better engine efficiency vs size

[letsdance (OP)]

As I proved with the designs I showed you, using the less powerful engine will produce a cheaper ship with lower speed and fuel usage while a higher power engine produce a slightly more expensive ship that use up more fuel but also is faster.

why didn't you use the engine i suggested? it would not be slower.

(A) Is the one I use in my current game.

thx =)

this one is tricky because of armor and because your design seems to be already about 35 % engines (including armor required for the engine tonnage). you can only improve it on a smaller scale.

it seems you used this engine x3:

Engine Power: 168     Fuel Use Per Hour: 210.39 Litres
Fuel Consumption per Engine Power Hour: 1.252 Litres
Engine Size: 10 HS    Engine HTK: 5
Thermal Signature: 168     Exp Chance: 14
Cost: 84    Crew: 14
Materials Required: 84x Gallicite
Military Engine
Development Cost for Project: 840RP

i suggest trying this one x4:

Engine Power: 135     Fuel Use Per Hour: 128.76 Litres
Fuel Consumption per Engine Power Hour: 0.954 Litres
Engine Size: 9 HS    Engine HTK: 4
Thermal Signature: 135     Exp Chance: 12
Cost: 67.5    Crew: 11
Materials Required: 67.5x Gallicite
Military Engine
Development Cost for Project: 675RP

it created a similar testdesign, and the result was a ship that is very slightly more expensive (911 instead of 900) but faster (5090 instead of 5040), cheaper to research and less fuel needed. can you try it and post the result?

i didn't test it but i it should also work with 9x of the same engine power modifier with HS 4 instead of 4x HS 9. this way you have more safety and even less research costs. (that consideration is also again more in topic concerning engine efficiency vs size - there should be a higher difference from HS 4 to 9).

if we stayed in this thread (engine efficiency vs size) there is no real improvement (without significant tradeoffs) possible for your design by increasing engine size. the reason is that (1) the ship barely has the minimum size for such possible improvements and it already has 35 % engines.

[Jorgen_CAB]

why didn't you use the engine i suggested? it would not be slower.

Ok here it is...

Code: [Select]

Iowa (B3) class Cruiser    10,850 tons     274 Crew     1433.13 BP      TCS 217  TH 796  EM 0
3668 km/s     Armour 5-43     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 6     PPV 53.46
Maint Life 2.53 Years     MSP 495    AFR 156%    IFR 2.2%    1YR 108    5YR 1613    Max Repair 112.71 MSP
Intended Deployment Time: 9 months    Flight Crew Berths 26    
Hangar Deck Capacity 1000 tons     Magazine 150    

265.2 EP (HS26) Ion Drive (3)    Power 265.2    Fuel Use 29.57%    Signature 265.2    Exp 8%
Fuel Capacity 270,000 Litres    Range 15.1 billion km   (47 days at full power)

Twin 15cm C3 Ultraviolet Laser Turret (6x2)    Range 0km     TS: 6000 km/s     Power 12-6     RM 4    ROF 10        0 0 0 0 0 0 0 0 0 0
Gas-Cooled Fast Reactor Technology PB-1 (7)     Total Power Output 31.5    Armour 0    Exp 5%
This design is classed as a Military Vessel for maintenance purposes
In my opinion it does not matters much, this ships is more expensive, but slightly faster (+68km/s) than Iowa (A) class of ships, it is better in fuel economy though. The biggest problem with either of the Iowa(B) class though is that they are oversized (+700-850t), that is a huge problem. We can't just redo our entire infrastructure just to accommodate the B version, it would certainly be voted down as too expensive in congress.  

So, we are still in the same spot... Iowa (B2) is about 35% more fuel efficient, 7% cheaper and 100t smaller then Iowa (B3)... while it is 11% slower... both ships are not legal for production though because they can't satisfy the two criteria of mission tonnage or total tonnage. If you redid the engines so the ship met both of these criteria they would become cheaper but much slower... like this...

