Fuel Economies

[Nightstar]

Now you're just being thickheaded.

If changing power modifier is out of scope, so is changing engine size, as that also effects efficiency. Therefore the ONLY engine comparison in scope is a 600 EP drive vs a 800 EP drive. Or proportions to that effect. Since comparing fast ships to slow ones is also ridiculous, we have no useful comparisons in scope. In fact, even that drive is out of scope, because it requires several hundred RP (tech) that isn't included in the previous drive's cost.

You're focusing on such a narrow scope as to ignore all the practical realities. This is silly.

[Charlie Beeler]

Now you're just being thickheaded.

If changing power modifier is out of scope, so is changing engine size, as that also effects efficiency. Therefore the ONLY engine comparison in scope is a 600 EP drive vs a 800 EP drive. Or proportions to that effect. Since comparing fast ships to slow ones is also ridiculous, we have no useful comparisons in scope. In fact, even that drive is out of scope, because it requires several hundred RP (tech) that isn't included in the previous drive's cost.

You're focusing on such a narrow scope as to ignore all the practical realities. This is silly.

Before making such a statement... go back a read the original post that is the focus of the discussion.   

• Ian posted that fuel efficiency per EP does not change as drive tech advances
• Alex posted that he believed this to be incorrect based on using smaller engines for the same EP on smaller ships represents improved fuel efficiency

That defines the scope of what I requested be splitoff from the main suggestions thread.  The point was too discuss this specific contention, not overall drive efficiency vs power output.

[Nightstar]

Within that scope, power mods do still count. You get massively increased fuel economy for the same speed at higher tech. Can't just ignore those cause you feel like it.

But, even ignoring those, on any ship with several engines, you can ditch an engine, and get better fuel efficiency that way. Smaller may not work if you have only one large engine, but otherwise less engine still works.

So yeah, I still think you're being silly.

[Charlie Beeler]

That's your opinion.

Professionally I daily have to parse project criteria from vague user statements. 

[davidb86]

Before making such a statement... go back a read the original post that is the focus of the discussion.   

• Ian posted that fuel efficiency per EP does not change as drive tech advances
• Alex posted that he believed this to be incorrect based on using smaller engines for the same EP on smaller ships represents improved fuel efficiency

That defines the scope of what I requested be splitoff from the main suggestions thread.  The point was too discuss this specific contention, not overall drive efficiency vs power output.

Charlie,

Ian did post "that efficiency per EP does not change as drive tech advances".  But he did this in the context of a suggestion that efficiency should be tied to the base engine tech.  The reason that many players find this unreasonable is that as has been shown by this thread, efficiency is not only it's own tech branch, but can also be modified by design considerations regardless of tech level.  The statement that efficiency should be tied to base engine tech is equivalent to complaining that you have to research multiple tech lines to make any of the weapon systems work instead of researching a single tech and getting a working weapon as was done in Starfire. 

Yes it is a true statement, but it misses the point that this is not a bug, an oversight or an unintended consequence; but a deliberate design choice that Steve made to allow more than one way to solve the tactical problems

[Charlie Beeler]

Charlie,

Ian did post "that efficiency per EP does not change as drive tech advances".  But he did this in the context of a suggestion that efficiency should be tied to the base engine tech.  The reason that many players find this unreasonable is that as has been shown by this thread, efficiency is not only it's own tech branch, but can also be modified by design considerations regardless of tech level.  The statement that efficiency should be tied to base engine tech is equivalent to complaining that you have to research multiple tech lines to make any of the weapon systems work instead of researching a single tech and getting a working weapon as was done in Starfire. 

Yes it is a true statement, but it misses the point that this is not a bug, an oversight or an unintended consequence; but a deliberate design choice that Steve made to allow more than one way to solve the tactical problems

I'm fully aware of that.  Please note that this seperation topic starts with Alex's reply post. 

[Nightstar]

You poor thing.

