Abstract:
Composite tanks are desirable for aerospace applications since they are much lighter than comparable metal tanks. Various polymeric compositions satisfy the requirements to make a Lox compatible tank.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 09/309,780 filed May 11, 1999, now U.S. Pat. No. 6,494,405 incorporated herein by reference. 
     U.S. Provisional Patent Application Ser. Nos. 60/084,986; 60/084,987; 60/084,988; 60/084,989; 60/084,990; 60/084,991; 60/084,992; all filed 11 May 1998, are incorporated herein by reference; priority of these applications is hereby claimed. Also incorporated herein by reference are all U.S. patent applications filed on 11 May 1999 by the present inventors, namely U.S. patent application Ser. Nos. 09/309,780, 09/309,/781 (now U.S. Pat. No. 6,334,589), 09/309,804 (now U.S. Pat. No. 6,491,259), 09/309,805 (now U.S. Pat. No. 6,375,125), 09/309,806 (now abandoned), U.S. Pat. No. 09/309,807 (now abandoned), and U.S. Pat. No. 09/309,808 (now abandoned). All patents mentioned herein are incorporated herein by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     The inventions described herein were made in the performance of work under one or more of the following: Lockheed Martin Michoud Space Systems IRAD M-21D, IRAD M-24D, IRAD M-28D, Cooperative Agreement No. NCC8-115 dated 1 Jul. 1996, General Dynamics RD-1 No. 611-5588-453 and reported in GDSS-ERR-90-600. 
     REFERENCE TO A “MICROFICHE APPENDIX” 
     Not applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to tanks for liquid oxygen. More particularly, the present invention relates to composite tanks for liquid oxygen. 
     2. General Background of the Invention 
     The following U.S. Patents are incorporated herein by reference: U.S. Pat. No. 5,056,367; 5,251,487; 5,380,768; 5,403,537; 5,419,139; and all references cited in those patents. 
     The following international applications published under the PCT are incorporated herein by reference: International Publication Nos. WO 97/18081 and WO 97/28401 and all references cited in those publications. 
     A fiber-reinforced composite is defined as a material consisting of fibers of high strength and modulus embedded in or bonded to a matrix with distinct interfaces or boundaries between them. In this form, both fibers and matrix retain their physical and chemical identities, yet they produce a combination of properties that cannot be produced by either constituent alone. In general, fibers are the principal load carrying members, while the surrounding matrix keeps them in desired location and orientation, transfers loads between fibers, and protects the fibers. The matrix material may be a polymer, a metal, or a ceramic. This disclosure focuses on polymer matrix composites. 
     The fibers can be made from a variety of materials. These materials include glass, graphite or carbon, polymers, boron, ceramics, or metals. Glass fibers include E-glass (electrical) and S-glass (structural) types. Carbon fibers include those made from different precursors, such as polyacrylonitrile (PAN) or pitch. Polymer fibers include, but are not limited to, aramid (Kevlar®), polyethylene (Spectra®), or PBO (Zylon®). Ceramic fibers may include silicon carbide (SiC) or aluminum oxide (Al2O3). 
     For cryogenic tanks, the preferred matrix material is a polymer. The preferred fiber is carbon fiber, more preferably PAN-based fibers, more preferably high strength (over 500 ksi) and high modulus (over 30 Msi) fibers. The most preferred fibers are ultra high modulus fibers (over 60 Msi), specifically M55J fiber by Toray. 
     The development of polymer matrix composite liquid oxygen tanks is a critical step in creating the next generation of launch vehicles. Future reusable launch vehicles need to minimize the gross liftoff weight (GLOW) by reducing the dry mass fraction. The (dry) mass fraction is the weight of the launch vehicle without fuel divided by the weight of the vehicle with fuel.  FIG. 1  is graph showing the effect of mass fraction on GLOW. Indicated on the graph is the RLV mass fraction target region as well as the mass fraction of the RLV without the weight reduction that composites could provide. It is clear that composite tanks are critical to enable future launch vehicles to meet required mass fractions. 
     The required mass fraction is possible due to the reduction of weight that composite materials can provide. Traditional oxygen tanks are usually made from metals. The space shuttle external tank (ET) has historically been made from  2219  aluminum and more recently  2195  aluminum/lithium alloy.  FIG. 2  shows a comparison between these two aluminum alloys and a typical composite material for a liquid oxygen tank for a launch vehicle. The chart shows that a composite tank provides up to 41% and 28% weight savings when compared to  2219  and  2195  aluminum tanks, respectively. 
     In addition to meeting the required mass fraction, a liquid oxygen tank must be compatible with oxygen. The ASTM definition for oxygen compatibility is the “ability of a substance to coexist with both oxygen and a potential source(s) of ignition within the acceptable risk parameter of the user.” It is imperative that materials are selected that will resist any type of detrimental, combustible reaction when exposed to usage environments. Typically, non-metallic materials are not used in these applications because most are easily ignited in the presence of oxygen. However, there are some polymeric materials with inert chemistries that may be used for this application and resist ignition. These chemistries were evaluated by fabricating coupons and testing them with various ignition mechanisms in the presence of liquid and gaseous oxygen. The testing performed reflected situations in launch vehicles that could be potential sources of ignition in composite. These tests included pressurized mechanical impact, particle impact, puncture, puncture of damaged, oxygen-soaked samples, electrostatic discharge, friction, and pyrotechnic shock. 
