the preferred embodiments of the present invention will now be described with reference to fig1 - 4 of the drawings . identical elements in the various figures are designated with the same reference numerals . fig1 shows an embodiment of the invention in which frozen fuel is loaded onto the aircraft . frozen fuel 2 enters the frozen fuel supply chamber 4 through inlet 6 . a refrigeration system 8 maintains the proper temperature in frozen fuel supply chamber 4 via cooling ports 10 . the frozen fuel supply chamber is insulated with insulating material 12 . temperature and fuel phase , as well as other characteristics such as viscosity , are monitored within the frozen fuel chamber 4 by monitoring elements 14 which , in the case of temperature may be thermistor - based , thermocouple - based , or other technology , and in the case of phase monitoring may consist of optical density / turbidity monitoring , ultrasound monitoring to look for liquid / solid boundaries , or other monitoring apparatus and associated transducers . pre - flight , during aircraft fuel loading , frozen fuel intake port 16 is maintained in the open position . at all other times it is sealed . during flight , frozen fuel outlet port 18 is open , unless a threat of crash or accident exists , in which case it may be sealed . port 20 allows for the supply of refrigerant . the position of each of ports 16 , 18 , and 20 is monitored and controlled by fuel monitoring and control system 22 . the fuel monitoring and control system 22 also monitors the temperature and phase information from monitoring elements 14 , and uses this information to control refrigeration system 8 to maintain the proper temperature in frozen fuel supply chamber 4 . most of the fuel carried by the aircraft is maintained in the frozen state . the amount of liquid fuel is maintained at a minimum which , nevertheless , is sufficient to meet the demands of each segment of the flight . frozen fuel leaves the supply chamber 4 and passes through a cutting / shaping apparatus 24 . this may shave slices off of a bar of fuel , shave a ribbon off of a cylinder of fuel , or create pellets , blocks , strips or spheres of frozen fuel . the cut / shaped fuel is moved by frozen fuel transport system 26 which is controlled by control system 22 . the rate of transport is determined by throttle position , pilot settings and other variables . frozen fuel then passes to warming chamber 28 , where it is melted by warming system 30 . the warming system has access to the warming chamber via ports 31 . warm gases or liquid may be supplied to the warming system via port 32 . alternatively , the system may provide electrical warming via current passing through a resistive element or heating by electromagnetic energy . if necessary , the warming chamber may be sealed by closing inlet door 34 and outlet valve 36 . this chamber is insulated by insulating material 38 . the temperature and phase ( and possibly other characteristics ) within the chamber are monitored by elements 40 , which are analogous to but not necessarily the same type as elements 14 in the frozen fuel supply chamber 4 . the relative degree of opening of each of ports 32 and 34 and valve 36 is monitored and controlled by fuel monitoring and control system 22 . the fuel monitoring and control system 22 also monitors the temperature and phase information from monitoring elements 40 , and uses this information to control warming system 30 . liquified fuel leaves the warming chamber and passes successively through valve 36 and through fuel line 42 to fuel pump 44 . pressure and flow upstream and downstream from the fuel pump are monitored by sensors 46 and 48 , information from these sensors is monitored by fuel monitoring and control system 22 , which also controls the fuel pump 44 . the fuel then passes through fuel line 49 to the fuel filter 50 . to prevent clogging by ice or remaining frozen fuel , the filter is equipped with a warming system 52 , which is controlled by fuel monitoring and control system 22 . the warming system has access to the filter via ports 54 . warm gases or liquid may be supplied to the filter warming system 52 via port 56 . alternatively , this warming system may be electrically powered by an electric current passing through a resistive element or by electromagnetic energy . the position of port 56 is monitored and controlled by fuel monitoring and control system 22 . the liquid fuel then passes successively through fuel line 58 , and intake valve 60 into the liquid fuel reservoir 62 . pressure and flow within fuel line 58 are monitored by sensor 64 which sends information to fuel monitoring and control system 22 . the liquid fuel reservoir 62 is insulated by insulating material 64 . temperature and phase ( or other characteristics ) within this reservoir are monitored by elements 66 which are analogous but not necessarily the same as elements 14 . these elements send their information to fuel monitoring and control system 22 . access to this reservoir is controlled by inlet valve 60 and outlet valve 74 . in the event of emergency such as impending crash , this chamber may be sealed by closing these valves . the positions of these valves are monitored and controlled by fuel monitoring and control system 22 . also , in the event of impending crash , the liquid fuel in reservoir 62 may be rapidly cooled or frozen by emergency refrigeration system 68 , which has access to the liquid fuel reservoir 62 by ports 72 . port 70 allows for the supply of refrigerant to emergency