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Old 11-01-2016, 09:13 PM   #1
Michael Thayne
 
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Default Approximating High-Tech and Ultra-Tech with Spaceships

So I've been fiddling with some numbers, trying to figure out how to get more mileage out of Spaceships at least until Vehicles 4e comes along. After struggling a bit, I think you can get a pretty good approximating of a lot of vehicle and weapon stats from other books if you use the following design switches.

Tank Hull: This is a second-order option that builds on the "Armor by Facing" rules from Pyramid #3/34. Vehicles with this option are built like tanks, literally, with a relatively narrow head-on profile, and a much broader overhead profile. This means that front and rear DR is doubled, but top and underside DR is halved.

Surface Combat Ammunition: Ammunition for conventional guns and launchers can be designated "surface combat", this means it only costs $20,000 per ton, but is limited to point-blank range. Such ammunition can be given shaped-charge warheads, which to half normal damage but with Armor Divisor (10).

Example: Zhukov-class Main Battle Tank is built as a TL7, SM +5 vehicle with spaces allocated as follows:

1 Major Battery
1 Tracked Drivetrain
2 Control Room
2 Internal Combustion Engine
14 Light Alloy

It cost $500,000 and weighs 30 tons. It has the design features Tank Hull and NBC Filters Only, and generally carries surface combat ammunition. The Armor and Volume rules reduce its SM to +4, and give it 112 dDR to distribute among its six facings. We'll distribute the DR like so:

* Front: 98 dDR (counts as 49 dDR)
* Sides: 14 dDR each
* Rear: 14 dDR (counts as 7 dDR)
* Top: 8 dDR (counts as 16 dDR)
* Underside: 6 dDR (counts as 12 dDR)

Its cannon does 3dx5(2) dDamage, or 7d(10) dDamage with shaped charge warheads. All these stats compare pretty favorably to the T-72, especially given that it weighs only 2/3 of what the T-72 weighs.

Thoughts? Are there other significant gaps in the Spaceships rules for emulating other real-world vehicles (I think these rules tweaks are enough to emulate fighter jets pretty well, but I haven't checked).
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Old 11-02-2016, 12:46 AM   #2
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

Do you add extra weight for vehicles? For example, an SM+4 tank weighs as much as a SM+5 spaceship?

Because I was always thinking that spaceships are built on lighter weight hulls than planetary-based vehicles, especially when they are wheeled or tracked.
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Old 11-02-2016, 02:08 AM   #3
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

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Originally Posted by Lord Azagthoth View Post
Do you add extra weight for vehicles? For example, an SM+4 tank weighs as much as a SM+5 spaceship?

Because I was always thinking that spaceships are built on lighter weight hulls than planetary-based vehicles, especially when they are wheeled or tracked.
For that, you just need to use the armor density rules from one of the Pyramid articles. When dealing with heavily armored vehicles, general SM does not equal Spaceships SM. Since the Spaceships system is built heavily mass, you should subtract SM rather than add weight.
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Old 11-02-2016, 02:27 AM   #4
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

I don't have Pyramid. Happen to know in which issue the article is?
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Old 11-02-2016, 06:01 AM   #5
Michael Thayne
 
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

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Originally Posted by Lord Azagthoth View Post
I don't have Pyramid. Happen to know in which issue the article is?
#3/34, "Alternate Spaceships", also has the "Armor by Facing" rules, rules for "ships" with tank treads, and similar useful things.
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Old 11-02-2016, 06:24 AM   #6
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

Tnx Michael.
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Old 11-02-2016, 08:29 AM   #7
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

ugg! I was looking for this article a month or two ago. I checked all the spaceships pyramids and divergent spaceships and couldn't find it. Thought I must have dreamed it up. Thanks!

I think gurps needs a lot more vehicles, so I'm glad to see this tank. I'm particularly glad to see that it got decent results!

