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atgxtg
Rear Admiral
Joined: 22 Mar 2009
Posts: 2460
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 Posted: Thu Apr 12, 2012 3:05 pm Post subject: |
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| crmcneill wrote: | | So why not just do separate charts for starfighters, space transports and capital ships? |
Becuase it would be A LOT more work and would require more than three categories. Starfighters could be lumped together but there is quite a big spread between freighters.
We7d need several cateogries to make it work. WEG relaized that long agon, it is why the rules in Tramp Freighters only apply to Light Freighters. And even lumping all the "light freighters" together causes problems. THe ships with the highest cargo capacity would end up with the potential to be the fastest simply becuase they have more cargo tonnage to play with.
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The Saga Edition Starships of the Galaxy Book (and the attendant Rancor Pit Conversion book) included the following rules for converting equipment: |
Doesn't work. The low "cargo capacitries" of Starfightersis due to thier practically non-existant storage space, not to the load being carried. You can only squueze so much in the truch and glove compartments. It isn't a question of mass or weight but of space. But something could be fitted externally. You don7t have to fit the laser cannon into the glove box on an X-Wing.
Also, there is no real reason why a ship couldn't carry more weight as a loss in performance (or vice versa).
If we used the ship's acceleration we could do all sorts of cool things that we can't do with just a generic table or with broad categories. Things like stripping off things from a fighter to make it faster, or building TIE uglies, or jettisoning the cargo in order to pick up some more speed, or kitbashing several engines together to get something like the Millennium Falcon. |
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CRMcNeill
Director of Engineering
Joined: 05 Apr 2010
Posts: 16178
Location: Redding System, California Sector, on the I-5 Hyperspace Route.
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| Posted: Fri Apr 13, 2012 1:11 am Post subject: |
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It sounds like you're trying to work up a master chart for engines for all the various types of ships. IMO, the way WEG did it is simpler; unless the characters are regularly switching up ship types, the drives that fit their ships are going to be relatively uniform.
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"No set of rules can cover every situation. It's expected that you will make up new rules to suit the needs of your game." - The Star Wars Roleplaying Game, 2R&E, pg. 69, WEG, 1996.
The CRMcNeill Stat/Rule Index
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
Posts: 2460
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| Posted: Fri Apr 13, 2012 10:06 am Post subject: |
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| crmcneill wrote: | | It sounds like you're trying to work up a master chart for engines for all the various types of ships. |
Not quite. What I am trying to do is to use one method for determining the speed of a ship so that we don't need lots of differernt tables. And a method for working up the cost of any engine so we aren't dependant on a handful of sample engines. If we rate engines in terms of thrust rather than speed we can have interchangeability.
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IMO, the way WEG did it is simpler; unless the characters are regularly switching up ship types, |
IMO it is simpler if the character are resitricted to YT-1300s or ships very similar to YT-1300s in term sof size, tonnage and performance. But if they stary from that things will break down. Any ship outside of the" sweet spot" either won't have enough spare tonnage to be able to use the engine table, or so much spare tonnage that the tonnage requirments of anyone of the table will be a non-ssue.
By basing performance on the Thrust-Mass ratio, we can scale the engine rules to work for any size ship. We can also get designs like the TIE fighter, which is fast in part due to it's low mass.
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the drives that fit their ships are going to be relatively uniform. |
Only for ships of a certain size and type. You have to remember than when GG6 was written, the only ship avaiable to PC smnuglers was the "Stock Light Freighter". it wasn't even a YT-1300 yet. All the rules were written to work for a ship approimately the same as the Stock Light Freighter.
But now we have a lot more ships to choose from. So some sort of universal method would be better than just a sample of engines for one type of ship.
What I was thinking of was rating each engine in terms of thrust, each ship in terms of tonnage (which can mostly be based off it's pre-existing cargo capcity) and then use the ratio and a table to get a SPACE speed. |
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ZzaphodD
Rear Admiral
Joined: 28 Nov 2009
Posts: 2426
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| Posted: Fri Apr 13, 2012 5:07 pm Post subject: |
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| crmcneill wrote: | | It sounds like you're trying to work up a master chart for engines for all the various types of ships. IMO, the way WEG did it is simpler; unless the characters are regularly switching up ship types, the drives that fit their ships are going to be relatively uniform. |
I have tried this several times... Its really hard to come up with something workable and still balanced. Its easy to end up with too cheap really fast engines for small ships if you manage to balance the other end of the scale.