refrigeration system 68 . the emergency refrigeration system 68 is controlled and monitored by fuel monitoring and control system 22 . liquid fuel passes out of reservoir 62 through valve 74 into fuel line 76 , and flows through the fuel supply system that is in common use for the aircraft . fig2 shows an embodiment of the invention in which liquid fuel is loaded onto the aircraft . the liquid fuel is then frozen . liquid fuel enters the fuel freezing and supply chamber 3 after passing successively through intake pipe 5 and intake valve 15 . pre - flight , during aircraft fuel loading , intake valve 15 is maintained in the open position . at all other times it is closed . the position of intake valve 15 is monitored and controlled by fuel monitoring and control system 22 . after entering the fuel freezing and supply chamber 3 in liquid form , the fuel is frozen in this chamber by refrigeration system 8 . thereafter , chamber 3 serves as a frozen fuel supply chamber , analogous in function to the frozen fuel supply chamber 4 , described in fig1 . all other components and operations of fig2 are the same as those shown in fig1 . although fig1 and fig2 show a single fuel pump and filter , clearly multiple fuel pumps and / or fuel filters may be provided . fig3 shows an embodiment of the invention in which liquid fuel is loaded onto the aircraft . the liquid fuel is then chilled but not frozen . liquid fuel enters the chilled fuel reservoir 7 after passing successively through intake pipe 5 and intake valve 15 . a refrigeration system 8 maintains the proper temperature in the chilled fuel reservoir 7 via cooling ports 10 . pre - flight , during aircraft fuel loading , intake valve 15 is maintained in the open position . at all other times it is closed . during flight , chilled fuel reservoir outlet valve 17 is open , unless a threat of crash or accident exists , in which case it may be closed . the position of each of valves 15 and 17 is monitored and controlled by fuel monitoring and control system 22 . chilled , but not frozen fuel leaves the reservoir 7 and passes through valve 17 into fuel supply line 25 . it then is pumped by fuel pump 45 , after which it passes through another segment of fuel supply line 25 . pressure and flow may be monitored within each of supply lines 25 , and this information is supplied to fuel monitor and control system 22 . fuel then passes through warming chamber intake valve 33 and enters the warming chamber . it leaves this chamber through warming chamber outlet valve 36 . if necessary , this chamber may be sealed by closing valves 33 and 36 . the position of valves 33 and 36 is monitored and controlled by fuel monitoring and control system 22 . after passing through fuel line 42 , fuel pump 44 , fuel line 49 , fuel filter 50 and intake valve 60 , the warmed fuel enters warmed fuel reservoir 61 . all other components and operations of fig3 are the same as those shown in fig1 . whereas fig3 shows two fuel pumps and one filter , clearly a greater ( or lower ) number of pumps and / or a greater number of filters may be provided . fig4 shows an embodiment of the invention in which a first composition is added to the fuel in order to decrease its combustibility and , thereafter , a second composition is added to a portion of the fuel , as needed by the aircraft engine , to at least substantially restore it to its original combustibility . fuel enters the first composition mixing chamber and reservoir 1 through supply line 5 and inlet valve 15 . first composition enters chamber 1 through first composition supply lines 11 . the first composition is stored in reservoir 9 which is filled through inlet port 21 . the properties of the mixture of fuel and the first composition , including temperature , infrared , optical and ultraviolet spectroscopy and ultrasound reflection and transmission may be monitored by sensors and transducers 19 . pre - flight , during aircraft fuel loading , valve 15 is maintained in the open position . at all other times , it is closed . during flight , valve 13 is open , unless a threat of crash or accident exists , in which case it may be closed . supply port 21 allows for loading first composition into its reservoir 9 . the position of each of valves 13 and 15 and supply port 21 is monitored and controlled by fuel monitoring and control system 22 . the fuel monitoring and control system 22 also monitors the information from sensors 19 and uses this information to control the amount of first composition to be released from reservoir 9 through supply lines 11 into first composition mixing chamber and reservoir 1 . most of the fuel carried by the aircraft is maintained as a mixture with the first composition . chemically stabilized fuel leaves chamber 1 passes through outlet valve 13 and through fuel line 23 . it is then pumped by fuel pump 35 , into fuel line 27 , through valve 37 into second composition mixing chamber 43 . pressure and flow may be monitored in each of supply lines 23 and 27 , and this information is supplied to fuel monitoring and control system 22 . pump 35 is controlled by control system 22 . the flow rate is determined by throttle position , pilot settings and other variables . stabilized fuel is mixed with second composition to reverse the stabilizing effect of first composition . the mixing with second composition occurs in second composition mixing chamber 43 . second composition is stored in reservoir 39 which is filled through supply port 33 . second composition enters the second composition mixing