Commercial starship lifeboat requirements

[PFVA63]

You can disagree, but you are wrong. I say this as a pilot - military and civilian. If you (as a military pilot, since civilian aircraft generally aren't equipped with ejection seats) ever ejected because your life support were compromised, you would be read the riot act by your commander, decertified as a pilot, and, at a minimum, given a non-judicial punishment. The correct action would be to simply descend below 10,000 feet and breathe ambient air. The ONLY time that ejection was appropriate was an unrecoverable out-of-control aircraft - basically if the aircraft was already a guaranteed loss and the only choice now was whether the military would lose a pilot, too.

Hi,

Here is a reference to a report entitled "Loss of cabin pressurization in U.S. Naval aircraft: 1969-90". The abstract for this document notes that;

"During the 22-year period from 1 January 1969 to 31 December 1990, there were 205 reported cases of loss of cabin pressure in US Naval aircraft; 21 were crew-initiated and 184 were deemed accidental. The ambient altitudes varied from 10,000 ft (3048 m) to 40,000 ft. (12192 m). The most common reason for crew-initiated decompression was to clear smoke and fumes from the cockpit/cabin (95%). The most common cause for accidental loss of cabin pressure was mechanical (73.37%), with aircraft structural damage accounting for the remaining 26.63%. Serious physiological problems included 1 pneumothorax, 11 cases of Type I decompression sickness, 23 cases of mild to moderate hypoxia with no loss of consciousness, 18 cases of hypoxia with loss of consciousness, and 3 lost aircraft with 4 fatalities due to incapacitation by hypoxia. In addition, 12 ejections were attributed to loss of cockpit pressure. Nine of the ejections were deliberate and three were accidental, caused by wind blast activation of the face curtain. Three aviators lost their lives following ejection and seven aircraft were lost. While the incidence of loss of cabin pressure in Naval aircraft appears low, it none-the-less presents a definite risk to the aircrew. Lectures on the loss of cabin/cockpit pressurization should continue during indoctrination and refresher physiology training."

Hi,

As shown above, the report makes mention not only of the loss of three aircraft (with four fatalities) due to "incapacitation by hypoxia", but also goes on to note that there were also nine cases of deliberate ejections "attributed to the loss of cockpit pressure."

As such it appears to me that "abandoning" an aircraft that has lost its 'life support' abilities can lead to a loss of life through hypoxia. And in addition to this over the period of time of that report there have been documented incidents where the crew has ejected due to the loss of the cockpit pressure part of their life support systems.

http://www.ncbi.nlm.nih.gov/pubmed/1599378

 

[PFVA63]

If you yourself are finding sources that suggest air change rates as low as 10 per hour, why are you still insisting on using the 20-30/hour rate? Your own sources suggest that's only appropriate in machine spaces. And even 10 sounds high:

http://en.wikipedia.org/wiki/Air_changes_per_hour

MegaTraveller has some data on life support power requirements that might help you understand a bit better. MegaTraveller requires 0.001 Mw per cubic meter of hull space - 1000 watts per cubic meter. As with your example, most take that as not including the fuel space, there being little opportunity to breathe air in a compartment designed to store liquid hydrogen. So, taking your 714 cubic meters, the little ship is allocating 714 kilowatts to manage the atmosphere and water systems. That alone would power a few hundred homes. Skylab ran to 283 cubic meters, and it got by on 8 kilowatts for everything. That should tell you there's lots of power available for cooling.

Here's another idea to think about:

V/T=k

V1/T1=V2/T2

Fancy way of saying that if you compress a gas, it heats up. So, to heat a given volume of air, you compress it: the more you compress it, the hotter it gets. Then when you want to cool it, you let the pressure off; if you return it to its previous volume, it will have the same temperature it previously had at that volume, less whatever was lost while you were doing it. Doesn't take any time at all - the temperature MUST fall as the air expands.

Hi,

Additional documentation that I posted about also indicated that for a submarine a total exchange rate of about 24 changes/hour was used and that on commercial aircraft 20 to 30 air changes an hour is used. Since the approximately 10 air changes per hour for Skylab, Mir, an the ISS are for vehicles/stations with only limited operational machinery onboard, I chose the 20 to 30 value as it seemed more appropriate, but you can chose any number that you wish if you like.

Looking at the number previously provided, the amount of heat and power required to raise the temperature of dry air from room temperature (say about 75 deg F or 24 deg C, 297 K) to about 2000 K can be calculated. One site that I saw on the internet suggested that since the specific heat capacity of dry air will change over this range it may be best to do this step-wise over small temperature increments.

Doing so, based on the equation that required heat energy will equal the mass of air (in kg) times the temperature change times the specific heat capacity of the air for the step, then from the info on this site ( http://www.engineeringtoolbox.com/dry-air-properties-d_973.html ) it appears that heating 848 kg of dry air from say 297 K to 300 K would take 1826 kJ. And going from 300 K to 325 K would take another 15232 kJ, etc.

