bluekieran
Mongoose
snrdg121408 said:
I think it's pointing out that an (external) cargo hatch is not an airlock.
Cargo bays and vacuum
- Thread starter Annatar Giftbringer
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I think it's pointing out that an (external) cargo hatch is not an airlock.
Reynard
Emperor Mongoose
Right, it's a big door that seals against the elements until opened. The cargo is not protected if the doors are opened. Ships that regularly must be exposed to adverse environmental conditions without external protection would most likely need be equipped with cargo airlocks so portions of cargo can be passed through without exposing the entire shipment. Expensive in both cost and loss of ship displacement. It would need to be very special to incur such a need.
The description in the books does say an airlock has machinery to pump atmosphere in and out of the space. I'm assuming(?) this isn't normally possible in other portions of a ship. That said, no pumping the air from a cargo hold before opening the hatch then replacing it once sealed again.
There is mention you can use an airlock as a security measure but the passageways and rooms to be evacuated must be connected back to the airlock. I can imagine bridge personnel opening a succession of iris valve portals through bulkheads then opening the airlock. Any non hatch or iris valve portal and any interior walls would not be proof against such decompression.
The description in the books does say an airlock has machinery to pump atmosphere in and out of the space. I'm assuming(?) this isn't normally possible in other portions of a ship. That said, no pumping the air from a cargo hold before opening the hatch then replacing it once sealed again.
There is mention you can use an airlock as a security measure but the passageways and rooms to be evacuated must be connected back to the airlock. I can imagine bridge personnel opening a succession of iris valve portals through bulkheads then opening the airlock. Any non hatch or iris valve portal and any interior walls would not be proof against such decompression.
bluekieran
Mongoose
Reynard said:
I imagine you'd have some O2 and N stored in liquid form to maintain pressure in the case of minor leaks, perhaps enough to re-pressurise the bay once or twice. After that, if you have the patience, you could use the airlock system to pump into the emptied bottles (even if you have to jury-rig some pipe), assuming you keep the inner door and the route to the cargo bay open.
snrdg121408
Mongoose
Morning PST bluekieran and Reynard,
I appear to be on a different page for this discussion and need to restart my comments.
Looking at the deck plans, which do not include how the plumbing, air/heating ducting and wire bundles are laid out, and record sheets in MgT HG 2e PDF 09/0116 the designs all appear to have pressurized cargo holds that have, presumably, air-tight hatches allowing access to the cargo bay and other compartments. My guess is that the penetrations in the bulkheads for plumbing, air/heating, and wire bundles can be sealed isolating each compartment. Technically, the wiring runs are passing through fittings that are isolate each compartment from the start. (Note that most of the basic theory is based on my twenty years in the USN on submarines and one surface ship.)
1. Closing a ship's hatches allows the environmental ducting to circulate and in theory equalize the atmospheric pressure within the hull. On the ships that do not have an external cargo hatch closing the ducts and plumbing lines to the compartments that need to stay pressurized, leaving the air/heating ducts and iris valve/manual hatch open while isolating the plumbing near an airlock I think one could depressurize the cargo hold. The problem is that access to the compartments normally connected through the cargo bay are not accessible. I also feel that if the air-tight hatch is manually operated that someone would be in a vacc suit to close the hatch and re-pressurize the space near the airlock.
2. On ships that have an external cargo hatch isolating all the ducts, plumbing, securing the air-tight hatches between compartments and opening the external cargo hatch would result in explosive decompression that would suck stuff out of the cargo bay that is not properly tied down. An alternate method would be to follow the same process in Item 1 above.
3. Installing airlocks at the cargo bay's access to the ship's interior would allow the bay to be de-pressurized/pressurized allowing access through the bay by personnel in vacc suits. Installation of airlocks in the cargo bay would use 2 d-tons and cost MCr0.1 per lock.
4. Make some or all of the cargo bay an airlock, with or without cargo hatches would allow the bay to be de-pressurized and pressurized much easier but at a cost of MCr0.1 and a minimum of 2 d-tons.
I appear to be on a different page for this discussion and need to restart my comments.
Looking at the deck plans, which do not include how the plumbing, air/heating ducting and wire bundles are laid out, and record sheets in MgT HG 2e PDF 09/0116 the designs all appear to have pressurized cargo holds that have, presumably, air-tight hatches allowing access to the cargo bay and other compartments. My guess is that the penetrations in the bulkheads for plumbing, air/heating, and wire bundles can be sealed isolating each compartment. Technically, the wiring runs are passing through fittings that are isolate each compartment from the start. (Note that most of the basic theory is based on my twenty years in the USN on submarines and one surface ship.)
