Launch and other space travel vehicles often include one or more fuel tanks for the storage of an appropriate fuel therein. These fuel tanks include an enclosed structure or a "pressure vessel", as well as structure for interconnecting a given fuel tank with another fuel tank or an engine. Relatively large amounts of fuel are required, and therefore each of the fuel tanks is typically defined by a plurality of fuel tank subassemblies which are appropriately interconnected. One common configuration for fuel tanks of this type which has been employed and which is admitted to be prior art is one in which two "combos" were interconnected by a barrel. Each combo was defined by a skirt which was welded to a dome body. Both ends of the skirt were open and the skirt was of a cylindrical configuration, extending concentrically about and along a central, longitudinal axis of the fuel tank. One end of the dome body was closed and defined by a "domed" surface which was centrally disposed about the central, longitudinal axis of the fuel tank, and further which was typically disposed between the two open ends of the skirt, while its opposite end was open and extended beyond one of the open ends of the skirt for interconnecting the dome body with both the skirt and the barrel. Definition of the open end of the dome body was actually provided by a cylindrical portion which extended from the outer perimeter of the domed surface to the opposite open end concentrically about and along the central, longitudinal axis of the fuel tank. There a generally T-shaped connector of sorts extended radially outwardly relative to the central, longitudinal axis of the fuel tank (i.e., the bottom "leg" of the T-shaped connector extended at least generally outwardly and away from the cylindrical portion of the dome body). One of the two "upper legs" of the T-shaped connector butted up against one of the ends of the skirt and was welded thereto, while the other of the "upper legs" of the T-shaped connector butted up against one of the two open ends of the cylindrical barrel and was welded thereto.
One known prior art method for assembling fuel tanks from the above-noted subassemblies used a system having a headstock and a longitudinally displaced tailstock which each functioned as a chuck of sorts to retain/hold a fuel tank subassembly. A track extended longitudinally between this headstock and tailstock and along which both the headstock and tailstock could axially move. A carriage of sorts was also movably interconnected with this track and had both a saw and a router attached thereto. Movement of this carriage was controlled by an appropriate operative interconnection with a drive assembly, which in turn was manually controlled by appropriate personnel. Welds between adjoining fuel tank subassemblies were provided by a welding assembly which was associated with the system as well.
Assemblage of a fuel tank using the above-noted system and in accordance with an admitted prior art protocol first entailed attaching one of the ends of a first skirt to the headstock. Operations personnel then placed a mark or the like a predetermined distance from the end of the skirt engaged by the headstock through use of a calibrated measuring tape, stick, or other item of fixed length. This "predetermined distance" corresponded with the length of the skirt as set forth on the relevant engineering drawing. Thereafter, the carriage was moved longitudinally along the track to bring the router into contact with the free end of the skirt through manual control of the longitudinal position of the carriage (and thereby the router) by appropriate personnel, and by what is commonly referred to as a "sneaking up" operation. That is, the carriage was moved to a certain longitudinal position and the skirt was rotated to see if the router engaged any portion thereof. If there was no engagement, the operator would try to estimate how much the router had to be moved longitudinally by visual analysis, and the carriage would then be moved longitudinally this amount to again check and see if the router would engage any portion of the skirt during rotation thereof. This was repeated until engagement was established.
Routering operations were effected on the noted end of the skirt by using relative rotational motion between the skirt and the router. Typically this involved rotating the skirt via rotation of the headstock. Furthermore, the router was moved longitudinally toward the headstock by longitudinal movement of the carriage along the track toward the headstock via the carriage drive assembly until the router reached the above-noted mark and which was determined through visual inspection by appropriate personnel. Further longitudinal movements of the carriage toward the headstock were then manually terminated by the appropriate personnel. Visual inspection of the machined end of the skirt was then undertaken by appropriate personnel. If any portion of the end of the skirt was visually determined to lack router markings, it was assumed that the skirt did not meet the minimum length requirement of the skirt for the subject fuel tank. Discussions were then typically undertaken with relevant personnel to determine how to best proceed (i.e., recover). If the entire circumference of the end of the skirt was determined to have router markings thereon through the noted visual inspection by appropriate personnel, appropriate personnel manually measured the length of the skirt at one radial location and then manually recorded this information in a log book.