     Applications include liquid oxygen for future launch vehicles, such as the Lockheed Martin Reusable Launch Vehicle (RLV). They could also potentially be used in other aerospace applications, including but not limited to, RFP (rocket fuel propellant) tanks and crew vehicle cabins. Other industries that may be interested in composite oxygen tanks include the air handling and medical industries. The ability to resist ignition may also be useful in chemical storage tanks and NGV (natural gas vehicle) tanks. 
     BRIEF SUMMARY OF THE INVENTION 
     The apparatus of the present invention solves the problems confionted in the art in a simple and straightforward manner. What is provided are composite tanks for liquid oxygen. 
     The composite tanks can be made in accordance with any of the methods disclosed in any reference incorporated herein by reference. The invention could be made, for example, using the method of U.S. Pat. No. 5,403,537. 
     The interior of the tanks disclosed herein typically have a volume of at least 1 liter, more often at least one gallon, and usually have a volume sufficient to allow their use to contain liquid oxygen for typical aerospace applications. 
     A mechanical impact of at least 10+ft-lbs at around −300 degrees F. (at around −350 degrees F. when densified oxygen (slush oxygen) is contained in the lank) is preferred, but is not a requirement. Historically materials have been required to pass the Lox mechanical impact test at 72 ft-lbs or otherwise be shown to be safe for use in application. Lox compatible composite materials have demonstrated the ability to resist combustion when subjected to any potential ignition source. For a composite tank, realistic potential ignition sources were determined to include, but are not limited to mechanisms such as pyrotechnic shock, friction, puncture, electrostatic discharge, and particle impact. These tests are taken to extreme levels. For example, in the puncture test, a sharpened serrated spike pierced a composite material while submerged in Lox without igniting the composite. This same puncture test has ignited Titanium, a material that is not oxygen compatible, and does not ignite aluminum. The pyrotechnic shock test was also an extreme test in that composites were placed in Lox and subjected to shock loads equivalent to existing metallic Lox tanks such as that on the External Tank. The friction test was extreme in that the composites were abraded to dust with a drill bit in pure oxygen without ignition. In the electrostatic discharge test, composites were subjected to energies that could far exceed any instrumentation or static build up; specifically, these composites do not ignite when subjected to 112.5 Joules from 5000 Volts. 
     The apparatus of the present invention includes composite tanks for liquid oxygen. The unique, nontraditional concept explored in one embodiment herein is to use fiber-reinforced PEAR composites to create liquid oxygen tanks. A PEAR material is one that is characterized by multiple ether and amide groups or linkages. An amide group is an organic group of atoms that is derived from a carboxylic acid and an amine. Ether is defined as any of a class of organic compounds structurally related to water in which hydrogen atoms have been replaced by organic groups. See  FIG. 3  for a reaction that produces ether and amide linkages. 
     Generally, there are two types of PEAR resins: hot melt and solution. 
     Several types of resins and composites have been subjected to an extensive battery of tests for their sensitivity to reaction in the presence of oxygen. Historically, the approach was to test the material in the standard mechanical impact test in liquid oxygen (LOX). If the material had an impact threshold of 72 foot-pounds, it was acceptable for use in oxygen environments, such as launch vehicle LOX tanks. If the material&#39;s threshold was less than 72 foot-pounds, it typically was not used. Due to limitations in the testing as well as differences in the material structures between metals and composites, standard high strength composite materials have not been able to pass at this level at typical RLV tank wall thicknesses. The approach taken here, which was developed in conjunction with NASA, was to use the standard mechanical impact test to rank composites with respect to each other. Furthermore, an evaluation of the compatibility of composites in oxygen environments would only be determined after testing composite materials with respect to specific ignition mechanisms while in the presence of oxygen. The ignition mechanisms tested included pressurized mechanical impact, particle impact, puncture, puncture of damaged, oxygen-soaked samples, electrostatic discharge, friction, and pyrotechnic shock. If the material could withstand ignition in these environments, it could possibly be considered oxygen compatible. 
     Several PEAR materials are undergoing evaluation in the standard mechanical impact test. It is expected to do well in liquid oxygen testing due to its high flammability resistance. See  FIG. 4  for a comparison of PEAR resin to a typical epoxy. 
     Another critical parameter for a composite tank is the ability to withstand repeated temperature changes (thermal cycles) without microcracking. One factor that contributes to microcrack resistance is toughness. PEAR resin is tougher than most standard epoxies. See FIG.  5 . One effect of thermal cycling is a loss of mechanical properties.  FIG. 6  shows how thermal cycling does not effect performance of PEAR materials. 
     The composite feedline of the present invention preferably has an inner diameter of around 1″ to 36″. 
     As used herein, “form of fiber” means unidirectional tape, slit tape, tow, fabric, woven fabric, chopped fiber, or felt. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWNGS 
       For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the drawings, wherein time is in seconds and mechanical impact is in foot-pounds: 
         FIG. 1  is a graphical representation of the effect of mass fraction on gross lift off weight; 