Better to stick to light transports (maybe include courier ships) and include the different engine classes above.
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
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| Posted: Fri Apr 13, 2012 9:54 pm Post subject: |
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| ZzaphodD wrote: | ]
I have tried this several times... Its really hard to come up with something workable and still balanced. Its easy to end up with too cheap really fast engines for small ships if you manage to balance the other end of the scale. |
That is the problem with the WEG approach. You get all the problems that came with scaling only worse. We have ships in the same "scale" with tonnage capacities ranging from hundred of tons to hundreds of thousands of tons.
INO the way to solve that is to rate the cost of each ton of engine on some factor of the engine)s Thrust Output per ton of engine, and the SPACE speed on the overall Thrust to Mass Ratio. That way everything would scale with the size of the ships and be consistent.
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Better to stick to light transports (maybe include courier ships) and include the different engine classes above. |
Then you don't need anything else. GG6 gives you a half dozen engines for light freighters. Maybe extrapolate the details for odd speed engines. |
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ZzaphodD
Rear Admiral
Joined: 28 Nov 2009
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| Posted: Sat Apr 14, 2012 2:19 am Post subject: |
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| atgxtg wrote: | | ZzaphodD wrote: | ]
I have tried this several times... Its really hard to come up with something workable and still balanced. Its easy to end up with too cheap really fast engines for small ships if you manage to balance the other end of the scale. |
That is the problem with the WEG approach. You get all the problems that came with scaling only worse. We have ships in the same "scale" with tonnage capacities ranging from hundred of tons to hundreds of thousands of tons.
INO the way to solve that is to rate the cost of each ton of engine on some factor of the engine)s Thrust Output per ton of engine, and the SPACE speed on the overall Thrust to Mass Ratio. That way everything would scale with the size of the ships and be consistent.
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Better to stick to light transports (maybe include courier ships) and include the different engine classes above. |
Then you don't need anything else. GG6 gives you a half dozen engines for light freighters. Maybe extrapolate the details for odd speed engines. |
Yeah, I have had a x (cost/tonnage/etc) per mass per Thrust rating approach too.. It was a while ago and I dont remember the issues really. You end up with too cheap light engines or too expensive heavy ones IIRC (I only had small courier to heavy freighter (still starfighter scale)). As engines cost/weight have other factors than a straight cost/weight to Thrust ratio, you end up with quite complicated formulas..
In the end I redid the GG6 engine list and sorted out some oddities (made faster engines heavier IIRC).
I had different cost / weight for different armour types (from Recycled to chromium), so the idea of having different engine 'classes' really fits into this.
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
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| Posted: Sat Apr 14, 2012 11:57 am Post subject: |
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| ZzaphodD wrote: | [
Yeah, I have had a x (cost/tonnage/etc) per mass per Thrust rating approach too.. It was a while ago and I don't remember the issues really. You end up with too cheap light engines or too expensive heavy ones IIRC (I only had small courier to heavy freighter (still starfighter scale)). |
I wish you could remember where it went wrong. I've got something in the works along those lines and it is looking good so far, so I'll probably run into the same problems.
I'm linking speed to the thrust/mass ratio, so the big ships end up needing a lot more thrust. For example a SSD needs something like 1000 times the thrust of a Corellian Corveette to get the same speed. So it's engines would cost about 100 times as much, assuming that both engines have the same efficiency.
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As engines cost/weight have other factors than a straight cost/weight to Thrust ratio, you end up with quite complicated formulas.. |
It is more complicated than just X credits per point of speed, or even X per speed per ton, but it isn't too bad. At least for engine design purposes. I've been using an engine efficiency squared formula that looks okay so far. It seems good enough so that we could do a table of engines for starfighters and light tonnage ships, and then just scale it up for larger ships.
