Train Speeds and Power Consumption

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Frightning
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Train Speeds and Power Consumption

Post by Frightning »

So I decided to run the numbers on train speeds as a function of wagon count/locomotive count using information in this post:
viewtopic.php?f=93&t=21001&p=149315
I also did a little research on real world diesel trains: Real things are roughly 5 times as powerful as the ones in the game currently (~3MW instead of 600kW). The top speed with 2 or fewer wagons is actually believable, despite what some people think: The world speed record for diesel locomotive is actually 271 km/h (!)
However, modern trains often 200+ wagons with just 4 locomotives for a roughly 50/1 ratio yet they can exceed 100km/h with such cargo loads.
The trains in factorio however drop below 100 km/h at a wagon-to-locomotive ratio of 9-to-1.

The tl;dr here is simple:
Train speeds drop too sharply with wagon count.

(If they had 3MW instead, then the numbers are too high until you start getting into the 20s, and again drop rapidly)

The issue is that realistically wagons don't add much wind resistance (which also scales quadratically with speed, not linearly as it does in factorio), but wagons DO add lots of friction (which scales linearly with added mass). So the physics numbers for trains might be worth adjusting so that train speed behaves in a more realistic manner.

Zeblote
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Re: Train Speeds and Power Consumption

Post by Zeblote »

Factorio trains are actually steam powered (they take coal or other flammable materials as fuel) so comparing them with modern diesel ones is unfair :D

silverkitty23
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Re: Train Speeds and Power Consumption

Post by silverkitty23 »

Well, there is one leeeeeeetle thing that might cause people to compare them to modern diesel locomotives:
diesel.png
diesel.png (91.87 KiB) Viewed 4703 times

Zeblote
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Re: Train Speeds and Power Consumption

Post by Zeblote »

silverkitty23 wrote:Well, there is one leeeeeeetle thing that might cause people to compare them to modern diesel locomotives:
diesel.png
They just named it wrong. It's clearly not a diesel engine because there's no diesel in factorio.

searker
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Re: Train Speeds and Power Consumption

Post by searker »

Personally, im quite happy with the current train-mechanics.

Ofc, they are waayy "underpowerd", but a "2-50-0" for example would not be that useful with the current capacity of a single wagon.

On the other hand, real freight-trains need a lot of space to accelerate and brake. Asuming a ingame 2-6-0 to be equivalent to a real 2-50, that would mean it´d need atleast one or two kilometres to accelerate to or slow down from a reasonable speed wich would be too much of a distance for the casual player (casual meaning no resource-tweaking-mod and therefore rather short distances).

tl;dr: The current loco-wagon-balance seems quite right in comparison to the overall scale of the game.
Last edited by searker on Sat Jun 04, 2016 9:03 pm, edited 1 time in total.

Frightning
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Re: Train Speeds and Power Consumption

Post by Frightning »

searker wrote:Personally, im quite happy with the current train-mechanics.

Ofc, they are waayy "underpowerd", but a "2-50-0" for example would not be that useful with the current capacity of a single wagon.

On the other hand, real freight-trains need a lot of space to accelerate and brake. Asuming a ingame 2-6-0 to be equivalent to a real 2-50, that would mean it´d need atleast one or two kilometres to accelerate to or slow down from a reasonable speed wich would too much of a distance for the casual player (casual meaning no resource-tweaking-mod and therefore rather short distances).

tl;dr: The current loco-wagon-balance seems quite right in comparison to the overall scale of the game.
I know that most people probably wouldn't ever get up to 2-50 type trains, but that doesn't mean that they can't tweak the math so that existing short trains continue to be fast but longer trains are slowed more realistically.

BlakeMW
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Re: Train Speeds and Power Consumption

Post by BlakeMW »

Zeblote wrote:
silverkitty23 wrote:Well, there is one leeeeeeetle thing that might cause people to compare them to modern diesel locomotives:
diesel.png
They just named it wrong. It's clearly not a diesel engine because there's no diesel in factorio.
"diesel engine" refers to a particular kind of engine capable of running on many different kinds of fuel, from coal dust to vegetable oil. It uses high compression to generate high temperatures which can ignite fuels which are difficult to ignite. Diesel fuel is of course designed for diesel engines but it's by no means the only thing they can run on. A diesel engine is one logical choice for a locomotive which must run on varied fuels. The other logical choice would be a wood gasifier type setup which generates methane gas from a carbon source and is burned in a conventional petrol (lpg) engine.

But in any case we can conclude "diesel locomotive" refers to the kind of engine used, not as a comparison to RL locomotives.

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Re: Train Speeds and Power Consumption

Post by SyncViews »

Modern freight trains can have over a hundred wagons, and commonly at least dozens.

Pretty sure even the biggest mega-factories look tiny compared to that, so is there any point trying to compare to real world rail physics directly? In fact, the train is likely longer than the distance between most players bases and the mines.
Maybe in the future they will add additional locomotives (with different trade offs), but for now seems fine that the common 3-4 wagon trains run fast, while longer runs slower. You can add extra locomotives as well, and the fuel usage is tiny currently.

As for "diesel engine". I guess that fact it apparently runs on solid fuel is a bit strange, I don't think building such an engine is at all possible unless it liquefies the wood/coal/etc. somehow, which would again seem odd to do on the locomotive itself.

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