         FIG. 2  is a graphical representation of material weight comparison; 
         FIG. 3  is a graphical representation of a reaction that produces ether and amide linkages; 
         FIG. 4  is a graphical representation of flammability of PEAR vs. epoxy; 
         FIG. 5  is a graphical representation of toughness of PEAR vs. epoxy; 
         FIG. 6  is a graphical representation showing modulus data after thermal cycling; 
         FIG. 7  is a schematic diagram of a halogenated prepreg autoclave vacuum bag; 
         FIG. 8  is a side view of the preferred embodiment of the apparatus of the present invention shown in a cylindrical tank general configuration; 
         FIG. 9  is an end view of the tank of  FIG. 8 ; 
         FIG. 10  is a perspective view of the preferred embodiment of the apparatus of the present invention showing a spherical tank; 
         FIG. 11  is a perspective view of the preferred embodiment of the apparatus of the present invention showing an ogived tank; 
         FIG. 12  is plan view of the preferred embodiment of the apparatus of the present invention showing a multi-lobe tank, general configuration; 
         FIG. 13  is an end view of the tank of  FIG. 12 ; 
         FIG. 14  is a side view of the tank of  FIGS. 12 and 13 ; 
         FIG. 15  is a side view of the preferred embodiment of the apparatus of the present invention showing a semi-conformal tank, general configuration; 
         FIG. 16  is a plan view of the tank of  FIG. 15 ; 
         FIG. 17  is a perspective of the preferred embodiment of the apparatus of the present invention showing a lifting body; 
         FIG. 18  is a perspective of the preferred embodiment of the apparatus of the present invention showing a winged body, and 
         FIG. 19  is a perspective of the preferred embodiment of the apparatus of the present invention showing a cylindrical stage, external tank type. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 8-9  show the preferred embodiment of the apparatus of the present invention designated generally by the numeral  10 . The shape of a composite LO 2  tank is not limited to, but may be any of the following: cylindrical, spherical, ogived, multi-lobe, or conformal. Composite LO 2  tanks may be part of but are not limited to any of the following launch vehicles types: lifting body or winged body. A composite tank may also be part of a separate stage such as the External tank of the spare shuttle. 
     A spherical tank  24  is simply a sphere as shown in FIG.  10 . Tank  24  can have a diameter of between about 1-150 feet. 
     An ogived tank  25  is a tank with an ogive shape along its sides. The sides can measure between about 1 and 150 feet wide or about 3 and 150 feet high. An example of an ogive tank  25  is the external Tank LO 2  tank.  FIG. 11  depicts a sketch of this concept. 
     Any of the tanks of  FIGS. 8-16  may also be part of a winged body vehicle  27  or a cylindrical stage  28  as shown in  FIGS. 18 and 19 , respectively. Winged body vehicles  27  can be generally cylindrically shaped, with wings on the sides. 
     A composite LO 2  may be part of a single stage to orbit vehicle or a multiple stage to orbit vehicle where a multiple stage to orbit vehicle is composed of at least 2 stages. 
     A cylindrical tank is one that has a basic body as a cylinder  11  as shown in  FIGS. 8-9 . Domes  12 ,  13  may be facing outward as shown in  FIG. 10 , but may also be internal or flat bulkheads capping off a cylinder. In  FIGS. 8 and 9 , a cylindrical tank  10  is shown having a general configuration that includes a cylindrically shaped side wall  11  and conically shaped dome end portions  12 ,  13 . 
     In  FIGS. 12-14 , the tank apparatus  10  is shown in a multi-lobe tank configuration. A multi-lobe tank  29  will have at least 2 lobes as shown in  FIGS. 12-14 . A multi-lobe tank may also have more than  2  lobes, but typically no more than  5  lobes. A multi-lobe Lox tank  29  may have one lobe with Lox and the other lobe or lobes may contain other propellants such as LH 2 . In  FIGS. 12-14 , two tank lobes  14 ,  15  are shown. However, it should be understood that though there are a minimum of two lobes in  FIGS. 12-14 , there may be more lobes for forming tank  10 . 
     In  FIGS. 15 and 16 , a conformal tank  30  is shown mounted between beams including an upper pair of beams  16 ,  17  and a lower pair of beams  18 ,  19 . Similarly, the tank  10  in  FIGS. 15 and 16  can be braced with additional vertically extending beams  20 - 23 . Each of the tanks  10 ,  24 ,  25 ,  29 ,  30  can have a length of for example 2-150 feet and a maximum transverse dimension of between 2 and 100 feet. In  FIGS. 8 and 9 , the cylindrically shaped tank provides a diameter of about 1-100 feet and an overall length of about 2-150 feet. The multi-lobe tank  29  of  FIGS. 14-16  provides an overall length of between about 4 and 150 feet, a width of 3-100 feet and a height of 2-100 feet. 
     A conformal tank  30  is any tank which aims to conform or shape itself to the vehicle inner mold line. Therefore, the shape of a conformal tank  30  will depend upon the vehicle body shape.  FIGS. 15-16  show an example of a conformal tank for a lifting body type launch vehicle  26 . A lifting body type vehicle  26  is depicted in FIG.  17 . The conformal tank  30  of  FIGS. 15 and 16  provides an overall length of between about 4 and 150 feet, a width of between 3 and 100 feet, and a height of between about 2-50 feet. 
     A PEAR tank can be fabricated using either of the uncured composite systems, any appropriate placement method, and any curing process. A listing of each of these systems, placement methods, and curing methods is found below. The best system to use depends on a variety of factors including, but not limited to, tank size and shape, composite material used, and available resources. Therefore, a decision on the best fabrication process must be made on a case-related basis. 
     Uncured Composite Systems:
         Prepreg Systems   “Wet” Resin system.       

