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Old 11-23-2009, 07:43 AM   #1
vicky_molokh
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Default [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Greetings, all!

An idea came to me about trying out Spaceships in comparison to Ultra-Tech and High-Tech. Notably, I'm interested in trying to compare SS-Mecha against HT Tanks (TL7-TL8) and UT tanks (TL9-TL12). No less than SM+4 ones, that is.

Also, it would be interesting to compare HT and WWII planes to those doable with SS (i.e. streamlined non-space-capable craft).

I'm especially interested in the mecha part of the comparison. Anyone tried that?

(I'm assuming that enabling superscience is allowed, but improving superscience should not be, unless it's a last resort.)

Thanks in advance!
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Old 11-23-2009, 09:53 AM   #2
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Battlesuits use significantly different armor types in Ultra-Tech than those in Spaceships. They provide something like 2-2.5 times as much DR per pound.

You need to do some serious figgling with armor layout for Spaceships-built tanks to have the same amount of armor as tanks in either HT or Ultra-Tech. You might need to use something like my super-dense ships thing in order to get enough armor available and to make sure a tank is scaled properly - a 68 ton Abrams is SM+5, for example, but in Spaceships that'd be pretty close to SM+6.

Spaceships jet engines are way, way more efficient than realistic jet engines. For example, the F-22 Raptor:

Empty Mass: 20 Tons
Engine Mass: 4 Tons (2 Pratt and Whitney F119's)
Fuel Capacity: 9 Tons Internal
Weapon Capacity: 1.5 Tons Internal, 10 Tons External (ignoring the gun system)
Thrust: 35 Tons
Range: 1840 miles with 2 external fuel tanks (13 tons of fuel, total mass 35 tons)
Supercruise speed: 1,220 MPH

The range gets you 131.5 miles per ton of fuel

This gets a total loaded mass of 20+9+1.5+10=40.5 tons if you include the hardpoints. If you don't include the hardpoints (like the figure for loaded weight on Wikipedia) it's only 30 tons. Those 4 tons of engines only provide 35 tons of thrust, giving you just over 1G of thrust. Spaceships assumes you get 1G per 5% of loaded mass as jet engines.

If you design it as an SM+5, 30 ton spacecraft, you get something like this:

Front
[1] Armor
[2] Control Room (Ejectable)
[3] Medium Battery (the 20mm gatling gun, plus 480 rounds)
[4] Tactical Sensors
[5] Defensive ECM
[6] Defensive ECM

Center
[1] Armor
[2] Medium Battery (internal missile/bomb loadout)
[3] External Hardpoint (capable of holding up to 5 tons)
[4] External Hardpoint (capable of holding up to 5 tons)
[5] Fuel Tank (Jet Fuel)
[6] Fuel Tank (Jet Fuel)
[Core] Fuel Tank (Jet Fuel)

Rear
[1] Armor
[2] Fuel Tank (Jet Fuel)
[3] Fuel Tank (Jet Fuel)
[4] Jet Engine (1/3 G)
[5] Jet Engine (1/3 G)
[6] Jet Engine (1/3 G)
[Core] Fuel Tank (Jet Fuel)


With the 5 tons of extra fuel tanks, the F-22 has a range of 1,840 miles, assumably at a supercruise velocity of 1,220 MPH. That means with 1.5 times as much fuel as it can carry internally, the F-22 can travel for 1.5 hours. Each of the six fuel tanks provides only ten minutes of jet fuel, not a full hour like it's listed in Spaceships.

It's maximum speed is also 1000 MPH slower than listed in Spaceships.

Last edited by Langy; 11-23-2009 at 10:15 AM.
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Old 11-23-2009, 11:02 AM   #3
vicky_molokh
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Interesting. After some fiddling, I found that indeed a Mech would only get about 250 armor on the front hull, and half the speed of a Light Tank at TL9 (assuming 2 legs . . . why don't legs improve with TL? We already have walking leg tech, even though it's very immature.).

OTOH, the mech gets better gAccel, and definitely a better Hnd, resulting in dodgy behavior (which tanks can't afford, really).

Are there plausible combat conditions which would favour the SS-mecha as it stands?
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Last edited by vicky_molokh; 11-23-2009 at 11:06 AM.
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Old 11-23-2009, 11:51 AM   #4
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Any situation where one-hit-one-kill weapons exist reguardless of amount of armor. If man-portable anti-tank weapons that can blast through a tank's frontal armor in one hit are commonplace, then a mech that can dodge better than a tank but carry the same payload is definitely preferable to a tank.

If you don't need to carry the huge payload of a tank, a battlesuit would be even better than a mech.
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Old 11-23-2009, 12:01 PM   #5
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Quote:
Originally Posted by Langy View Post
Any situation where one-hit-one-kill weapons exist reguardless of amount of armor. If man-portable anti-tank weapons that can blast through a tank's frontal armor in one hit are commonplace, then a mech that can dodge better than a tank but carry the same payload is definitely preferable to a tank.

