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Author
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Topic: LOX venting
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art540
Member Posts: 432
From: Orange, California USA
Registered: Sep 2006
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posted 12-26-2006 05:32 PM
   
Does anyone know how or why the Redstone and Jupiter LOX venting appeared to be coming from the bottom of the tank instead of midway up the missile near the top of the LOX tank? I have stared at those images for decades without understanding the mechanics of it.......... |
LCDR Scott Schneeweis
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posted 12-26-2006 07:06 PM
The "how" is pretty easy...lox vent line is depicted in this diagram:  The "why" is possibly related to (in this case - undesired) impact of propulsive venting on the missile during boost phase..its would be easier to nulify asymetrical LOX venting when it sat down closer to the turbine exhaust nozzle (which swiveled for steering control) and the gimbaled S-3D. ------------------
Scott Schneeweis
URL http://www.SPACEAHOLIC.com/ [Edited by LCDR Scott Schneeweis (December 26, 2006).] |
art540
Member Posts: 432
From: Orange, California USA
Registered: Sep 2006
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posted 12-27-2006 08:46 AM
Thank you very much for the feedback. I do see the LOX fill line but not a vent line?The next question is was venting actually done after flight pressurization and the vehicle was in flight? I have noted venting LOX just before ignition but not once vehicle was in flight. Most systems had to add pressure to the LOX tank after ignition and I have not noted venting after liftoff. The venting in flight being lower to the the turbine exhaust makes sense so the question now is was venting done during flight or was there a risk of venting in flight? The Army was very conservative in design. [Edited by art540 (December 27, 2006).] |
LCDR Scott Schneeweis
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posted 12-27-2006 04:24 PM
There was continued phase transition (LO2 to GO2) after launch that had to be counteracted...RP-1 required supplemental GN2 to sustain the correct pressure head to the turbine but in the case of the oxidizer, I suspect LOX boil-off was the mechinism exploited to sustain its respective tank pressure...as a number of variables impact boil-off and too high a pressure may induce turbo-pump failure or tank rupture, mid-flight venting would have been a nessessary design attribute of the missile. |
art540
Member Posts: 432
From: Orange, California USA
Registered: Sep 2006
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posted 12-27-2006 05:12 PM
Thank you, Scott. I will have to study the lox issues with Redstone and Jupiter. Most missiles required a separate gas pressure supply for the LOX tank such as those with a common bulkhead like Atlas and Centaur. I don't recall hearing that boiloff was sufficient to mantain tank pressure especially as the tank level lowered. This makes the subject more fun; what we can learn from a simple question. Most missiles seemed to have the LOX tank pressurized at about T-60 seconds and no further venting except for Jupiter and Redstone took place up to ignition. |
LCDR Scott Schneeweis
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posted 12-27-2006 08:42 PM
Acknowledged..I would just add that positive pressurization for the Atlas and Centaur tanks were required to maintain their structural integrity (unlike Jupiter/Redstone, Atlas and Centaur had very thin walled monocoque tanks to save weight..they would have otherwise collapsed). |
art540
Member Posts: 432
From: Orange, California USA
Registered: Sep 2006
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posted 12-28-2006 08:49 AM
Another reason for Atlas/Centaur pressurization was that the tanks common bulkhead had to be rigid enough to stand the g-forces and weight of the propellant above; hence a higher pressure was amintained during flight in the lower
(fuel) tank. There are some interesting stories and images about lost pressure in the Atlas. |
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