If I have done the math right then, the sum of all the sub steps of going from 297 K to 2000 K appear to be 1,243,385 kJ (or 1,243 MJ). Which, if I did the conversion correctly would equal 345.4 kW-hr.

As such, I believe that would mean that if you try and do all this heating over a 1 minute period this would take 20.7 MW of power assuming perfect efficiency. In addition, if it were to take another minute to cool the air down from 2000 K back to room temperature, then the total 2 minute time period required would mean that all of the air onboard the ship would be involved in either being heated up or cooled down.

If instead we assume a much shorter time period to heat the air of say 10 seconds so that the total time that the air is being heated or cooled (and hence volume/mass) is limited (once again assuming that my math is correct) it appears to me that this would require 124.3 MW of power assuming ideal efficiency.

As for Skylab, I do not believe that they heated their air up to an extremely high temperature and then re-cooled it. In general, I believe that there would likely be a big difference between the power required for basic life support and that for heating of the air onboard to a very high temperature and then cooling it.

 

[PFVA63]

Hi,

In digging a little deeper in some of the Traveller stuff I have I came across a couple additional things that might be of interest.

Specifically, in the GURPS Traveller 'World Tamer's Handbook" there is a section on diseases with notional lengths of time for incubation, periods of activity and recovery. There are also rules for diagnosis and treatment as well.

Looking at the table provided in that booklet it appears that the incubation for different types of diseases can range from 1 to 90 days in those rules, with active periods ranging from 5 to 150 days and recovery periods from 2 to 360 days.

Also in Mongoose's "Starports" book they make specific reference to a situation where;

"Spores from an exotic species of a plant have found a way onboard the Player Character's ship and started to germinate."

This book also goes on to note another "Adventure Seed where some spores have infiltrated the systems of a starport noting that "The Starport's ventilation system is a prime location" for these spores and what they grow in to. While not specifically a starship, it appears that the ventilation system of this starport can be susceptible to infestations by spores etc.

 

[aramis]

1) WTH is TNE, not GURPS.
2)Mongoose writes/edits from a very NON-simulationist perspective. A lot of "rule of Cool" inclusions are present despite making no sense at all. Just look at the BS on the space encounters table... a 1/36 chance of "Alien Derelict"?
3) Most of mongoose is not OTU. Unless it says "Third Imperium" it's not talking about the OTU.

Your choice of sources (and misreferencing them) is dubious. (Oh, and the only hit when I googled to make certain SJG hadn't reused the WTH name was to a torrent file's list of contents...)

 

[rancke]

Also in Mongoose's "Starports" book they make specific reference to a situation where;

"Spores from an exotic species of a plant have found a way onboard the Player Character's ship and started to germinate."

The player characters appear to have been criminally lax in their decontamination procedures. Procedures that are so ubiquitous and so effective that they're not even mentioned in any of the rules or setting material but simply taken for granted.

This book also goes on to note another "Adventure Seed where some spores have infiltrated the systems of a starport noting that "The Starport's ventilation system is a prime location" for these spores and what they grow in to. While not specifically a starship, it appears that the ventilation system of this starport can be susceptible to infestations by spores etc.

The contractor would appear to have used a sub-standard ventillation system, probably expecting to get away with it because a ventillation system for a starport on a world with breathable air is a lot less critical than a life support system.

(And how do I know the starport is on a world with breathable atmosphere? Because if the air wasn't breathable, the starport would have had a life support system instead of a ventillation system).


Hans

 

[PFVA63]

1) WTH is TNE, not GURPS.
2)Mongoose writes/edits from a very NON-simulationist perspective. A lot of "rule of Cool" inclusions are present despite making no sense at all. Just look at the BS on the space encounters table... a 1/36 chance of "Alien Derelict"?
3) Most of mongoose is not OTU. Unless it says "Third Imperium" it's not talking about the OTU.

Your choice of sources (and misreferencing them) is dubious. (Oh, and the only hit when I googled to make certain SJG hadn't reused the WTH name was to a torrent file's list of contents...)

Hi,

The reference to the GURPS instead of TNE was just an honest mistake, and I'm not really sure I see what is specifically dubious about making such a mistake unless you are trying to imply that you believe that I am using a pirated copy of the books off of a torrent file. (If you somehow think that I do not have a copy of these books, I can easily send you a photo of both of them). As for the Mongoose Starports book it specifically state "The Third Imperium" on the cover.

PS. In fact, looking through my books and such, it appears that I actually have two copies of the World Tamer's Handbook, as I had bought them at different times, having forgot that I had previously picked up a copy off eBay earlier. Both TNE and the basic Traveller GURPS settings were not systems that I used much, but over time I did pick up the basic rules and some additional titles produced for both systems, for reference. I do however quite like the GURPS Traveller: Interstellar Wars book.

[Edit]PPS. Rather than wait, here are copies of two photos of my copy of the books in question, one showing the covers and the other showing two of the specific sections in question.

 

[PFVA63]

The player characters appear to have been criminally lax in their decontamination procedures. Procedures that are so ubiquitous and so effective that they're not even mentioned in any of the rules or setting material but simply taken for granted.



