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atgxtg
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 Posted: Thu Jun 10, 2010 2:49 pm Post subject: YT-1300 |
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Here is a sample write-up, the YT-1300, that I am using as a baseline to test the fddesign system. I am working with the assumption that the YT-1300 has amass of around 250mt (I might go with 267mt), and a cost of 100,000 credits (new, per the rulebook).
Type: Light Freighter
Tonnage: 250 mt
Ion Drive: Space 4 4% Mass 10mt 36!EU 10K (1000 cr/ton)
Hyperdrive: x2 6% Mass 15mt 50EU 10K (667Cr/ton)
Hyperdrive: x12 0.4% Mass 1 ton (9EU/NA) 234 Cr (234Cr/ton)
Maneuverability: 1D 7.5mt 8EU 7.5K
(uses Space engine chart, reading Space as Pips of maneuverability)
Shields: None
Cargo Space: 100mt 10EU 2.5K (25Ct/ton)
Crew: 2 0.2mt
Passengers: 6 0.6mt
Consumables: 8 people 2 months 4mt 4K (250Cr/person/month, 0.25mt/person/month)
Sensors: 40/20/10 10mt 10EU 10K
Enhancements: +5 Scan +1mt, +1EU +1K
+1 Focus +1mt, +1EU, +1K
Laser Cannon F/C 2D, DMG 4D 3.33mt 18EU 3K
Power Required: 133EU
Power Generator: (136EU) 17mt 13.6K (100 Cr/EU)
Mass Subtotal: 166.63mt
Hull (166.63/2=)
Toughness: 25 pips/8D+1 (character sclae)/2D+1 (starfighter scale)
83.3mt 20.825K (250Cr *83.3mt)
Armor: +5 pips 20.825K (50xHull per pip)
Total Mass: 253.9mt Cost: 104, 484 credits |
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ZzaphodD
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| Posted: Thu Jun 10, 2010 4:48 pm Post subject: |
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Ok, atgxtg, Ill avoid the quote bonanza and try to chime in here instead..
I would go for specific engines and weapons, like in GG6. Even if you have the formulas 'behind the scene', create specific ship parts with names. It lends the system both atmosphere and credibility in the game.
I remember that my engines also had a 'Thrust' rating. The ratio between thrust and tonnage gave the Space rating. As 'benchmark' engines I had a series of CEC engins with the same model numbers as their thrust rating, for example CEC Thrustmaster 400 Ion engine.
When it came to armour I think it was a mix of SW canon material and some home made sci-fi-ish home brews.. what I can remember..
-Recycled durasteel plating. Basically very cheap (almost free) but heavy compared to hull bonus. This is basically stripping ship hulls from armour and welding it to own ship.
-Durasteel. Standard Armour.
-Crystally Aligned Durasteel. 'Sci-fi mumbo jumbo' strengthened armor. More expensive but lighter compared to hull bonus.
-Reflec Armour (think naboo ships, but this was pre prequels). Very expensive, effective vs lasers and not anything else. Very light.
I know I had one more, but cant remember atm.
Last edited by ZzaphodD on Thu Jun 10, 2010 5:49 pm; edited 1 time in total |
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atgxtg
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| Posted: Thu Jun 10, 2010 5:46 pm Post subject: |
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[quote="ZzaphodD"]Ok, atgxtg, Ill avoid the quote bonanza and try to chime in here instead.. | ZzaphodD wrote: | n than I am Gunga Din
[quote="ZzaphodD"]
I would go for specific engines and weapons, like in GG6. Even if you have the formulas 'behind the scene', create specific ship parts with names. It lends the system both atmosphere and credibility in the game. |
It would be nice but problematic due to reasons explained after the next quote.
| ZzaphodD wrote: |
I remember that my engines also had a 'Thrust' rating. The ratio between thrust and tonnage gave the Space rating. As 'benchmark' engines I had a series of CCE engins with the same model numbers as their thrust rating, for example CCE Thrustmaster 400 Ion engine. |
That is almost exactly how I had it set up prior to deconstucting Tramp Freighters. The Baov Space 4 Engine was a Boav 1000 engine that put out 1000 points of thrust. 1000 Thrust divided by 250mt gave a Space rating of 4. Truth to tell that is really a measure of acceleration, not speed, but top speed from an ion drive in space is infinite.
