Author Topic: Falcon-9 propellant feed system.  (Read 3114 times)

Falcon-9 propellant feed system.
« on: 01/14/2018 04:29 AM »
How do the propellant tanks of the falcon-9 booster stage feed 9 of its engines...will there be a single opening on the tank and then distribute to the engines or there are 9 opening on the tanks.
What could be the distribution scheme for both LOX and RP1 propellant tanks!!
« Last Edit: 01/16/2018 04:59 AM by akhil3101 »

Offline Hobbes-22

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Re: Falcon-9 propellant feed system.
« Reply #1 on: 01/14/2018 07:14 AM »

Offline deruch

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Re: Falcon-9 propellant feed system.
« Reply #2 on: 01/14/2018 10:12 AM »
Called the LOXtopus.  And there's actually 10 holes, because in addition to the 9 feed lines (1 per engine) there's also a tank fill/drain line.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline old_sellsword

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Re: Falcon-9 propellant feed system.
« Reply #3 on: 01/14/2018 03:43 PM »
This is the bottom of the first stage tank:



The RP-1 plumbing is much different since that picture was taken (presumably that's v1.0 hardware). Instead of those tiny holes around the transfer tube, they have much larger holes in the base of the RP-1 tank.
« Last Edit: 01/14/2018 07:17 PM by old_sellsword »

Offline Hobbes-22

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Re: Falcon-9 propellant feed system.
« Reply #4 on: 01/14/2018 05:30 PM »
Do you have some more information on that? esp the report that contains that drawing of the propellant feed system.
« Last Edit: 01/14/2018 05:30 PM by Hobbes-22 »

Offline old_sellsword

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Re: Falcon-9 propellant feed system.
« Reply #5 on: 01/14/2018 06:10 PM »
Do you have some more information on that? esp the report that contains that drawing of the propellant feed system.

I unfortunately haven't been able to find where it came from, but I'd be really interested if anyone else knows. There are some other pictures that seem to have come from the same place, I found them on this website. I contacted the owner of the site through this forum actually, but didn't get anywhere with that.

Online Roy_H

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Re: Falcon-9 propellant feed system.
« Reply #6 on: 01/14/2018 06:21 PM »
Do you have some more information on that? esp the report that contains that drawing of the propellant feed system.
I have no insight, but I find the drawing curious. Obviously red pipes for RP1 and blue for O2 with nice straight runs for RP1 for outer engines. The center engine has to have a curved route from the outlet between between engines 1 & 2 (not shown in the drawing but clearly visible in the photo).
What I find is curious is that the RP1 for center engine is plumbed into the LOXtopus, which in turn has two outlets, one for the center engine and the other for fill/drain. So the tank fill/drain shares the same pipe to the main tank as center engine. I would have bet almost anything that the fill/drain would have it's own direct connection to the main tank to avoid having a split in the feed from the tank to the center engine. Wouldn't this split junction cause unwanted turbulence and possibly cavitation?
« Last Edit: 01/14/2018 06:28 PM by Roy_H »
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Offline Jim

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Re: Falcon-9 propellant feed system.
« Reply #7 on: 01/14/2018 06:29 PM »
I would have bet almost anything that the fill/drain would have it's own direct connection to the main tank to avoid having a split in the feed from the tank to the center engine. Wouldn't this split juncture cause unwanted turbulence and possibly cavitation?

no, because the fluid is not moving in the closed off fill/drain branch.
It is common to branch the fill/drain line off of a feed line.  They don't make a dedicated line into the tank.
« Last Edit: 01/14/2018 06:30 PM by Jim »

Re: Falcon-9 propellant feed system.
« Reply #8 on: 01/16/2018 04:48 AM »
This is the bottom of the first stage tank:



What could be the diameter of these openings....because these openings seem small for the flow rate of the propellant...or the feedlines dia increases afterwards??

Offline speedevil

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Re: Falcon-9 propellant feed system.
« Reply #9 on: 01/16/2018 06:45 AM »

What could be the diameter of these openings....because these openings seem small for the flow rate of the propellant...or the feedlines dia increases afterwards??
The flowrate per engine is 270kg/s or so for both propellants.

Neglecting to properly measure things, it looks like the top guys hat width is about equal to the outside of the flange of the tubes on the tank,, call it 30cm, or 25cm internal.
20cm will lead to, with a flow of 270l/s a speed of ten meters a second or so.

Neglecting a bunch of stuff, and assuming it's water, and plugging it into the first pipe-flow calculator I find, I get ~1PSI pressure drop over 5m of pipe, with that diameter.
In other words, probably not enough to matter in a meaningful way.

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