The contractor would appear to have used a sub-standard ventillation system, probably expecting to get away with it because a ventillation system for a starport on a world with breathable air is a lot less critical than a life support system.

(And how do I know the starport is on a world with breathable atmosphere? Because if the air wasn't breathable, the starport would have had a life support system instead of a ventillation system).


Hans

Hi,

I suspect that you could take interpret the info any such way that you wish. However, since the specific reference comes out of a 1D6 table relating to a "Pests in Residence" table in the Starport Encounters section of the booklet, (specifically appearing under the "Infestation" heading of the "Significant Encounters" table) it appears to be a potential result for any player ship.


As for the location of the starport in question, it is listed as being in the Rhylatinople Highport above Rhylanor. It is described as an "entirely self sufficient star city" and that "Its sealed habitat is sustained by more than 20 bio-domes which cleanse the air of carbon dioxide and generate vast quantities of oxygen."

 

[Fritz_Brown]

As shown above, the report makes mention not only of the loss of three aircraft (with four fatalities) due to "incapacitation by hypoxia",

Do you know what hypoxia is? It's a lack of oxygen - and when used in this case indicates incapacitation of the aircrew. In other words, the aircraft crashed because no one was flying it anymore. The reason they died was they either failed to notice the situation or they failed to properly correct it. So, inapplicable to your scenario.

As such it appears to me that "abandoning" an aircraft that has lost its 'life support' abilities can lead to a loss of life through hypoxia.

I'm sure you mean that the other way around, so I'll address it in that fashion. Yes, hypoxia can kill you - but only if you don't take care of it. That would almost always be by: descent below 10,000 feet and breathing ambient air. Not really a good reason to eject with such a simple solution.

And in addition to this over the period of time of that report there have been documented incidents where the crew has ejected due to the loss of the cockpit pressure part of their life support systems.

First, since 1/4 of those cited incidents (the accidental ones) were due to aircraft structural damage, we can ascertain that at least some of those were not going to be controllable in landing - meaning a crash. So, yes, the US Navy will advise the crew to eject - it's that whole "unrecoverable out-of-control flight" condition. That accounts for some of the ejections.

Nine of the ejections were deliberate and three were accidental, caused by wind blast activation of the face curtain.

Do you know what those were? They were cases of the canopy being torn off the aircraft or something like a bird entering the canopy. These people 1) didn't leave the craft willingly, and 2) were likely dead before ejection. I think we can scratch those 3 off the list. (These would be akin to claiming a "lifeboat" scenario when the bridge was ripped from the ship; sorry, no.)

there were 205 reported cases of loss of cabin pressure in US Naval aircraft; 21 were crew-initiated and 184 were deemed accidental.

Now, let's look at numbers: 205 cases of "loss of cabin pressure", but only 9 deliberate ejections. First, you have to reduce the number of ejections, as it's obvious that some of them were multi-seat aircraft (12 total ejections with 7 aircraft lost = ~5 that were multi-seat). If you intelligently assume that all 3 of the accidental ejections were losses, you get 4 aircraft lost due to loss of cabin pressure. So, 4 out of 205... works out to 1.95%. (BTW, the numbers for ejections falls well within the number for "aircraft structural damage" - it's very likely all of the ejections were due to this reason.)

Now, none of this points to proper procedure when confronting loss of cabin pressure. It only states what has happened (you have to be very careful when citing abstracts, particularly where aviation safety mishaps are concerned - there are assumptions made in language that many laymen fail to grasp), not what should have happened. Hmmm, but there is a hint here about that issue, where it says:

Lectures on the loss of cabin/cockpit pressurization should continue during indoctrination and refresher physiology training.

Yep, that's right, they need to continue to be trained on what the proper procedure is. Because it isn't "bailout, bailout, bailout". And, I will guarantee you that any crews who did eject based on simple loss of cabin pressure* were given re-training (that is, they were de-certified) as to proper procedure before being allowed back in the cockpit, and likely disciplined.

I will caveat my previous statement with one consideration: the US Navy is more willing to eject from a damaged aircraft in cases that an US Air Force pilot would land. This is because of the inherent problems and dangers of landing an aircraft on a moving postage stamp in the ocean, constrained by a lack of fuel to remain airborne. However, in no case should a simple loss of cabin pressure cause an unlandable condition. This difference in landing sites changes the equation from one that is not an unrecoverable out-of-control flight situation to one that is.

* I keep insisting on "simple loss of cabin pressure" because there are plenty of things that will complicate matters: contamination of the emergency oxygen supply (like some idiot put regular air in there, or there's oil in the liquid oxygen), structural damage, fire, etc. However, my original statement still stands: the only reason to eject (or bailout) is if you can't put the aircraft safely on the ground.

One other note: "loss of cabin pressure" is not the same thing as a taint in life support in a starship. It is a case of actually losing your atmosphere to the outside vacuum. This is a much different scenario than "oh dear, there's a virus running loose." Of course, even then, you wouldn't abandon ship - nor even lock yourselves in somewhere - you would use your emergency gear to handle the situation. Hmmm, why does that sound familiar?

that you could use the lifeboat/lifepod as a 'safe haven' and potential escape craft for those who have not shown signs of the disease.