Anyway, perhaps I should rephrase. While you're right about smaller engines not necessarily being more fuel efficient, this is irrelevant to the real discussion: Higher tech engines being more fuel efficient.

This quote, right at the very top of the topic:

No matter what flavour of engine you use for an identical power output you consume the same amount of fuel per Engine Power Hour.

It's dead wrong. Alex's post is true anyway, barring external things like having to use smaller engines.

[Charlie Beeler]

Now look at the entire quote.  Ian is very specific in drive tech progression is what is being addressed.  That fundamental statement is correct.  Nothing about advancing the drive tech, drive tech only, improves fuel efficiency.  Only other implementation factors effect fuel efficiency.

The devil is in the details.

For clarity here is the entire original post....

No matter what flavour of engine you use for an identical power output you consume the same amount of fuel per Engine Power Hour. What this means is that a conventional engine is as fuel efficient as a Magneto-plasma drive, just you can generate more power in the same space. There is no  improvement in fuel efficiency as your engine tech improves.

This doesn't seem quite right. Almost like (in wet navy terms) as saying a reciprocating steam engine is as efficient as a high pressure steam engine is as efficient as a diesel engine is as efficient as a nuclear reactor.

With the recent changes to fuel requirements it is surely not beyond the realms of possibility to  increase engine efficiency as the tech improves. 

[Conscript Gary]

I can comment on the numbers when I'm at a proper computer, but the graphs at the bottom of each sheet should get the basic point across: that when sizes are fixed and all efficiency techs are equal, upgrading an engine to the next level of propulsion tech can result in an increased speed with no change in range (as is typically done), an increased range with no change in speed, or some happy medium. All within the bounds of the base power modifier tech (base minimum modifier is 0.5 modifier right? Has to be, otherwise you couldn't make commercial engines)

[TheDeadlyShoe]

interesting discussion at any rate. going through the math was informative.

[Conscript Gary]

Now to address the original argument I made a copy of that spreadsheet and held power modifiers constant but varied engine size from 20 to 1.

Now, let's compare between these two methods of engine upgrade. 1) Using a lower power modifier in the same engine size and 2) Using the same power modifier in a smaller engine.
I'll only consider cases here where the speed after the upgrade does not go down, though the full data for all modifiers and sizes below the datum are available in the aforementioned spreadsheets here and here. I'll only walk through the ion -> magneto-plasma upgrade in this post, but again the rest of the charts are in the docs.

1) Reducing power output in a fixed engine size though reduced power modifiers



At an equal power modifier, a speed increase of 33% is attainable with no change in range
At an equal power output, a range increase of 105% is attainable with no change in speed

2) Reducing Power output at a fixed power modifier through reduced size engines



At an equal size, a speed increase of 33% is attainable with no change in range
At a nearly equal power output, a range increase of 0.57% is attainable with a speed increase of 0.9%

I think those numbers speak for themselves

[Rod-Serling]

Charlie Beeler, I've got to admit, you've made me a little upset due to your attitude toward this discussion. You obviously think you are right and that IanD's statement is correct, and you blatantly disregard many good points by other members simply because they do not fall in to what you consider to be the realm of the discussion. They were, however, relevant. If the engines had the same fuel efficiency, then they would be completely identical.   
In any case, both you and IanD are incorrect in any case, and like you said yourself. . .

The devil is in the details.

For my analysis I will gladly adhere to your rules. Power / Efficiency Modifiers will remain at 1. Fuel Consumption will remain at 1, and engine size will remain a constant 10HS.   

However, trans-newton engines are very special. They don't exist in the real world obviously, and exhibit very strange characteristics. The most important characteristic is that they constantly require fuel to maintain their speed. This is very much like a commercial airliner, or an automobile, and very much unlike a traditional spacecraft. This implies that Trans-Newton engines are affected by some kind of Trans-Newton drag.   