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In the end I redid the GG6 engine list and sorted out some oddities (made faster engines heavier IIRC). |
Yeah. There are a few problems with GG6. One of the faster engines is actually less efficient that the supposedly slower engines. How much you need to alter the engines depends on how much mass you decide the ships have. Especially where you put the starfighters. To make sense, if a 24 ton engines can push a YT-2400 around at SPACE 12, an A-Wing, engine must be a lot smaller than 24 tons. Just how much smaller would depend on the reative mass of the two ships.
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I had different cost / weight for different armour types (from Recycled to chromium), so the idea of having different engine 'classes' really fits into this. |
I'd like to see what you had for armor. Eventually I want to finish that ship design system I started. I got it to the point where I can use it as tool for modifying ships, but it isn't finished yet. In fact, that was why I was wondering about what most people considered the tonnages should be for some ships. It gives the ballpark figure to work with for desiign purposes. |
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Orion
Lieutenant Commander
Joined: 16 May 2008
Posts: 146
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| Posted: Sat Apr 21, 2012 2:07 am Post subject: |
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@atgxtg First let me say I would love to see this, so when you do finish it please share. 
As a suggestion to possibly make completing it a bit easier why not abstract the mass a bit, possibly by using a variation of the size scale, for this purpose only. What I mean is similar to those who have suggested giving tramp freighters there own scale of 8D instead of 6D starfighter scale. That is you give the ships what amounts to a mass scale and define the thrust/mass by that scale, so that when you put an engine on a different scaled ship its thrust is affected by the difference in the two scales.
Creating the mass scale would be just grouping similar sized ships together and since, unlike my example you don't have to work with the the existing scale you can define as many mass groups as you like, even leaving gaps if you don't feel that any of the ships fit in that mass group. This way you don't have to worry about what seems like a realistic or reasonable mass for each ship, just whether they are similar enough to be in the same mass group. |
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
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| Posted: Sat Apr 21, 2012 10:44 am Post subject: |
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| Orion wrote: | | @atgxtg First let me say I would love to see this, so when you do finish it please share. |
If I finish this I will certainly let people know about it. Even those who don't want to build thier own ships from scrath might like to swap out sensors or power cores.
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As a suggestion to possibly make completing it a bit easier why not abstract the mass a bit, possibly by using a variation of the size scale, for this purpose only. |
Because it doesn't solve the problem. It's not that I need masses to work out the thrust-to-mass ratios (TMRs) for various ships. I don't. I can get the TMRs from the listed acceleration (in Gs) and SPACE ratings.
I need to mass to figure out how much room there is for the various systems that are going to go into a ship. THat gives us a limit as to how much they can mess around with it in play (and keep the same performance stats). For example, if somebody wanted to build something like a YT-1300 they would select various systems from power core to engines, weapons hyperdrive, nav computer, etc. Ideally, by the time they wre finished they would have about 100 tons left over for cargo..Without some sort of mass figure it becomes difficult to differentiate ships of a similar type but differernt cargo capacity. Like between a YT-1300, Ghtroc 720, YG-4210 and so on. Ultimately, I7d need to sub-dvide "light" freighter into 3-5 seperate scales, and I think that would be more work that just having a tonnage stat.
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Creating the mass scale would be just grouping similar sized ships together and since, unlike my example you don't have to work with the the existing scale you can define as many mass groups as you like, even leaving gaps if you don't feel that any of the ships fit in that mass group. This way you don't have to worry about what seems like a realistic or reasonable mass for each ship, just whether they are similar enough to be in the same mass group. |
I think using tonnage as a stat would still be easier and simplier. Especially since we will need a tonnage stat anyway.
But, I could come up with a few standardized tonnages, i.e. a 50t ship, 100 ton, 150t, 200t, 250t and so on.
By using D Space and extrapolation I7ve gooten the YT-1300 down to about 180 tons (with cargo),the Ghrtoc 720 at around 240 tons, and the Z-10 Seeker at 140/180 tons. Most things are looking good, but there are a few flies in the ointment.
The Boosch-Chii stardrive, was supposed an older military drive for starfighters, but if it can drive a light freighter at SPACE 10 and weights 18 tons, it makes me wonder what sort of fighter it was designed for. Was it some type of assault gunboat, or are the fighters heavier than I had expected.