Code: [Select]

Iowa (B3) class Cruiser    9,950 tons     255 Crew     1341.605 BP      TCS 199  TH 643  EM 0
3231 km/s     Armour 5-41     Shields 0-0     Sensors 1/1/0/0     Damage Control Rating 5     PPV 53.46
Maint Life 2.65 Years     MSP 442    AFR 150%    IFR 2.1%    1YR 90    5YR 1343    Max Repair 91.035 MSP
Intended Deployment Time: 9 months    Flight Crew Berths 28    
Hangar Deck Capacity 1000 tons     Magazine 150    

214.2 EP (HS21) Ion Drive (3)    Power 214.2    Fuel Use 31.57%    Signature 214.2    Exp 8%
Fuel Capacity 270,000 Litres    Range 15.5 billion km   (55 days at full power)

Twin 15cm C3 Ultraviolet Laser Turret (6x2)    Range 0km     TS: 6000 km/s     Power 12-6     RM 4    ROF 10        0 0 0 0 0 0 0 0 0 0
Gas-Cooled Fast Reactor Technology PB-1 (7)     Total Power Output 31.5    Armour 0    Exp 5%
This design is classed as a Military Vessel for maintenance purposes
This was pretty much as close as I could do it, there are another 50t or so you could add, but that does not matter much in the end.

The end result is that you can never just make the ship bigger and get the same speed but better fuel economy without allow for the other ship to add more engine to increase it speed at the same size. You may not compare apples with pares, that is a no no. If you must compare, all thing must be equal except one, in this case the engines must be the same size as must all the mission based tonnage. If you reduce the mission tonnage in favour of engines you must compare the same number of total ship tonnage over several ships that contain the exact same mission tonnage. The problem with different number of ships is that you introduce the problem with requirement of different numbers of slipways, this is equally bad as comparing different sizes.

In any way you twist and turn you will need to sacrifice something to gain something else.

I put no value in if you choose speed, fuel economy, or future upgrade possibilities/costs as a priority, all criteria has to be made from a strategic versus economic point of view. whichever path you choose must lead to a healthy empire for you..  

[alex_brunius]

this one is tricky because of armor and because your design seems to be already about 35 % engines (including armor required for the engine tonnage).

Why would you include the armor in the engine tonnage? If we have the same final size armor will be identical regardless of what we put inside the ship.

The engine is 30% and you suggested 50% always was the optimal.

i suggest trying this one x4:

4 x 9HS engines leads to 1800 ton engines out of 5000 = 36% engines, so closer to what I think is optimal already ( 30% ) then what you initially claimed to be optimal (50%).

[letsdance (OP)]

In my opinion it does not matters much, this ships is more expensive

no it's not. it's cheaper. Iowa (A) was 1454 BP while Iowa (B3) is 1433.13 BP. Iowa (B3) is cheaper, faster and needs less fuel and research points.

The end result is that you can never just make the ship bigger and get the same speed but better fuel economy

we just did exactly that!

The problem with different number of ships is that you introduce the problem with requirement of different numbers of slipways, this is equally bad as comparing different sizes.

yes but it's only a problem for a 1:1 compare like we're doing here. in reality you just build as many ships as you have slipways, or build as many slipways as you want to build ships later (besides, cheaper designs will build faster, and again faster if they are larger).

looking at it the other way round, if you did your design using more efficient engines in first place, you wouldn't be able to make a 1:1 transition to higher power engines that fit your shipyards as well. but this is not about specific games or designs, it's just to show that you can make your ships faster and cheaper while needing less RPs and fuel in return for a small size increase.

once people start to accept this as a fact, maybe we can actually discuss it or maybe someone convinces me that i'm wrong and we can close the topic =)

[letsdance (OP)]

Why would you include the armor in the engine tonnage?

cause large engine = more armor and smaller engine = less armor. this has to be part of the calculation. i count the engine size by adding or removing it and looking at the stats (that also includes crew and engineering spaces). the basic topic is increasing engine size for overall benefits in general. i assume the benefits of this is capped at 50 % engines, but i see no difference if i'm wrong and that cap is actually 45 or 55 %.

4 x 9HS engines leads to 1800 ton engines out of 5000 = 36% engines

higher if you include the overhead in the % calculations. you're also ignoring that it increases the total ship size as well, changing percentages. maybe it could be improved further. i chose this because it was the first one i found that showed a clear advantage in every regard. that's sufficient to proof my point, isn't it?

so closer to what I think is optimal already ( 30% )

earlier this thread you talked about 25 %.

