AnotherDilbert
SOC-14 1K
You are of course the complete master of your own game.
Whatever I can quote from the published material only applies to some theoretical OTU that, I fear, is not all that consistent.
Landing Atmo capable ships
- Thread starter gchuck
- Start date
Whatever I can quote from the published material only applies to some theoretical OTU that, I fear, is not all that consistent.
That is true. 33 cm equivalent hard steel is a bit more than the belt armor of a Missouri-class battleship. A thousand points from a laser rifle is not going to create a hole large enough for a person to step through in that, not from the infantry energy weapons described in Striker. Somewhere between LBB2 and Striker, the ship's hull underwent a metamorphosis of some sort, which makes it very difficult to use LBB2 and Striker in the same analysis.
Timerover51
SOC-14 5K
However, in The Chamax Plague, Double Adventure 5, the Chamax appear to have no trouble burning one meter holes in both the ship hull and bulkheads. As that is GDW published material, it would appear to rule against the idea of hull thickness equal to 33cm of armor.
Then there is the interesting snippet from the ANNIC NOVA.
Bulkheads require 1000 points of damage to put a circa one meter hole in it. Allowing for a much greater resistance with that thickness of steel, I would put the bulkhead thickness at around 20 to 25 millimeters of steel plating, as they do have to withstand explosive decompression and the pressure differential of standard pressure on one side and vacuum on the other, with a flat surface increasing the stress on the plate.
Side Note: The 12 inch/30.5cm thick armor belt of the Iowa-calss battleships was both sloped, and recessed within the hull. The outer hull plating over the armor belt was 60 pound, 1.5 inch/3.8cm, with the combined armor thickness being over 34 centimeters. From the Nevada-class to the Maryland-class battleships, US ships had a 13.5 inch or 34 centimeter thick vertical side belt of face-hardened steel.
Right, up until Striker the standard was you could cut your way into a hull. Made roleplay easier. Then for some reason Striker decided the hulls were battleship armor, which made things easier for adventures like Secret of the Ancients, where your hull has to hold up under enormous pressure and in which they declare that a civilian hull can withstand up to 1000 atmospheres pressure - impressive considering few of the canon civilian ship hulls have a shape suited to withstanding high pressure. However, that put an end to cutting one's way into a ship with one's laser rifle.
So, the milieu pretty much divides into pre-Striker, with hulls and bulkheads about an inch thick and in which an HE missile can inflict 1-6 hits, and post-Striker, with battleship hulls that would be pretty much impervious to any non-nuclear warhead you could mount on a 50-kilogram missile.
"For some reason" = High Guard. The Striker conversion ratings are not based on Book 2, they are based on Book 5.
MegaTraveller matches Book 5 and Striker, because it was a (brave) attempt at fusing the two systems together. It almost made it, too. (The original aim was to give everything hit points, so you could use one standard damage system, but they ran out of time.)
kilemall
SOC-14 5K
That isn't really a point of divergence for me, as I have come to the conclusion the missile damage is really kinetic and the HE warhead is more about the shot pattern the missile is setting up, the 1-6 is just luck of the draw as to how much of the shot cloud intercepts the ship.
AnotherDilbert
SOC-14 1K
Nothing I know of suggests that hulls were easily penetrated.
Early ship descriptions delineated limited points of entry, suggesting to me that it was not trivial to penetrate the hull.
Rules were given for penetrating bulkheads, but not for penetrating hull, again suggesting to me that it wasn't trivial.
That missiles are essentially Sidewinders, and that spaceships are unarmoured are your assumptions, not presented by canon. Early canon does not say much about this, so you can of course assume anything you want. I made other assumptions, and was not at all surprised by Striker.
Incidentally, 33 cm of hard steel equivalent is about 24 mm of bonded superdense...
Note that is takes about 50 Chamax hunters and many rounds to break through a bulkhead. It's not trivial even for aliens...
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AnotherDilbert
SOC-14 1K
A 1 kg penetrator striking at 100 km/s would hit with a kinetic energy of ~1 ton of TNT or a 0.001 kt nuke.
That is something like 1000 times the energy of a current 120 mm APDS round that easily penetrates 33 cm of hard steel equivalent.
I would agree that the kinetic energy is enough.
Not to prevent the pleasure of arguing...
Just remember that ship design rules in Traveller are allegoric (an allegory is a story in which every component is a metaphor) It would take millions of design hours to do what we do in 20 minutes. So while we use "real world words" such as runways, bulkeads... the relationship to the "real world" is tenous, analogous at best, often methaphorical. We do not design starships, we set-up story props that strike the imagination as Starships.
