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  Apollo 13: Service module oxygen tank details

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Author Topic:   Apollo 13: Service module oxygen tank details
robsouth
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From: West Midlands, UK
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posted 03-19-2014 12:08 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
There are a few things that maybe cS members could answer regarding Apollo 13.
  • What was the manufacturer's serial number for Oxygen Tank 2? I have seen it ending with a 8 and a 9.
  • What was the surge tank and where was it?
  • How many O2 tanks/bottles in the CM for the re-entry phase?
  • Did Apollo's 7 to 12 all carry the same defective O2 tanks?
  • Was the contractor assembling the O2 tanks and the subcontractors building some of its components told of the change from 28 to 65 volts?

Jim Behling
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posted 03-19-2014 12:21 PM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
What was the surge tank and where was it? Did Apollo's 7 to 12 all carry the same defective O2 tanks?
The surge tank was in the CM and use for repressurization and to protect against depressurization in case of a leak

The O2 tanks were not defective. 13 had a "damaged" one.

Sy Liebergot
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posted 03-19-2014 12:37 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
Not true. I'll answer in a while.

Michael Davis
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posted 03-19-2014 12:39 PM     Click Here to See the Profile for Michael Davis   Click Here to Email Michael Davis     Edit/Delete Message   Reply w/Quote
Actually, the oxygen tank was defective in a sense. It had originally been designed to run on the 28 volt DC power of the CSM. The tanks were redesigned to also run on the 65 volt DC ground power. All components were altered to accept 65 volts except for the heater thermostatic switches. This directly contributed to the accident by allowing damage to the heater thermostat.

This change dated back to 1965, so all of the previous Apollo missions had flown with the same defect.

Sy Liebergot
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posted 03-19-2014 01:04 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
What was the manufacturer's serial number for Oxygen Tank 2?
Don't know.
quote:
What was the surge tank and where was it?
The 3.7 lb capacity surge tank was located in the CM. Its function was the absorb pressure fluctuations in the oxygen system.
quote:
How many O2 tanks/bottles in the CM for the re-entry phase?
The cabin volume along with the 3.7 lb capacity surge tank and the three 1 lb capacity emergency repress bottles provided sufficient breathing oxygen after SM sep.
quote:
Did Apollo's 7 to 12 all carry the same defective O2 tanks?
The design of the cryo O2 tanks was the same for Apollo 7-12 and 2TV-1 & 2TV-2. That is, the potential for failure given the same identical circumstances was present.
quote:
Was the contractor assembling the O2 tanks and the subcontractors building some of its components told of the change from 28 to 65 volts?
Yes.

A good reference is: MSC-02545 NASA Manned Spacecraft Center Internal Note, Apollo 13 Cryogenic Oxygen Tank 2 Anomaly, Anomaly Report No. 1.

YankeeClipper
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posted 03-19-2014 01:55 PM     Click Here to See the Profile for YankeeClipper   Click Here to Email YankeeClipper     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
What was the manufacturer's serial number for Oxygen Tank 2? I have seen it ending with a 8 and a 9.
Apollo 13's Oxygen Tank No. 2 (S/No. 10024X-TA0008) which exploded was originally assigned to Apollo 10.

moorouge
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posted 03-19-2014 02:19 PM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
My understanding to the '13' problem apart from the change in voltage was that the tank was dropped during its removal from the '10' SM. This shook loose a drainage tube and resulted in the oxygen having to be boiled off by using the heaters to empty the tank during a countdown simulation. It was then that the insulation became charred setting up the conditions for the spark that caused the tank to explode when the 'stir' was requested.

Sy Liebergot
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posted 03-19-2014 03:39 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
Well, there goes my lecture "Apollo 13: Anatomy of the Failure." LOL.

The Apollo 13 tank failure chronology is in an appendix in my autobio.

wickball
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posted 03-19-2014 05:28 PM     Click Here to See the Profile for wickball   Click Here to Email wickball     Edit/Delete Message   Reply w/Quote
Good to hear from you again, Sy.

robsouth
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posted 03-19-2014 06:12 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Wow! Some fabulous answers there, thanks to everyone. And thanks to Sy, who better to get a response from other than the main man right on the scene back in 1970!

