Approximating High-Tech and Ultra-Tech with Spaceships

[sir_pudding]

Originally Posted by ericbsmith

Armor/Volume rule only takes it from dDR 5 to dDR6, since five units of armor doesn't significantly increase dDR. If using my optional rules for partial dDR a SM+5 streamlined ship would qualify for dDR 1.5 each, giving dDR 7.5 for five systems of Light Alloy, and a final dDR 9 after adding them together and multiplying for Armor/Volume.

Isn't that ridiculously high DR for an aircraft?

[ericbsmith]

Originally Posted by sir_pudding

Isn't that ridiculously high DR for an aircraft?

It's basically a "pilots bathtub" which is how some fighter craft are designed (most notably the A-10 Warthog, but I do believe that other fighters have some armor surrounding the cockpit). It doesn't cover any of the other systems in this design at all. Honestly, I'd probably go with just a couple armor systems over the cockpit section and leave the rest of the plane unarmored.

[Michael Thayne]

Okay, here's a submarine I designed with little reference to real-world subs, designed to be used by a supervillain and a small crew if henchmen, primarily as a getaway vehicle or for smuggling.

After I'd finished designing it, I looked up stats for real attack subs. Turns out it's tiny compared to them. That makes sense for a supervillain who doesn't just have a few billion to blow on a single vehicle, and/or needs to construct it in secret. I was inspired to include torpedo tubes after reading about torpedos being used by drug smugglers, but of course those could also be used for terrorism.

TL 8
SM +7

Front
[1-2] Metallic Laminate Armor (12 dDR)
[3] Control Room
[4] Torpedo Tubes (Major Battery)
[5] Enhanced Array
[6] Habitat (two cabins, intended for officers)

Central
[1-2] Metallic Laminate Armor (12 dDR)
[3] Submarine Ballast Tanks
[4-5] Habitat (four bunkrooms, intended for crew)
[6] Fission Reactor (provides one power point)
[core] Fission Reactor (provides one power point)

Rear
[1-2] Metallic Laminate Armor (12 dDR)
[3] Engine Room
[4-5!] Screw Propellers
[6] Fission Reactor (provides one power point)
[core] Fission Reactor (provides one power point)

Options: Nautical Lines, Stealth Hull
Cost: $10.1M

Oddly, Pyramid #3/34 has no rules for sonar—I assumed it costs the same as normal sensors, which seems fair given that in Ultra-Tech sonar is actually cheaper than radar.

The sub is 90 feet long. Based on this errata, it should be able to dive to a depth of 2000 feet.

[Michael Thayne]

Hmmm... you know, I played around with the numbers some, and based on the assumption that the standard unstreamlined spaceship is a cylinder with the length given on Spaceships p. 9, it looks like steel armor only gives about 2/3 of the DR it should. Based on the Cutting Edge issue of Pyramid, the "light alloy" comes out better, but still only 85% of what it again ideally should give. I wonder if this explains a lot of the apparent inconsistencies between Spaceships and other sources re: armor?

[Michael Thayne]

On closer inspection, it looks like the armor stats in Spaceships are just consistently ~5/6 of what you'd derive from the various "Armor Design" Pyramid articles. NBD if you're looking for something quick and dirty, but I suspect the latter were chosen with an eye on making RAW Battlesuits feasible (as soon as we get rules for Battlesuit servomotors...) So GMs should probably feel comfortable bumping up spaceship DR about 20% when necessary.

[The_Ryujin]

Originally Posted by Michael Thayne

On closer inspection, it looks like the armor stats in Spaceships are just consistently ~5/6 of what you'd derive from the various "Armor Design" Pyramid articles. NBD if you're looking for something quick and dirty, but I suspect the latter were chosen with an eye on making RAW Battlesuits feasible (as soon as we get rules for Battlesuit servomotors...) So GMs should probably feel comfortable bumping up spaceship DR about 20% when necessary.

The armors in Spaceships are, as far as I can tell, based on the simple Ultra-Tech assumption that TL9 armor has a WM of 0.135, TL10 armor has a WM of 0.09, TL11 has a WM of 0.06 and TL12 has a WM of 0.4. Also keep in mind that the numbers tend to be rounded off a lot in these books.

To give you an example, the baseline idea for the ships in the series were that they were unstreamlined cylinders like most of the ships in Transhuman Space.

A SM +5 30 tons ship is 45ft long and would have a volume of 3,000 cubic feet. This means that it's end caps are about 9ft across. This gives it a a surface area of ~1,436 square feet.

Now in order to completely cover a ship, you need 1 armor in each of a ships three sections. For a 30tons ships this means it would need 9,000lbs of armor to match the values to match the armor stats listed in the books.

If we give the ship TL9 Advanced Metallic Laminate, at SM+5 it would have DR50 which whould weight 1,437×50×0.135 = 9,692lbs... a bit much but not that far off.

However there's a reason for this.

