryogenic fuel missions, range extension, and reserves for Alternate mission segment (MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim)
a controller on board the aircraft configured to selectively control fuel flow from the at least one cryogenic fuel tank and the plural non-cryogenic fuel tanks to the engines (a control system arranged to control the respective flow rates of hydrocarbon fuel and hydrogen fuel within the conveying system [0010]), the controller configured to supply the cryogenic fuel is-to the engines as a main fuel that will normally be used by the engines to propel the aircraft during the typical range Block mission segment, the controller being further configured to reserve the non-cryogenic fuel as a reserve or range extending fuel, which the controller is configured to provide to the engines to propel the aircraft on an exception basis such as for airports where there is no cryogenic fuel availability, or missions that exceed the distance of the typical range mission plus reserves (“so that the fraction x may be varied between zero and unity during any part of a flight mission” [0055] shows the controller can be configured to use each type of fuel and any combination at any portion of the flight and “an engine system capable of utilising hydrocarbon fuel, and a combination of hydrocarbon fuel and hydrogen fuel, as well as hydrogen fuel alone” [0055], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]; furthermore classifying fuel as either “main” or “reserve or range extending”, or airports where there is no cryogenic fuel availability, amounts to simple nomenclature of renaming the fuels and/or amounts or use, to simply their intended uses, for which MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim; Swann).,
wherein the at least one cryogenic fuel tank and the plural non-cryogenic fuel tanks are volumetrically configured to together enable the aircraft to be adequately fueled to fly the design long range mission without running out of fuel, while enabling the controller to control the engines to prioritize the utilization of the cryogenic fuel to propel the aircraft in normal flight during the typical range Block mission segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; furthermore MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim)
Swann is silent about:
a venting system configured to monitor temperature and pressure of the cryogenic fuel stored by the at least one cryogenic fuel tank and provide controlled venting of the at least one cryogenic fuel tank to the atmosphere to avoid excessive pressure buildup within the at least one cryogenic fuel tank as the cryogenic fuel contained by the at least one cryogenic fuel tank boils off;
However Kamath teaches:
a venting system configured to monitor temperature and pressure of the cryogenic fuel stored by the at least one cryogenic fuel tank and provide controlled venting of the at least one cryogenic fuel tank to the atmosphere to avoid excessive pressure buildup within the at least one cryogenic fuel tank as the cryogenic fuel contained by the at least one cryogenic fuel tank boils off (“The fuel storage system 10 may further comprise a safety release system 45 adapted to vent any high pressure gases that may be formed in the cryogenic fuel tank 22” [0047], and “An LNG tank with one or more vent lines 41 for removal of gaseous natural gas, formed by the absorption of heat from the external environment” [0059]).
It would have been obvious to a person having ordinary skills in the art before the effective filing date of the claimed invention to provide Swann with Kamath's structure discussed above in order to “release any high pressure gases in the event of an over pressure inside the fuel tank” [0047].
Swann in view of Kamath is silent about:
and to provide motive flow for engine variable inlet guide vanes actuation and/or engine oil cooling without consuming the stored quantity of non-cryogenic fuel
However, Kawai teaches a dual fuel gas turbine (title), and :
and to provide motive flow for engine variable inlet guide vanes actuation and/or engine oil cooling (the fuels may be used for ancillary purposes such as oil cooling or providing hydraulic pressure in the engine. For example, the fuel may pass through an oil cooler and/or through a hydraulic system before going to fuel nozzles in the gas turbine engine [0013]) without consuming the stored quantity of non-cryogenic fuel (the tanks in Kawai do not consume he stored fuel)
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath with Kawai’s structure as discussed above in order to provide “the liquid fuel to satisfy the ancillary systems, such as oil cooling and/or engine hydraulic pressure” (Kawai [0014]) since “[cryogenic] fuels may not be able to provide oil cooling or hydraulic pressure” as taught by Kawai [0013].
Swan teaches a dual fuel system and “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], indicating that the non-cryogenic fuel may meet the reserve requirements, but Swann in view of Kamath and Kawai, as discussed so far, does not explicitly teach:
the non-cryogenic fuel tanks are sized to independently satisfy at least said Alternate mission segment regulatory reserve requirements
However, Schwarze teaches:
airports where there is no cryogenic fuel availability (a further optimization parameter may be to consider the availability of various fuel types at origin and destination airports [0016]; this was already discussed above, but Schwarze provides additional teachings)
wherein the non-cryogenic fuel tanks are sized to independently satisfy at least said Alternate mission segment regulatory reserve requirements ([0023] Through skilled control of the fuel supply, a significant performance advantage over the entire mission may thus be achieved with exploitation of the various mass-specific energies of the fuels. This advantage may be even greater independently thereof if a specific component of the fuels is not used during the mission, for example, if it is intended for a following mission or provided as a reserve); and
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath and Kawai with the teachings of Schwarze in order to take “several different optimization parameters […] into consideration, according to which the supply with multiple fuels may be optimized” as taught by Schwarze [0012]. Furthermore, this portion of the claim describes intended use, and a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim.