The problem with that method is that it doesn't work with Tramp Freighters. In TF most of the ion engines yield the same thrust per ton (125 if we assume a "stock light freighter" has a mass of 250mt). But TF has a rapidly increasing price scheme. In theory you should be able to put 2 Space 4 Ion drives of a ship to get the same effect as a Space 8 drive but for whatever reason it doesn't work that way in Tramp Freighters.
It's a shame, since that is what prevents me from using a thrust/mass formula for Space or from writing up a bunch of standard drives by thrust rating, Like a Boav 1000, Corellian 2500 or so on. Instead I use the engines fromTrampFreighters as a baseline to get the mass and cost of engines for ships of differernt masses. For example, a fighter that masses 125mt can buy engines for half the cost and mass of standard freighter. I could do a table of premade engines, but they would only be useful for a certain tonnage range.
Unless.... I worked out a non lineral thrust/mass function. For example if you put a Boav Space 4 engines designed for a 250mt freighter on a 125mt starfighter you only get a +1 increase instead of double. A sqaure root of thrust/mass ratio or even a cube root wuld work.
So Thrust/mass times the cube root of the mass ratio.
| ZzaphodD wrote: |
When it came to armour I think it was a mix of SW canon material and some home made sci-fi-ish home brews.. what I can remember..
-Recycled durasteel plating. Basically very cheap (almost free) but heavy compared to hull bonus. This is basically stripping ship hulls from armour and welding it to own ship.
-Durasteel. Standard Armour.
-Crystally Aligned Durasteel. 'Sci-fi mumbo jumbo' strengthened armor. More expensive but lighter compared to hull bonus.
-Reflec Armour (think naboo ships, but this was pre prequels). Very expensive, effective vs lasers and not anything else. Very light.
I know I had one more, but cant remember atm. |
Currently, the armor's mass is factored into the mass of the hull,so technically armor has no mass (I got that from D6 Ships).
I could add a option for other types of armor and have then take up some tonnage (or give some back). |
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ZzaphodD
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| Posted: Thu Jun 10, 2010 6:21 pm Post subject: |
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| atgxtg wrote: | | The problem with that method is that it doesn't work with Tramp Freighters. In TF most of the ion engines yield the same thrust per ton (125 if we assume a "stock light freighter" has a mass of 250mt). But TF has a rapidly increasing price scheme. In theory you should be able to put 2 Space 4 Ion drives of a ship to get the same effect as a Space 8 drive but for whatever reason it doesn't work that way in Tramp Freighters. |
Ill have to say I dont really follow you here. What do you mean with 'In TF most of the ion engines yield the same thrust per ton'? The different engines in TF gives different Space ratings, which should translate to different Thrust ratings. If the Thrust / Engine tonnage ration is the same I fail to see the problem.
| Quote: |
Currently, the armor's mass is factored into the mass of the hull,so technically armor has no mass (I got that from D6 Ships).
I could add a option for other types of armor and have then take up some tonnage (or give some back). |
But im talking about adding armour, which should mean more weight (and decreased maneuverability). |
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atgxtg
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| Posted: Thu Jun 10, 2010 7:11 pm Post subject: |
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| ZzaphodD wrote: |
Ill have to say I dont really follow you here. What do you mean with 'In TF most of the ion engines yield the same thrust per ton'? The different engines in TF gives different Space ratings, which should translate to different Thrust ratings. If the Thrust / Engine tonnage ration is the same I fail to see the problem. |
The thrust to engine tonnage for most of the engines in TF are the same, but the cost are not. Let me give some examples.
