Starship crush depth;

[Blue Ghost]

This is a follow up to my resurrection of the old "Operational Depth" thread. My thought here is that people probably don't want to wade through the miles of posts in the old thread, and want to get to the heart of the matter.

Back in 2009 Hemdian noted that in Adventure 13 "Signal GK"; Commercial vessels (traders, merchants, liners) can withstand up to 1,000° K and up to 1,000 atmospheres. Military vessels can handle temperatures to 1,500° K and pressures to 2,000 atmospheres. System defense boats are specifically constructed to handle temperatures to 2,500° K and pressures to 3,000 atmospheres.
I just looked at my reprint of the classic adventures, and indeed there's a chart there with a this little factoid.

I'm having a hard time coming to grips with this. Even for the far future this seems very unreasonable, particularly with all of the usual caveats about weakpoints like airlocks and fittings for maneuver drive exhaust, turrets, and other weak points around the ship.

I really need some people to weigh on this. Does there need to be an official ruling on this, or is this rule good as is?

*EDIT* I meant Adventure 12, "Secret of the Ancients"

 

[HG_B]

Even for the far future this seems very unreasonable, particularly with all of the usual caveats about weakpoints like airlocks and fittings for maneuver drive exhaust, turrets, and other weak points around the ship.

I really need some people to weigh on this. Does there need to be an official ruling on this, or is this rule good as is?

Unless you are using rocket drives, there is no exhaust outlets. With the enormous strength of Trav ship hulls, 3000 atmos. is easy peasy.

 

[Fovean]

I believe 3000 atm would be around the 20km (give or take a few km) mark on an earth-like world with standard density H20, or appx 20,000 meters (60,000 feet). We recently (2012, let's say TL8) saw a specially designed submersible get to about 11,000 meters (roughly 32,000 feet) which is appx 1000 atm so I think by the time you're in a TL12 SDB, 3000 atm would be well within suspension-of-disbelief.

http://news.nationalgeographic.com/...rench-challenger-deepest-returns-science-sub/

 

[HG_B]

I believe 3000 atm would be around the 20km (give or take a few km) mark on an earth-like world with standard density H20, or appx 20,000 meters (60,000 feet). We recently (2012, let's say TL8) saw a specially designed submersible get to about 11,000 meters (roughly 32,000 feet) which is appx 1000 atm so I think by the time you're in a TL12 SDB, 3000 atm would be well within suspension-of-disbelief.

http://news.nationalgeographic.com/...rench-challenger-deepest-returns-science-sub/

We did the Mariana Trench in 1960 (TL 6)
http://en.wikipedia.org/wiki/Bathyscaphe_Trieste

 

[Fovean]

True that, the Cameron excursion was the first thing that popped into my head.

 

[Drakon]

Farnsworth's input

I am reminded of an exchange during an episode of Futurama. "Well, it's a spaceship, so somewhere between 0 and 1 atmosphere."

But seriously folks 1 atmosphere every 33 feet or 10 meters. So 3,000 atmosphere is 30 Kilometers.

 

[aramis]

Unless you are using rocket drives, there is no exhaust outlets. With the enormous strength of Trav ship hulls, 3000 atmos. is easy peasy.

To be somewhat snarky, and misapplying a quote: Fr Steven says, "The Doors! The Doors! In Wisdom, be attentive!"

I'd use about 1/10 the pressure limits given in A12. Mostly due to the doors.

Keep in mind: the Deepsea Challenger, tested to 11000m depth equivalent (16500 PSI = 114 MPa) Remember: 10 Bar=1MPa=10.1325 Atm. It's pressure hull is 64mm (2.5") thick. So, 64mm of steel is good, in a sphere, for 1125atm. A typical space hull is equivalent (according to MT and Striker) to 330mm, but not being a cylinder nor sphere, is probably worth about 1/10 that. And that would be half the thickness and half the pressure resistance. So, about 560 Atm.

But I can't be certain.

The doors, however, are considerably thinner. Even if of BSD, the doors are not full thickness, and appear to be about 1/3 thickness at best (irises being about 2-3cm thick).

 

[HG_B]

A typical space hull is equivalent (according to MT and Striker) to 330mm, but not being a cylinder nor sphere, is probably worth about 1/10 that. And that would be half the thickness and half the pressure resistance. So, about 560 Atm.

That's only for CT. Other versions have the strength tremendously higher than that. WAY higher.

 

[Blue Ghost]

Unless you are using rocket drives, there is no exhaust outlets. With the enormous strength of Trav ship hulls, 3000 atmos. is easy peasy.

Every traveller ship I've ever seen, except for the Annic Nova, has "rocket like" exhaust ports The venerable flying wedge scout ship is the one most seen from the back.

