At KSC complex 39 there is a 900,000 gallons LOX storage tank. It was used for Apollo Saturn V, the Space Shuttle and lately for the SpaceX Falcon 9 Full Thrust rocket.

But why such a large tank for 900,000 gallons LOX or 3,913 t?

The Saturn V was loaded with 4,317,333 lb or 1,958 t LOX, only 50% of the storage tank capacity.

Was the tank designed for the never built nor flown Nova C8 needing about 3,133 t LOX? (I simply scaled the 1,958 t LOX for the Saturn V by 8/5, the numbers of the F-1 rocket engines used for the first stages of both rockets.)

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    $\begingroup$ Related: Was LC39 built with a larger rocket in mind? $\endgroup$ – Russell Borogove May 28 at 21:30
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    $\begingroup$ "Fueling the Saturn promised to be another problem. The booster required 182,200 liters of liquid oxygen (LOX), six times the amount expended by the Jupiter missile. The LOX would evaporate at a rate of 163 liters every minute during fueling and up until launch; some provision for replenishing this loss was required.". From hq.nasa.gov/office/pao/History/SP-4204/ch2-4.html Still, twice the size seems quite excessize, that alone won't be the explanation. Unfortunately most of the references I am finding are quite hard to track down. $\endgroup$ – Polygnome May 29 at 7:57

Excess capacity was needed in the storage sphere to allow for multiple attempts in a launch campaign.

Much of the propellant was recovered during a scrub but not all.

The storage spheres were loaded from waves of tanker trucks and it was a lengthy process - weeks to several months.

It would have been embarrassing to run out of propellant after a series of scrubs.

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    $\begingroup$ Not only tanker trucks: "MSFC announced on September 7 that four barges carrying 400,000 gallons of vitally needed liquid oxygen were on route to KSC after being dispatched from MTF. The shipment, together with 40,000 gallons brought into KSC by truck and rail tank cars, would replenish the liquid oxygen lost on August 19 at Launch Complex 39." From this page. Only a month to replenish lost 800,000 gallons. $\endgroup$ – Uwe May 28 at 22:53
  • $\begingroup$ Interesting. Don't remember them using barges during Shuttle! Thanks for the link. $\endgroup$ – Organic Marble May 28 at 22:57
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    $\begingroup$ Combining this with @DrSheldon's answer below - worth bearing in mind how early this decision was reached. In Oct 1962 they were predicting six SV & four SI per year by 1967 (Moonport ch 8). So you not only need the capacity to cope with a scrub, but you'd want to have a buffer for the next flight coming down the line - there might not be time to fully reload the tanks between them. $\endgroup$ – Andrew May 29 at 9:24
  • $\begingroup$ Couldn't they have built a LOX production facility right at the launch complex to avoid the trucks and barges? The Linde process only needs air and (electrical) energy... $\endgroup$ – Erlkoenig May 29 at 10:29
  • $\begingroup$ @Erlkoenig sure. All it takes is money and time. $\endgroup$ – Organic Marble May 29 at 11:48

Partial answer: I can identify the manager responsible for the decision, and the date, but not the reason why.

LC-39 was the sole topic at a meeting of the Launch Operations Working Group on 18-19 July [1962] that brought together 113 representatives from LOD, MSFC, and the launch vehicle contractors: Boeing, North American, Douglas, and General Electric. [...] Following Donald Buchanan's report on the crawler and launcher-umbilical tower, Chester Wasileski briefed the meeting on propellant systems. Although LC-39 would involve no new propellants, loading requirements would dwarf LC-34 operations. Each pad would need storage for approximately 3,407,000 liters of LOX, 946,000 liters of RP-1, 2,460,000 liters of LH2, and 946,000 liters of LN2.

Moonport, ch. 6

Chester T. Wasileski was the manager of the KSC facilities and systems management group. The above quote in turn cites LOD, "Minutes of the Saturn C-5 Launch Operations Working Group Meeting, 18-19 July 1962," 8 Aug. 1962, pp. 1-5 and app. 9., which I have been unable to find.

The Kennedy Space Center Story describes the size of the tank (p. 39), but does not explain why.

The Apollo Spacecraft: A Chronology, Apollo Program Summary Report, and a search of NTRS yield no useful results.

I agree with Organic Marble that it is desirable to have enough propellant for more than one launch attempt. In addition, it is worth noting that the LOX was the first cryogen loaded into the Apollo-Saturn stack, and thus most susceptible to boiloff.

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    $\begingroup$ 3,407,000 liters of LOX, that is 900,000 gallons. $\endgroup$ – Uwe May 29 at 14:17
  • $\begingroup$ The decision for the LOR (Lunar Orbit Rendezvous) was officially announced at a press conference on July 11, 1962. After that decision, the Nova C8 or Saturn C8 were out $\endgroup$ – Uwe May 29 at 14:24
  • $\begingroup$ @Uwe: Yeah, the decisions on the mission mode and building LC39 happened during overlapping time frames. Launching the Nova at KSC was considered early in the process; Moonport has sketches of a Nova on a mobile launch platform, and concerns were raised whether the VAB was large enough for Nova. However, I have found no information one way or the other whether Nova had an impact on the LOX storage tank design. $\endgroup$ – DrSheldon May 29 at 15:47

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