A couple more question. I believe the O2 tank that exploded, had already had two or three cryo-stirs before during the mission, why didn't it fail during those?

And if the subcontractor that made the thermostat had been told to incorporate the capability to handle 65 volts dc power, why didn't they do so?

Sy Liebergot
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posted 03-19-2014 06:39 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
And if the subcontractor that made the thermostat had been told to incorporate the capability to handle 65 volts dc power, why didn't they do so?
North American Aviation was notified, but for some reason the thermostat subcontractor didn't get the word.

Sy Liebergot
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posted 03-19-2014 10:35 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
I believe the O2 tank that exploded, had already had two or three cryo-stirs before during the mission, why didn't it fail during those?
Lucky!

moorouge
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posted 03-20-2014 01:54 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
Sy very kindly signed and corrected a typo error in my summary of the '13' flight from my 1975 edition of 'Manned Spaceflight' when he was at Pontefract.

There is one other odd ball fact about this incident. It might be claimed that it happened just because someone went for a break halfway through doing a job. The shelf the tank was sat on was held in place by three bolts. During its removal two were removed and the third loosened when breaktime came. After the break it was assumed that all the bolts had been undone, a crane was attached and the shelf lifted. However, it was still held in place by the loosened bolt and pulled out of the hoist and dropped about a couple of inches back into place in the SM. This was the jolt that misplaced the drainage tube.

On edit - Sy will correct me if wrong (again!), but I believe the critical factor was the length of time the heaters were on to boil off the oxygen - some few hours. In flight a tank stir only lasted a few minutes.

Sy Liebergot
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posted 03-20-2014 08:00 AM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
Again, please read the appendix in my book or more importantly: MSC-02545 NASA Manned Spacecraft Center Internal Note, Apollo 13 Cryogenic Oxygen Tank 2 Anomaly, Anomaly Report No. 1.

By the way, I'll be in UK in June. Check the June Sightings schedule, here.

David Carey
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posted 03-20-2014 11:40 AM     Click Here to See the Profile for David Carey   Click Here to Email David Carey     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Sy Liebergot:
North American Aviation was notified, but for some reason the thermostat subcontractor didn't get the word.
Hello Sy!

Interestingly the Flight Control Division (MSC)-produced Command/Service Module Systems Handbook for CSM 108-111 also failed to receive the update.

See the last image (next-to-last post) in this thread.

I would be curious to know if these schematic revisions formed the basis for the flown A13 CSM Systems Data FDF which sold at Heritage in 2013?

Not that anything could be done, but perhaps information onboard — like that on the ground — still reflected the outdated 28V supply to thermostat and heater.

Sy Liebergot
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posted 03-20-2014 08:52 PM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
I believe the tank notation of 114 watts @ 28 vdc is the heater rating. There is no thermostat rating labeled. We would be interested in the current draw of the heaters when activated, not the static value of the thermostat (P=VI;I = P/V; I=114w/28vdc= 4.1 amps)

David Carey
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posted 03-21-2014 02:55 PM     Click Here to See the Profile for David Carey   Click Here to Email David Carey     Edit/Delete Message   Reply w/Quote
Exactly so, Sy.

What I hadn't considered was that the 65 volt 'over-condition' for the heater was a spec change strictly for ground-based procedures, in this case an earlier de-tanking at KSC.

NAA must have signed off on a 28 volt heater system seeing 65 volts applied on the ground, but the resulting over-current that fused the series thermostat contacts pre-flight was 'the miss' (along with the bad fill/drain tube).

In re-reading your book appendix and the A13 accident investigation report, it's amazing - in hindsight - that the drain-rate discrepancy between tanks didn't escalate to a "stop everything" red-flag concern.

It didn't help to have instrumentation unable to report the excessive temperature of the tank of course, but did schedule pressure play a role in pressing forward?

In any case, if I'm now understanding correctly, the heater/thermostat supply was 28 volts DC from the fuel cells during flight so the schematics are correct for an as-flown space craft.

On that note, thanks to the cS member kind enough to confirm the flown and training cryo schematics referenced above were the same in showing the lower 28 volt heater spec.

carmelo
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posted 03-21-2014 03:23 PM     Click Here to See the Profile for carmelo   Click Here to Email carmelo     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by moorouge:
It might be claimed that it happened just because someone went for a break halfway through doing a job.
Was identified a responsable?

robsouth
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posted 03-25-2014 08:05 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Is it true to say that there was a minute between the switch being flicked to stir the cryo tanks and the 'event'?