Swann in view of Kamath, Kawai and Schwarze teaches the controller being further configured to reserve the non-cryogenic fuel as a reserve or range extending fuel, which the controller is configured to provide to the engines to propel the aircraft on an exception basis such as for airports where there is no cryogenic fuel availability, or missions that exceed the distance of the typical range mission plus reserves, as already discussed above. However, to clear any doubt, Scharzer also teaches:
the controller (“a conveying system to convey hydrocarbon and hydrogen fuel from the fuel stores to the engine system and a control system to control the respective flow rates of the fuel within the conveying system”, Abstract) being further configured to reserve the non-cryogenic fuel as a reserve or range extending fuel, which the controller is configured to provide to the engines to propel the aircraft on an exception basis such as for airports where there is no cryogenic fuel availability, or missions that exceed the distance of the typical range mission plus reserves (“a conveying system to convey hydrocarbon and hydrogen fuel from the fuel stores to the engine system and a control system to control the respective flow rates of the fuel within the conveying system” […] “a reserve of hydrocarbon fuel is entirely combusted before any of a reserve of hydrogen fuel, Abstract, “In accordance with the present invention, a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055])
Regarding claim 2, Swann in view of Kamath, Kawai and Schwarze teaches the invention of claim 1. Swann further teaches:
the controller ([0010]) is configured to control provisioning of the non-cryogenic fuel to the engines ([0010]) as:
an amount of reserve or range extending fuel (“a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve,” Swann [0055], and “a dual-fuel propulsion system for providing an aircraft comprising the system 100 with a range which is extended beyond that achievable using hydrogen fuel only stored in tank 112” [0058] and “may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058] and “the hydrocarbon fuel thus serves an additional purpose, beyond enabling range-extension” [0064]; the use of cryogenic fuel or a combination of fuels is also taught on [0003]),
Swann in view of Kamath and Kawai does not teach the reserve or range extending fuel being specifically defined based on regulatory requirements as claimed.
However, Schwarze teaches:
an amount of which complies with regulatory requirements to allow the aircraft to change destination airport from an initially scheduled destination airport and another destination airport different from the initially scheduled destination airport (Schwarze teaches a control unit that controls multiple types of fuel according to different requirements and parameters [0024] and different factors as optimization parameters, including: art of regulatory requirements to allow the aircraft to change destination from a first airport and another airport different from the first airport (Schwarze “fuel is not yet permitted for specific flight phases in specific countries” Schwarze [0017]; examiner’s note: Schwarze use of the allowed type of fuel, enables to aircraft to proceed to another airport/location where other types of fuel are allowed);
Regarding claim 4, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed claim 1. Swann further teaches:
the controller is configured to control the engines to uses the non- cryogenic fuel and the cryogenic fuel independently or in conjunction to provide energy to propel the aircraft in flight ([0055], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]).
Regarding claim 6, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 1. Swann in view of Kamath, Kawai and Schwarze is silent about using the cryogenic fuel as claimed.
However, Kamath teaches:
the aircraft is further configured to use a cryogenic fuel (Kamath Fig 8 and paragraph [0084] “LNG”) to cool the non-cryogenic fuel or to thereby keep non-cryogenic fuel temperatures down in order to reduce non-cryogenic fuel vapor flammability (Fig 8 and paragraph [0084] “Fuel-to-fuel Cooler (FFC) 504 for heat exchange between gasified LNG and the jet fuel”; Fig 8 shows a “return to Aircraft Tank 524” line on the left side of the image; “to transfer heat between the first fuel in the first fuel system and the second fuel in the second fuel system […] and/or from jet fuel to gasified LNG at high LNG % demand” [0087], [0092]). The recitation “in order to reduce non-cryogenic fuel vapor flammability” simply states an intended purpose and amounts to a statement of intended use or desired result, for which MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim. In this case, the prior art teaches all the structural limitations of the claims as mapped and discussed as well as heat being transferred between jet fuel and LNG (Kamath [0084, 0087, 0092]) with the clear purpose of ”controlling fluid temperatures in an aircraft utilizing dual fuels” (Kamath [0092]), the system being capable of achieving the claimed intended uses and desired results; thus teaching all the structural requirements of the claim.