Ship handling in CT or T5, for one thing, does not make difference between an empty and a loaded ship. G3 is G3 loaded or light. CT does not make allowance for mass as different of volume. A 400 dt subsidized merchant ship is built as an empty wharehouse while a 400 dt SDB (or any warship) is likely packed as tight as possible with gear, redundant systems, extra compartment and bulkeads and stores. Yet save for weapons, armor(which account for extra bulkeads without saying so) and computer there is no "overcharge for military standard of efficiency, redundancy and damage control" (Although T5 get close to it if you "overbuild" your ship by business standards). Even when talking Armor, do we reffer to shell, structural, subdivision, combined effect, overall vs critical vs selective? I see only "Armor Points". Fine with me, more room for my imagination.
So really, I hope you do as you please.
Have fun
Selandia
Just remember that ship design rules in Traveller are allegoric (an allegory is a story in which every component is a metaphor) It would take millions of design hours to do what we do in 20 minutes. So while we use "real world words" such as runways, bulkeads... the relationship to the "real world" is tenous, analogous at best, often methaphorical. We do not design starships, we set-up story props that strike the imagination as Starships.
Ship handling in CT or T5, for one thing, does not make difference between an empty and a loaded ship. G3 is G3 loaded or light. CT does not make allowance for mass as different of volume. A 400 dt subsidized merchant ship is built as an empty wharehouse while a 400 dt SDB (or any warship) is likely packed as tight as possible with gear, redundant systems, extra compartment and bulkeads and stores. Yet save for weapons, armor(which account for extra bulkeads without saying so) and computer there is no "overcharge for military standard of efficiency, redundancy and damage control" (Although T5 get close to it if you "overbuild" your ship by business standards). Even when talking Armor, do we reffer to shell, structural, subdivision, combined effect, overall vs critical vs selective? I see only "Armor Points". Fine with me, more room for my imagination.
So really, I hope you do as you please.
Have fun
Selandia
mike wightman
SOC-14 10K
Traders and Gunboats - the hull is equivalent to a bulkhead:
shaunhilburn
SOC-12
Realistically, spacecraft radiation shielding would be comprised of inner and outer steel hulls each about 1/2 inch thickness, with about 4 inches of borated polyethylene filler. Look it up - its a common shielding material used in laboratory accelerators and nuclear powerplants.
Such shielding is much lighter than the misconception of "battleship armor". Furthermore, spacecraft in vacuum won't experience blast effects from thermonuclear weapons except at ranges of a few dozen meters.
I *can *see the need for a pressure-resistant hull, but no more than the limit at which explorers would need a heliated EVA breathing mixture at high pressure; probably no more that 6 atmosphere.
A 1000 point for a person sized hole how much just to perforate said bulkhead?
Timerover51
SOC-14 5K
Looking at The Traveller Book, the damage for a laser carbine is 4D, for a laser rifle is 5D, while all of the following weapons do 3D of damage: body pistol, automatic pistol, revolver, carbine, rifle, and automatic rifle, and submachine gun. The shotgun does 4D damage, but I think that it is safe to discount that as a bulkhead penetrating weapon. I have no idea as to why all of the projectile-firing weapons save the shotgun have the same damage rating.
Based on my data from penetration of plating in World War 2, you should be able to make a pinhole perforation with about 10 points of damage. The problem with that is it would mean that a pinhole perforation should be possible with small arms fire from weapons equivalent to the US .30-06 cartridge or the NATO 7.62mm, using AP ammunition. A pinhole leak would be sufficient to depressurize a compartment, but it would take some time, and would assume that nothing would end up blocking the leak.
The World War 2 British .303 AP round and the US .30 caliber had the probability of penetrating seven-tenths of an inch of Special Treated Steel (light armor) with a 5% probability at close range (about 100 yards) and normal 90 degree angle impact. Mild steel penetration of both rounds under the same conditions was on the order of one inch. The US .50 AP round of World War 2 could perforate over an inch of Homogenous Armor Plate at 200 yards. Current hard-core ammunition will do better.
The 40mm High-Explosive Dual-Purpose grenade for the M-79 or M-203 grenade launchers would also be able to make at least a pinhole perforation of the bulkhead, and likely more on the order of an inch in diameter.
I go with one inch/25mm bulkheads in my ships to stop the small arm rounds completely even at close range. If I have an 80 foot/24 meter diameter cylindrical hull of HY-80 steel, which approximates World War 2 light armor plating, I would have a large safely margin for an operational rating of 3 atmospheres pressure with a potential collapse rating of 6 atmospheres pressure. I say a large safely margin as US World War 2 submarine hulls made of vanadium alloy steel rated at about 50,000 pounds yield point of seven-eights inch thickness for a 16 foot diameter hull were rated for an operational depth of 450 feel and a collapse depth of 900 feet. Hull strength varies directly with diameter. It should be noted that the Subsidized Freighter in Traders and Gunboats has a maximum diameter of 15 meters. With that hull diameter, my standard thickness would have a much larger operating margin. I also assume a thin outer hull with insulation between.