     A prepreg consists of reinforcement, such as graphite, glass, or Kevlar®, which is impregnated with a resin. A wet resin system is one where liquid resin is placed on the reinforcement at the time of manufacture. 
     Placement Methods for Prepreg Systems:
         Fiber Placement   Tape Placement   Filament Winding   Hand Lay-up       

     Placement Methods for Wet systems:
         Filament Winding   Resin Infusion/Resin transfer molding   Hand Lay-up       

     Fiber placement is an automated process where a robotic arm with a dispensing head is used to place several pieces of prepreg tow or slit tape, typically approximately 0.125 inches wide by 0.0055 inches thick, onto a mandrel in a desired orientation. Tape placement is a similar automated process, but the placement head is attached to a gantry rather than a robotic arm, and it places prepreg tape, typically 12 or 14 inches wide, onto the tool or mandrel. Filament winding is a process in which continuous prepreg tow or continuous fiber with wet resin is wound onto a rotating mandrel in a prescribed way. Hand lay-up is when prepreg, usually tape or fabric, or dry material and wet resin is manually applied to a tool or mandrel. Resin infusion or resin transfer molding is where resin is injected or otherwise forced into a dry reinforcement fabric or preform. 
     Curing Processes:
         Autoclave   Oven Cured (with or without vacuum bag)   Radiation Cure (such as electron beam)   In-Situ Cure       

     Curing of a composite material is the application of energy (heat or radiation) and possibly pressure to cause a chemical reaction and form a compact, solid part. The cure method may be any of the following: autoclave (elevated temperature and pressure), vacuum-bag oven cure (elevated temperature and vacuum pressure), oven cure (elevated temperature, ambient pressure), radiation cure (typically ambient temperature and pressure with radiation, such as electron beams or x-ray radiation), or in-situ curing in which the material is cured as it is placed (with for example, heat and mechanical pressure).  FIG. 7  illustrates an example of a bagging scheme and autoclave cure, for a PEAR composite. Typical autoclave cycle is 1 hour at 177° C./350° F. at 621 kpa (90 psi) with a post cure at 218° C. (425° F.) postcure. 
     The foregoing detailed description is a description of Embodiment 7. Please see the patent applications incorporated herein by reference (and particularly the documents attached to the U.S. Provisional Patent Applications) for a detailed description of the other embodiments of the present invention. 
     One could combine features of the different embodiments to create a Lox compatible tank or feedline; e.g. one could line or coat the hybrid tank or feedline of embodiment 3. 
     Parts List 
     The following is a list of parts and materials suitable for use in the present invention: 
     
       
         
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                   
               
               
                 Material 
                 Generic Description 
                 Trademark 
                 Supplier 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Embodiment 1 - Cyanate Ester Composites for Oxygen Containment 
               
             
          
           
               
                 prepreg 
                 any appropriate fiber 
                   
                   
               
               
                   
                 reinforced with 
               
               
                   
                 cyanate ester resin; 
               
               
                   
                 (prepreg may be 
               
               
                   
                 impregnated in the 
               
               
                   
                 form of slit tape, tow, 
               
               
                   
                 uni-tape, fabric, 
               
               
                   
                 chopped fiber, and/or 
               
               
                   
                 felt) 
               
               
                 prepreg 
                 graphite fiber- 
                 Reinforcement fiber, 
                 Bryte 
               
               
                   
                 reinforced cyanate 
                 such as graphite like 
                 Technologies 
               
               
                   
                 ester resin; (prepreg 
                 IM7 fiber, with any 
               
               
                   
                 may be impregnated 
                 of 1522, 1522-1, 
               
               
                   
                 in the form of slit 
                 1510, or any 
               
               
                   
                 tape, tow, uni-tape, 
                 modified version of 
               
               
                   
                 fabric, chopped fiber, 
                 these 
               
               
                   
                 and/or felt) 
               
               
                 prepreg 
                 fiber-reinforced 
                 Any reinforcement 
                 Bryte 
               
               
                   
                 cyanate ester resin; 
                 fiber which is further 
                 Technologies 
               
               
                   
                 (prepreg may be 
                 defined in a 
               
               
                   
                 impregnated in the 
                 subsequent row, such 
               
               
                   
                 form of slit tape, tow, 
                 as IM7, impregnated 
               
               
                   
                 uni-tape, fabric, 
                 with any of 1522, 
               
               
                   
                 chopped fiber, and/or 
                 1522-1, 1510, or any 
               
               
                   
                 felt) 
                 modified version of 
               
               
                   
                   
                 these 
               
               
                 Prepreg 
                 reinforced cyanate 
                 Any reinforcement 
                 Hexcel 
               
               
                   
                 ester resin; (prepreg 
                 fiber which is further 
                 (formerly 
               
               
                   
                 may be impregnated 
                 defined in a 
                 part of 
               
               
                   
                 in the form of slit 
                 subsequent row, such 
                 Cytec 
               
               
                   
                 tape, tow, uni-tape, 
                 as IM7, impregnated 
                 Fiberite) 
               
               
                   
                 fabric, chopped fiber, 
                 with 954-3, 954-2, or 
               
               
                   
                 or felt) 
                 any modified version 
               
               
                   
                   
                 of these 
               
               
                 fiber 
                 intermediate 
                 Examples: IM7, IM6, 
                 Hexcel 
               