Regarding claim 7, Swann in view of Kamath, Kawai and Schwarze teaches the invention ad discussed for claim 1. Swann in view of Kamath, Kawai and Schwarze is silent about:
The controller is further configured to use the non-cryogenic fuel to heat the cryogenic fuel before the cryogenic fuel enters the engines
However, Kamath teaches:
the controller is further configured to use a non-cryogenic fuel to heat a cryogenic fuel before the cryogenic fuel enters the engines (Kamath Claim 1, where ‘first fuel’ is jet fuel [0084] and ‘second fuel’ is LNG [0084]).
Regarding claim 9, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 1. Swann further teaches:
Wherein the controller is further configured to switch the plurality of engines individually (Swann [0025]; and Fig 1 shows an individual engine and a dedicated controller 130; [0087]) between cryogenic fuel and the non-cryogenic fuel during flight ([0010-0025, 0068]).
Regarding claim 10, See 112(a) rejection above. Swann teaches:
A method of operating an aircraft designed and configured to fly a design long range mission (Title; aircraft [0073]; aircraft propulsion system enters air [0011]) and a typical range mission, the method comprising:
configuring aircraft aerodynamic structure overall geometry and design weights (aircraft (abstract) has fuselage) as a function of both a design long range mission (a long range [0003]) burning non-cryogenic fuel (“an engine system capable of producing thrust by: an engine system capable of producing thrust by: [0008] (i) combusting hydrocarbon fuel; (i) combusting hydrocarbon fuel” [0007-0008]) and a typical range mission, wherein the typical mission comprises a Block mission segment (flights not requiring a long range [0003]) burning cryogenic fuel (the aircraft propulsion system is capable of burning cryogenic fuel [0004, 0006, 0026, 0091], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]) and an Alternate mission segment (Alternate is known in the art as part of mission planning) burning non-cryogenic fuel (In accordance with the present invention, a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, [0055]), wherein the typical range Block mission segment is shorter in distance than the design long range Block mission segment (flights not requiring a long range [0003]) and the distance ratio between the typical range Block mission segment and the design long range Block mission segment is between 0.2 and 0.5 ( Swann teaches “For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; Swann is silent about a ratio of typical range mission to design long range mission is between 0.2 and 0.5. However, “the ratio between the typical range mission and the design long range mission” was recognized as a result-effective variable, i.e., a variable which achieves a recognized result, in the prior art, in this case the ratio of typical range mission to design long range mission is between 0.2 and 0.5 depending on sizing and capacity ratios between the different tanks, such that the determination of the optimum or workable ranges of said variable, in this case the ratio between the quantity of the different types of fuel that would allow flights with ranges between 0.2 to 0.5 of the design long range mission, may have been characterized as routine experimentation; it is noted that the claimed range of 0.2 to 0.5 discussed above is not further supported by in the application with any indication that the claimed range leads to any unexpected results. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B). Where the general conditions of a claim are disclosed in the prior art, in this case adjusting the fuel capacities on a flight -by-flight or seasonal basis [0092], it has been held that the discovery of optimum or workable ranges, in this case a range ratio between 0.2 and 0.5, by experimentation requiring only routine skill in the art, in this case the ability to adjust capacities, would have been an obvious extension of prior art teachings. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); MPEP 2144.05(II)(A).;
provisioning at least one cryogenic fuel tank housed within the aircraft aerodynamic structure to store cryogenic fuel (“An aircraft propulsion system includes […] a hydrogen fuel store”, abstract; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), including volumetrically sizing cryogenic fuel storage capacity of the at least one cryogenic fuel tank for a typical range Block mission segment excluding reserves for the Alternate segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003]), the volumetrically sizing of the storage amount comprising volumetrically sizing cryogenic fuel storage amount of the at least one cryogenic fuel tank to be smaller than an amount required for cryogenically fueling the aircraft for a mission that includes the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for the Alternate segment (Dual-fuel aircraft have therefore been proposed which use both hydrogen fuel and hydrocarbon fuel (typically kerosene) in order to allow the range of an aircraft to be extended beyond that achievable using hydrogen fuel alone [0003], and it is noted that [0003] as a whole teaches the relationship between tank size and range, and presents pros and cons to be considered when the different types of fuels are used; and “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092] “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], and reserves are known in the art to be used to reach alternates and/or give the flight crew options during the flight); wherein the volumetric capacity of the cryogenic fuel tank is sized without accounting for the Alternate mission segment regulatory reserve requirements of the aircraft (Also see rejection under 112a; Swann teaches “x, 1−x of the total fuel energy flow rate Ė being represented by the hydrocarbon and hydrogen fuel energy flow rates respectively […] a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, rather than the aircraft's entire store of hydrocarbon being completely exhausted, so that the fraction x may be varied between zero and unity during any part of a flight mission, rather than only during the first portion of the flight mission. In the case of an aircraft which can in principle be powered solely by hydrogen, a relatively small store of hydrocarbon fuel may be carried on board, so that hydrocarbon or a combination of hydrocarbon and hydrogen may be combusted during parts of a flight mission in order to reduce total RF and/or ERF (or more generally climate warming impact) caused by the flight mission. Such an aircraft requires an engine system capable of utilising hydrocarbon fuel, and a combination of hydrocarbon fuel and hydrogen fuel, as well as hydrogen fuel alone” [0055]);
provisioning plural non-cryogenic fuel tanks housed within the aircraftsecondary fuel source for the aircraft (“An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]”; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), for the purposes of Pure non-cryogenic fuel missions, range extension, and reserves for Alternate mission segment (MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim),
the at least one cryogenic fuel tank and the plural non-cryogenic fuel tanks being volumetrically configured to together enable the aircraft to be adequately fueled to fly the design long range mission without running out of fuel, while enabling the engines to prioritize the utilization of cryogenic fuel to propel the aircraft in normal flight during the typical range Block mission segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; furthermore MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim);
configuring the aircraft to selectively route non-cryogenic fuel or cryogenic fuel to engines ([0010]), including routing the cryogenic fuel from the at least one cryogenic fuel tank to the engines as a main fuel to propel the aircraft during the typical range Block mission segment, and reserving the non-cryogenic fuel as a reserve or range extending fuel for routing to the engines on an exception basis such as for airports where there is no cryogenic fuel availability, or missions that exceed the distance of the typical range Block mission segment plus reserves for the Alternate segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; “so that the fraction x may be varied between zero and unity during any part of a flight mission” [0055] shows the controller can be configured to use each type of fuel and any combination at any portion of the flight and “an engine system capable of utilising hydrocarbon fuel, and a combination of hydrocarbon fuel and hydrogen fuel, as well as hydrogen fuel alone” [0055], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]; furthermore classifying fuel as either “main” or “reserve or range extending”, or airports where there is no cryogenic fuel availability, amounts to simple nomenclature of renaming the fuels and/or amounts or use, to simply their intended uses, for which MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim)
Swann is silent about:
monitoring temperature and pressure of the cryogenic fuel stored by the at least one cryogenic fuel tank and providing controlled venting of the at least one cryogenic fuel tank to the atmosphere to avoid excessive pressure buildup within the at least one cryogenic fuel tank as the cryogenic fuel contained by the at least one cryogenic fuel tank boils off;
However Kamath teaches:
monitoring temperature and pressure of the cryogenic fuel stored by the at least one cryogenic fuel tank and providing controlled venting of the at least one cryogenic fuel tank to the atmosphere to avoid excessive pressure buildup within the at least one cryogenic fuel tank as the cryogenic fuel contained by the at least one cryogenic fuel tank boils off (“The fuel storage system 10 may further comprise a safety release system 45 adapted to vent any high pressure gases that may be formed in the cryogenic fuel tank 22” [0047], and “An LNG tank with one or more vent lines 41 for removal of gaseous natural gas, formed by the absorption of heat from the external environment” [0059]).
It would have been obvious to a person having ordinary skills in the art before the effective filing date of the claimed invention to provide Swann with Kamath's structure discussed above in order to “release any high pressure gases in the event of an over pressure inside the fuel tank” [0047].
Swann in view of Kamath is silent about:
and to provide motive flow for engine variable inlet guide vanes actuation and/or engine oil cooling without consuming the stored quantity of non-cryogenic fuel
However, Kawai teaches a dual fuel gas turbine (title), and:
and to provide motive flow for engine variable inlet guide vanes actuation and/or engine oil cooling (the fuels may be used for ancillary purposes such as oil cooling or providing hydraulic pressure in the engine. For example, the fuel may pass through an oil cooler and/or through a hydraulic system before going to fuel nozzles in the gas turbine engine [0013]) without consuming the stored quantity of non-cryogenic fuel (the tanks in Kawai do not consume he stored fuel)
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath with Kawai’s structure as discussed above in order to provide “the liquid fuel to satisfy the ancillary systems, such as oil cooling and/or engine hydraulic pressure” (Kawai [0014]) since “[cryogenic] fuels may not be able to provide oil cooling or hydraulic pressure” as taught by Kawai [0013].
