[Spaceships] Paying more for better system?

[mlangsdorf]

Originally Posted by Sorenant

For example, if you take Sentou Yousei Yukikaze, the world is about early TL9 yet the computer installed in the MC's plane is clealy way above the ones expected for that TL: At TL9 and SM+4 airplane, you get C5 computer while Yukikaze is at very least C7 (equivalent to TL12) but more likely C10 or so (can pilot better than aces, unbelieveable EW capability and intelligence analysis).

Well, just making it a Genius computer puts you at C7. You could also make it a Compact SM+5 system for C8. That's enough for a IQ 10 volitional AI (Ultra-Tech p 25) or IQ 12 mind emulation (Ultra Tech p 27). With a Talent relating to EW and Intelligence Analysis, it could be effectively IQ 16 for those skills, plus having them at IQ+4 through training.

Alternately, it could just be a plot device that doesn't obey the standard rules.

[Varyon]

Originally Posted by ericbsmith

It probably still doesn't offer enough of a boost to fit realistic Tank DR though, but it is a step in the right direction.

The T-72A (HT244), at least, is buildable with Spaceships, provided you're willing to "zoom in" and get rid of some of the abstraction. The T-72A actually averages somewhere just south of dDR 20. With 12 armor modules (the least needed for the -1 SM to get the tank down to its actual SM+4 dimensions), you'd need each to give dDR 5 (keeping in mind you'd average 4 modules per section), which with the x1.8 multiplier of having 12 modules means a base dDR of 2.78, which doesn't seem inappropriate for early TL 8 metallic laminate (mature TL 8 metallic laminate is a full dDR 3). The linked post clearly lacked access to Pyramid #3/34, so let's redo the drivetrain, engine, and fuel tank - its performance is consistent with a single tracked drivetrain using 2 PP, so that'll take up 3 modules (2 ICE's, 1 drivetrain). Range is consistent with using internal fuel, so no need for a separate fuel tank module. That leaves it with 2 empty modules for wiggle room, although it may use up part of that for some Passenger Seating. The rest is probably armor, actually, as dDR2.78 may be a bit high for the T-72A's armor (13 modules would mean a base of around dDR 2.5, which I think sounds a bit more feasible).

[ericbsmith]

So I've been going through these suggestions with more care and have a couple comments.

Originally Posted by mlangsdorf

* Sensor Arrays can be Fine (Sensitive) or Fine (Long-Ranged). Sensitive arrays add +1, or +2 for Very Fine, to skill rolls to use the Sensor, while Long-Ranged arrays increase their Active Sensor Range by +1 or +2 for Very Fine.

With sensors, any bonus to Scan *IS* a bonus to range, since the primary use for high skill is to offset range penalties. There's no need to have separate bonuses here.

Originally Posted by mlangsdorf

* Reaction engines can be ... Fine (Efficient) for a 20% improvement in delta-V. Same for Very Fine and Cheap, but 40% improvement and -25% decrease, respectively.

I'm not a rocket scientist, but it seems that a 20% and 40% boost in delta-v is unrealistically huge. I'm having a hard time finding any accurate numbers for realistic rockets over the years, but my gut just tells me that it's not right. Most rockets using the same fuel have Isp within 10% of one another, and delta-V is just Isp multiplied by the Ln of (full mass / empty mass); most increases in delta-V come from reducing empty mass of the entire rocket by tiny fractions, and those mass savings can come from anywhere from computers to better structural materials for the fuel tanks.

[Fred Brackin]

Originally Posted by ericbsmith

So

I'm not a rocket scientist, but it seems that a 20% and 40% boost in delta-v is unrealistically huge.

Realistically, anything that boosts Delta-V at all becomes the new standard and everyone's choice. If all "normal" rocket engines in use are effectively "Very Fine" that might partially explain why they are so expensive.

Rocket engines are more likely to vary by power-to-weight ratio. For example the "Merlin" engine used in the Falcon-9 by Space-X gives out 150 lbs of thrust per lb of engine. The standard number used in Ve-2 was 100 lbs per lb. This might be where the weight savings that allow for the landding gear come from.