               
                   
                 modulus, high 
                 IM2; Note: Preferred 
               
               
                   
                 strength graphite 
                 is IM7 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, fabric, woven 
               
               
                   
                 fabric) chopped fiber, 
               
               
                   
                 or felt 
               
               
                 fiber 
                 intermediate 
                 Examples: T650, 
                 Amoco 
               
               
                   
                 modulus, high 
                 T800, T300 
               
               
                   
                 strength graphite 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, fabric, woven 
               
               
                   
                 fabric, chopped fiber, 
               
               
                   
                 or felt 
               
               
                 fiber 
                 high modulus, 
                 Example: M55J 
                 Toray 
               
               
                   
                 intermediate strength 
               
               
                   
                 graphite 
               
               
                   
                 (uni-directional tape, 
               
               
                   
                 slit tape, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or 
               
               
                   
                 felt) 
               
               
                 fiber 
                 glass (E, S, or C 
                 Fiberglas ® 
                 Owens/ 
               
               
                   
                 type) 
                   
                 Corning 
               
               
                 fiber 
                 Aramid 
                 Kevlar ® 
                 Hexcel 
               
               
                 resin 
                 cyanate ester 
                 954-2A, 954-3 
                 Hexcel 
               
               
                   
                   
                 Note these are 
                 (formerly 
               
               
                   
                   
                 typically supplied in 
                 available 
               
               
                   
                   
                 as prepregs with 
                 from 
               
               
                   
                   
                 reinforcement 
                 Fiberite) 
               
               
                 resin 
                 cyanate ester 
                 1510 
                 Bryte 
               
               
                   
                   
                 Note this has 
               
               
                   
                   
                 typically been 
               
               
                   
                   
                 supplied as a wet 
               
               
                   
                   
                 resin (as opposed to a 
               
               
                   
                   
                 prepreg); however, 
               
               
                   
                   
                 the inventors have 
               
               
                   
                   
                 had Bryte 
               
               
                   
                   
                 specifically tailor the 
               
               
                   
                   
                 1510 resin and 
               
               
                   
                   
                 supply it as a prepreg 
               
               
                   
                   
                 form. 
               
               
                 resin 
                 cyanate ester 
                 1545 
                 Bryte 
               
               
                   
                   
                 Note this has 
               
               
                   
                   
                 typically been 
               
               
                   
                   
                 supplied as a wet 
               
               
                   
                   
                 resin 
               
               
                 resin 
                 cyanate ester 
                 1522, 1522-1 
                 Bryte 
               
               
                   
                   
                 Note: these are both 
               
               
                   
                   
                 supplied as prepregs; 
               
               
                   
                   
                 the 1522-1 may also 
               
               
                   
                   
                 be supplied as resin 
               
               
                   
                   
                 only; the 1522 
               
               
                   
                   
                 family is a blend of 
               
               
                   
                   
                 epoxy-cyanate ester- 
               
               
                   
                   
                 bromine 
               
             
          
           
               
                 Embodiment 2 Halogenated Composites for Oxygen Systems 
               
             
          
           
               
                 prepreg 
                 graphite fiber- 
                 Reinforcement fiber, 
                 Bryte 
               
               
                   
                 reinforced 
                 which is further 
               
               
                   
                 halogenated epoxy 
                 defined in a 
               
               
                   
                 resin 
                 subsequent row, 
               
               
                   
                   
                 which is impreg- 
               
               
                   
                   
                 nated with a 
               
               
                   
                   
                 halogenated resin 
               
               
                   
                   
                 such as 1522, 
               
               
                   
                   
                 1522-1 or any 
               
               
                   
                   
                 modified version of 
               
               
                   
                   
                 these (the 1522 
               
               
                   
                   
                 family is a blend of 
               
               
                   
                   
                 epoxy-cyanate ester- 
               
               
                   
                   
                 bromine) 
               
               
                 prepreg 
                 graphite fiber- 
                 Reinforcement fiber, 
                 Hexcel 
               
               
                   
                 reinforced 
                 which is further 
               
               
                   
                 halogenated epoxy 
                 defined in a 
               
               
                   
                 resin 
                 subsequent row, 
               
               
                   
                   
                 impregnated with 
               
               
                   
                   
                 F155 resin 
               
               
                 fiber 
                 intermediate 
                 Examples: IM7, 
                 Hexcel 
               
               
                   
                 modulus; high 
                 IM6, IM2; Note: 
               
               
                   
                 strength graphite, 
                 Preferred is IM7 
               
               
                   
                 which may be 
               
               
                   
                 uni-directional tape, 
               
               
                   
                 slit tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 intermediate 
                 Examples: T650, 
                 Amoco 
               
               
                   
                 modulus, high 
                 T800, T300 
               
               
                   
                 strength graphite, 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, fabric, tow, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 high modulus, 
                 Example: M55J 
                 Toray 
               
               
                   
                 intermediate strength 
               
               
                   
                 graphite 
               
               
                   
                 (uni-directional tape, 
               
               
                   
                 slit tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or 
               
               
                   
                 felt) 
               
               
                 fiber 
                 glass (E, S, or C 
                 Fiberglas ® 
                 Owen/ 
               
               
                   
                 type) 
                   
                 Corning 
               
               
                 fiber 
                 Aramid 
                 Kevlar ® 
                 Hexcel 
               