I7ve got a similar problem with the KDY Galaxy-15 engine (I've been raiding Wookieepedia for component names and data). 7 such engines can drive a Nebulaon-B frigate, but IG-88 managed to suqeeze one into his his own IG-2000 ship. Consdiering the differences in size and supposed mass, the IG-200 should by zipping by at speeds an A-Wing pilot would envy. Unless, maybe he doesn't have enough power to get full speed out of it. But even so, I'd expect the engine to have a mass severtal times that of the mother ship.
Hopefully, I can either resolve these discrepancies or they will be so uncommon that I can ignore them. |
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Bren
Vice Admiral
Joined: 19 Aug 2010
Posts: 3868
Location: Maryland, USA
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| Posted: Sat Apr 21, 2012 2:33 pm Post subject: |
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| atgxtg wrote: | | But, I could come up with a few standardized tonnages, i.e. a 50t ship, 100 ton, 150t, 200t, 250t and so on. |
Something about a set of standard tonnages seems...familiar.  |
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
Posts: 2460
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| Posted: Tue Apr 24, 2012 9:39 am Post subject: |
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| Bren wrote: | | atgxtg wrote: | | But, I could come up with a few standardized tonnages, i.e. a 50t ship, 100 ton, 150t, 200t, 250t and so on. |
Something about a set of standard tonnages seems...familiar. |
I know., We do it in the real world all the time, and for a lot of good reasons, some of which could carry over into the RPG. The size of the docking bays for one. |
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Orion
Lieutenant Commander
Joined: 16 May 2008
Posts: 146
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| Posted: Mon Apr 30, 2012 9:31 pm Post subject: |
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| atgxtg wrote: | | I got something that seems to work with most of what exists already, but would love to see what othe rpeople think the masses should be for things like X-Wings ... |
How does 8.5mt sound for one? |
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atgxtg
Rear Admiral
Joined: 22 Mar 2009
Posts: 2460
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| Posted: Tue May 01, 2012 10:09 am Post subject: |
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| Orion wrote: | | atgxtg wrote: | | I got something that seems to work with most of what exists already, but would love to see what othe rpeople think the masses should be for things like X-Wings ... |
How does 8.5mt sound for one? |
For an X-Wing? To me it seems a bit light.I got to cram 4 laser cannons into the thing, and with what data there is on the tings, they probably tip the scales at 2 tons each. Im either going to need a bit moremass to work with for design purposes, or else completely reword the systems to make them smaller and lighter. But if I make the systems smaller and lighter then it would really mess up the freighters. |
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Bren
Vice Admiral
Joined: 19 Aug 2010
Posts: 3868
Location: Maryland, USA
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| Posted: Tue May 01, 2012 12:57 pm Post subject: |
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Might be worth approaching it from the other end by first determining a minimum tonnage.
Have you done a sum of the parts for the x-wing based on existing tonage per system and if so, what's the total? |
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Orion
Lieutenant Commander
Joined: 16 May 2008
Posts: 146
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| Posted: Tue May 01, 2012 1:27 pm Post subject: |
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| atgxtg wrote: | | Orion wrote: | | atgxtg wrote: | | I got something that seems to work with most of what exists already, but would love to see what othe rpeople think the masses should be for things like X-Wings ... |
How does 8.5mt sound for one? |
For an X-Wing? To me it seems a bit light.I got to cram 4 laser cannons into the thing, and with what data there is on the tings, they probably tip the scales at 2 tons each. Im either going to need a bit moremass to work with for design purposes, or else completely reword the systems to make them smaller and lighter. But if I make the systems smaller and lighter then it would really mess up the freighters. |
It's the unloaded weight of an F16 which is slightly larger than an X-wing. I figured with the advances in metallurgy and technology, they could be about equivalent. The loaded weight is 12mt, but that still won't be enough for what your saying you need, perhaps doubling them, to 17mt or 24mt. Btw, why do you think the laser cannons would weigh 2mt each? The 30mm cannon on the A-10 weights around that at 1.8mt, but that's counting the weight of almost 1200 rounds of ammunition the cannon itself only weights 280kg not counting the feed system and drum, what about the laser cannon is so heavy? The A-10 is larger still and heavily armored and it's unloaded weight is about 11mt and loaded is about 21mt. The Raptor is over 6m longer than the X-wing and it's weights are about 20mt and 29mt. |
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