[weby]

Originally Posted by ericbsmith

I'm not a rocket scientist, but it seems that a 20% and 40% boost in delta-v is unrealistically huge. I'm having a hard time finding any accurate numbers for realistic rockets over the years, but my gut just tells me that it's not right. Most rockets using the same fuel have Isp within 10% of one another, and delta-V is just Isp multiplied by the Ln of (full mass / empty mass); most increases in delta-V come from reducing empty mass of the entire rocket by tiny fractions, and those mass savings can come from anywhere from computers to better structural materials for the fuel tanks.

It depends. Reaction engines are a category of engines where rocket engines is just one(well two if you count HEDM as separate) type.

For Rocket engines, yes there would likely not be (at least not much) d-v increase, but you may see the engine create more thrust for the same mass engine, allowing you to mount less engines and get the same acceleration.

But for things like Fission or Fusion engines you would likely be able to gain more d-v by better designed engine. In fact some of them do gain more d-v by TL as it is and as I see it the others not gaining such is likely a simplification as realistically a higher TL engine should be able to produce and transfer more energy to the reaction mass increasing it's speed and thus ISP.

[mlangsdorf]

Originally Posted by ericbsmith

So I've been going through these suggestions with more care and have a couple comments.

With sensors, any bonus to Scan *IS* a bonus to range, since the primary use for high skill is to offset range penalties. There's no need to have separate bonuses here.

Active sensors have a maximum range (Spaceships p 45). I think there's a useful distinction between a Level 10 sensor with a range of 3 LS, a level 9 Fine (Sensitive) array with range of 2 LS that is picks up signals within its range as well as the Level 10 sensor, and a level 9 Fine (Powerful) array with a 3 LS range that can't pick up objects within its range as well as either of the other sensors.

Originally Posted by ericbsmith

I'm not a rocket scientist, but it seems that a 20% and 40% boost in delta-v is unrealistically huge.

Me neither, but I recently read Ignition! which is a history of early liquid fuel rockets. Certainly within the range of "chemical rocket fuel" there's space for trade-offs that could give ISP differences of -20% to +40%. The table of exotic rocket fuels in WW2: Motor Pool p 13 has a variation of 240 to 320 in ISP between kerosene/nitric acid and octane/oxygen, and that's not including the range of exotic rocket fuels that were developed post-WWII. Building a rocket engine to use Cl3F is not a trivial challenge, but if we could, we can get ISPs in the 350+ range.

I can believe that HEDM technology could have similar variations just between metallic hydrogen and metastable helium, and the various nuclear engines could have ISP variations based on the energy of the reaction you're eventual using. Nuclear light bulbs, for instance, seem like they would have space for a higher ISP design that heats the exhaust to even higher amounts but then require exotic materials for the nozzles and such.

On top of that, a 20% or 40% improvement is not that much compared to the TL advances, which are usually 3x or more. If a TL 10 Fusion Rocket has a delta-V of 60 mps per tank, I'm okay with the best TL 9 Fusion Rocket having a delta-V of 17 mps per tank.

[vicky_molokh]

Originally Posted by mlangsdorf

Active sensors have a maximum range (Spaceships p 45). I think there's a useful distinction between a Level 10 sensor with a range of 3 LS, a level 9 Fine (Sensitive) array with range of 2 LS that is picks up signals within its range as well as the Level 10 sensor, and a level 9 Fine (Powerful) array with a 3 LS range that can't pick up objects within its range as well as either of the other sensors.

Remember that active sensors can detect objects beyond their 'maximum' range at -2 per doubling of range.

[mlangsdorf]

I missed that, but it illustrates my point: the Fine (Sensitive) array is flat out better than the Fine (Powerful) within 2 LS, and usually worse at longer ranges. At 10 LS, the Sensitive array is at -5 but the Powerful array only at -4. Which option you want depends on how you expect to use the array but either option is a lot of money for a little advantage.

[Sorenant]

Originally Posted by mlangsdorf

I'm coming a little late to the discussion, but in addition to the suggestions already proposed, you could adapt I want to expand on weby's suggestion that you use the existing GURPS equipment quality rules to Spaceships and allow people to buy Fine, Very Fine, or Cheap Spaceship components.
<snip>

Originally Posted by mlangsdorf

Well, just making it a Genius computer puts you at C7. You could also make it a Compact SM+5 system for C8. That's enough for a IQ 10 volitional AI (Ultra-Tech p 25) or IQ 12 mind emulation (Ultra Tech p 27). With a Talent relating to EW and Intelligence Analysis, it could be effectively IQ 16 for those skills, plus having them at IQ+4 through training.