chamber 43 , through inlet ports 29 . the properties and composition of the mixture in chamber 43 are monitored by sensors and transducers 41 , which operate in a manner analogous to sensors and transducers 19 . fuel monitoring and control system 22 monitors the information from these sensors 41 and uses the information to control the amount of second composition which is added . the positions of valves 37 and 36 are monitored and controlled by fuel monitoring and control system 22 . treated fuel leaves second composition mixing chamber 43 , passes through valve 36 and supply line 42 , is pumped by fuel pump 44 , enters fuel line 49 , and passes through the fuel filter 50 . the filter is linked to a filter cleaning system 53 , which either continuously and / or intermittently cleans and / or resupplies the filtering material . the filter cleaning system has access to the filter through ports 55 . filtering and cleaning agents may be supplied and removed through supply port 57 . an alternative to the addition of second composition to reverse the effect of first composition is to filter out the first composition . in such an embodiment , the second composition reservoir , mixing chamber and associated ports and valves would be eliminated , as would fuel pump 35 and its associated supply line . in this embodiment , treated fuel would pass directly from valve 13 and fuel line 23 to the fuel line 42 . in this embodiment , the first composition would be removed by fuel filter 50 . the pressure and flow rate within the fuel supply lines is monitored by sensors 46 , 48 , and 64 , which send information to the fuel monitoring and control system 22 . fuel leaves the filter 50 and passes through supply line 58 , through valve 60 into the fuel reservoir 63 . the temperature , composition and other properties of the fuel in this chamber are monitored by sensors and transducers 67 which are linked to fuel monitoring and control system 22 . at any time , only a minority of the fuel is maintained in fuel reservoir 63 , since the combustibility of this fuel is greater than that in first composition mixing chamber and reservoir 1 . fuel leaves reservoir 63 passes through valve 74 into fuel line 76 and flows through the fuel supply system that is in common use for the aircraft . whereas fig4 shows two fuel pumps and one filter , clearly a greater ( or lower ) number of pumps and / or a greater number of filters may be provided . in the event of anticipated crash , an additional supply of first composition is situated in reservoir 69 . it could be rapidly added to the fuel in reservoir 63 to stabilize it , through inlet ports 73 . first composition is supplied to reservoir 69 through supply port 71 . examples of both the first and the second chemical compositions are discussed above in the “ summary of the invention ”. such compositions are well known as evidenced by the various u . s . patents and publications , the following of which are incorporated herein by reference : u . s . pat . nos . 6 , 319 , 855 6 , 319 , 852 6 , 318 , 124 6 , 315 , 971 6 , 208 , 014 6 , 174 , 926 6 , 172 , 120 6 , 171 , 645 6 , 159 , 540 6 , 159 , 295 6 , 140 , 254 6 , 132 , 837 6 , 131 , 305 6 , 130 , 152 6 , 107 , 350 6 , 099 , 749 6 , 090 , 448 6 , 090 , 439 6 , 063 , 714 6 , 048 , 804 6 , 037 , 277 6 , 037 , 275 6 , 022 , 812 6 , 010 , 762 5 , 972 , 826 5 , 955 , 140 5 , 807 , 494 5 , 928 , 723 5 , 877 , 100 5 , 847 , 443 5 , 807 , 607 5 , 804 , 508 5 , 795 , 556 5 , 789 , 819 5 , 788 , 950 5 , 753 , 305 5 , 750 , 415 5 , 744 , 118 5 , 736 , 425 5 , 723 , 368 5 , 680 , 713 5 , 561 , 318 5 , 523 , 615 5 , 504 , 042 5 , 494 , 858 5 , 470 , 802 silica aerogels , ernest orlando , lawrence berkeley national laboratory ( web site ). charles f . kettering and the 1921 discovery of tetraethyl lead , by bill kovarik ( web site ). separation methods in biochemistry , by c . j . morris and p . morris ; john wiley & amp ; sons , new york ; pp 188 - 193 ; 207 - 211 ; 236 - 237 ; 380 - 382 . aerogel materials and tungsten engineered materials , by marketech international , inc . ( web site ). options for cooling or freezing the fuel include refrigeration systems as are known in the art . other options include the use of a liquified inert gas such as nitrogen , helium or other noble element . yet another option is the use of carbon dioxide in either liquid form ( under pressure ) or solidified . the inert gases and carbon dioxide also have the advantages of fire retardation properties . they could , in the event of impending crash , be placed in close proximity to , or in direct contact with the fuel , as an additional combustion retardant . options for warming the fuel include a number of methods of exposure to a warm surface . the surface may be warmed by ambient air , by hot engine gases , or by hot engine oil . alternatively , an electric current may be passed through a resistive element as a source of heat or the fuel may be warmed by electromagnetic energy . i ) the entire quantity of fuel is stored as one ( or a small number of ) large block ( s ) of fuel : a ) methods in which small pieces are not cut off of the large block : i ) an extrusion process : the frozen fuel is a waxy substance , which can be forced to change shape by pressure applied from the outside of its container . pressure may be applied by a screw - type mechanism which forces waxy fuel from the larger end to the smaller end of a funnel - shaped segment . such a mechanism would control the movement of frozen fuel from the supply chamber to the