Again: why do you need a 'safe haven' that allows escape from the ship in this scenario? Also, are you putting crew in these things? If so, who the heck is running the ship?

By segregating those that appear in an infectious state from those that are not currently exhibiting signs of an illness the thought would be that you could potentially delay or avoid the infection from spreading.

And, no one has argued with that. We've simply pointed out that it is an extremely silly suggestion that you do that with lifeboats.

As for lifeboats in Traveller, a couple people have already noted the description of some of the examples currently in Traveller Canon.

And, I believe that most have also pointed to the fact that there really isn't a good reason for them (except possibly in military craft). The fact that some exist (much like the fact that some people have ejected from perfectly good aircraft) doesn't mean that they should exist by dint of reason and logic.

BTW, back here:

As I've tried to note there may be many times were a lifeboat/lifepod may also serve as a 'safe haven' very similar in fact to how the Lunar Module of Apollo 13 was said to have served as a 'lifeboat' to the crew of the stricken command module during their mission eventhough it never separated from the command module until it was discarded prior to re-entry.

You commit a fallacy. Just because they called the Lunar Module a "lifeboat" doesn't mean it actually served as one (nor was designed as one). A failure of someone to adequately express themselves does not now mean that any "safe haven" is called a "lifeboat". They did not use the LM as a lifeboat, they used it as a refuge until they could recover the craft. And, since they never could have (as far as I know) used the craft for re-entry, it never could have really been considered a lifeboat at all - unless you think they could have orbited earth in it while they waited for another craft to come up and get them (and that wouldn't have worked).

As a suggestion, actually go back and re-read the hundreds of posts responding to your scenarios/ideas. Try and learn from them. The people who wrote most of them are knowledgeable individuals who have a great breadth and depth of experience. I've learned quite a bit in my 9 years here. (Though still not enough to understand vehicle/robot building in CT. :nonono: )

 

[Fritz_Brown]

and I'm not really sure I see what is specifically dubious about making such a mistake unless you are trying to imply that you believe that I am using a pirated copy of the books off of a torrent file.

Aramis said "dubious", not "nefarious". It meant your choice of those particular books, rather than something with more standing in canon. The reference to "torrent" was to ensure that the GURPS folks hadn't somewhere used "WTH" in their writings - he found out he was right. He was checking his own memory/reasoning against solid sources. It's something you should try.

 

[PFVA63]

Do you know what hypoxia is? It's a lack of oxygen - and when used in this case indicates incapacitation of the aircrew. In other words, the aircraft crashed because no one was flying it anymore. The reason they died was they either failed to notice the situation or they failed to properly correct it. So, inapplicable to your scenario....

Hi,

Yes I am familiar with the term hypoxia, and I believe that you overlooked one additional item. It may also be that the crew of an airplane was aware of an issue but were unable to correct it in time. It is my understanding that cabin pressurization exists specifically to support the crew and that the loss of cabin/cockpit pressure would therefor be a loss of a life support system, and is such it seems very muchly applicable to me to the topic in question.

...I'm sure you mean that the other way around, so I'll address it in that fashion. Yes, hypoxia can kill you - but only if you don't take care of it. That would almost always be by: descent below 10,000 feet and breathing ambient air. Not really a good reason to eject with such a simple solution....

Hi, what I meant to say was;

"As such it appears to me that "abandoning" an aircraft that has lost its 'life support' abilities (such as the loss of cabin pressure which can lead to a loss of life through hypoxia) is a valid option."

Although you mention decent to an altitude below 10,000 feet it is not specifically clear that this could always be accomplished, especially if initially flying at a relatively high altitude.

...Do you know what those were? They were cases of the canopy being torn off the aircraft or something like a bird entering the canopy. These people 1) didn't leave the craft willingly, and 2) were likely dead before ejection. I think we can scratch those 3 off the list. (These would be akin to claiming a "lifeboat" scenario when the bridge was ripped from the ship; sorry, no.)...

I do not believe that I suggested considering them. I specifically tried to focus on the specific cases of deliberate ejection.

...Now, let's look at numbers: 205 cases of "loss of cabin pressure", but only 9 deliberate ejections. First, you have to reduce the number of ejections, as it's obvious that some of them were multi-seat aircraft (12 total ejections with 7 aircraft lost = ~5 that were multi-seat). If you intelligently assume that all 3 of the accidental ejections were losses, you get 4 aircraft lost due to loss of cabin pressure. So, 4 out of 205... works out to 1.95%. (BTW, the numbers for ejections falls well within the number for "aircraft structural damage" - it's very likely all of the ejections were due to this reason.)...

I would rather see more specific information before jumping to such broad conclusions as I suspect that more information is likely available.

