psusi

How the heck do you pipe LOX?

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Dosephshih    45
On 2020/1/4 at 8:26 AM, psusi said:

I liquefied a bunch of oxygen to fuel the rocket but I can't seem to pipe the damn stuff over to it!  I ran only 1000g/s and looped it back to pre-cool the pipes but that was taking forever.  I tried switching to just running supercoolant through the pipes at -220 for several cycles and it didn't seem to exchange much heat with the pipes.  I went back to LOX and 1000g packets still get up to -180 half way there.

I faced the same problem as you recently, and would like to share my build as well, although I am still very new to LOX.

1. Pre-cool of the LOX is depends on how far you need to pipe. In my case it is about 1 screen, approx 60-70 titles away from the storage chamber. The leaving temperature of -195C seems ok to me. When it reach the rocket, it is about -190C. Then it loop back to the chamber, it is well below -183C.

2. Use as much ISULATION as possible. But I have only 2000kg insulation on hand, so i only build partly with INSULATION. Other parts i use igneous, it is still acceptable. Stupid me forgot ceramic totally.

3. I use extra pipe bridge, it looks faster to move the liquid to reduce the heat gain. (Not sure about this, may need to further test)

 

On 2020/1/4 at 5:43 PM, Coolthulhu said:

To sum up:

  • Short pipes
  • Loop back
  • Ensure all packets are 10kg/s. Note: automation-disabled pump usually outputs one 4kg packet after disabling - take care of that.
  • Overcool the LOX to just above solidification temperature. Make sure to do that before pumping.
  • Pipe as much as you can through true vacuum that never gets any gases/liquids/solid on it

Hi, may I ask if there is any automation setup to pump the LOX IF there is a rocket sitting there? Now, my build will pump LOX when it is below -195. Since there is loop back, so it just keep pump most of the time. I cannot figure out this part yet.

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nakomaru    1,451
8 hours ago, Dosephshih said:

may I ask if there is any automation setup to pump the LOX IF there is a rocket sitting there?

Start a timer for the duration of your trip upon launch and then run your fill automation once it finishes.

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Coolthulhu    1,040
8 hours ago, Dosephshih said:

Hi, may I ask if there is any automation setup to pump the LOX IF there is a rocket sitting there?

Not to my knowledge - the rocket outputs a signal when it's ready and a scanner outputs one when the rocket is coming back. You could use the scanner signal to start refuelling, though.

I use something simpler: a memory cell is set manually (clock sensor), then reset when the fuel starts looping back (pipe element detector). The memory cell output controls a pump and a shutoff. The shutoff is to avoid sending that last 4kg packet a pipe inevitably outputs at the end.

  • Thanks 1

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Why not just leave the loop running constantly? No risk of pipes warming up between launches. Increase in cooling costs will be marginal, and an appropriately designed loop has no pumping costs

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Hellshound38    82

I gave up on all solutions besides 1,000 g/s because every other method takes an order of magnitude more design for a marginal gain.

Build the 1,000 g/s valve within the cold liquidizer, and vent the excess to space instead of recycling and it works flawlessly. Regardless of issues with production, loading, rocket heat, lag, automation ect ect.

 

 

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psusi    188
1 hour ago, caffeinated21 said:

Why not just leave the loop running constantly? No risk of pipes warming up between launches. Increase in cooling costs will be marginal, and an appropriately designed loop has no pumping costs

The pipes won't heat up anyway.  I suppose I could have the return loop go through radiant pipes in the liquid oxygen to bring the temperature back down and then head back out instead of dumping out a vent and having to be re-pumped.  I was worried about making sure that it cooled off off before going back out and never combining into a packet larger than 1 kg but since it seems to be working fine at 10 kg maybe I'll do that instead of using an atmo sensor to manually turn the flow on and off when a rocket lands.

54 minutes ago, Hellshound38 said:

I gave up on all solutions besides 1,000 g/s because every other method takes an order of magnitude more design for a marginal gain.

Build the 1,000 g/s valve within the cold liquidizer, and vent the excess to space instead of recycling and it works flawlessly. Regardless of issues with production, loading, rocket heat, lag, automation ect ect.

 

 

Yea but it takes 10x longer to fuel the rocket.  I haven't had any problems just using 10 kg with a return pipe.

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Hellshound38    82
54 minutes ago, psusi said:

 

Yea but it takes 10x longer to fuel the rocket.  I haven't had any problems just using 10 kg with a return pipe.

Most of the time between launches is the travel time. Depending on the distance of the planet, Increasing the loading time 10x, is probably less then a 5% reduction in mass/time.

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