1. Closing a ship's hatches allows the environmental ducting to circulate and in theory equalize the atmospheric pressure within the hull. On the ships that do not have an external cargo hatch closing the ducts and plumbing lines to the compartments that need to stay pressurized, leaving the air/heating ducts and iris valve/manual hatch open while isolating the plumbing near an airlock I think one could depressurize the cargo hold. The problem is that access to the compartments normally connected through the cargo bay are not accessible. I also feel that if the air-tight hatch is manually operated that someone would be in a vacc suit to close the hatch and re-pressurize the space near the airlock.
2. On ships that have an external cargo hatch isolating all the ducts, plumbing, securing the air-tight hatches between compartments and opening the external cargo hatch would result in explosive decompression that would suck stuff out of the cargo bay that is not properly tied down. An alternate method would be to follow the same process in Item 1 above.
3. Installing airlocks at the cargo bay's access to the ship's interior would allow the bay to be de-pressurized/pressurized allowing access through the bay by personnel in vacc suits. Installation of airlocks in the cargo bay would use 2 d-tons and cost MCr0.1 per lock.
4. Make some or all of the cargo bay an airlock, with or without cargo hatches would allow the bay to be de-pressurized and pressurized much easier but at a cost of MCr0.1 and a minimum of 2 d-tons.
It would seem very odd to me if you could not depressurize specific areas of a starship. They operate in a vacuum and being able to evacuate the atmosphere of a section for repairs, or having to repressurize after repairs or damage should be the norm.
If you can pressurize it, and depressuriaing it, by default it's an airlock. However a cargo hold isn't going to contain all the fancy gadgets like decontamination, bad stuff analyzers, cleaning cycle, etc, that an airlock should have.
There should be some limitations (and risks) to not having an airlock, cargo or otherwise. But the function should be inherent as long as it holds pressure. The rest would be left up to the ref.
If you can pressurize it, and depressuriaing it, by default it's an airlock. However a cargo hold isn't going to contain all the fancy gadgets like decontamination, bad stuff analyzers, cleaning cycle, etc, that an airlock should have.
There should be some limitations (and risks) to not having an airlock, cargo or otherwise. But the function should be inherent as long as it holds pressure. The rest would be left up to the ref.
snrdg121408
Mongoose
Hello phavoc,
You can pressurize and depressurize the interior of an airliner but it is not an airlock.
The escape trunk on a submarine is a type of airlock since the trunk is a compartment that has a hatch at the top and a hatch at the bottom. Closing the lower hatch allows the trunk to be flooded and equalized with sea pressure allowing the upper hatch to be opened. This allows less air loss in the boat's interior and flooding. The upper hatch can be closed from inside the boat and the water removed allowing the lower hatch to be opened repeating the process.
Looking at the Traveller deck plans an airlock is a chamber with two air-tight hatches that has one hatch located on the hull separated by at least 1.5 meters is a second hatch allowing access into the ship's people compartment. With both hatches closed the chamber can be pressurized and depressurized without affecting the pressure on the spaces in the hulls interior.
Two compartments with a common bulkhead and a single hatch between them can be pressured and depressurized independently. When one compartment is depressurized you can, in theory anyway, open the hatch until the two are close to the same pressure. This is not an airlock even though the compartments can be pressurized and depressurized.
David Weber's short story Ms Midshipwoman Harrington has a detail that the passageway outside of a local weapon control station would be depressurized during combat. IIRC there are a number of other Honor Harrington stories that sections of the interior are depressurized during combat.
phavoc said:
You can pressurize and depressurize the interior of an airliner but it is not an airlock.
The escape trunk on a submarine is a type of airlock since the trunk is a compartment that has a hatch at the top and a hatch at the bottom. Closing the lower hatch allows the trunk to be flooded and equalized with sea pressure allowing the upper hatch to be opened. This allows less air loss in the boat's interior and flooding. The upper hatch can be closed from inside the boat and the water removed allowing the lower hatch to be opened repeating the process.
Looking at the Traveller deck plans an airlock is a chamber with two air-tight hatches that has one hatch located on the hull separated by at least 1.5 meters is a second hatch allowing access into the ship's people compartment. With both hatches closed the chamber can be pressurized and depressurized without affecting the pressure on the spaces in the hulls interior.
Two compartments with a common bulkhead and a single hatch between them can be pressured and depressurized independently. When one compartment is depressurized you can, in theory anyway, open the hatch until the two are close to the same pressure. This is not an airlock even though the compartments can be pressurized and depressurized.