If you don't need to carry the huge payload of a tank, a battlesuit would be even better than a mech.
Right. If you can't shrug off incoming fire, your choices are basically "dodge" and "hide." Presumably "dodge" will favor the mecha given what we think about them (although if the weapons in question are zero time of flight, like lasers, even "dodge" might be irrelevant). That leaves "hide." If this is "hide behind something," then smaller battlesuits or mechas might be advantageous. However, if one needs to rely on careful shaping or large heavy power plants to produce enough ECM to hide the fighter, the tank could be advantaged.
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Old 11-23-2009, 04:43 PM   #6
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Quote:
Originally Posted by Langy View Post
If you design it as an SM+5, 30 ton spacecraft, you get something like this:

Front
[1] Armor
[2] Control Room (Ejectable)
[3] Medium Battery (the 20mm gatling gun, plus 480 rounds)
[4] Tactical Sensors
[5] Defensive ECM
[6] Defensive ECM

Center
[1] Armor
[2] Medium Battery (internal missile/bomb loadout)
[3] External Hardpoint (capable of holding up to 5 tons)
[4] External Hardpoint (capable of holding up to 5 tons)
[5] Fuel Tank (Jet Fuel)
[6] Fuel Tank (Jet Fuel)
[Core] Fuel Tank (Jet Fuel)

Rear
[1] Armor
[2] Fuel Tank (Jet Fuel)
[3] Fuel Tank (Jet Fuel)
[4] Jet Engine (1/3 G)
[5] Jet Engine (1/3 G)
[6] Jet Engine (1/3 G)
[Core] Fuel Tank (Jet Fuel)
-- Are you sure you're using SM+5 values for the components? A SM+5 Fuel Tank is 1.5 tons for example. And Jet Engines are 1G at SM+5. A case could be made for TL7 fuel efficiencies in many cases though :)

-- Most modern aircraft DR is below the resolution of Spaceships. You can physically punch through the skin of most TL8 aircraft. But lets assume some Light Alloy or something on the front at least.
-- All of the external hardpoints can be dealt with using one External Clamp module. Not sure why you used a Medium Battery instead of a Hangar Bay or something to reflect internal stores.

-- Jet Engines in Spaceships are efficient, but its never stated if thats endurance at max speed or not. Six hours endurance at some sort of cruise doesn't seem to outlandish in the design below.


Generic Air Dominance Fighter (TL8)
This is an example of an atmospheric fighter.

It uses an streamlined 30 ton (SM+5) hull that is 45 feet long.

Front Hull System
[1] Light Alloy Armor (dDR 1).
[2] Tactical Array (comm/sensor 4).
[3] Control Room (C2 computers, comm/sensor 2, and one control station).
[4] Defensive ECM.
[5] Major Battery (fixed 1cm rapid-fire conventional gun).
[6] Fuel Tank (1.5 tons of jet fuel).

Central Hull System
[1] External Clamp.
[2-6] Hangar Bays (five tons total capacity).
[core] Fuel Tank (1.5 tons jet fuel).

Rear Hull System
[1-5] Fuel Tanks (1.5 tons jet fuel each).
[6] Jet Engine (1G acceleration, 6 hours endurance).

It has a winged hull.
The vessel is operated by a single pilot.

TL Spacecraft dST/HP Hnd/SR HT Move LWt. Load SM Occ dDR Range Cost
PILOTING/TL8 (High-Performance Aircraft)
8 Fighter 20 3/4 12 10/1,250 30 5.1 +5 1SV 1/0/0 15,000 $1.363M
Top air speed is 2,500 mph.
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Old 11-23-2009, 06:42 PM   #7
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Armor values are going to be very low because Spaceships assume a very low weight to volume ratio.

For ease, let's handwave the Hull table into metric units (yards=meters, tons = metric tons)...

A cube Hull, 10 meters in dimensions, would be 1000m volume.
This should be a SM+7 spacecraft (Hull table assumes that a sphere/cube would be less than half listed length, let's say 1/3 the value; and a 30m hull is SM+7)... weighing 300 tons.

If this hypothetical ship had the density of water, it would be 1000 tons.

Thus SS assume 1/3 the density of water, which is quite light weight for (smaller) combat craft.

Also, remember that SS assumes at least a 3:1 length to width ratio... if the vessel is stubbier, you'll need to lower the SM. This coupled with "High-Density Spaceship" rules might fix the problem.