I tend to use cylindrical hulls for the best strength-to-weight ratio, similar to submarine practice. I can flattened the hulls to a degree without loosing too much in terms of safety.
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AnotherDilbert
SOC-14 1K
AnotherDilbert
SOC-14 1K
Starships are not submarines.
Traveller starships regularly travel at >100 km/s and >1000 km/s on long interplanetary trips. At that speed a 1 kg micrometeoroid would hit with the energy of a 0.1 kt nuke.
Such large micrometeoroids are rare, but even a 10 g fragment would hit with the energy of a tonne of TNT.
Real armour has its uses, in addition to the radiation shielding of course...
Timerover51
SOC-14 5K
Your 10 gram fragment would penetrate your 33cm of armor plate.
Your 33 centimeters of armor plate is just about 13 inches of steel plating. An inch thickness of steel plating weighs 40 pounds (approximately) per square foot, so your 33 centimeters/13 inches of plating would weigh 520 pounds per square foot or over 2.5 metric tons per square meter of hull. Bending that thickness of plating would not be possible, so every piece of hull plating would have to be formed when it was still hot. Now, that weight would not include all of the needed supporting structure simply for the weight involved, not counting additional support if intended to stop some form of impact attack. I have not calculated the surface area of one of the standard star ships in Traveller, but over 2.5 tons of mass per square meter is going to add up really fast, and is also going to cost a lot more than the given hull cost.
As for it taking 100 points of damage to make a pinhole leak in a bulkhead, while taking only 1000 points of damage for a roughly meter size hole, that is what I call picking numbers off of the ceiling. Do you have any hard data to support such a claim, besides the rules of course?
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Or you can use the statement from Beltstrike and allow a active maneuver drive make the ship immune to that sorta stuff.
AnotherDilbert
SOC-14 1K
A TL15 starship would have something like 24 mm of bonded superdense armour (which would be roughly 330 mm hard steel equivalent), not ancient submarine steel.
I agree those numbers are probably picked out of thin air, but then so is your assumption of inch-thick outdated submarine hull.
Using real data is great, and I am thankful for what you have shown us.
But I'm not completely convinced that report covers neither bonded superdense armour nor laser weapons.
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AnotherDilbert
SOC-14 1K
This is after Striker, when canon already clearly mandated strong hulls.Or you can use the statement from Beltstrike and allow a active maneuver drive make the ship immune to that sorta stuff.
If you want thin hulls, just say the magic words: "IMTU ..."
High Guard was entirely abstract. Nothing to base numbers on. About the only thing I can think of is that they needed something that stood more than a snowball's chance against a nuke, else nukes would have been the ultimate weapon in that game. I do agree that High Guard hints at a much stronger hull, but there's not enough to High Guard to base concrete numbers on.
Semi-agreed. More likely kinetic than anything else. Book 2 gives you the 1-6 with potential to damage the power plant, jump drive, maneuver drive, computer, and so forth, but Book 5 only gives you a single weaker impact - you could damage the maneuver drive, but the plant, jump drive, and computer are out of reach. Clearly there's some degree of divergence.
Well, as with many things Traveller, there are the odd bits that create headaches. Through most of the adventures, bulkheads describe the interior structural partitions. However, there's one bit that defines the bulkhead to include the rear hull: Introductory Adventure, The Imperial Fringe.
"The port side of the aft bulkhead contains an iris valve which leads into the now empty commo bay (room 13). A retractable ladder reaches to the ground when extended. This entry is the main point of access to the ship when it is landed on a hospitable world. ... The starboard side of the aft bulkhead contains a large sliding panel door opening into the air/raft storage bay (room 14)."
It's easy to infer from that description that the hull is being considered a bulkhead - and as this is the first adventure many players encounter, it's easy to draw the conclusion that the thousand point penetrations they discuss later for bulkheads also applies to the hull.
Then there's the Traders and Gunboats reference cited by Mike, which seems pretty straightforward.
Then, there are the chamax you discussed and Timerover cited (I love that pair of adventures). Their ship's hull is described as, "resistant to damage as any starship bulkhead, with 1000 hit points being required for a breach." When they attack a ship, "Ship bulkheads require 1000 points to breach, interior walls 100 points. The holes made by acid action will be about 1 meter across,..." Same values as for penetrating bulkheads and partitions by laser. The description of Shaarin Challenger makes clear there are meter-wide hull breaches, as does the description of the unfortunate sunward-bound pinnace, but the only value the gamemaster is given for dealing with any attacks on a hull that might occur during play is that ship bulkhead value.
Since 1000 points is not likely to carve a man-size hole in battleship armor, it's pretty clear the pre-Striker armor was not of the same caliber as post-Striker armor. It was probably more like what shaunhilburn is describing, or possibly some variation on a Whipple shield.