...Now, none of this points to proper procedure when confronting loss of cabin pressure. It only states what has happened (you have to be very careful when citing abstracts, particularly where aviation safety mishaps are concerned - there are assumptions made in language that many laymen fail to grasp), not what should have happened. Hmmm, but there is a hint here about that issue, where it says: ....

Yep, that's right, they need to continue to be trained on what the proper procedure is. Because it isn't "bailout, bailout, bailout". And, I will guarantee you that any crews who did eject based on simple loss of cabin pressure* were given re-training (that is, they were de-certified) as to proper procedure before being allowed back in the cockpit, and likely disciplined....

I never said that the procedure would be to "bailout, bailout, bailout" but rather there were situations where pilots did bail out of their aircraft after the loss of cabin/cockpit pressure (which I presume they likely did for a very good reason).

...I will caveat my previous statement with one consideration: the US Navy is more willing to eject from a damaged aircraft in cases that an US Air Force pilot would land. This is because of the inherent problems and dangers of landing an aircraft on a moving postage stamp in the ocean, constrained by a lack of fuel to remain airborne. However, in no case should a simple loss of cabin pressure cause an unlandable condition. This difference in landing sites changes the equation from one that is not an unrecoverable out-of-control flight situation to one that is.

* I keep insisting on "simple loss of cabin pressure" because there are plenty of things that will complicate matters: contamination of the emergency oxygen supply (like some idiot put regular air in there, or there's oil in the liquid oxygen), structural damage, fire, etc. However, my original statement still stands: the only reason to eject (or bailout) is if you can't put the aircraft safely on the ground....

And my concern here would be that if the pilot is concerned that he may loose consciousness before safely reaching a breathable atmosphere etc, bailing out may be a very valid option.

...One other note: "loss of cabin pressure" is not the same thing as a taint in life support in a starship. It is a case of actually losing your atmosphere to the outside vacuum. This is a much different scenario than "oh dear, there's a virus running loose." Of course, even then, you wouldn't abandon ship - nor even lock yourselves in somewhere - you would use your emergency gear to handle the situation. Hmmm, why does that sound familiar?...

I used the examples of aircraft, ships, cars and houses as real world examples of specific cases where a person may well 'abandon' a very high value item in specific response to concerns about people abandoning multi-million (or even multi-hundred million) credit starships.

...Again: why do you need a 'safe haven' that allows escape from the ship in this scenario? Also, are you putting crew in these things? If so, who the heck is running the ship?...

Hi,

I was not the 1st person to suggest a 'safe haven' but rather (if I am recalling correctly) it was proposed by others as a means of dealing with certain issues on a starship rather than having to have a lifeboat/lifepod or other such craft.

...And, no one has argued with that. We've simply pointed out that it is an extremely silly suggestion that you do that with lifeboats....

I disagree.

...And, I believe that most have also pointed to the fact that there really isn't a good reason for them (except possibly in military craft). The fact that some exist (much like the fact that some people have ejected from perfectly good aircraft) doesn't mean that they should exist by dint of reason and logic....

I believe that ships that also carry a large number of passengers would specifically also make good candidates for the carriage of additional small craft/lifeboats/lifepods etc (for just one example)

...BTW, back here:

You commit a fallacy. Just because they called the Lunar Module a "lifeboat" doesn't mean it actually served as one (nor was designed as one). A failure of someone to adequately express themselves does not now mean that any "safe haven" is called a "lifeboat". They did not use the LM as a lifeboat, they used it as a refuge until they could recover the craft. And, since they never could have (as far as I know) used the craft for re-entry, it never could have really been considered a lifeboat at all - unless you think they could have orbited earth in it while they waited for another craft to come up and get them (and that wouldn't have worked).

...

Hi, I do not believe that to be a fallacy. Specifically it appears that it was a craft used as a lifesaving device, providing the necessary life support systems that the command module was unable to provide.

 

[Carlobrand]

Hi,

Additional documentation that I posted about also indicated that for a submarine a total exchange rate of about 24 changes/hour was used and that on commercial aircraft 20 to 30 air changes an hour is used. Since the approximately 10 air changes per hour for Skylab, Mir, an the ISS are for vehicles/stations with only limited operational machinery onboard, I chose the 20 to 30 value as it seemed more appropriate, but you can chose any number that you wish if you like.

Your figures for - a WW-II sub? - are for a crowded environment dominated by machinery. Traveller gives us an environment in which each person is allocated a space of 54 cubic meters, and most of that walls except in the drive room and bridge.

The reason you're changing air in the first place is air quality. In a space dominated by machinery, there is a need to push through air at a high rate to carry off heat and odors and such from the machinery. Same applies in a commercial kitchen or a basement parking garage - two areas featured in my link that have air change rates of 15-30 per hour. Skylab's 10 served a structure constructed with computer and science equipment that required a fairly controlled environment for optimal performance. A classroom - a setting with 20 or so souls in a space of perhaps 10 or so square meters - can be served by 3 or 4 air changes per hour; that might be appropriate for a passenger lounge. Atpollard's 0.35, if I have it right, serves spaces like a hotel room or other setting where occupancy is light; that would be appropriate for passenger rooms and hallways.