EDIT: oh, you came up with custom options. hmmm. I was going to suggest a different way to split up the armor, then it turned out to be a different way of saying the same thing. Any research behind the ammo numbers?
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Last edited by ericthered; 11-02-2016 at 08:37 AM.
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Old 11-02-2016, 08:42 AM   #8
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

Here's another build of a TL7 fighter jet, modeled on the F-15:

Light Alloy Armor x5 (dDR 12 for the cockpit only)
Control Room x2
Tactical Array
Defensive ECM x3
Jet Engine x2 (Afterburning Turbofan; 1 G acceleration; Top Speed 2,500 mph)
Fuel Tank x2 (Provides one hour of fuel)
Medium Battery (3 fixed mount 16cm missile launchers)
Major Battery (fixed mount with 2.5cm very rapid fire conventional gun)
Maneuver Enhancement x3

The armor is designed to protect the pilots from antiaircraft fire rather than add to the plane's survivability. Cost is $1.57Móless than a tenth of a real F-15!
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Old 11-02-2016, 09:52 AM   #9
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

Quote:
Originally Posted by Michael Thayne View Post
Here's another build of a TL7 fighter jet, modeled on the F-15:

Light Alloy Armor x5 (dDR 12 for the cockpit only)
Control Room x2
Tactical Array
Defensive ECM x3
Jet Engine x2 (Afterburning Turbofan; 1 G acceleration; Top Speed 2,500 mph)
Fuel Tank x2 (Provides one hour of fuel)
Medium Battery (3 fixed mount 16cm missile launchers)
Major Battery (fixed mount with 2.5cm very rapid fire conventional gun)
Maneuver Enhancement x3

The armor is designed to protect the pilots from antiaircraft fire rather than add to the plane's survivability. Cost is $1.57M—less than a tenth of a real F-15!
I get $3.115M and only dDR5 at SM+5. The Defensive ECM and Tactical Array cost $300k each, so $1.4M just for those four systems. You also left out Emergency Ejection. I suspect you forgot to add Streamlining (lowers dDR) and Wings (increases cost somewhat, as well as giving a big Handling bonus).

Three Maneuver Enhancements is overkill. Base Handling for SM+5 is 0, +0 for being 1G, -1 for TL 7, +4 for Wings gives a handling of +3. Maximum Handling bonus is +5, so two Maneuver Enhancements maxes out the bonus. A third only acts as a redundancy in case of damage; it would be better off with some more fuel.

Also, Spaceships standard layout is to list which section each module is installed in. It makes it easier to check/test designs if you use something approximating the standard layout; it also helps if you make sure to list the SM and TL. E.g.:
Center
[1-5] Light Alloy Armor
[6,Core] Control Room
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Last edited by ericbsmith; 11-02-2016 at 10:19 AM.
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Old 11-02-2016, 11:33 AM   #10
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Default Re: Approximating High-Tech and Ultra-Tech with Spaceships

Quote:
Originally Posted by ericbsmith View Post
I get $3.115M and only dDR5 at SM+5. The Defensive ECM and Tactical Array cost $300k each, so $1.4M just for those four systems. You also left out Emergency Ejection. I suspect you forgot to add Streamlining (lowers dDR) and Wings (increases cost somewhat, as well as giving a big Handling bonus).

Three Maneuver Enhancements is overkill. Base Handling for SM+5 is 0, +0 for being 1G, -1 for TL 7, +4 for Wings gives a handling of +3. Maximum Handling bonus is +5, so two Maneuver Enhancements maxes out the bonus. A third only acts as a redundancy in case of damage; it would be better off with some more fuel.

Also, Spaceships standard layout is to list which section each module is installed in. It makes it easier to check/test designs if you use something approximating the standard layout; it also helps if you make sure to list the SM and TL. E.g.:
Center
[1-5] Light Alloy Armor
[6,Core] Control Room
and the resulting stats would be nice.

Its worth noting that sensor arrays are a base of $60K, but tactical arrays are multiplied by x5 for final cost.

The dDR is concentrated on the cock pit using a house rule not fully explained yet... It'd be nice to have.

Where are the rules on converting Gs of acceleration into actual vehicle speeds? I could do some math on that, but It'd be nice to have an official source...

Working on getting my own stats for this jet.
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