------------

In the end a stubby craft with a length to width ratio of 1.5:1 with a density close to that of Steel (possible with very high density armor), should use a SM entry 2 lower than what the length would suggest... but use the armor column for craft 3 SM larger than the vessels actual SM.
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Old 11-23-2009, 06:48 PM   #8
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Tzeentch, read the rest of my post. I calculated the number of modules from the actual mass of the various items - the F-22 holds 9 tons of fuel and has 4 tons of jet engines, for example. It also only has a thrust/weight ratio of about 1.0, which is why its three jet engines only provide 1G of thrust.

I used a medium battery because the F-22 usually has either two or three types of missiles/bombs - in ground attack mode, it carries 2 AMRAAMs, 2 Sidewinders, and one type of bomb (either 8 small diameter bombs, 2 JDAMS, or 2 WCMDs as listed in Wikipedia). It doesn't actually matter if it's a Medium Battery or if its a Hangar Bay, of course, but I prefer an internal weapons battery be listed as an actual weapon battery instead of a hangar bay.

I gave it armor to fill up space. The only parts that I know have the right number of systems are the engines, internal weapons, and fuel tanks - I don't have mass estimates for the rest of the fighter. You could just as easily switch an Armor system for a third Defensive ECM system, but I don't know what else you could put on an F-22 fighter jet without it not making much sense. Can't outfit it with more weapons, since it doesn't carry any more guns, for example. Same deal with the external clamp/hardpoint issue.

Quote:
-- Jet Engines in Spaceships are efficient, but its never stated if thats endurance at max speed or not. Six hours endurance at some sort of cruise doesn't seem to outlandish in the design below.
True, but I used the F-22's maximum range (total) to figure out how much fuel endurance each fuel tank supplied. It was 10 minutes per tank. Six hours at cruise seems excessive for any normal jet engine.

Other jet engines can be much more efficient - an A-10 Thunderbolt II has a very long ferry range, giving it a time in the air of around eight hours, but when used in combat it might have an endurance of between two and four hours (depending on what the stats mean on the A-10's Wikipedia page).

Last edited by Langy; 11-23-2009 at 06:56 PM.
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Old 11-23-2009, 09:44 PM   #9
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Quote:
Originally Posted by Langy View Post
Tzeentch, read the rest of my post. I calculated the number of modules from the actual mass of the various items - the F-22 holds 9 tons of fuel and has 4 tons of jet engines, for example. It also only has a thrust/weight ratio of about 1.0, which is why its three jet engines only provide 1G of thrust.
Spaceships 7: Strange and Alien Spacecraft has a Turbofan and Afterburning Turbofan module that might fit this better.
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Old 11-24-2009, 03:27 AM   #10
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Default Re: [Spaceships] SS Mecha vs. HT/UT Tanks, and 'ships vs. jets

Quote:
Originally Posted by Langy View Post
True, but I used the F-22's maximum range (total) to figure out how much fuel endurance each fuel tank supplied. It was 10 minutes per tank. Six hours at cruise seems excessive for any normal jet engine.

Other jet engines can be much more efficient - an A-10 Thunderbolt II has a very long ferry range, giving it a time in the air of around eight hours, but when used in combat it might have an endurance of between two and four hours (depending on what the stats mean on the A-10's Wikipedia page).
There's much more to an aircraft's range, endurance and speed figures than wikipedia is going to tell you.

For example: You're using the supercruise speed and the F-22's listed range to determine it's endurance, which will lead to some funny numbers. Supercruise is not the 'cruise speed' of the F-22. It's the top speed at which the F-22 can fly without engaging afterburners, which are horribly inefficient from a fuel burn perspective. Off of the top of my head, I'd say that it's maximum range is found at a speed roughly half of that at which it supercruises - giving us an endurance of three hours. Furthermore, it's maximum-range speed is different from it's maximum endurance speed - I'd guess maximum endurance is found at a speed roughly 70% of maximum range speed, giving us about four overall hours of flight time. Guesstimating from what I know about the fuel burn of an F-16 at high altitude (about 3000 pounds per hour, plus or minus 1500 depending on loading, speed, and altitude, doubled for two engines, divided by 26000 pounds of total fuel) gives us about 4.33 hours of endurance - not the six hours that spaceships claims, but close enough and with enough fudge factors that I'd call it a good approximation.

Supercruise on the F-22 corresponds to about Mach 1.5 - I'd guess that the top speed for the F-22 at full burn and at high altitudes with empty bays and almost-dry tanks will fall at about Mach 2.2 - Basic fractions reveal that that's a top speed of 1790 MPH, and because of the altitude differences in which those numbers are achieved, it might be much more. - Again, it doesn't match up with the values in spaceships, but I'd call it fairly close, and I also don't know about the assumptions made in spaceships about the realm of flight in which those numbers are achieved.

Last edited by RedRager; 11-24-2009 at 03:30 AM. Reason: Enhanced Clairity.
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