Aramis; interesting.
HG_B; if you can provide a book title or a link, I'll happily let myself get convinced.
HG_B; if you can provide a book title or a link, I'll happily let myself get convinced.
Starship crush depth;
- Thread starter Blue Ghost
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??? Go visit a sub or warship.
Nevermind then.
Does anyone else have any constructive input?
Does anyone else have any constructive input?
Drakon
SOC-14 1K
I believe what HG is attempting to explain is that on warships, and submarines, the latching mechanism makes this a non issue, even at our pathetic tech level.
You use the submarine arraingment because the pressure gradient across the hatch in space is only one atmosphere. When one enters the atmosphere, then the pressure vector can reverse and you have the potential for a much higher pressure gradient across the hatch. So you rig the hatch to take the potentially higher pressure gradient, as the opposite issue is trivial from an engineering standpoint.
A submarine hatch will work in a vacuum better than an airline hatch will work in gas giant's atmosphere.
This should be standard for any ship designed for gas giant refuelling. It occurs to me that for many commercial vessles that will never find themselves in the bowls of a dense atmosphere it may be cheaper to rig them like an airliner.
Now, if this is not convincing, since the airlock as two doors, simply rig them in opposite directions. Then you are covered regardless of the pressure vector across the airlock, if not the individual hatch.
You use the submarine arraingment because the pressure gradient across the hatch in space is only one atmosphere. When one enters the atmosphere, then the pressure vector can reverse and you have the potential for a much higher pressure gradient across the hatch. So you rig the hatch to take the potentially higher pressure gradient, as the opposite issue is trivial from an engineering standpoint.
A submarine hatch will work in a vacuum better than an airline hatch will work in gas giant's atmosphere.
This should be standard for any ship designed for gas giant refuelling. It occurs to me that for many commercial vessles that will never find themselves in the bowls of a dense atmosphere it may be cheaper to rig them like an airliner.
Now, if this is not convincing, since the airlock as two doors, simply rig them in opposite directions. Then you are covered regardless of the pressure vector across the airlock, if not the individual hatch.
BraselC5048
SOC-8
I actually went with 1-piece sliding hatches that don't open in or out. The door tracks, and the latches, hold the door against pressure either way. That way the door can be opened against a pressure difference either way, while a hinged hatch will be impossible to open in one direction in that situation.
I also specified a 1.5 atmosphere pressure differential either way, with that being below the fatigue limit. Since I made it out of aerospace grade titanium, (in existence today), that equates to a 2.5 atmosphere pressure difference before something fails. At the usual (IMTU) 0.7 atmosphere pressure in the hull, that's 3.2 atmospheres. If you increase the pressure inside to 1.4 atmospheres, you can go into an environment of 3.9 atmospheres. Although, IMTU there's only enough air aboard the ship to pressurize the hull to 1.4 atmospheres. The walls are 1.5 cm thick, BTW, supported on 1.5 meter centers.
On the plus side, every internal wall is a pressure bulkhead good against the same pressure, so if there's a hull breach in a 2.8 atmosphere environment, it's limited to one compartment, rather then immediately wiping out everything inside the ship, as would happen on a submarine.
You could make it good against higher pressures, but (in universe) that weight is either going to come out of that available for cargo or armor. And why make it so much stronger it would need to be anyway?
Of course, anybody with crystaliron or superdense will be able to build ships stronger.
I also specified a 1.5 atmosphere pressure differential either way, with that being below the fatigue limit. Since I made it out of aerospace grade titanium, (in existence today), that equates to a 2.5 atmosphere pressure difference before something fails. At the usual (IMTU) 0.7 atmosphere pressure in the hull, that's 3.2 atmospheres. If you increase the pressure inside to 1.4 atmospheres, you can go into an environment of 3.9 atmospheres. Although, IMTU there's only enough air aboard the ship to pressurize the hull to 1.4 atmospheres. The walls are 1.5 cm thick, BTW, supported on 1.5 meter centers.
On the plus side, every internal wall is a pressure bulkhead good against the same pressure, so if there's a hull breach in a 2.8 atmosphere environment, it's limited to one compartment, rather then immediately wiping out everything inside the ship, as would happen on a submarine.
You could make it good against higher pressures, but (in universe) that weight is either going to come out of that available for cargo or armor. And why make it so much stronger it would need to be anyway?
Of course, anybody with crystaliron or superdense will be able to build ships stronger.
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Drakon
SOC-14 1K
Not a problem, the only time you need higher internal pressure is when you have higher external pressure. You can bleed external gasses into the ship, probably filtering and scrubbing it down before letting it into the ship.
Okay, that's what I didn't get. I was under the opinion that it was external hatches that were being presented as the example. Indeed, an internal hatch on a navy ship is designed to be water tight in case of a breach.
It still makes me wonder how Traveller vessels can withstand the pressures mentioned in Adventure 12.
It still makes me wonder how Traveller vessels can withstand the pressures mentioned in Adventure 12.
Easterner9504
SOC-13
The most vulnerable part of a submarine is not the hull or the hatch. It is the welding. What do you think are the odds starships do not use 20th Century welding techniques? Hatches use a system called a plug which makes them tighter under pressure not less.
http://books.google.com/books?id=8f...ssure can submarine hatches withstand&f=false
http://www.fleetsubmarine.com/phorum/read.php?f=5&i=26&t=20
http://books.google.com/books?id=8f...ssure can submarine hatches withstand&f=false
http://www.fleetsubmarine.com/phorum/read.php?f=5&i=26&t=20
Same issue with airplanes - it's the seams that fail, not the hatches.
http://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243
The fuselage failure was along rivet lines.
I've seen the Air Emergency episode of that disaster. In fact I remember the day it happened (I was still in film school at the time). Incredible incident. It makes one wonder what if something like that happened to the players' ship ... perish the thought :smirk:
Drakon
SOC-14 1K
Depends on flight profile at time of incident. During reentry, which I believe is the most stressful part of the flight, one could end like like Challenger.
Except that traveller ships do not land anything at all like the US NASA STS shuttles. Traveller ships come in with enough power to be at near-zero relative velocity to the atmosphere crossed, and to retain that near-zero profile all the way down, and can land at almost any relative velocity they choose.
STS shuttles, however, enter at 33000 km/h, has almost no thrust (a few dozen newtons worth - pretty meaningless). They have to land at under 700 km/h and do so by converting portions of the hull into hot gasses via atmospheric friction.
Funny thing, having 675 G-hours of delta-V... it makes a 2 hour landing a non-issue.
I'm thinking a starship's hull is more robust than the shuttle. Like Aramis pointed out, during the two accidents (or disasters) the space shuttle program has had, the vehicles have fallen apart where the separate pieces are attached or joined to one another. The Challenger incident is particularly interesting from an engineering standpoint as the "pilotage" or forward cabin, the living area, was blown clear. In theory an emergency drogue shoot might have slowed that section enough to allow for a hard water landing, but one in which the crew might have survived. But, who knew something like that would happen?
But, getting back on topic, the reason I brought up the topic was that I had some undersea adventures drafted which required the players to use undersea vehicles. The last thing I wanted was for the players to say "Oh, let's just take the ship down, grab the treasure and/or people trapped down there, and get back to the surface. And swap out the red artificial ruby in the ship's LASER turret for an emerald so we can zap any kaiju sized beasties we find down there. Easy!" I want the players to sweat it out a little in their vehicle as they traverse the depths of planet-X
Just me.
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