David Weber's short story Ms Midshipwoman Harrington has a detail that the passageway outside of a local weapon control station would be depressurized during combat. IIRC there are a number of other Honor Harrington stories that sections of the interior are depressurized during combat.
snrdg121408
Mongoose
Hello infojunky,
Disregard the request below
Please provide the CT source since I seem to have missed the material when I was digging through my books. I've checked CT Adventure 5 Trillion Credit Squadron. Note to self move the FFE CT CD-ROM up the wish list.
Thank you infojunky for scaring a way the gremlins that had cloaked the information in my first few passes
CT LBB 2 Starships 2e 1977/1981 "Special Situations pp. 33-35
Decompression pp. 33-34: Starships, (and any other vessels) depressurize their interiors before combat whenever possible., the passengers and crew resorting to vacc suits for safety and comfort. This procedure minimizes the danger due to explosive decompression as a result of battle. In some cases, selected areas remain pressurized (perhaps the hold, for the safety of delicate cargo) while other areas are depressurized.
Any number of areas in the ship may be depressurized in a span of one turn (1,000 seconds). Repressurization requires one turn. In practice the following parts of the ship may be individually pressure regulated: engineering section, hold, bridge, staterooms (all as one group; on some ships, in groups of four or more), turrets (individually). The pilot controls depressurization from the bridge.
Hull hits result in explosive decompression if the pressure has not already been lowered. Explosive decompression kills all persons in that section unless a vacc suit is available and put on immediately. Throw dexterity to put on a vacc suit in an emergency; apply DMs of double the vacc suit skill."
However being able to pressure and depressurize the interior does not make it an airlock.
Infojunky said:
Disregard the request below
Please provide the CT source since I seem to have missed the material when I was digging through my books. I've checked CT Adventure 5 Trillion Credit Squadron. Note to self move the FFE CT CD-ROM up the wish list.
Thank you infojunky for scaring a way the gremlins that had cloaked the information in my first few passes
CT LBB 2 Starships 2e 1977/1981 "Special Situations pp. 33-35
Decompression pp. 33-34: Starships, (and any other vessels) depressurize their interiors before combat whenever possible., the passengers and crew resorting to vacc suits for safety and comfort. This procedure minimizes the danger due to explosive decompression as a result of battle. In some cases, selected areas remain pressurized (perhaps the hold, for the safety of delicate cargo) while other areas are depressurized.
Any number of areas in the ship may be depressurized in a span of one turn (1,000 seconds). Repressurization requires one turn. In practice the following parts of the ship may be individually pressure regulated: engineering section, hold, bridge, staterooms (all as one group; on some ships, in groups of four or more), turrets (individually). The pilot controls depressurization from the bridge.
Hull hits result in explosive decompression if the pressure has not already been lowered. Explosive decompression kills all persons in that section unless a vacc suit is available and put on immediately. Throw dexterity to put on a vacc suit in an emergency; apply DMs of double the vacc suit skill."
However being able to pressure and depressurize the interior does not make it an airlock.
snrdg121408 said:
Airliners are not spaceships. Submarines are not spaceships. The correct analogy would be either the space shuttle, the ISS, or a space capsule.
While one certainly CAN pressurize and depressurize the main cabin of an airliner, it's not meant for that. And a submarine that allows water into a compartment not built for it would cause severe damage to any item that cannot be submerged. With a few exceptions, you can expose a lot of things to a vacuum without damaging them (perishables and plants would not do well).
LHA's have well decks that can be opened and flooded, closed and drained. A spacecraft with a cargo hold should, on occassion, expect to need to open their cargo hold to deliver a cargo in a vacuum - assuming the cargo was capable of handling vacuum that is. That is the environment they operate in, thus it would not be unusual.
Airlocks function far more effectively than depressurizing an entire section, such as a cargo hold.
I've always thought that Traveller ships engaging in combat should depressurize before getting depressurized explosively by an internal hit. Explosive decompression is dangerous to anyone in the section, what with flying debris and all that. Plus since Traveller ships don't have magical force fields like they do in Star Trek or Star Wars, crews should be suiting up before combat (just like they do in the HH universe). It would be the common sense thing to do.
snrdg121408
Mongoose
Hello phavoc.
A submarine is a ship that is designed to travel through "inner space" was is another name for transiting in the crushing pressure of the ocean depths and is just as deadly as "outer space" a ship has to prevent breaking a part from the pressure differential between the vacuum of space and the ship's interior.
Regardless the discussion is pressurization and depressurization which has the same results regardless of environment or pressure.