Swann teaches a dual fuel system and “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], indicating that the non-cryogenic fuel may meet the reserve requirements, but Swann in view of Kamath and Kawai, as discussed so far, does not explicitly teach:
wherein the non-cryogenic fuel tanks are dimensioned to independently satisfy at least said Alternate mission segment regulatory reserve requirements
However, Schwarze teaches:
airports where there is no cryogenic fuel availability (a further optimization parameter may be to consider the availability of various fuel types at origin and destination airports [0016]; this was already discussed above, but Schwarze provides additional teachings)
wherein the non-cryogenic fuel tanks are sized to independently satisfy at least said Alternate mission segment regulatory reserve requirements ([0023] Through skilled control of the fuel supply, a significant performance advantage over the entire mission may thus be achieved with exploitation of the various mass-specific energies of the fuels. This advantage may be even greater independently thereof if a specific component of the fuels is not used during the mission, for example, if it is intended for a following mission or provided as a reserve); and
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath and Kawai with the teachings of Schwarze in order to take “several different optimization parameters […] into consideration, according to which the supply with multiple fuels may be optimized” as taught by Schwarze [0012]. Furthermore, this portion of the claim describes intended use, and a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim.
Regarding claim 13, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 10. Swann further teaches:
using the non-cryogenic fuel and the cryogenic fuel independently or in conjunction to provide energy for the engine to propel the aircraft in flight ([0055]).
Regarding claim 14, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 10.
Swann in view of Kawai, as discussed so far, is silent about
using the non-cryogenic fuel as a motive or cooling fluid at all flight phases, when the cryogenic fuel is the only fuel the engines are consuming
However, Kawai teaches:
using the non-cryogenic fuel (“liquid fuel”) as a motive or cooling fluid at all flight phases, when the cryogenic fuel (“gaseous fuel”) is the only fuel the engines are consuming (Kawai [0013-0014]).
Regarding claim 15, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 10.
Swann in view of Kamath, Kawai and Schwarze is silent about using the cryogenic fuel as claimed.
using cryogenic fuel to cool or keep non-cryogenic fuel temperatures down in the plural non-cryogenic fuel temperatures down in order to reduce non-cryogenic fuel vapor flammability
However, Kamath teaches:
using cryogenic fuel (Kamath Fig 8 and paragraph [0084] “LNG”) to cool or keep non-cryogenic fuel temperatures down in the plural non-cryogenic fuel temperatures down in order to reduce non-cryogenic fuel vapor flammability (Fig 8 and paragraph [0084] “Fuel-to-fuel Cooler (FFC) 504 for heat exchange between gasified LNG and the jet fuel”; Fig 8 shows a “return to Aircraft Tank 524” line on the left side of the image; “to transfer heat between the first fuel in the first fuel system and the second fuel in the second fuel system […] and/or from jet fuel to gasified LNG at high LNG % demand” [0087], [0092]). The recitation “in order to reduce non-cryogenic fuel vapor flammability” simply states an intended purpose and amounts to a statement of intended use or desired result, for which MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim. In this case, the prior art teaches all the structural limitations of the claims as mapped and discussed as well as heat being transferred between jet fuel and LNG (Kamath [0084, 0087, 0092]) with the clear purpose of ”controlling fluid temperatures in an aircraft utilizing dual fuels” (Kamath [0092]), the system being capable of achieving the claimed intended uses and desired results; thus teaching all the structural requirements of the claim.
Regarding claim 16, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 10. Swann in view of Kamath, Kawai and Schwarze is silent about:
using the non-cryogenic fuel to heat the cryogenic fuel before the cryogenic fuel enters the engines
However, Kamath teaches:
using the non-cryogenic fuel to heat the cryogenic fuel before the cryogenic fuel enters the engines (Kamath Claim 1, where ‘first fuel’ is jet fuel [0084] and ‘second fuel’ is LNG [0084]).
Regarding claim 17, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 10. Swann further teaches:
Switching between the cryogenic fuel and the non-cryogenic fuel to supply to each of the engines individually (Swann [0025]; and Fig 1 shows an individual engine and dedicated controller 130; see Swann [0087]).