GURPS normally follows a 1.5 based progression and since TL10 Nanocomposite would give it DR70, TL9 armor should give it only ~DR46.7. Plugging that into the equation gives us 9,052lbs. A close enough match!

At TL10, Nanocomposite would give it DR70 and a WM of 0.09 which gives us 9,046lbs. Once again, right about on target.

TL11 Diamondoid would give it DR100 and a WM of 0.06. This gives us only 8,615lbs worth of armor but one again if we follow the 1.5 progression then diamondoid should have DR105 and that gives us 9,046lbs again!

TL12 Exotic Laminate has DR 150 and a WM of 0.04 which gives us a final weight of 8,615 again and as you probably have guess by now it's DR should be 157.5 which once again gives 9,046lbs.

So if you want to custom armor you spaceships, remember that they got the surface area of cylinder that has a volume of (ships weight in pounds/20) cubic feet.

[Michael Thayne]

Originally Posted by The_Ryujin

The armors in Spaceships are, as far as I can tell, based on the simple Ultra-Tech assumption that TL9 armor has a WM of 0.135, TL10 armor has a WM of 0.09, TL11 has a WM of 0.06 and TL12 has a WM of 0.4. Also keep in mind that the numbers tend to be rounded off a lot in these books.

To give you an example, the baseline idea for the ships in the series were that they were unstreamlined cylinders like most of the ships in Transhuman Space.

A SM +5 30 tons ship is 45ft long and would have a volume of 3,000 cubic feet. This means that it's end caps are about 9ft across. This gives it a a surface area of ~1,436 square feet.

Now in order to completely cover a ship, you need 1 armor in each of a ships three sections. For a 30tons ships this means it would need 9,000lbs of armor to match the values to match the armor stats listed in the books.

If we give the ship TL9 Advanced Metallic Laminate, at SM+5 it would have DR50 which whould weight 1,437×50×0.135 = 9,692lbs... a bit much but not that far off.

However there's a reason for this.

GURPS normally follows a 1.5 based progression and since TL10 Nanocomposite would give it DR70, TL9 armor should give it only ~DR46.7. Plugging that into the equation gives us 9,052lbs. A close enough match!

At TL10, Nanocomposite would give it DR70 and a WM of 0.09 which gives us 9,046lbs. Once again, right about on target.

TL11 Diamondoid would give it DR100 and a WM of 0.06. This gives us only 8,615lbs worth of armor but one again if we follow the 1.5 progression then diamondoid should have DR105 and that gives us 9,046lbs again!

TL12 Exotic Laminate has DR 150 and a WM of 0.04 which gives us a final weight of 8,615 again and as you probably have guess by now it's DR should be 157.5 which once again gives 9,046lbs.

So if you want to custom armor you spaceships, remember that they got the surface area of cylinder that has a volume of (ships weight in pounds/20) cubic feet.

How did you get that volume figure? It looks like you're assuming a density of 20 lbs. per cubic foot. However, that 30 ton weight statistic is loaded weight. Water is about 60 lbs. per cubic foot. Few common materials are 1/3 the density of water, 40% to 120% is more common for hydrocarbons and organic matter. And an ore hauler will be hauling cargo significantly more dense than water—silica is 2.65x as dense as water, metals can be 8x as dense as water or more. So if you're looking to make an assumption about spaceship density, assuming 60 lbs. per cubic foot is probably better as a simplified approximation.

(In the end, though, you seem to have reached a similar conclusion to what I did about Spaceship armor WM. Probably a good mathematical reason for this that I'm too lazy to figure out right now.)

[RyanW]

Originally Posted by Michael Thayne

And an ore hauler will be hauling cargo significantly more dense than water—silica is 2.65x as dense as water, metals can be 8x as dense as water or more.

When I created some house rules for armor density before the Pyramid version was published, I think I used 7x for steel, 1x for ice and organic, and 3x for everything else.

[Michael Thayne]

Hmmm, I played around with creating an SM +3, TL 7 sedan, in part using the mecha rules from Pyramid #3/40. Initial sketch:

Steel Armor x3 (5 DR not dDR, I think TL6 cars are unstreamlined but by TL7 they count as streamlined)
Control Room
Passenger Seat x3 (No Life Support)
Internal Combustion Engine
Wheeled Drive Train
Cargo (300 lbs.—I think the stat in the Pyramid article was supposed to be "0.15 tons", not "0.015 tons")
Maneuver Enhancement (maybe 2 of these)

This leaves a lot of extra space—though Spaceships assumes SM 3 ships are 3 tons, which is high for a car. Even if you up the number of space needed for passengers / cargo, though, you still end up with a fair amount of extra spaces. Nice for a spy car though!

(EDIT: Actually, what Spaceships would call a SM+3 vehicle is just about perfect for an SUV. Double the size of the engine, add more passengers / cargo, maybe some extra fuel, and the result is surprisingly realistic.)

[Michael Thayne]

TLDR; Spaceships is more consistent with the rest of GURPS than it's widely given credit for. You just sometimes need to increase armor values by anywhere from 10% to 50%.