The helium tank issue brought back some very old memories re the Saturn first stage- I’m talking 1963-64. Working at Boeing at a facility which had some large steam- accumulators to run steam ejectors to simulate 100K altitudes for early ramjets ( BOMARC ) gave us a facility which allowed us to simulate some parts of the S-1C first stage oxygen tankage system using the accumulators as a large air supply to evaluate the LOX tank pressurization system. The GOX ( gaseous oxygen ) in the fight bird used some bleed oxygen from the turbo pumps to maintain some pressure in the LOX tank to prevent pump cavitation . It was mounted on the top of the dome and fed by a approx 4 inch diameter tube running up the outside of the tank. The concern was the effects of impingement on the top dome of relatively high velocity oxygen. So we built an upside down 1/8 section of the dome ( like a ski ramp-) mounted the distributor upside down in the correct relative location. The flight design distributor was like a large 3-4 foot diameter trash can with half of the cylinder made of ‘ regimesh ‘ - sort of a multilayer screen to break up the flow and then run it with air and monitor with tufts and some instruments the impingement and internal pressures, etc. Each test run was about 30 seconds on condition. But we had various photo and instrumentation and flow measurement problems which with running certain specific flow rates required so we made several test runs. About the 5th or 6th run ( 30 seconds each ) the distributor exploded ! Luckily We had some high speed cameras focused on the distributor .As the Engineer in charge I ordered 3 copies of the film to be made ASAP. Examination of some of the parts indicated a fatigue failure ( high pressure, high flow and supersonic noise can do a lot of things ). The test was on a friday. I called the designers in New orleans and told them I had destroyed the distributor- after convincing them I was NOT joking- they hopped a plane to be in Seattle by Monday .
Monday afternoon when I got the file, I was “ invited “ into the Seattle Program Directors office ( George Stoner ) to show the film and explain as best I could what happened. The film showed the beginning of a seam in the regimesh starting to unzip.[ NOTE- In normal flight the SIC stage runs for about 2 minutes and 40 seconds- our total test time on that unit was close to 3 minutes !! ]
Getting together with the designers- I suggested three changes - adopted- 1) an intermediate dome in the distributor with many many 1/4-3/8 holes, 2) the above ( below in flight attitude ) cylinder not of regimesh but many many 3/8 holes and 3) a change to holes in the supply tube from slots.
We fabricated such a design and ran and ran and ran it for three to four times the normal expected flight time with no problems other that some minor ‘ working” of fastener holes evidenced by smudges around the fasteners. As far as I know- that was the design that flew.
SideNote - we used 4 inch diameter SS tubing - special run of about 30 feet. Leftover tubing from the initial build was sold to a local junkyard as no problems were anticipated. I chased the tubing down, bought it back to fabricate the new tube design ( about 3 -4 feet used for the tests ) . The remainder tubing was again sold. Junkyard sold several 3 foot sections as local clam guns - ( seattlelites know what they are )