Let's assume for now that a YT-1300 is a typical freighter, and has a mass of 250mt.
Now, using the replacement ion engines as a guide, the Space 6 Engine, masses 12 mt, and costs 20,000 credits. If we assume that the thrust rating is the Speed times the mass, then the Space 6 engine would have a thrust rating of 6x250=1500. Since the engine has a mass of 12 tons, the engine has an output of 125 thrust/ton, and a cost of 16667credits/ton.
The space 12 Engine masses 24 tons, and cost 500000 credits. Going with Speed times mass again, this engine would have a thrust rating of 12x250= 3000. With a mass of 24 tons, the engine has an output of 125 thrust/ton, same as the Space 6 engine, but a cost of 20833 credits/ton.
Now, if if standard Newtonian physical applied, why would someone use the Space 12 engine if two Space 6 engines give the same performance (1500x2=3000 thrust, 3000/250= Space 12), but cost 10,000 credits less? Or use 3 Space 4 engines and save 20,000 credits!
So most of the designs in Tramp Freighters have the same efficiency, but are more powerful because they are larger.
Originally, I wanted to allow for different design efficiencies with different thrust output per ton, More effcient designs would be much more expense per ton, but if I do so it will:
1) Make the Engines from Tramp Freighters instantly overpriced.
2) Make it hard to explain why the ships aren't faster, since you, for example, could make a YT-1300 as fast an a A-Wing by putting in three engines, and sacrificing 20 tons of cargo space.
I thought of too solutions:
1) Use the Tramp Freigher engines as baselines and scale them up or down to match the size of the hip being fitted to. So a starfighter engine might be have the size/cost for the same rating, and an ISD engine might be 6500 times the size and cost.
That is what I am currently doing.
2) Make the relationship between max speed and the thrust/mass ratio non linear. That way you would need more than twice the thrust to move twice as fast and everything would work out okay. If that were true then the faster engines in Tramp Freighters would be more powerful and the gigher costs would make sense.
I'm playing around with a square root formula, and looking at the acceleration ratings in the New Essential Guide to Vehicles to see if I can make this idea work.
Did you follow that, or did I loose you somewhere?
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But im talking about adding armour, which should mean more weight (and decreased maneuverability). |
Should mean, but doesn't, at least according to D6 Space. In Space, armor doesn't increase the mass of the hull. This can be explained by assuming that the hull is being made of better materials. Remember this is factoring it into the design, not adding it after the fact. So using the YT-133 design as an example, it means that a 83 ton hull that gives +5 pips of armor is just made out of stronger materials, and is why it costs twice as much as an unarmored hull. |
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ZzaphodD
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| Posted: Thu Jun 10, 2010 7:27 pm Post subject: |
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Ok, so the solution is then to think up of a good sci-fi mumbo jumbo reason why engines cannot be combined. At least not for double the effect. The 'single engine' bought might however be a system of several smaller engines (as several ships have several engines).
Well, if armor does not have any weight, then well have to scrap that rule.
I remember now that you could also reinforce the interior integrity of the hull. This cost both weight and space (I had both) but was rather effective and did not show up as tons of armour. |
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Grimace
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| Posted: Thu Jun 10, 2010 7:50 pm Post subject: |
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Or use power as a reason to not have 2 engines at Space 6 or 3 engines at Space 4.
Say 1 engine takes X energy to run. 2 engines on the same ship are going to use not double the amount of energy, but a greater amount. That would explain why a person would invest in a Space 8 engine at a higher price. Not only less cargo space, but less energy usage. |
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ZzaphodD
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| Posted: Thu Jun 10, 2010 8:06 pm Post subject: |
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But of course the best way is to change the 'faulty' rules from GG6. Even in GG6 one could, with just a little leap of logic, claim that buying two cheap engines should give you a very good speed.
Im no rocket scientist, but can you really say that if I have a certain 'low grade' engine and and another Ill get double speed out of it?