Alternately, it could just be a plot device that doesn't obey the standard rules.

Here's my attempt of recreating Yukikaze with your enhancements:

FFR-41 Mave "Yukikaze"

Front Hull
1-2		Advanced Metallic Laminate [400K]
3		Medium Battery† [600K]
4-5		Fuel Tank [60k]
6		Defensive ECM [1M]
core		Multipurpose Arrays (Sensitive) [10M]	comm/sensor 7

Central Hull
1-2		Advanced Metallic Laminate (200K)
3-5		Fuel Tank (90K)
6		Defensive ECM (1M)
core		Control Room (Genius;High Capacity) (25.02M) 	C7; comm/sensor 4; two stations

Rear Hull
1-2		Advanced Metallic Laminate (400K)
3		Fuel Tank (60K)
4		Defensive ECM (1M)
5-6		Jet Engine (2M)

+Winged (500K)
+Stealth Hull (500K)

† 1x Fixed Conventional Gun; 2x Turret Missile Launcher

TL 9; SM+6; Streamlined
dST/HP: 30
HT: 12
Hnd/SR: 4/5
Move 20/1750 (7 hours)
LWt.: 100
Load: 0.2
Occ: 2SV
dDR: 10
Cost: $42.83M

I didn't knew exactly how to handle Compact, do I double the CF (Compact Genius computer is worth +248 CF)?
Also, is it possible to have an engine that occupies two slots and say it's a single thing (like Spinal Battery)? It's mostly fluff so it seems probably but by the rules one of the engines could be disabled/destroyed while the other is operational, which would make it strange. Maybe it's "half-destroyed" as in badly damaged: burning, smoking but still somehow operational?

Non-Volitional AI "Yukikaze"
TL9 C7 Base Cost: $10K
Advantage: Soul of the Machine 4 [20] (Based on this advantage from Pyramid, gives bonus to Piloting, Electronic Operation, Gunner, Artillery and Navigation)
Skills: Piloting (High-Performance Airplane) DX+6 [8]; Artillery (Guided Missile) IQ+5 [4]; Artillery (Cannon) IQ+4 [2]; Gunner (Cannon) DX+4 [1]; Navigation (Air) IQ+4 [2]; Electronic Operation (EW) IQ+5 [4]; Electronic Operation (Sensors) IQ+5 [4]
Total CP: 45 (+225$)
Final Cost: $32.5K

While making up the AI I encountered two problems: Can AIs learn DX based skills like Piloting and Gunner? I think there should be one but I couldn't find an upper limit of how many points can an AI have, did I miss it or it really doesn't exist as RAW?

[Sorenant]

Not really related to the question at hand but for the sake of it, here's also the other prominent ship from Sentou Yousei Yukikaze:

Nuclear Aeriel Aircraft Carrier "Banshee"

Front
1		Light Alloy (5M)
2		Secondary Battery* (60M)
3-4		Hangar Bay (2M)
5		Enhanced Array (20M) coomm/sensor 10
6		Habitat (40 Bunkrooms, 10 Cabins, 10 Briefing Rooms) (10M)
core		Defensive ECM (100M)

Central
1		Light Alloy (5M)
2		Secondary Battery* (60M)
3-4		Hangar Bay (2M)
5-6		Habitat (10 Cabins, 10 Luxury Cabins, 20 Sick-bays, 10 Offices) (20M)
core		Control Room (20M) C7 comm/sensor 8 10 stations

Rear
1		Light Alloy (5M)
2		Secondary Battery* (60M)
3-4		Cargo Hold (-)
5-6		Nuclear Thermal Rocket, Ram-Rockets (250M)

Winged +50M


TL		9
dST/HP		150
Hnd/SR		2/6
HT		13
Move		10/1,250
LWt		10,000
Load		2,222
SM		+10
Occ		220ASV
dDR		10
Cost		$619M