Regarding claim 19, Swann teaches:
An aircraft configured to fly a design long range mission (Title; aircraft (abstract); aircraft propulsion system enters air [0011]), the aircraft including an engine (abstract), the aircraft comprising:
aerodynamic structure overall geometry and design weights (inter alia, aircraft (Abstract) has fuselage) configured as a function of both the design long range mission (a long range [0003]) burning non-cryogenic fuel (“an engine system capable of producing thrust by: an engine system capable of producing thrust by: [0008] (i) combusting hydrocarbon fuel; (i) combusting hydrocarbon fuel” [0007-0008]) and a typical range mission (flights not requiring a long range [0003]), wherein the typical range mission comprises a Block mission segment burning cryogenic fuel (the aircraft propulsion system is capable of burning cryogenic fuel [0004, 0006, 0026, 0091], “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058]) and an Alternate mission (Alternate is known in the art as part of mission planning) segment burning non-cryogenic fuel (In accordance with the present invention, a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, [0055]), wherein the typical range Block mission segment is shorter in distance than a design long range Block mission segment (flights not requiring a long range [0003]) and the distance ratio between the typical range Block mission segment and the design long range Block mission segment is between 0.2 and 0.5 ( Swann teaches “For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092]; Swann is silent about a ratio of typical range mission to design long range mission is between 0.2 and 0.5. However, “the ratio between the typical range mission and the design long range mission” was recognized as a result-effective variable, i.e., a variable which achieves a recognized result, in the prior art, in this case the ratio of typical range mission to design long range mission is between 0.2 and 0.5 depending on sizing and capacity ratios between the different tanks, such that the determination of the optimum or workable ranges of said variable, in this case the ratio between the quantity of the different types of fuel that would allow flights with ranges between 0.2 to 0.5 of the design long range mission, may have been characterized as routine experimentation; it is noted that the claimed range of 0.2 to 0.5 discussed above is not further supported by in the application with any indication that the claimed range leads to any unexpected results. In re Antonie, 559 F.2d 618, 195 USPQ 6 (CCPA 1977); MPEP 2144.05(II)(B). Where the general conditions of a claim are disclosed in the prior art, in this case adjusting the fuel capacities on a flight -by-flight or seasonal basis [0092], it has been held that the discovery of optimum or workable ranges, in this case a range ratio between 0.2 and 0.5, by experimentation requiring only routine skill in the art, in this case the ability to adjust capacities, would have been an obvious extension of prior art teachings. In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955); MPEP 2144.05(II)(A).
disposed within the aerodynamic structure, a first fuel tank means for storing a quantity of cryogenic fuel on board the aircraft (“An aircraft propulsion system includes […] a hydrogen fuel store”, abstract; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), the first fuel tank means having a volumetric capacity sized to store sufficient cryogenic fuel to provide thrust to fly the aircraft for a typical range Block mission segment excluding reserves for the Alternate segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003]), the first fuel tank means being volumetrically sized to be smaller than a size that would be required to store sufficient cryogenic fuel for cryogenically fueling the aircraft to provide thrust to fly the aircraft for a mission that includes the distance of the typical range Block mission segment and an additional portion of the design long range Block mission segment to exceed the distance of the typical range Block mission segment plus reserves for the Alternate segment (Dual-fuel aircraft have therefore been proposed which use both hydrogen fuel and hydrocarbon fuel (typically kerosene) in order to allow the range of an aircraft to be extended beyond that achievable using hydrogen fuel alone [0003], and it is noted that [0003] as a whole teaches the relationship between tank size and range, and presents pros and cons to be considered when the different types of fuels are used; and “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092] “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], and reserves are known in the art to be used to reach alternates and/or give the flight crew options during the flight); wherein the volumetric capacity of the cryogenic fuel tank is sized without accounting for the Alternate mission segment regulatory reserve requirements of the aircraft (Also see rejection under 112a; Swann teaches “x, 1−x of the total fuel energy flow rate Ė being represented by the hydrocarbon and hydrogen fuel energy flow rates respectively […] a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve, rather than the aircraft's entire store of hydrocarbon being completely exhausted, so that the fraction x may be varied between zero and unity during any part of a flight mission, rather than only during the first portion of the flight mission. In the case of an aircraft which can in principle be powered solely by hydrogen, a relatively small store of hydrocarbon fuel may be carried on board, so that hydrocarbon or a combination of hydrocarbon and hydrogen may be combusted during parts of a flight mission in order to reduce total RF and/or ERF (or more generally climate warming impact) caused by the flight mission. Such an aircraft requires an engine system capable of utilising hydrocarbon fuel, and a combination of hydrocarbon fuel and hydrogen fuel, as well as hydrogen fuel alone” [0055]);