1.) 60% launchers, 25% engines (8 of them)

and the design we discussed now had 35 %. but that's nitpicking, isn't it? if my suggested engines improve the ship the way i predicted, it doesn't really matter. unless you want to discuss if the optimum engine space is not 50 % but 45 %, but that would require you to agree with my basic assumption in first place.

[Jorgen_CAB]

no it's not. it's cheaper. Iowa (A) was 1454 BP while Iowa (B3) is 1433.13 BP. Iowa (B3) is cheaper, faster and needs less fuel and research points.
we just did exactly that!
Yes but it's only a problem for a 1:1 compare like we're doing here. in reality you just build as many ships as you have slipways, or build as many slipways as you want to build ships later (besides, cheaper designs will build faster, and again faster if they are larger).

looking at it the other way round, if you did your design using more efficient engines in first place, you wouldn't be able to make a 1:1 transition to higher power engines that fit your shipyards as well. but this is not about specific games or designs, it's just to show that you can make your ships faster and cheaper while needing less RPs and fuel in return for a small size increase.

once people start to accept this as a fact, maybe we can actually discuss it or maybe someone convinces me that i'm wrong and we can close the topic =)

You don't seem to understand what I'm saying or we are just talking in circles, I do think I understand perfectly well what you mean... it's just that you don't seem to have any rules for limitations.

I probably looked at the wrong figure for the price of the Iowa A versus B3 but it does not change anything, Iowa B3 is still larger and you must allow model A to have same tonnage too or take the size as a difference. The price does not matter alone, it is what you sacrifice. In the comparison between Iowa A and B3 for example you have a huge gap of 850t, that can be filled with more stuff for a slightly higher price, an extra 100BP or so is not a huge price to pay for a ship that are lets say 4-500km/s extra speed if that is what you want, that will take Iowa A in the same size as Iowa B3. So you will trade higher production value and fuel usage for more speed. You can't seriously say that each time you increase the size of Iowa A you can do the same with Iowa B3 ad infinitum do you?

You don't have infinite number of yard space, slipways or maintenance facilities to produce or maintain your ships.

If you have a large empire and standard maintenance facilities in certain places at 10.000t you can't just keep bloating that number, it is not realistic to do so. You must set a few criteria that can't be broken... it is IMPOSSIBLE to compare otherwise.

Can you please stipulate the constraints for these designs and I will be happy to oblige with a comparison in designs and what the benefit and drawback for each one are?

In my opinion the ships you compare MUST have the same size and number slipways otherwise you throw the whole concept of a fair comparison out the window because you just assume that the underlying infrastructure you need to build things can be expanded into infinity.

I will also add that the example I gave was just examples to show that there are differences between them, it does not matter that one is more expensive, faster, slower, more or less fuel efficient, larger or smaller. As long as on example is not better in all areas there is a trade of. No single example so far has had that except for your designs where you used way too much fuel in which I agree that low powered engines are better, they should be for long range ships.

The only thing that you really proved (in my opinion) is that there is a line between weight of fuel to the power setting of the engine in terms of economy of building the ship giving all else is equal. In other words there are always an optimum way to construct your engines if you want your ship to go relatively far.

[Jorgen_CAB]

One more thing on a difference that may or may not matter to you. A bigger ship have bigger TCS and higher Thermal output than a ship that is smaller with the same speed. This is also something you must consider as a drawback of a larger ship versus a smaller ship. While larger ships in general can have deeper armour for less weight which I think is a bonus in favour of larger ships, especially in beam combat.

