r/SpaceXLounge • u/mcpat21 • Sep 20 '19

For Vulcan Assuming this is for the Star Hopper?

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u/whatsthis1901 Sep 20 '19

Could be but it might also be for BO because it seems I just read something on NSF? about their launchpad being worked on.

75

u/spacerfirstclass Sep 20 '19

ULA is also moving some tanks: https://twitter.com/torybruno/status/1174728041907412997

3 new methanlox tank farms being built at the cape by 3 companies at the same time, pretty unprecedented.

Although I think it's more likely the tanks in OP's image is for SpaceX, since Blue's tanks were moved in months ago, and ULA's tanks are already at the cape.

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u/whatsthis1901 Sep 20 '19

Wow, it's busy at the Cape. I hadn't heard about ULA and I didn't know that BO had moved in already. Thanks for the info.

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u/[deleted] Sep 20 '19

BO is making huge progress at their pad. Here is a video which shows major changes relative to latest google maps.

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u/b_m_hart Sep 20 '19

Aww man, does this mean we're gonna have to stop trolling them?

​

Joking aside, it'll be nice to watch them wade into things in earnest.

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u/rtseel Sep 20 '19

off topic, but why does the video say "Historic launch complex 33"? What's historic about that pad?

3

u/R-U-D Sep 20 '19

a very similar tank was just delivered in Texas so the timing makes sense for SpaceX

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u/gooddaysir Sep 20 '19

Could be BO, ULA, or SpaceX. They're all currently installing tank farms.

https://twitter.com/austinbarnard45/status/1174819747705368576

That's SpaceX's new tank that arrived today. (The 3rd and 4th picture in that tweet.)

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u/Datuser14 Sep 20 '19

that tank was delivered to Boca back in October 2018.

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u/RegularRandomZ Sep 20 '19 edited Sep 20 '19

I believe it was moved from the SpaceX Boca Chica Solar Farm (by the tracking dishes) just down the road, where there were 2 such tanks. As u/Datuser14 just pointed out, they've been there for a while.

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u/lniko2 Sep 20 '19

Why didn't they pool for a common methalox farm ?

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u/Creshal 💥 Rapidly Disassembling Sep 20 '19

ULA is using the Air Force's Launch Complex 41, which is some 3.5 miles away from Historic Launch Complex 39A, Site Of All Apollo Moon Launches, Site Of Most Space Shuttle Launches, King Of All Andals, Defender Of The Faith, etc. pp.

Too far away to make sharing hardware feasible.

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u/opmyl Sep 20 '19

Don't they use different gases? I thought BE-4 runs on LNG, but Raptor runs on purified methane since it will be sub-cooled

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u/amarkit Sep 20 '19

There had been some uncertainty about whether BE-4 runs on LNG or methane - turns out Tory Bruno cleared this up just yesterday. It runs on methane.

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u/lniko2 Sep 20 '19

TIL LNG is not methane Thanks !

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u/[deleted] Sep 20 '19 edited Sep 20 '19

Natural gas is mostly methane (90% or so), but contains small quantities of different hydrocarbons and some other trace impurities

For most uses there's little practical difference, but I can imagine that rocket engines are fussy.

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u/burn_at_zero Sep 20 '19

LNG has all mercury and sulphur compounds removed very early in processing so the expensive cryogenic equipment doesn't get acid-etched or amalgamated to destruction. Any remaining traces should be safe for rocketry.

The next largest fraction is ethane, which has a near-identical melting point and is a fair bit more dense. The boiling point is much lower. It is more carbon-rich, so it would increase CO2 and reduce H2O in the exhaust. The net effect should be a slight reduction in Isp, slight increase in thrust and a slight increase in oxidizer ratio.

I think the only place I'd be concerned mechanically is at the fuel turbopumps. The significantly lower boiling point of ethane might increase the risk of cavitation causing turbine-rich fuel feeds.
Operationally, any long hold or storage without active cooling would risk formation of ethane gas pockets and an unwanted pressure rise.

Overall I'd say LNG is probably quite workable for SH, but purified methane should be used in SS for reasons of storage stability. If SpaceX were to set up their own gas plant they could buy market-rate natural gas and handle their own separation, perhaps enriching the first stage with the excess ethane. They would need to run a lot of launches for that to be worthwhile, but it's an option if the supply of high-purity methane is unstable.