disposed within the aerodynamic structure, a second fuel tank means for storing non- cryogenic fuel on board the aircraft (“An aircraft propulsion system includes […] a hydrocarbon fuel store”, abstract; one of ordinary skill would plan for fuel tanks to be within the aircraft due to aerodynamic reasons), the second fuel tank means for storing a quantity of non- cryogenic fuel as a secondary fuel source for the aircraft (“an engine system capable of producing thrust by: an engine system capable of producing thrust by: [0008] (i) combusting hydrocarbon fuel; (i) combusting hydrocarbon fuel” [0007-0008] “the system 100 may operate throughout a flight mission fueled by hydrocarbon fuel only or hydrogen fuel only or a combination of both hydrocarbon fuel and hydrogen fuel” [0058], “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055]), for the purposes of Pure non- cryogenic fuel missions, range extension, and reserves for Alternate mission segment (MPEP2114(II) provides that the intended use does not differentiate the claimed apparatus from a prior art apparatus if the prior art apparatus teaches all the structural limitations of the claim),
a controller on board the aircraft configured to supply the engine with the cryogenic fuel from the first fuel tank means to consume and burn (a control system arranged to control the respective flow rates of hydrocarbon fuel and hydrogen fuel within the conveying system [0010]) to propel the aircraft (Title) for the typical range Block mission segment without supplying the engine with the non-cryogenic fuel from the second fuel tank means to consume and burn to propel the aircraft for the typical range Block mission segment (“For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092])
Swann is silent about:
a venting system configured to monitor temperature and pressure of the cryogenic fuel stored by the first fuel tank means and provide controlled venting of the first fuel tank means to the atmosphere to avoid excessive pressure buildup within the first fuel tank means as the cryogenic fuel contained by the first fuel tank means boils off;
However Kamath teaches:
a venting system configured to monitor temperature and pressure of the cryogenic fuel stored by the first fuel tank means and provide controlled venting of the first fuel tank means to the atmosphere to avoid excessive pressure buildup within the first fuel tank means as the cryogenic fuel contained by the first fuel tank means boils off (“The fuel storage system 10 may further comprise a safety release system 45 adapted to vent any high pressure gases that may be formed in the cryogenic fuel tank 22” [0047], and “An LNG tank with one or more vent lines 41 for removal of gaseous natural gas, formed by the absorption of heat from the external environment” [0059]).
It would have been obvious to a person having ordinary skills in the art before the effective filing date of the claimed invention to provide Swann with Kamath's structure discussed above in order to “release any high pressure gases in the event of an over pressure inside the fuel tank” [0047].
Swann in view of Kamath is silent about:
supplying the non-cryogenic fuel from the second fuel tank means to cool components of the engine and/or provide motive flow while the engine consumes and burns the cryogenic fuel for the typical range Block mission segment.
However, Kawai teaches a dual fuel gas turbine (title), and:
supplying the non-cryogenic fuel from the second fuel tank means to cool components of the engine and/or provide motive flow (the fuels may be used for ancillary purposes such as oil cooling or providing hydraulic pressure in the engine. For example, the fuel may pass through an oil cooler and/or through a hydraulic system before going to fuel nozzles in the gas turbine engine [0013]) while the engine consumes and burns the cryogenic fuel for the typical range Block mission segment. (the tanks in Kawai do not consume the stored fuel)
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath with Kawai’s structure as discussed above in order to provide “the liquid fuel to satisfy the ancillary systems, such as oil cooling and/or engine hydraulic pressure” (Kawai [0014]) since “[cryogenic] fuels may not be able to provide oil cooling or hydraulic pressure” as taught by Kawai [0013].
Swan teaches a dual fuel system and “a portion of the initial mass of hydrocarbon fuel in a dual-fuel aircraft is held in reserve” [0055], indicating that the non-cryogenic fuel may meet the reserve requirements, but Swann in view of Kamath and Kawai, as discussed so far, does not explicitly teach:
the non-cryogenic fuel tanks are sized to independently satisfy at least said Alternate mission segment regulatory reserve requirements
However, Schwarze teaches:
airports where there is no cryogenic fuel availability (a further optimization parameter may be to consider the availability of various fuel types at origin and destination airports [0016]; this was already discussed above, but Schwarze provides additional teachings)
wherein the non-cryogenic fuel tanks are sized to independently satisfy at least said Alternate mission segment regulatory reserve requirements ([0023] Through skilled control of the fuel supply, a significant performance advantage over the entire mission may thus be achieved with exploitation of the various mass-specific energies of the fuels. This advantage may be even greater independently thereof if a specific component of the fuels is not used during the mission, for example, if it is intended for a following mission or provided as a reserve); and
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Swann in view of Kamath and Kawai with the teachings of Schwarze in order to take “several different optimization parameters […] into consideration, according to which the supply with multiple fuels may be optimized” as taught by Schwarze [0012]. Furthermore, this portion of the claim describes intended use, and a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim.