And is it right to say that it wasn't an explosion but a build up of pressure that ruptured the O2 tank and caused the SM panel to be forced off?

moorouge
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posted 03-26-2014 01:21 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by robsouth:
And is it right to say that it wasn't an explosion but a build up of pressure that ruptured the O2 tank and caused the SM panel to be forced off?
You are probably strictly correct. However, by this criteria one could claim also that bombs rupture rather than explode. The results are the same are they not?

Jim Behling
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posted 03-26-2014 08:29 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by moorouge:
However, by this criteria one could claim also that bombs rupture rather than explode. The results are the same are they not?
That would only be a lie for school children.

Jeff
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posted 03-26-2014 09:22 AM     Click Here to See the Profile for Jeff   Click Here to Email Jeff     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by moorouge:
The results are the same are they not?
Completely depends on whether you’re speaking of a High order detonation or a Low order detonation.

moorouge
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posted 03-26-2014 11:41 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Jim Behling:
That would only be a lie for school children.

Gonzo
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posted 03-26-2014 03:12 PM     Click Here to See the Profile for Gonzo   Click Here to Email Gonzo     Edit/Delete Message   Reply w/Quote
Don't EVEN go there again...

They aren't the same. Bombs explode. It's an intentional, uncontrolled chain reaction where nothing is holding it back.

Vessels rupture due to an excessive build-up of internal pressure.

So the vessel did not "explode" in a technical sense. It ruptured in a big way.

Blackarrow
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posted 03-26-2014 06:27 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
All of this would be very clear to those of you who wrote to NASA in June, 1970, for a free copy of the "Report of Apollo 13 Review Board."

moorouge
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posted 03-27-2014 06:39 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by Gonzo:
So the vessel did not "explode" in a technical sense. It ruptured in a big way.
To quote the Bard - "A rose by any other name would smell as sweet."

Whether rupture or explosion, the effect on '13' was devastating. Fortunately it was neither that accounted for the police cars.

robsouth
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posted 03-31-2014 04:52 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
When did it become official that Swigert would replace Mattingly?

I have read that it was 72 hours before launch, 2 days before launch and on the Friday before the launch on Saturday.

robsouth
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posted 04-16-2014 09:14 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Were certain fuel cells linked to certain Buses? If so, could they swap them around or were they tied into that Bus?

For example, was fuel cell 3 tied into Bus B and therefore it was not able to put fuel 3 onto Bus A?

Also could O2 tanks 1 and 2 supply oxygen to any of the fuel cells or did each fuel cell have a dedicated O2 tank?

What I'm getting at is, could any O2 tank supply any fuel cell and could any fuel cell supply any Bus? Or were there only certain combinations allowed?

This is only related to the set up on Apollo 13.

moorouge
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posted 04-17-2014 03:06 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
I've no doubt that Sy will have the definitive answer to your specific query.

However, whether they could or could not manipulate the fuel cells on '13' after the rupture/explosion ( ) did not arise as they didn't know exactly what the problem was. On the ground they were dealing with symptoms and had, initially, no real idea what was exactly the root cause of the problem.

The thought processes that led to the shutting down of the fuel cells are detailed in the various anomaly reports and in the voice transcripts.

Jim Behling
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posted 04-17-2014 11:02 AM     Click Here to See the Profile for Jim Behling   Click Here to Email Jim Behling     Edit/Delete Message   Reply w/Quote
Any of the three fuel cells could power any of the two buses.

The reactants tanks were connected to a common feedline to the fuel cells. Individual fuel cells could be isolated from the feedline but not the tanks. That is why 13 had the problem. The remaining O2 tank couldn't be isolated and it bled out.

robsouth
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posted 04-23-2014 12:50 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Wasn't one of the Buses tied up to one of the Fuel Cells on Apollo 13 to prevent a similar incident to the one that happened during the Apollo 12 launch?

Also, was a master caution and warning alarm turned off that could have alerted the crew to the build up of pressure in the O2 tank?

I believe that there was a procedure for dealing with high pressure in a cryo tank.

All times are CT (US)

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