So what we are looking for is something like this..
'Low grade' Ion engine 500 Thrust, 10000 Cr, 10 ton
'Med grade' Ion engine 750 Thust, 20000 Cr, 12 ton
'High grade' Ion engine 1000 Thrust, 25000 Cr, 15 ton
Actual numbers are just examples.
So prices increase more than the increase in thrust(high tech). Tonnage is the other way around. This means that putting in more 'low grade' engines will save you money (low tech) but cost you weight. If you want to make doubling up on engines even less effective, reducing added trhust from second engine to 80% of its own actual thrust might be an idea.
Edit: I had my engines require thust/10 Power (EU in your rules). |
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atgxtg
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| Posted: Thu Jun 10, 2010 9:29 pm Post subject: |
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| ZzaphodD wrote: | | But of course the best way is to change the 'faulty' rules from GG6. Even in GG6 one could, with just a little leap of logic, claim that buying two cheap engines should give you a very good speed. |
Then all the ships will be zipping around at Space 10+. The limiting factor in TF is the high cost. In the real world one of the main reasons why people don't just double up thier enine power is that doing so increases the mass. The engine tends to take up a larger pencentage of the craft than in Tramp Freighters. For example, a modern fighter jet, the F-15 Eagle, has a mass on about 12.7mt, about 27% (3.4mt) of which is taken up by engines. Tossing on another pair of engines would up the aircraft to 16.1mt and up the engines to 42% of the craft. Probably for a modest (25% or so) speed gain.
| ZzaphodD wrote: |
Im no rocket scientist, but can you really say that if I have a certain 'low grade' engine and and another Ill get double speed out of it? |
No, but not for the reasons you think.
In space there is no max speed the way there in in an atomsphere. Cars, planes and boats have a max speed becuase of resistance and friction. In space as long as you run the engines, you continue to acclerate. The limiting factor is the fuel.
What does double is the accleration. If you double the thrust/mass ratio you double the rate that a rocket acclerates.
Now, for comparsion, if you were to do this with a car, the result would be a bit different. Let's say you had an old VW Beetle and you replaced the 60hp engine with a more modern 120hp engine that weighted the same. Would the beele go twices as fast? No. ZWhile the engine is twice as powerfl, the powertrain is still the same, the tires are still as effiecenet as they used to be, and the car has the same coeffecient of drag. The et effect would be about a 26% increase in speed, assuming the VW can stand the increased stresses. To get twice the speed you'd need a 480hp (8 times as powerful) engine.
Now if we used the cube function for a ship's SPace rating, then mutiple engines would become unpracticle for speed, since you would need a lot of engines to get a big speed boost.
| ZzaphodD wrote: |
So what we are looking for is something like this..
'Low grade' Ion engine 500 Thrust, 10000 Cr, 10 ton
'Med grade' Ion engine 750 Thust, 20000 Cr, 12 ton
'High grade' Ion engine 1000 Thrust, 25000 Cr, 15 ton
Actual numbers are just examples.
So prices increase more than the increase in thrust(high tech). Tonnage is the other way around. This means that putting in more 'low grade' engines will save you money (low tech) but cost you weight. If you want to make doubling up on engines even less effective, reducing added trhust from second engine to 80% of its own actual thrust might be an idea. |
That is roughly what I had, before Tramp Freighters. But the problem with it is that it will be realtively cheap and easy to ramp up a ship's Space rating by buying more engines or just a bigger engine. Using your 1000 thrust, 25K engine as an example, finding one that puts out 2000 thrust for 50K is still a cheap way to double the ship's speed.
Edit: I had my engines require thust/10 Power (EU in your rules).[/quote]
Not bad. Right now, I have the EU cost =1 per ton of engine. So more efficnent engines are more effecient in output per power consumed too. but that could be changed. |
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atgxtg
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| Posted: Thu Jun 10, 2010 9:39 pm Post subject: |
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| Grimace wrote: | Or use power as a reason to not have 2 engines at Space 6 or 3 engines at Space 4.