...Looking at the number previously provided, the amount of heat and power required to raise the temperature of dry air from room temperature (say about 75 deg F or 24 deg C, 297 K) to about 2000 K can be calculated. One site that I saw on the internet suggested that since the specific heat capacity of dry air will change over this range it may be best to do this step-wise over small temperature increments.
....

2000 k? 2273 C? 4123 F?

So, that we all understand: you're using an air change figure 10 times higher than needed and a temperature four or five times higher than suggested in your effort to prove that you're right.

 

[Fritz_Brown]

Yes I am familiar with the term hypoxia, and I believe that you overlooked one additional item. It may also be that the crew of an airplane was aware of an issue but were unable to correct it in time. It is my understanding that cabin pressurization exists specifically to support the crew and that the loss of cabin/cockpit pressure would therefor be a loss of a life support system, and is such it seems very muchly applicable to me to the topic in question.

Your scenario is specifically about what to do when the situation is noticed and handled. So, no, not the same.

But, let's look at it: if they fail to correct the situation, how will bailing out improve the situation? In only one case could it - when the pilot dies or goes totally unconscious from hypoxia in some aircraft in which there is no ability to land the aircraft from the other seat. Even then, the aircraft would be flown to a lower altitude if possible, and an attempt to wake the pilot made, before abandoning the aircraft (likely only when fuel totally ran out). Again, however, this goes back not to a situation of "loss of cabin pressure" or even "loss of life support" - it goes back to an unrecoverable, out-of-control flight situation.

Although you mention decent to an altitude below 10,000 feet it is not specifically clear that this could always be accomplished, especially if initially flying at a relatively high altitude.

Which is why you should listen to those who know what they are talking about. If they cannot descend to a lower altitude in time, then ejecting from the aircraft will surely kill them - since the ejection system will carry them through the same thin atmosphere ... and at a much slower rate than an emergency descent in an aircraft.

I would rather see more specific information before jumping to such broad conclusions as I suspect that more information is likely available.

No jumping involved at all. I flew military aircraft for a number of years. I KNOW that this abstract is giving information which can only be deciphered by someone familiar with aircraft mishaps. You can look for more information on the internet if you so desire, but I don't understand why you would do so when you already have someone knowledgeable on the subject discussing it with you.

BTW, in case my opinion is inadequate, I polled three aircraft crewmembers in my office - their experience includes F4s, RF4s, KC-135s, B-52s and B1s - and every last one of them said the same thing: they would never leave an otherwise functioning aircraft if their sole problem was a loss of cabin pressure or a contaminated O2 system. Every last one of them had the same reaction I did concerning the abstract you quoted, and to the idea of ejecting because you couldn't reach a lower altitude quickly enough. If that's inadequate, I can go around the building and ask all the other fighter/bomber pilots/WSOs/OSOs/navigators who work here.

I never said that the procedure would be to "bailout, bailout, bailout" but rather there were situations where pilots did bail out of their aircraft after the loss of cabin/cockpit pressure (which I presume they likely did for a very good reason).

In this context, yes, you are - by definition - arguing about what should be done. I stated in the beginning that someone might do so, and they would be in trouble for doing so solely on the basis of a loss of cabin pressure. As to a "good reason", I explained there were good reasons - but they weren't loss of cabin pressure.

And my concern here would be that if the pilot is concerned that he may loose consciousness before safely reaching a breathable atmosphere etc, bailing out may be a very valid option.

See above.

I used the examples of aircraft, ships, cars and houses as real world examples of specific cases where a person may well 'abandon' a very high value item in specific response to concerns about people abandoning multi-million (or even multi-hundred million) credit starships.

No. Read the rest of what I wrote - specifically, the fictional example from the Imperial Lancet.

it was proposed by others as a means of dealing with certain issues on a starship rather than having to have a lifeboat/lifepod or other such craft.

Yes, it was proposed as an alternative to the lifeboat issue, since lifeboats don't make much sense in your scenario.

I disagree.

Duh. We're explaining why that disagreement is unfounded.

I believe that ships that also carry a large number of passengers would specifically also make good candidates for the carriage of additional small craft/lifeboats/lifepods etc (for just one example)

And, it has been explained time and again that there are very few good reasons to abandon a spacecraft at all, and all of those involve actual destruction of the spacecraft such that existence in small, vulnerable, scattered units is preferable. Many of us have postulated that even those reasons (for civilian craft) are so infrequent that the carrying of lifeboats is economically unsound.

Oh, and stop tossing in "small craft". If we're talking lifeboats being carried, they are dedicated space that cannot be used for other purposes. A "small craft" is carried for other purposes, but could serve as a "lifeboat" in extremis. They are not the same thing when arguing whether they should be carried.

I do not believe that to be a fallacy.

Fine. Believe what you want - but it is a fallacy. If I call you a kumquat, that doesn't make you one, and it is a fallacy to believe otherwise.