               
                 resin 
                 halogenated epoxy 
                 F155 resin (in which 
                 Hexcel 
               
               
                   
                   
                 the halogen is 
               
               
                   
                   
                 Bromine) 
               
               
                 resin 
                 halogenated cyanate 
                 EX 1522-1 (in 
                 Bryte 
               
               
                   
                 ester 
                 which the halogen 
               
               
                   
                   
                 is Bromine) 
               
               
                 resin 
                 halogenated 
                 Avimid N (in which 
                 Cytec 
               
               
                   
                 thermoplastic (may 
                 case the halogen is 
                 Fiberite 
               
               
                   
                 be considered a 
                 Fluorine); this 
                 (formerly 
               
               
                   
                 pseudothermosetting 
                 material is supplied 
                 from 
               
               
                   
                 one) 
                 as a prepreg 
                 DuPont) 
               
               
                 resin 
                 halogenated epoxy, 
                 Examples: EPON 
                 Shell 
               
               
                   
                 wet resin 
                 1162, 1183 (both of 
               
               
                   
                   
                 these have Bromine 
               
               
                   
                   
                 as a halogen) 
               
             
          
           
               
                 Embodiment 3 - Hybrid Composites for Oxygen Propulsion Systems 
               
             
          
           
               
                 primary fiber or 
                 intermediate 
                 Examples: IM7, 
                 Hexcel 
               
               
                 interior fiber (but not 
                 modulus, high 
                 IM6, IM2; Note: 
               
               
                 both, unless resins 
                 strength graphite, 
                 Preferred is IM7 
               
               
                 are different) 
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 primary fiber 
                 intermediate 
                 Examples: T650, 
                 Amoco 
               
               
                 or interior 
                 modulus, high 
                 T800, T300 
               
               
                 fiber (but 
                 strength graphite, 
               
               
                 not both un- 
                 which may be uni- 
               
               
                 less resins 
                 directional tape, slit 
               
               
                 are different) 
                 tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 primary fiber or 
                 high modulus, 
                 Example: M55J 
                 Toray 
               
               
                 interior fiber (but not 
                 intermediate strength 
               
               
                 both unless resins are 
                 graphite intermediate 
               
               
                 different) 
                 modulus, high 
               
               
                   
                 strength graphite, 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 primary fiber or 
                 glass (E, S, or C type) 
                 Fiberglas ® 
                 Owens/ 
               
               
                 interior fiber (but not 
                   
                   
                 Corning 
               
               
                 both unless resins are 
               
               
                 different) 
               
               
                 primary fiber or 
                 Aramid 
                 Kevlar ® 
                 Hexcel 
               
               
                 interior fiber (but not 
               
               
                 both unless resins are 
               
               
                 different) 
               
               
                 primary resin or 
                 cyanate ester 
                 954-2A, 954-3 
                 Hexcel 
               
               
                 interior resin (but not 
                   
                 Note these are 
                 (formerly 
               
               
                 both unless fibers are 
                   
                 typically supplied in 
                 available 
               
               
                 different) 
                   
                 as prepregs with 
                 from 
               
               
                   
                   
                 reinforcement 
                 Fiberite) 
               
               
                 primary resin or 
                 cyanate ester 
                 1510 
                 Bryte 
               
               
                 interior resin (but not 
                   
                 Note this has 
               
               
                 both unless fibers are 
                   
                 typically been 
               
               
                 different) 
                   
                 supplied as a wet 
               
               
                   
                   
                 resin (as opposed to 
               
               
                   
                   
                 a prepreg); however, 
               
               
                   
                   
                 the inventors have 
               
               
                   
                   
                 had Bryte 
               
               
                   
                   
                 specifically tailor the 
               
               
                   
                   
                 1510 resin and 
               
               
                   
                   
                 supply it as a prepreg 
               
               
                   
                   
                 form. 
               
               
                 primary resin or 
                 cyanate ester 
                 1545 
                 Bryte 
               
               
                 interior resin (but not 
                   
                 Note this has 
               
               
                 both unless fibers are 
                   
                 typically been 
               
               
                 different) 
                   
                 supplied as a wet 
               
               
                   
                   
                 resin 
               
               
                 primary resin or 
                 cyanate ester 
                 1522, 1522-1 
                 Bryte 
               
               
                 interior resin (but not 
                   
                 Note: these are both 
               
               
                 both unless fibers are 
                   
                 supplied as prepregs; 
               
               
                 different) 
                   
                 the 1522-1 may also 
               
               
                   
                   
                 be supplied as resin 
               
               
                   
                   
                 only; the 1522 
               
               
                   
                   
                 family is a blend of 
               
               
                   
                   
                 epoxy-cyanate ester- 
               
               
                   
                   
                 bromine 
               
               
                 primary resin or 
                 halogenated epoxy 
                 F155 resin (in which 
                 Hexcel 
               
               
                 interior resin (but not 
                   
                 the halogen is 
               
               
                 both unless fibers are 
                   
                 Bromine) 
               
               
                 different) 
               
               
                 primary resin or 
                 halogenated cyanate 
                 EX 1522-1 (in which 
                 Bryte 
               
               
                 interior resin (but not 
                 ester 
                 the halogen is 
               
               
                 both unless fibers are 
                   
                 Bromine) 
               
               
                 different) 
               