Traveller started with a magical force field called the Black Globe Generator and MgT has the White Globe Generator. Yes they both not standard like Star Trek or Stars Wars.
Thanks to infojunky I was able to find that the combat rules in CT LBB 2 has CT ships depressurizing for combat. CT LBB 5 HG combat rules being more abstract does not, crossing my fingers gremlins are not messing with my book, appear to mention depressurizing for combat. I seem to recall that either one of the other books or JTAS mentioned something on the subject too, but so far my efforts have fallen short. With my luck I'll find the information and won't remember where to post the information.
phavoc said:
A submarine is a ship that is designed to travel through "inner space" was is another name for transiting in the crushing pressure of the ocean depths and is just as deadly as "outer space" a ship has to prevent breaking a part from the pressure differential between the vacuum of space and the ship's interior.
Regardless the discussion is pressurization and depressurization which has the same results regardless of environment or pressure.
Traveller started with a magical force field called the Black Globe Generator and MgT has the White Globe Generator. Yes they both not standard like Star Trek or Stars Wars.
Thanks to infojunky I was able to find that the combat rules in CT LBB 2 has CT ships depressurizing for combat. CT LBB 5 HG combat rules being more abstract does not, crossing my fingers gremlins are not messing with my book, appear to mention depressurizing for combat. I seem to recall that either one of the other books or JTAS mentioned something on the subject too, but so far my efforts have fallen short. With my luck I'll find the information and won't remember where to post the information.
snrdg121408
Mongoose
Hello infojunky,
No wonder why I found the information you must have transmitted the information telepathically. Thank you for the providing the material. Is TB part of the CT CD-ROM?
No wonder why I found the information you must have transmitted the information telepathically. Thank you for the providing the material. Is TB part of the CT CD-ROM?
Infojunky said:
Condottiere
Emperor Mongoose
As I recall, we used to have actual bulkhead doors.
Unlike a personnel airlock, opening up the cargo hatch exposes a very large internal area, so you'll probably want an armoured reinforced partition that would prevent anything penetrating the interior.
If you don't want to pay for or install a specific cargo airlock, you can compensate by adding a bulkhead partition, and adding a door there.
Unlike a personnel airlock, opening up the cargo hatch exposes a very large internal area, so you'll probably want an armoured reinforced partition that would prevent anything penetrating the interior.
If you don't want to pay for or install a specific cargo airlock, you can compensate by adding a bulkhead partition, and adding a door there.
Reynard
Emperor Mongoose
Most don't consider or realized there's internal bulkhead partitioning on ships and those partitions will have hatches or iris valves which are environment proof compared to interior doors and walls. Blocks of staterooms and most optional rooms will have doors and normal walls that offer no protection. CT and possibly other edition listed them with much lower damage resistance and such.
When deck plans are made, bulkhead walls should be displayed if only as a thicker line. Bridge, engineering, cargo bays, hangars and living areas can all be sectioned. The idea is to lessen the impact of decompression or as security measures. A cargo bay will have it's bay door to the outside and all doors going to the ship interior will be hatches and iris valves isolating whatever environment condition is inside.
Ship's life support circulates air through ductwork as well as flow through rooms and corridors and there would be mechanisms to shut down ducts between bulkheads in emergencies with overrides on the bridge and engineering. Same for bulkhead doors.
When deck plans are made, bulkhead walls should be displayed if only as a thicker line. Bridge, engineering, cargo bays, hangars and living areas can all be sectioned. The idea is to lessen the impact of decompression or as security measures. A cargo bay will have it's bay door to the outside and all doors going to the ship interior will be hatches and iris valves isolating whatever environment condition is inside.
Ship's life support circulates air through ductwork as well as flow through rooms and corridors and there would be mechanisms to shut down ducts between bulkheads in emergencies with overrides on the bridge and engineering. Same for bulkhead doors.
snrdg121408
Mongoose
Hello infojumky,
I have the softcover of the FFE CT books. I really need to pick up the CD-ROMS.
Infojunky said:
I have the softcover of the FFE CT books. I really need to pick up the CD-ROMS.
snrdg121408 said:
The CDs and a tablet are a dangerous combination. Since I got got my iPad, darned near my entire Traveller collection is within arms reach 24/7. (I am Such a Geek). At my desk it isn't uncommon for the bookstand, the computer screen and the tablet to have something Traveller open on it at once.
snrdg121408
Mongoose
Hello infojunky,
I surrender since my stuff is mainly hard/soft cover books with a few items stored on my computer. Thank you for the help as always.
Infojunky said:
I surrender since my stuff is mainly hard/soft cover books with a few items stored on my computer. Thank you for the help as always.