Say 1 engine takes X energy to run. 2 engines on the same ship are going to use not double the amount of energy, but a greater amount. That would explain why a person would invest in a Space 8 engine at a higher price. Not only less cargo space, but less energy usage. |
A possibility. The only thing is someone might just be willing to pay the power for the increased speed.
I'm leaning towards using a cube or square root increase and blaming it on "gavimentic resistance". After all, vehicles in Star Wars behave as in they are in an atmosphere, why not treat them as if they are for speed calculations?
Using a cube root relationship, and a 250mt freighter as an example, if a 10t engine provides Space 4:
2 engines (20mt) provide Space 5
4 engines (40mt) provide Space 6
8 Engines (80mt) Provide Space 8
27 Engines (270mt) provide Space 12
With this method, adding another engine or 3 might be worth considering as a way to boost speed, but isn't as efficient as buying a better engine.
It also has a nice perk of working with Tramp Freighters. The faster engines will be providing much more thrust per ton with a doubling or cubing formula. |
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ZzaphodD
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| Posted: Fri Jun 11, 2010 6:21 am Post subject: |
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I think we miss the most obvious reason.
If you want to double your thrust output installing a second engine will probably require a complete rebuilding of the ship = expensive. You dont see that many airplanes with added engines.. I cant see why spaceships should be easier to modify.
If we are talking building from scratch, then I would assume that racking up with lots of 'low grade' engines could be a solution. Perhaps the corellian corvette is one such ship given its configuration. However, I again assume that there are lots of costs we dont consider in making these engines into a working system.
There is also the difference between having 1000 bhp from a cutting edge racing engine and just having two large V10:s drive the same car. You dont have the same response time that a high space rating (which is more than plain acceleration) assume with 20 low grade engines.
All in all, I think the solution lies in making combining engines less effective because of difficulties in making the engines work in sync. |
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atgxtg
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| Posted: Fri Jun 11, 2010 10:11 am Post subject: |
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| ZzaphodD wrote: | I think we miss the most obvious reason.
If you want to double your thrust output installing a second engine will probably require a complete rebuilding of the ship = expensive. You dont see that many airplanes with added engines.. I cant see why spaceships should be easier to modify. |
Not missed, just not an issue when designing a ship, only whne modfiying it. And, since the ion drives are realtively small in Tramp Freighters, it's not that much of an issue envenwhen modfiying a ship. Finding 10 tons on a 260mt freighter isn't early as hard as, say, finding another 10mt in a 70 ton fighter.
| ZzaphodD wrote: |
If we are talking building from scratch, then I would assume that racking up with lots of 'low grade' engines could be a solution. Perhaps the corellian corvette is one such ship given its configuration. However, I again assume that there are lots of costs we dont consider in making these engines into a working system. |
In general it is easier to use mutiple small engines than one big engine. That is why supercarriers, cruise ships, and bulk freighters all have multiple engines. That an the lower cost, and how much easier they are to install, manufacture and work with.
| ZzaphodD wrote: |
There is also the difference between having 1000 bhp from a cutting edge racing engine and just having two large V10:s drive the same car. You dont have the same response time that a high space rating (which is more than plain acceleration) assume with 20 low grade engines. |
Not really. Assume that the two V10s provide the same combined hp and torque as the racing engine, as have the same mass, you would get the same response time and top speed. In the real world the reason why that doesn't happen is becuase the two V10's have a combined mass about 3 times that of the racing engine. And since the engine is a big part of the mass of a real vechile, tripplig the engine mass greatly increses the mass of the vechile, resulting in lower accleration and top speed.
| ZzaphodD wrote: |
All in all, I think the solution lies in making combining engines less effective because of difficulties in making the engines work in sync. |
Except in both Star Wars and the real world, mulitple engines are quire common on ship and aircraft. For most purposes two 1000 thrust engines will give the same performace as one 2000 thrust engine. Usually slighly better.