               
                 primary resin or 
                 halogenated 
                 Avimid N (in which 
                 Fiberite 
               
               
                 interior resin (but not 
                 thermoplastic (may 
                 case the halogen is 
                 (formerly 
               
               
                 both unless fibers are 
                 be considered a 
                 Fluorine); this 
                 from 
               
               
                 different) 
                 pseudothermosetting 
                 material is supplied 
                 DuPont) 
               
               
                   
                 one) 
                 as a prepreg 
               
               
                 primary resin or 
                 halogenated epoxy, 
                 Examples: EPON 
                 Shell 
               
               
                 interior resin (but not 
                 wet resin 
                 1162, 1183 (both of 
               
               
                 both unless fibers are 
                   
                 these have Bromine 
               
               
                 different) 
                   
                 as a halogen) 
               
               
                 primary resin or 
                 thermoplastically 
                 977 resins; most 
                 Hexcel or 
               
               
                 interior resin (but not 
                 toughened epoxies 
                 preferred is 977-6 
                 Cytec 
               
               
                 both unless fibers are 
                   
                   
                 Fiberite 
               
               
                 different) 
               
               
                 primary resin or 
                 polyimide (a pseudo- 
                 Avimid R1-16 
                 Cytec- 
               
               
                 interior resin (but not 
                 thermosetting type) 
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 primary resin or 
                 polyimide 
                 Avimid N 
                 Cytec- 
               
               
                 interior resin (but not 
                   
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 primary resin or 
                 polyimide 
                 PIXA 
                 Cytec- 
               
               
                 interior resin (but not 
                   
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 primary resin or 
                 polyimide 
                 Avimid K3B 
                 Cytec- 
               
               
                 interior resin (but not 
                   
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 primary resin or 
                 polyimide 
                 Avimid NR150 
                 Cytec- 
               
               
                 interior resin (but not 
                   
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 primary resin or 
                 polyimide (a pseudo- 
                 Avimid R 
                 Cytec- 
               
               
                 interior resin (but not 
                 thermosetting type) 
                   
                 Fiberite 
               
               
                 both unless fibers are 
                   
                   
                 (formerly 
               
               
                 different) 
                   
                   
                 Dupont) 
               
               
                 resin-rich interior 
               
               
                 surface (fiber - IM7, 
               
               
                 resin - epoxy such as 
               
               
                 977-6 or cyanate 
               
               
                 ester/bromine/epoxy 
               
               
                 blend 1522) 
               
             
          
           
               
                 Embodiment 4 - Toughened Epoxy Composites for Oxygen Systems 
               
             
          
           
               
                 prepreg 
                 fiber-reinforced 
                 Reinforcement fiber, 
                 Hexcel or 
               
               
                   
                 toughened epoxy; 
                 such as graphite like 
                 Cytec 
               
               
                   
                 (prepreg may be 
                 IM7 fiber with 
                 Fiberite 
               
               
                   
                 impregnated in the 
                 977, specifically 977- 
               
               
                   
                 form of slit tape, uni- 
                 6 
               
               
                   
                 tape, fabric, tow, 
               
               
                   
                 chopped fiber, or 
               
               
                   
                 felt) 
               
               
                 prepreg 
                 fiber-reinforced 
                 Reinforcement fiber, 
                 Toray or 
               
               
                   
                 toughened epoxy; 
                 such as M55J fiber 
                 Cytec 
               
               
                   
                 (prepreg may be 
                 with 977-6 resin 
                 Fiberite 
               
               
                   
                 impregnated in the 
               
               
                   
                 form of slit tape, uni- 
               
               
                   
                 tape, fabric, tow, 
               
               
                   
                 chopped fiber, or 
               
               
                   
                 felt) 
               
               
                 fiber 
                 intermediate 
                 Examples: IM7, IM6, 
                 Hexcel 
               
               
                   
                 modulus, high 
                 IM2; Note: Preferred 
               
               
                   
                 strength graphite, 
                 is IM7 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 intermediate 
                 Examples: T650, 
                 Amoco 
               
               
                   
                 modulus, high 
                 T800, T300 
               
               
                   
                 strength graphite, 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, tow, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 high modulus, 
                 Example: M55J 
                 Toray 
               
               
                   
                 intermediate strength 
               
               
                   
                 graphite 
               
               
                   
                 (uni-directional tape, 
               
               
                   
                 slit tape, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or 
               
               
                   
                 felt) 
               
               
                 fiber 
                 glass (E, S, or C 
                 Fiberglas 
                 Owens/ 
               
               
                   
                 type) 
                   
                 Corning 
               
               
                 fiber 
                 Aramid 
                 Kevlar ® 
                 Hexcel 
               
               
                 resin 
                 thermoplastically 
                 977 resins; most 
                 Hexcel or 
               
               
                   
                 toughened epoxies 
                 preferred is 977-6 
                 Cytec 
               
               
                   
                   
                   
                 Fiberite 
               
               
                 toughening material 
                 thermoplastic 
                 (present in 977-6 
                 Hexcel or 
               
               
                   
                 material 
                 resin, believed to be 
                 Cytec 
               
               
                   
                   
                 proprietary to the 
                 Fiberite 
               
               
                   
                   
                 supplier) 
               
             
          
           
               
                 Embodiment 5 - Polyimide Composites for Oxygen Systems 
               
             
          