[letsdance (OP)]

As long as on example is not better in all areas there is a trade of.

yes, there is! and in my oppinion, the tradeoff for faster, cheaper, cheaper to research and more fuel efficient designs should be more than a small increase in size. so far, everyone (including you) argued that you cannot achieve these improvements for this tradeoff, using lower power engines. so instead of discussing the topic, i was busy proofing that it's possible at all.

i don't think a 1,000 shipyard capacity (like in your example) increase is a sufficient tradeoff for the named benefits. in reality you won't see it that way anyways, because usually you design your ship to fit into your spaceyard and not the other way round. but spaceyard size is plannable and not that expensive. you'll have your ships sooner (because larger and cheaper) and you also need less minerals, fuel refineries and tankers.

all this is actually off-topic here, because this thread was about better efficiency vs size scaling. i started the issue we're discussing now here http://aurora2.pentarch.org/index.php/topic,7472.0.html. my main problem is, that lower power engines should make a ship slower. i suggested (in the other thread) to keep engine costs the same for all power levels. that way, if you stack lower power engines your ship at least becomes more expensive instead of cheaper. it would also make high power engines more attractive for large ships. another suggestion was to reduce the impact of engine power on fuel consumption.

A bigger ship have bigger TCS and higher Thermal output than a ship that is smaller with the same speed.

yes but that's a small effect, in your Iowa example it's 10 %. for the TCS, if your enemy is using a lower resolution sensor than your ship size (and only then!) he will spot you from 20 % farer away.

[Jorgen_CAB]

Yes... you can argue, if you feel like it, there is not enough difference for the benefit and I personally design my ships with slower cheaper engines for the reason you just gave.

But if you feel that speed IS more important than a small increase in cost and fuel efficiency that is as valid a choice as any other, that is the ONLY thing I'm trying to explain. You are trying to convince me and other that this choice is non existent where there actually IS a choice.

If you add 1000 ton to your shipyard or not does not matter, because ALL designs you compare with must be allowed to use that full size, it does not matter if it is 10.000 or 100.000t we are talking about. That is why you can't compare this...

Speed: 4000
Cost: 1000
Fuel efficiency: 1
Size: 10000
Everything else: 1

With this...

Speed: 4000
Cost: 1000
Fuel efficiency: 0.8
Size: 11000
Everything else: 1

Becasue then the first design could be...

Speed: 4300
Cost: 1100
Fuel Efficiency: 1
Size: 11000
Everything else: 1

If you value the cost and fuel efficiency over the speed that is your decision to do so, one which I happen to mostly agree with is the better choice in most cases. But, it is not the only choice, a higher speed can mean allot at times, it can mean that you win instead of loosing a fight. Sometimes speed alone can be the single factor for winning an engagement, mission tonnage does not mean squat. That can happen.

If we can agree on this I have no issue discussing if say +400km/s extra speed is worth an extra +10% production cost and -20% fuel efficiency or whatever it might be. Just as long as we agree you can't compare two ships of different size as if they were equal.

[letsdance (OP)]

Just as long as we agree you can't compare two ships of different size as if they were equal.

sure, i never denied that. i just think the disadvantages of larger size is too low compared to the benefits. but it's probably better to take this to the other thread http://aurora2.pentarch.org/index.php/topic,7472.0.html

[Jorgen_CAB]

sure, i never denied that. i just think the disadvantages of larger size is too low compared to the benefits. but it's probably better to take this to the other thread http://aurora2.pentarch.org/index.php/topic,7472.0.html

OK, I will debate it there then...

In the spirit to be on topic in this thread I think that Alex suggestion in this post had pretty good merits

http://aurora2.pentarch.org/index.php/topic,7448.msg75697.html#msg75697

[alex_brunius]

Moved post to other thread.

Edit:

And to continue on my on topic suggestion linked:
What would happen if missile engines would also use the values using the same fuel consumption vs size formula I suggested?

( fuel consumption factor = SQRT(10/HS) )

We know that 1MSP = 1/20HS, so the Missile engine formula would look like this:

( Missile fuel consumption factor = SQRT(200/MSP) )

Code: [Select]

MSP Fuelconsumption
0.10 44.72
0.20 31.62
0.30 25.82
0.40 22.36
0.50 20.00
0.60 18.26
0.70 16.90
0.80 15.81
0.90 14.91
1.00 14.14
1.10 13.48
1.20 12.91
1.30 12.40
1.40 11.95
1.50 11.55
1.60 11.18
1.70 10.85
1.80 10.54
1.90 10.26
2.00 10.00
2.10 9.76
2.20 9.53
2.30 9.33
2.40 9.13
2.50 8.94
2.60 8.77
2.70 8.61
2.80 8.45
2.90 8.30
3.00 8.16
3.10 8.03
3.20 7.91
3.30 7.78
3.40 7.67
3.50 7.56
3.60 7.45
3.70 7.35
3.80 7.25
3.90 7.16
4.00 7.07
4.10 6.98
4.20 6.90
4.30 6.82
4.40 6.74
4.50 6.67
4.60 6.59
4.70 6.52
4.80 6.45
4.90 6.39
5.00 6.32