 

[CosmicGamer]

The ONLY time that ejection was appropriate was an unrecoverable out-of-control aircraft - basically if the aircraft was already a guaranteed loss and the only choice now was whether the military would lose a pilot, too.

And if there is still some small amount of control, it is not uncommon for a pilot to stay with the plane to ensure it does not crash in a populated area.

If what is known to be a undetectable in early stage and untreatable and uncontainable disease do you get on a lifeboat not knowing if you've brought on board possibly contaminated environment and people thus risking spreading the disease to yourself, rescue vessels, and further for the small chance you get lucky and somehow are able to flee and save your skin or do you do the noble thing

For overall safety of the larger population, would the government or some other organization require life boats based on diseases? Risk increased spread of a deadly disease?

Perhaps an adventure is to see if the characters side with crew that mutiny and fleeing passengers or the captain who will do whatever possible to prevent any spread of the disease off the ship.

Summary:
A disease has panic factor so might trigger some to flee but unstoppable deadly diseases do not seam like a logical reason for organizations to support having a lifeboat. If the issue is a failure of the life support system, I'd think combat damage, electronics failure or whatever other reasons for failure would be more likely than disease - assuming a poor design where the life support system is centralized and not multiple independent systems for different portions of the ship.

 

[Fritz_Brown]

assuming a poor design where the life support system is centralized and not multiple independent systems for different portions of the ship.

And, without any sort of emergency equipment - like vacc suits and rescue balls. (You can always shut it all down and have everyone in a contained environment.)

 

[Carlobrand]

Your image -

...

...

- brings to mind a problem I hadn't considered. Given that the ship routinely cools power plant products that reach tens of millions of degrees, I think you are grossly underestimating the ship's ability to cool air quickly. However, we've been arguing for compartmentalization. Having a bunch of lines from different compartments feed back to the power plant, as the image shows, kinda creates a problem for that concept. A hit on one part of the ship or on the power plant could damage those lines or damage the atmospheric recycling element within the power plant, resulting in life support failure in several compartments far removed from the point of damage.

If we want to treat each compartment as sufficient within itself, then its air recycling system ideally should not transit through other sections. In that case, your image changes from one with lines concentrating on the power plant to one with several distinct and separate closed systems, but they wouldn't be able to take advantage of the power plant's heat output or cooling systems.

I considered incorporating "hot lines" with some working fluid to carry heat back to the separate systems, but that still makes them dependent on the power plant as a possible point of failure: power plant goes, and you're stuck using some alternate method of generating heat, powered by your batteries or solar or whatever emergency power grid you have. If one decides to go that route, then it's easier to use power from the power plant to power that system than to run some uber-hot working fluid through tubes in your ship and risk a line break flash-cooking some hapless passenger.

That loses the advantage of free heat and cooling (unless you're in something small that has very few compartments, like a boat). However, we are still left with a fairly generous 1000 watts per cubic meter - less whatever the water system's needing - with which to sterilize and recondition our air. With that budget, I remain confident that we could come up with some system that could make sure a virus or bacteria that got sucked into the intake wouldn't survive the trip to the outflow vents.

Any recycling system has to break carbon dioxide molecules up in order to provide the needed O2 - unless we're suggesting the ship isn't doing that but is living off stored O2 instead (which creates big problems in other ways). Now, we can come up with ways of doing that without hurting the poor little bacteria if we want, but I don't see why a ship designer would do that when he could instead kill two birds with one stone. I remain confident that a far-future designer would use methods that would also make his air system deadly for bacteria. Especially after their unfortunate contact with those filthy Terrans, Vilani society would have been looking at that problem for many centuries - it would surprise me greatly if they had not come up with some solution by the time of the founding of the Imperium.

 

[CosmicGamer]

If the issue is a failure of the life support system, I'd think combat damage, electronics failure or whatever other reasons for failure would be more likely than disease - assuming a poor design where the life support system is centralized and not multiple independent systems for different portions of the ship.

The underlined is an assumption needed for the life support system to be easily compromised to the point where it is a possible danger.

And, without any sort of emergency equipment - like vacc suits and rescue balls. (You can always shut it all down and have everyone in a contained environment.)

This, and numerous other possibilities, including the life boats, are the solutions once the ships life support is somehow compromised. Unfortunately some solutions are very short term unless additional preparations are made ahead of time.

 

[atpollard]

[Edit]PPS. Rather than wait, here are copies of two photos of my copy of the books in question, one showing the covers and the other showing two of the specific sections in question.

... but no pictures of you holding a newspaper as proof of life. I suspect time lords may be involved. o:

OK, just kidding.

 

[PFVA63]

... but no pictures of you holding a newspaper as proof of life. I suspect time lords may be involved. o:

OK, just kidding.

I like that

 

[PFVA63]

Your figures for - a WW-II sub? - are for a crowded environment dominated by machinery. Traveller gives us an environment in which each person is allocated a space of 54 cubic meters, and most of that walls except in the drive room and bridge. ...

In addition to the submarine data, I have also provided info that shows a 20-30 change per hour rate for modern passenger aircraft, and data typically used on modern surface ships.