Now I'm by no means an expert in physics, I have the basic understanding that to maintain speed while under the effects of drag, a force of identical magnitude of the drag must be applied from the other end.   

So, in Aurora terms, that TN engine that sports a 500km/sec top speed, is constantly accelerating at 500km/sec^2, and being pushed back by drag at 500km/sec^s


Now, let's look again at the original quote.   

No matter what flavour of engine you use for an identical power output you consume the same amount of fuel per Engine Power Hour. What this means is that a conventional engine is as fuel efficient as a Magneto-plasma drive, just you can generate more power in the same space. There is no  improvement in fuel efficiency as your engine tech improves.   

This doesn't seem quite right. Almost like (in wet navy terms) as saying a reciprocating steam engine is as efficient as a high pressure steam engine is as efficient as a diesel engine is as efficient as a nuclear reactor.   

With the recent changes to fuel requirements it is surely not beyond the realms of possibility to increase engine efficiency as the tech improves.     

hxxp: en. wikipedia.  rg/wiki/Fuel_efficiency

Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work

Now, let's take a look at Conscript Gary's excellent spreadsheets.   

A Size-10 Nuclear Thermal Engine can push our 2000-Ton craft 50 billion kilometers at a rate of 1,250km/sec using only 500,000 liters of fuel.   
A Size-10 Nuclear Pulse Engine can push our 2000-Ton craft 50 billion kilometers at a rate of 2,000km/sec using only 500,000 liters of fuel.   

We already know how much "carrier fuel" we transferred into "kinetic energy or work", it was 500,000 liters in both cases. But how much work did each engine do?

Let's use Joules.   
J=N*m
N = Newtons of force applied
m = meters the force was applied for.   

So, so how many Newtons?

N = kg*A
kg being the weight of the object
A being the acceleration in m/s^2

Our 2000-ton craft weighs 2,032,093kg (Long Ton, it's not written tonnes and Steve is from London, you could use Short or Metric tons, result will be the same)

Our NTE is accelerating at 1,250,000m/s^2, providing 2,540,116,250,000 Newtons of force
Our NPE is accelerating at 2,000,000m/s^s, providing 4,064,186,000,000 Newtons of force

J=N*m
We burned for 50,000,000,000,000 meters, so
J=N*50 trillion
Our NTE converted 500,000 liters of fuel into 127.   005812 Yottajoules of work.   
Our NPE converted 500,000 liters of fuel into 203.   2093 Yottajoules of work.   
(1 Yottajoule = 1,000,000,000,000,000,000,000,000 joules)

This means that a Nuclear Pulse Engine is 60% more fuel efficient than a Nuclear Thermal Engine.   

This increase in fuel efficiency allows us to go faster, or go farther, depending on your needs. If the engines had the same fuel efficiency, then they would literally be identical. Your only chance to change anything would be to change the power modifiers, size, and other stuff.   

Now where you and IanD get mixed up, is that Fuel Efficiency is not the same as Fuel Economy. I'm going to quote our ever-reliable source, wikipedia.
hxxp: en. wikipedia. org/wiki/Fuel_economy_in_automobiles#Fuel_economy_statistics

While the fuel efficiency of petroleum engines (the ability to transform the chemical energy of the fuel into power) has increased since the beginning of the automotive era, this has not necessarily resulted in greater fuel economy or less fuel consumption. The mass, shape, and size of a car, also affect fuel economy and so does the automobile's design, which may be to produce more power and speed rather than greater economy and range.   

In conclusion, IanD is completely wrong. Engine Technology advancement is directly increasing fuel efficiency. Fuel economy, however, is a different issue, and depends on the design of the engine. But we wern't talking about fuel economy were we?

[Conscript Gary]

I'd rather stick to the definition of fuel efficiency used by the game, that of how much fuel is consumed per unit of engine power. Semantics just bog down an argument.