           
               
                 prepreg 
                 fiber-reinforced 
                 Reinforcement fiber, 
                 Cytec 
               
               
                   
                 toughened epoxy; 
                 such as graphite like 
                 Fiberite 
               
               
                   
                 (prepreg may be 
                 IM7 fiber with an 
                 (formerly 
               
               
                   
                 impregnated in the 
                 Avimid 
                 DuPont) 
               
               
                   
                 form of slit tape, uni- 
               
               
                   
                 tape, fabric, chopped 
               
               
                   
                 fiber, or felt) 
               
               
                 fiber 
                 intermediate 
                 Examples: IM7, 
                 Hexcel 
               
               
                   
                 modulus, high 
                 IM6, IM2; Note: 
               
               
                   
                 strength graphite, 
                 Preferred is IM7 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, slit 
               
               
                   
                 tape, fabric, tow, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 intermediate 
                 Examples T650, 
                 Amoco 
               
               
                   
                 modulus, high 
                 T800, T300 
               
               
                   
                 strength graphite, 
               
               
                   
                 which may be uni- 
               
               
                   
                 directional tape, tow, 
               
               
                   
                 slit tape, fabric, 
               
               
                   
                 woven fabric, 
               
               
                   
                 chopped fiber, or felt 
               
               
                 fiber 
                 high modulus, 
                 Example: M55J 
                 Toray 
               
               
                   
                 intermediate strength 
               
               
                   
                 graphite 
               
               
                 fiber 
                 glass (E, S, or C 
                 Fiberglas 
                 Owens/ 
               
               
                   
                 type) 
                   
                 Corning 
               
               
                 fiber 
                 Aramid 
                 Kevlar ® 
                 Hexcel 
               
               
                 resin 
                 polyimide (a pseudo- 
                 Avimid R1-16 
                 Cytec- 
               
               
                   
                 thermosetting type) 
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
               
                 resin 
                 polyimide 
                 Avimid N 
                 Cytec- 
               
               
                   
                   
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
               
                 resin 
                 polyimide 
                 PIXA 
                 Cytec- 
               
               
                   
                   
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
               
                 resin 
                 polyimide 
                 Avimid K3B 
                 Cytec- 
               
               
                   
                   
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
               
                 resin 
                 polyimide 
                 Avimid NR 150 
                 Cytec- 
               
               
                   
                   
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
               
                 resin 
                 polyimide (a pseudo- 
                 Avimid R 
                 Cytec- 
               
               
                   
                 thermosetting type) 
                   
                 Fiberite 
               
               
                   
                   
                   
                 (formerly 
               
               
                   
                   
                   
                 Dupont) 
               
             
          
           
               
                 Embodiment 6 - Lined/Coated Composites for Oxygen Systems 
               
             
          
           
               
                 liner 
                 polyimide 
                 Kapton 
                 DuPont 
               
               
                 liner 
                 polyimide/ 
                 Kapton/Teflon 
                 DuPont 
               
               
                   
                 fluoropolymer 
               
               
                 liner 
                 Metallized polyimide 
                 metallized Kapton 
                 Sheldahl 
               
               
                   
                   
                 film 
               
               
                 liner 
                 Metallized 
                 metallized FEP 
                 Sheldahl 
               
               
                   
                 fluoropolymer 
               
               
                 liner 
                 Multilayer metallized 
                 (the multilayer 
                 Sheldahl 
               
               
                   
                 polymer 
                 metallized polymer 
               
               
                   
                   
                 liner disclosed in 
               
               
                   
                   
                 U.S. Pat. No. 
               
               
                   
                   
                 5,419,139 with 
               
               
                   
                   
                 Kapton or FEP 
               
               
                   
                   
                 being used as the 
               
               
                   
                   
                 film layer) 
               
               
                 coating 
                 fluoropolymer 
                 PCTFE (dispersion 
                 General 
               
               
                   
                   
                 coated) 
                 Plastics 
               
               
                 coating 
                 fluoropolymer 
                 PTFE 
                 Plasma 
               
               
                   
                   
                   
                 Processes 
               
               
                 fiber 
                 graphite fiber 
                 IM7 
                 Hexcel 
               
               
                 resin 
                 epoxy resin 
                 977-2 
                 Hexcel or 
               
               
                   
                   
                   
                 Cytec 
               
               
                   
                   
                   
                 Fiberite 
               
               
                   
               
             
          
         
       
     
     The following list describes the parts shown in FIG.  7 :
     A) BASE PLATE: Aluminum, ⅝″ thick with no deep scratches or pits. (If surface is damaged, a thin caul plate must be used to provide a smooth tool surface);   B) BREATHER: Airtech Super 10 or Ultraweave 1032;   C) SEALANT TAPE: Schnee-Moorehead 5626 or Airtech GS-213;   D) LAMINATE: Lay-up Orientation (example: [0,45,90,-45]2S);   F) RELEASE FILM: Airtech, A4000R Release Film, (1 mil);   G) CAUL SHEET: Torr, EL82, 50 DURO, 48″ width, 0.063″ Thick;   H) VACUUM COUPLING: 2 required, 1 source &amp; 1 transducer. Minimum of two plies of breather under couplings;   I) VACUUM BAG: Airtech, DP1000 SHTG, 2 mil;   J) THERMOCOUPLE: 2 required, opposite edges of laminate, mid ply.   

     All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise. 
     The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.