Regarding claim 20, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 19. Swann further teaches:
the cryogenic fuel comprises hydrogen ([0003]) and the noncryogenic fuel comprises fossil fuel (Kerosene, [0003]).
Regarding claim 21, Swann in view of Kamath, Kawai and Schwarze teaches the invention as discussed for claim 20. Swann further teaches:
the aircraft further comprises a further engine ([0087, 0088] Figs. 2, 3), configured to consume the same one of the cryogenic fuel or the non cryogenic fuel as the first mentioned engine (two separate turboprop engines 222A, 222B, each including a respective propeller, and each of which may combust hydrocarbon only, hydrogen only or a combination of both hydrocarbon or hydrogen within a combustion arrangement described above in relation to the turbofan engine 122 of the system 100.0087]).
Response to Arguments/Remarks
Applicant’s arguments have been considered, but they are not persuasive because they do not apply to the new combination of references, i.e., adding a new reference to the old combination of references, that was necessitated by applicant’s amendment. However, to the extent possible, applicant’s arguments have been addressed in the body of the rejections above, at the appropriate location.
The combination of the references, as discussed in the rejection, provides the structure that meets all the claimed limitations.
Applicant argues on page 9:
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Examiner’s response: Examiner respectfully disagrees, Figure 7 of the present application appears to indicate cryogenic fuel can bee used in step 510:
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Applicant argues on pages 10-11:
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Examiner’s response: The examiner respectfully disagrees with the arguments above, the Prior art teaches an apparatus that meets the limitations, and “should only be carried if the corresponding hydrogen capacity is required”, as taught by Swann and mentioned in the remarks above, further support the idea of using smaller tanks. A decision to employ a fixed size of tanks in the design would be an engineering decision based on teachings discussed in the prior art, providing advantages and disadvantages that would be considered by the engineers, and others, when making such decision, understanding that tradeoffs such as limitations in using a particular type of fuel beyond certain ranges. Decisions about fuel tank sizes, independent of type of fuel, require similar analysis, an infinitely large tank would provide infinite range, but space and weight limitations would prevent such decision (and additional fuel weight requires additional energy/fuel to be spent to carry it). Swann teaches in its entirety the use of hydrocarbon fuel and hydrogen fuel “in order to reduce climate warming impact caused by at least one of carbon dioxide, water vapour and condensation trails and/or increase climate cooling impact caused by condensation trails produced by the aircraft propulsion system” (abstract), and the discussion above would not lead teach away from the invention.
Applicant argues on page 14:
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Examiner’s response: Examiner respectfully disagrees, Swann is used to teach, inter alia, Swann teaches “For flights not requiring a long range, an aircraft may run entirely or mostly on hydrogen” [0003], “An aircraft propulsion system of the invention preferably allows the capacity for stored hydrogen to be adjusted according to the ranges of flight missions which an aircraft comprising the system is required to carry out. For example, the hydrogen storage capacity of a system of the invention may be provided by a plurality of similar or identical removable tanks, allowing the number, and hence total capacity, of the tanks to be adjusted, for example on a flight-by-flight or seasonal basis” [0092], clearly teaching the use of hydrogen as the fuel for flights; Swann also teaches “However, hydrogen tanks are heavy, and should only be carried if the corresponding hydrogen capacity is required. On the other hand, hydrocarbon tanks are (in most cases) fairly light per unit of fuel energy, so having more hydrocarbon fuel-tank installed capacity than is necessary for the proposed flight does not incur a significant weight penalty” [0091], making it obvious some of the advantages and disadvantages of choosing each type of fuel for different uses/portions of a flight, and the advantages and disadvantages of using each type of fuel tank. A POSITA would make design and engineering decisions based on the prior art and take into account the obvious space and weight limitations present in any aircraft design. Schwarze is used, as discussed in the rejection, to teach that using hydrocarbon as a reserve fuel was known in the art. A POSITA would identify the above teachings, as discussed in the rejection, as guidance when making design decisions about tank sizing and capacity, and application of each type of fuel
It is not clear if the “adjust hydrocarbon tank capacity based on mission length” mentioned in the arguments above is being introduced by Applicant as the Applicant’s interpretation of the points discussed in the rejection, or if it was extracted from any particular document.
The examiner respectfully believes the responses above, and the information presented in the body of the rejection, address all the Applicant’s concerns presented in the remarks.
Correspondence
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/ROBERTO TOSHIHARU IGUE/Examiner, Art Unit 3741
/PHUTTHIWAT WONGWIAN/Supervisory Patent Examiner, Art Unit 3741
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