I knew I shouldn't have dismissed the thread as unresolved, because now I'm really flumoxed by all this.

 

[Blue Ghost]

To be somewhat snarky, and misapplying a quote: Fr Steven says, "The Doors! The Doors! In Wisdom, be attentive!"

I'd use about 1/10 the pressure limits given in A12. Mostly due to the doors.

Keep in mind: the Deepsea Challenger, tested to 11000m depth equivalent (16500 PSI = 114 MPa) Remember: 10 Bar=1MPa=10.1325 Atm. It's pressure hull is 64mm (2.5") thick. So, 64mm of steel is good, in a sphere, for 1125atm. A typical space hull is equivalent (according to MT and Striker) to 330mm, but not being a cylinder nor sphere, is probably worth about 1/10 that. And that would be half the thickness and half the pressure resistance. So, about 560 Atm.

But I can't be certain.

The doors, however, are considerably thinner. Even if of BSD, the doors are not full thickness, and appear to be about 1/3 thickness at best (irises being about 2-3cm thick).

Well, I need it for a proposal. I had this really cool undersea adventure all drafted up, and this little factoid puts a major hole in it. I don't want to bring up a "photon torpedo" debate here, and propose rewriting the game, but, is there any chance that those rules were written strictly for that adventure under special circumstances, and really don't apply to aqueous environments like sea water? Any chance at all?

 

[robject]

Sure. Allow that "submersible" hulls can be specified during design.

 

[HG_B]

Every traveller ship I've ever seen, except for the Annic Nova, has "rocket like" exhaust ports The venerable flying wedge scout ship is the one most seen from the back.

That's because the artists who drew them were not versed in the ship design rules. So, just dismiss them as having anything to do with how Trav ships work & are made.

 

[Blue Ghost]

That's because the artists who drew them were not versed in the ship design rules. So, just dismiss them as having anything to do with how Trav ships work & are made.

HG_B; er, no. Sorry, not gonna happen. You may want to revisit the rules yourself.

 

[HG_B]

HG_B; er, no. Sorry, not gonna happen. You may want to revisit the rules yourself.

No need. CT 1st Ed ('77) was the only one that had a rocket. Past that, no. YOU are deficient in Trav knowledge.

 

[Carlobrand]

...Back in 2009 Hemdian noted that in Adventure 13 "Signal GK"; Commercial vessels (traders, merchants, liners) can withstand up to 1,000° K and up to 1,000 atmospheres. Military vessels can handle temperatures to 1,500° K and pressures to 2,000 atmospheres. System defense boats are specifically constructed to handle temperatures to 2,500° K and pressures to 3,000 atmospheres.
I just looked at my reprint of the classic adventures, and indeed there's a chart there with a this little factoid. ...

Uh, where exactly is that in the book? I can't find.

 

[Lycanorukke]

Uh, where exactly is that in the book? I can't find.

It's the wrong book I think.

I found the numbers on p18 of Adventure 12: Secret of the Ancients.

 

[Blue Ghost]

Yeah, it's in adventure 12, sorry about that.

 

[tjoneslo]

To be somewhat snarky, and misapplying a quote: Fr Steven says, "The Doors! The Doors! In Wisdom, be attentive!"

I'd use about 1/10 the pressure limits given in A12. Mostly due to the doors.

The doors, however, are considerably thinner. Even if of BSD, the doors are not full thickness, and appear to be about 1/3 thickness at best (irises being about 2-3cm thick).

I disagree with this assessment. The reason for building an SBD to withstand 3K atmospheres is a side effect of having a significant layer of armor to withstand enemy fire. If you don't armor the doors to the same level as the rest of the craft, they become an obvious weak point for weapons fire. That seems like a huge design flaw.

 

[leo knight]

I seem to rcall something from back in the day about SDBs loitering in gas giants. Could this, and wilderness refueling, justify the hull strength?

 

[Blue Ghost]

No need. CT 1st Ed ('77) was the only one that had a rocket. Past that, no. YOU are deficient in Trav knowledge.

You know what, dude? I'm not going to start a flame war here. In all the years I've been playing and reading the material it's always thrusters. Heck, even the deck plans show them.

The issues been somewhat resolved, but I'm going to do more research and see what T5 comes up with regarding this issue.

I mean, if a ship can withstand that much pressure and extreme temperatures, then ... well, it doesn't leave a whole lot of challenge for a variety of situations. I brought up Venus because it's essentially got a "liquid" atmosphere that's superheated and corrosive. If that's the case, then, well, there wouldn't be much challenge in going there.

Other bits of a ship I would think would suffer; antenna, pito tubes (if there are any), sensor arrays of a variety of sorts, missile/turret hatches/tubes/barrels, thin parts of the air frame, etc.

Just me.