I've been working with the idea of speed being a square root function of the thrust to mass ratio. This means that A ship will need 4 times the thrust to go twice as fast.
I started working up some engines with differernt thrust/mass outputs. A standard freighter engine will have an output of around 400/ton, while a high performace engine, like the Novadex J-77 will have an output of around 800-900/ton. (I used some real wolrd jet engines for models and scaled up the effciency by a factor of 100).
This seems to work fin, except that the engines on the Millennium Falcon will need to be 24mt instead of 16. (Or else the MF has more efficient engines than an A-Wing). |
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ZzaphodD
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| Posted: Fri Jun 11, 2010 4:10 pm Post subject: |
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One of the main reason for having twin engines on fighters is for safety reasons. If one cuts out, you have the other one as a backup. Two engines are not more effective.
You have the answers in the example about the V10 (even if your starting reasoning is wrong as were talking two 'cheap' engines). Two engines = thrice the weight. Do the same thing for starships and you are home free. |
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atgxtg
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| Posted: Fri Jun 11, 2010 4:57 pm Post subject: |
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| ZzaphodD wrote: | | One of the main reason for having twin engines on fighters is for safety reasons. If one cuts out, you have the other one as a backup. Two engines are not more effective. |
In many situations they are. There are a host of design considerations that go into real world craft that won't be a factor for RPG purposes. For instance the merits of placing the engine in the front, middle or rear of a vehicle.
| ZzaphodD wrote: |
You have the answers in the example about the V10 (even if your starting reasoning is wrong as were talking two 'cheap' engines). Two engines = thrice the weight. Do the same thing for starships and you are home free. |
No, I'm not home free because starship engines are so efficient. Going back to the V10 example, the engine weights something along the lines of 325kg, or about a fifth the weight of, say, s Dodge Viper. Adding a second engine would increase the mass of the car by 20%
By comparison the engine on a "light Freighter" in Star Wars only weights 10 ton, or only 4% of the mass of the freighter. Adding a second engine would increase the mass of the freighter by only 4%. In fact, not even that, since the 10 tons will probably come off of the cargo capacity. The engines in Star Wars are a few thousand times more efficient that what we can come up with today.
That is one reason why in the real world they make more powerful engines-so they can get more bang for the buck. In Star Wars, they are getting such a high power output that the weight cost is negligible. So the added weight isn't as a discouraging a factor as in would be in life.
If the engines on a TY-1300 massed 50 tons or so then tossing in 2, 3 or 4 engines for more speed just isn't practical. You'd have to gut the ship just to find the room. But at 10 tons, tossing in an extra engine or 3 is not much of a problem.
I still think the best solution is to limit the speed they way planes, ships and cars are limited in real life, by a non linear increase between power and speed. |
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Grimace
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| Posted: Fri Jun 11, 2010 10:33 pm Post subject: |
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| atgxtg wrote: |
A possibility. The only thing is someone might just be willing to pay the power for the increased speed.
I'm leaning towards using a cube or square root increase and blaming it on "gavimentic resistance". After all, vehicles in Star Wars behave as in they are in an atmosphere, why not treat them as if they are for speed calculations?
(snip)
With this method, adding another engine or 3 might be worth considering as a way to boost speed, but isn't as efficient as buying a better engine.
It also has a nice perk of working with Tramp Freighters. The faster engines will be providing much more thrust per ton with a doubling or cubing formula. |
That's what I was trying to get you to think about. Basically, like you said, use some techno-babble like your "gravimetric resistance" or whatever and make the addition of more engines useful but not nearly as efficient as buying a single, better engine. That, coupled with the additional tonnage and more energy usage, will make most think twice about doing it to save some credits. Sure you'll have some that want the "acme rocket" variety of ship with multitudes of lower grade engines for a cheaper price, and they'll get some added benefit of greater speed, but not near what they would get if they invested more credits and bought a better single engine. |
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