If you wish to do a more complex estimate based on the specific spaces that could also easily be done.

...The reason you're changing air in the first place is air quality. In a space dominated by machinery, there is a need to push through air at a high rate to carry off heat and odors and such from the machinery. Same applies in a commercial kitchen or a basement parking garage - two areas featured in my link that have air change rates of 15-30 per hour. Skylab's 10 served a structure constructed with computer and science equipment that required a fairly controlled environment for optimal performance. A classroom - a setting with 20 or so souls in a space of perhaps 10 or so square meters - can be served by 3 or 4 air changes per hour; that might be appropriate for a passenger lounge. Atpollard's 0.35, if I have it right, serves spaces like a hotel room or other setting where occupancy is light; that would be appropriate for passenger rooms and hallways. ...

Hi, I posted on this somewhere before but a I recall in addition to air quality is the need to provide adequate circulation to prevent 'dead spots' where moisture or gases can collect. Also, since we are talking about a fully enclosed environment the air flow will provide the actual cooling for many spaces, for example.

Here is a source, which I have posted previously ( www.gl-group.com/infoServices/rules/pdfs/gl_i-1-21_e.pdf‎ ) for modern commercial surface ships.

...2000 k? 2273 C? 4123 F? ...

I originally assumed a temperature of only a few hundred degrees F and, if I am recalling correctly, you claimed that was too low a temperature. As I noted in a previous post, if there are other values that you would wish, we could easily look at those. As I have indicated previously, the 2000 K value was chosen as the highest value that seemed reasonable base on your assertions that the plant could put out multi-thousand degree temperatures.

...So, that we all understand: you're using an air change figure 10 times higher than needed and a temperature four or five times higher than suggested in your effort to prove that you're right....

I disagree. specifically I believe that values for modern ships and planes will likely be much more suitable and similar to a space ship than those used for land architectural uses, where the "deck heights' may be different (especially for the ground floor).

As for the Skylab, it is my understanding that the actual amount of electronics onboard was fairly low, and nothing like the 1 dton of computers that may likely be on a 100 dton ship.

Additionally, Skylab appears that it was basically a fairly simply laid out space, no where as complex in its lay out as most deckplans that I have seen for Trvaller type ships.

As such, I do not agree that the number of air changes per hour is "10 times higher than needed ' nor that the temperature is "four or five times higher than suggested".

As I have noted previously, I have provided initial estimates based on the discussions on this board and what I think are reasonable starting points. If alternate numbers are thought to be better those can be looked at.

 

[PFVA63]

Your image -

- brings to mind a problem I hadn't considered. Given that the ship routinely cools power plant products that reach tens of millions of degrees, I think you are grossly underestimating the ship's ability to cool air quickly. However, we've been arguing for compartmentalization. Having a bunch of lines from different compartments feed back to the power plant, as the image shows, kinda creates a problem for that concept. A hit on one part of the ship or on the power plant could damage those lines or damage the atmospheric recycling element within the power plant, resulting in life support failure in several compartments far removed from the point of damage.

If we want to treat each compartment as sufficient within itself, then its air recycling system ideally should not transit through other sections. In that case, your image changes from one with lines concentrating on the power plant to one with several distinct and separate closed systems, but they wouldn't be able to take advantage of the power plant's heat output or cooling systems.

I considered incorporating "hot lines" with some working fluid to carry heat back to the separate systems, but that still makes them dependent on the power plant as a possible point of failure: power plant goes, and you're stuck using some alternate method of generating heat, powered by your batteries or solar or whatever emergency power grid you have. If one decides to go that route, then it's easier to use power from the power plant to power that system than to run some uber-hot working fluid through tubes in your ship and risk a line break flash-cooking some hapless passenger.

That loses the advantage of free heat and cooling (unless you're in something small that has very few compartments, like a boat). However, we are still left with a fairly generous 1000 watts per cubic meter - less whatever the water system's needing - with which to sterilize and recondition our air. With that budget, I remain confident that we could come up with some system that could make sure a virus or bacteria that got sucked into the intake wouldn't survive the trip to the outflow vents.

Any recycling system has to break carbon dioxide molecules up in order to provide the needed O2 - unless we're suggesting the ship isn't doing that but is living off stored O2 instead (which creates big problems in other ways). Now, we can come up with ways of doing that without hurting the poor little bacteria if we want, but I don't see why a ship designer would do that when he could instead kill two birds with one stone. I remain confident that a far-future designer would use methods that would also make his air system deadly for bacteria. Especially after their unfortunate contact with those filthy Terrans, Vilani society would have been looking at that problem for many centuries - it would surprise me greatly if they had not come up with some solution by the time of the founding of the Imperium.

Hi,

I believe that I had noted this previously specifically noting how difficult/unlikely it would be to try and provide multiple sets of piping/ducting for given systems.

If you would wish to try and sketch up something showing how you would suggest trying to run both air supply and return systems as well as water piping and sanitation to all sections of a ship while trying to avoid others, I would be interested in seeing that.