In which case yes, propulsion technology has no bearing on the liters of fuel required to produce an hour of engine power.
Engine size, power modifier, and fuel consumption tech do. Should propulsion technology be included in that list? I would lean towards saying no. Those three existing factors provide plenty of room for playing with efficiency in my opinion. Fuel tech lets you use less fuel with no bearing on speed. Engine tech lets you go faster with no bearing on fuel usage. Two sides of the same coin.

(also I stuck some spiffy color-coding to the results on those spreadsheets)

edit: And then I got curious as to the gains/lack thereof from matching power from differing engine sizes and made yet another spreadsheet.



Holding power modifier, fuel consumption tech and ship components fixed, and using smaller engines to match the old in power output. Engine ratio is 0.25. Results in:
Increased fuel consumption to the order of ~20% with a size-50 starting engine that peters off to parity at smaller sizes.
Increased range to the order of ~15% with a size-50 starting engine that peters off by size-21.
Decreased range starting at size-20 engines, ending at around a ~5% loss for miniature engines.

Those trends were fairly consistent across upgrades, which fits the math, so I wondered how the engine ratio factored into things, with several fixed starting engine sizes.



Engine ratio (Total size / Engine size) has no bearing on fuel consumption, as expected by the math.
But as the ratio of engine-to-ship increases, the less possible it is to increase your range with a size-based upgrade.

So unless you consider ~5-15 HS less of a target cross section to be worth having no upgrade in speed, barely any upgrade in range, and an increase in fuel usage, it's not a terribly viable upgrade method.

[Charlie Beeler]

Rod-Sterling, so happy that your upset.  It made you look deeper into the subject didn't it. 

I do thank you for an excellent example of bypassing the point. 

Whether the proper term is efficiency or economy, they are habitually used interchangeably on this board for discussing engine fuel use, Ian's statement that drive tech advancement does not change the fuel needed to cover a set distance is quite correct.  The key points are that only drive tech changes are specified and that the engine size is constant.  I infer, yes this may be incorrect, that Ian's intent is refitting existing ships with new drive techs.   

Your analysis related to joules for thrust is a nice touch that has nothing to do with movement in Aurora.  The basis of Aurora drives is that it is inertialess and does not adhere to Newtonian physics.  Kinetic energy does not apply.  No acceleration.  So all that detail work is irrelevant to the discussion.

Within Aurora fuel consumption has a baseline of 1 liter produces 1 engine propulsion point per hour.  This does not change from one drive tech to another, period.  This function is what Ian's post is pointing out.  Not advancing tech for Fuel Consumption. Not Maximum or Minimum Power Modifiers. And specificly not different sized engines.  All of those do have a direct effect on fuel consumption. 

[alex_brunius (OP)]

Your analysis related to joules for thrust is a nice touch that has nothing to do with movement in Aurora.  The basis of Aurora drives is that it is inertialess and does not adhere to Newtonian physics.  Kinetic energy does not apply.  No acceleration.  So all that detail work is irrelevant to the discussion.

Ofcourse it does have everything to do with movements in Aurora.

The ship is moving faster which we all agree is off great value, to acomplish this while still not burning any more fuel is indeed an increase in efficiency, but that extra efficiency is spent on increasing speed.

You are ignoring the merit and value of this speed gain and the fact that it in practice easilly can be interchanged for a huge increase in fuel efficiency if the designer of the next generation engine chooses to do so.

As many have already pointed out a next gen engine with the same power output, size and same fuel effeciency tech would have significantly better fuel efficiency/fuel economy. In the Aurora the universe this is what matters when we build our ships.

I acknowledge your theoretical point, but what we are trying to say is that it doesn't matter because in practice more advanced engines will let you design more fuel efficient engines without losing anything, both through a design using a lower fuel burn ratio, or through a design using less space. If More advanced engines also gave you a direct bonus to fuel efficiency then that tech line would become even more powerful and overpowered, it already lets you design better engines (in whatever area you choose to improve) for Starships, Fighters, FACs and Missiles, I think it's powerful enough.