The free end of one dome body was attached to the tailstock either before or after prepping the end of the skirt in the above-noted manner. More specifically, the free end of that upper leg of the above-noted T-shaped connector which was to interface with the barrel was engaged by the tailstock. Advancement of the tailstock longitudinally toward the headstock was then undertaken to position the free end of the other upper leg of the T-shaped connector in abutting engagement with the end of the skirt which was prepped in the above-noted manner. A circumferential weld was then made between the skirt and the dome at this butt joint. The resulting structure was again commonly referred to as a combo. The tailstock then released the dome body and proceeded longitudinally away from the headstock for preparation of a barrel for attachment to the combos.
Only one of the upper legs of the T-shaped connector on the free end of the dome body thereby remained after pursuing the protocol thus far described. Actions were then undertaken to prepare the free end of this remaining leg of the T-shaped connector of the dome body for attachment to one of the ends of the open-ended, cylindrical barrel. The carriage would be moved to a certain longitudinal position for sawing a section off of the subject leg of the T-shaped connector through manual operator control of the longitudinal position of the carriage relative to the dome body. The specified length of the combo would be known from the corresponding engineering drawing(s) and was measured from the end of the skirt engaged by the headstock. A mark was placed at this longitudinal position on the dome body in generally the same manner set forth above in relation to the skirt. Operations personnel would manually control longitudinal movement of the carriage (and thereby the saw) to place the saw in the desired longitudinal position for producing a circumferential cut about the entire perimeter of the remaining free leg of the T-shaped connector on the free end of the dome body (using relative rotational movement between the saw and dome body). This "desired longitudinal position" was one which was slightly beyond the location of the noted mark (i.e., further from the headstock) since routering operations were done after these sawing operations. Routering operations were conducted on the subject end of the dome body generally in the manner discussed above in relation to the skirt. Measurement of the length of the combo was manually made by operations personnel (the distance between the end of the skirt mounted on the headstock and the free end of the remaining free leg of the T-shaped connector defining the free end of the dome body) upon completion of this routering, and this value was manually recorded in a log book by appropriate personnel. This combo was then removed from the headstock, and another combo was built in the same manner as the foregoing.
The barrel commonly used in prior art fuel tank designs, like the skirt, was an open-ended cylinder having a pair of longitudinally spaced free and open ends as noted. One of these ends was attached to the tailstock, and the carriage was then longitudinally moved to position the saw thereon at a certain longitudinal location proximate the opposite end through manual control of the drive assembly by appropriate personnel. Typically operations personnel would manually measure in a certain distance from this end of the barrel (e.g., 2 or 3 inches) and place a mark thereat. Operations personnel would then manually control the longitudinal position of the carriage to dispose the saw just beyond this location (i.e., closer to the free open end opposite that engaged by the tailstock). Relative rotational movement between the barrel and the saw was then undertaken to produce a circumferential cut on the barrel, typically by rotating the barrel through rotation of the tailstock. Thereafter, this end of the barrel was also routered through operations personnel manually controlling the longitudinal position of the carriage relative to the tailstock and through relative rotational motion between the barrel and the router (typically via rotation of the tailstock), and further generally in the manner discussed above in relation to the skirt, to obtain the desired length.
Advancement of the tailstock with the barrel attached thereto longitudinally toward the headstock with one of the combos attached thereto was then made to dispose the "prepped" end of the barrel in abutting engagement with the "prepped" end of the remaining free upper leg of the T-shaped connector on the end of the dome body of the combo currently attached to the headstock. Welding operations were then initiated to create a circumferential weld between this combo and the barrel. Thereafter, the barrel was released by the tailstock and its remaining free end was prepared for attachment to the other combo which was previously assembled and which could now be attached to the tailstock. In this regard, a mark was placed on the barrel a predetermined length from the end of the skirt engaged by the headstock, and thereafter sawing and routering operations were undertaken generally in the manner discussed above to obtain the desired length for the combo and barrel interconnected therewith. Appropriate personnel would then manually measure the end length of the combo with the barrel attached thereto and manually record the same in a log book. After having mounted the previously formed combo in the tailstock and longitudinally advancing the same toward the barrel to position the remaining free end of the barrel in abutting engagement with the prepped end of the remaining free upper leg of the T-shaped connector on the free end of the dome body of the second combo, welding operations were initiated to complete the definition of the fuel tank.