The result would be missile engines that are ranging from 3.07 times ( 0.1MSP ) less fuel efficient to 6.32 times ( 5 MSP ) less fuel efficient
Considering how little importance fuel and fuel efficiency has for missiles today ( few designs even have as much as 5 or 10% fuel ) I think such a development could be quite interesting, since fuel would then be an even more important factor to consider and balance in the missile design even earlier before you have the max power mod researched.

And it could make beam weapons more interesting since even if they are still badly out-ranged it would not be quite as bad, and since there is a higher chance to encounter slower more fuel efficient missiles.

Another gain is that it would allow making missile engines all the way up to 20 MSP (1HS) and have a perfectly smooth transition to small fighter engines at 1HS.

Some potential problems might be re-balance of detection sensors and MFCs needed.

[letsdance (OP)]

any suggestion that reduces missile range has my vote =)

[sloanjh]

And to continue on my on topic suggestion linked:
What would happen if missile engines would also use the values using the same fuel consumption vs size formula I suggested?

( fuel consumption factor = SQRT(10/HS) )

Let me make sure I understand this suggestion:  You're suggesting that the fuel efficiency of an engine grow like the sqrt of the size of the engine, correct?  So an engine 4x as big would only require 2x the fuel to go the same distance in the same size ship?

If so, I think this is a great idea for multiple reasons:

1)  One of the things Steve wanted to accomplish in the original Aurora was to bias ship design away from the swarms of small ships found in Starfire and towards single, big ships.  Although this has been somewhat successful, the fact that almost everything in a ship design scales linearly with size means that the isn't a strong selection pressure towards big ships.  This suggestion would add selection pressure for big ships - doubling the ship size would mean that the fuel tankage would only go up by a factor of sqrt(2)x (rather than 2x), leaving the remaining volume for payload.
2)  Ditto for specialist designs (small single-role ships) vs. general designs (larger multi-role ships).
3)  Cutting missile ranges significantly would probably swing the balance towards beam combatants, which is probably a good thing.

The amount of pressure applied could be adjusted by adjusting overall fuel efficiency - the bigger a percentage of the ship tankage required, the more pressure for big ships there would be.

I think this is worth a suggestion in the official thread, if you haven't made one already.

John

[alex_brunius]

Let me make sure I understand this suggestion:  You're suggesting that the fuel efficiency of an engine grow like the sqrt of the size of the engine, correct?

Yes, and also moving the 1.0 modifier to a bit higher size engines (10HS), to allow more fuel guzzling smaller engines for fighters and FACs and make engine size in that range actually a choice instead of just lets go with as many 1HS engines as I need.

The current formulas in use are:
Missile Engines: Fuel Modifier = (Engine Size in MSP / 5) ^ (-0.683)
Ship Engines: Fuel Modifier = 1 - (Engine Size in HS/100)

So the main improvement is just as you say moving from a linear scale for ship engines to an exponential one more similar to what is used in missiles. Another desirable thing is that such a formula would allow even bigger engines of 100+ HS without reaching zero fuel consumption.

Note: My formula can be expressed in a more similar way as well:

Missile Engines: Fuel Modifier = (Engine Size in MSP / 200) ^ (-0.5)
Ship Engines: Fuel Modifier = (Engine Size in HS / 10) ^ (-0.5)

It's of course possible to play around with the exponent in the formula too to get higher or lower impact of engine size on fuel efficiency.

For example using 0.4 instead lowers size impact and gives a HS 50 engine 52% consumption instead.
Or 0.6 raises size impact and gives a HS 50 engine 38% consumption.

( I mostly put 0.5 or SQRT there for a simple and elegant formula   )


But I feel the "natural" origin or 1.0 modifier of the formula is well defined at 10HS = 500 ton engines.