frozen fuel transport system . in addition , the funnel shaped segment could be warmed to facilitate passage of the fuel through the funnel segment . ii ) a length of fuel element is situated so that most of it is frozen . it may be shaped like a stick of butter . one end of the stick passes through a warming region ( where warm is defined as a temperature above the freezing point of the fuel ). drops of liquid fuel fall from the melting fuel stick into a collector . the liquid fuel then moves through a fuel line to a liquid fuel reservoir . iii ) the fuel is frozen in large sheets , which are then rolled up like a roll of carpet . it could be loaded onto the aircraft as a roll , or could conceivably be unrolled from one container , passed into the aircraft as a wide ribbon of frozen fuel , and re - rolled as it is taken into the aircraft . during the flight , as fuel is needed , the roll is gradually unrolled , and a continuous ribbon of frozen fuel is supplied . it could be transported by a conveyor belt - like apparatus to a “ distant ” melting chamber , or melted nearer to the roll . iv ) the fuel is frozen into a string - like shape and rolled up like a ball of twine . there would be a similar unrolling process as in i ( a )( iii ), above . b ) methods in which small pieces are cut off of the large block . i ) a guillotine - like apparatus cuts small slices of solid fuel off of a rectangular , margarine - stick shaped block of fuel . the slices fall onto a conveyor belt which transports the fuel to a melting chamber . the advantage of situating the melting chamber distant from the guillotine is the greater separation of the far more combustible liquid fuel from the less combustible solid fuel . alternatively , rather than transporting the slices to a distant location , they could be melted near the cutting apparatus . ii ) same concept as i ( b )( i ) but the frozen fuel element is cylindrical , rather than rectangular . slicing is carried out perpendicularly to the central axis of symmetry of the cylinder . i ) the fuel is cylindrical in shape . it rotates continuously about its central axis of symmetry . a cutting blade ( like a cheese knife ) is applied to the surface which cuts off a continuous ribbon of fuel . the fuel is processed as in i ( a )( iii ), above . ii ) the fuel is stored as a large number of small pieces , to be used as needed : a ) the fuel is shaped in cubic or rectangular blocks . these are arranged in a 3 dimensional grid . a series of conveyor belts moves the fuel . there is one belt for each row , running right / left . this passes the fuel element to another conveyor belt , moving perpendicular to the right / left ones , i . e . front / back . additional conveyor apparatus could allow for many layers of fuel elements to be built up ( in the up / down direction ). b ) the fuel could be loaded as spherical elements . the advantage of spherical elements is that they could roll over each other and roll on a smooth surface . they could then be pumped into the aircraft , and possibly “ flow ” or roll through a fuel line from storage tank to warmer . on the other hand , increased storage space would be required for a given amount of fuel , compared to storing cubic or rectangular blocks , which “ fit together ”. also , the greater surface area of spherical elements would mean increased combustibility , compared to cubic or rectangular elements . in general , the total fuel surface area ( or more specifically the area to volume ratio or area to mass ratio ) for any of the methods under ii is greater than those involving fuel with similar shape and only a single ( or small number of ) fuel block ( s ), as in i . spherical fuel elements have the least favorable surface area to volume ratio among those shapes discussed herein . c ) same as ii ( b ) but cylindrical elements are used . these can roll , though not as freely as the spherical ones . as compared with spherical elements , they have the advantages of less surface area and less lost storage volume . d ) the fuel is contained in hard / smooth - surfaced spherical shells with multiple holes . the advantage is that these can roll easily . the shells roll or are propelled to a warming chamber , where the fuel melts and drips out of the shell . the disadvantage of the approach is the waste of space , and that the shells add weight . there has thus been shown and described a novel method and apparatus for treating fuel to temporarily reduce its combustibility which fulfills all the objects and advantages sought therefor . many changes , modifications , variations and other uses and applications of the subject invention will , however , become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof . all such changes , modifications , variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention , which is to be limited only by the claims which follow .
a method and apparatus are disclosed for treating fuel to temporarily reduce its combustibility , and thereafter restore its combustibility . as used in an aircraft , the method comprises the following steps : treating aircraft engine fuel to substantially reduce its combustibility in open air ; carrying the treated fuel in a fuel tank of an aircraft ; increasing the combustibility of a portion of the treated fuel , as needed by the aircraft engine ; and supplying the increased restored combustibility fuel to the aircraft engine . using this method , the preponderance of the fuel on board the aircraft is maintained at low combustibility for safety .