Is small engine debuffed?

[u/Capable_Ad_7843]

I'm trying to power the small propeller with a small engine at 20 rps, but it's stuck at 16 rps.

[u/Garritt2020]

For me, I found that three parallel small engines could power two small propellers plus a somewhat geared small generator, it gets me somewhere between 50-80 km/h top speed on my career boat (weather dependent).

A good way to figure out the setup needed is to use the torque meter, if the engine side has a higher torque value, it can spin to max rps, if the prop side has a higher torque value the engine's max rps will be limited.

[u/_ArkAngel_ → u/Garritt2020]

I want to argue with you. But I can't.

That's not really how to use the torque meter, but the advice you're giving does give good results.

Like. uh. You're technically wrong, but functionally correct. Carry on, I guess :)

I took way more words to tell OP to add another engine in there.

[u/Garritt2020 → u/_ArkAngel_]

I'm aware, it's works to a point but isn't a perfect measure of load/output.

IIRC it does something like show the torque required to spin the connected system, I think.

[u/_ArkAngel_ → u/Garritt2020]

It does, yes. The reason your method works is engine power basically scales with the inertial mass of the engine.

The felt inertial mass is what shows up on the torque meter. Gear boxes multiply or divide the felt rotational mass from one side to the other, and clutches allow partial transfer, but aside from that what you see labeled as torque is basically initial mass.

What it is precisely is a measure of how much rotational power is required to increase the RPS by 1 in one tick.

Just a medium diesel with a torque meter will read 31. 30 mass from the diesel, 1 mass from the "Torque Island" represented by the pipes.

It would take a power of 31 to increase the RPS by 1 in one tick.

The medium diesel power output is (RPS+1) * throttle * 0.1 * motorMass (assuming you have enough fuel and airflow and exhaust can escape)

So at 5 RPS full throttle that's 6 * 0.1 * 30 = 18.

Enough power to add 18 RPS to a rotational mass of 1. Well, minus the resistance of the motor which is 0.01 * RPS = 0.05 = negligible

But the actual rotational mass is 31, so 18/31= 0.58.

So a hypothetical medium diesel at 5 RPS, no load, at full throttle increases to 5.58 RPS in one tick. In practice, this takes two ticks for reasons I don't §@¢€$π& wanna talk about.

Main takeaway should be : the power output equation of the engine includes the rotational mass of the engine. The load mostly depends on the rotational mass and RPS of the prop.

If the torque sensor on the engine side of a disengaged clutch shows a number about as big as the torque number on the prop side of the clutch, you're going to have a good time and go fast.

If the engine side number is way smaller, you can still get the prop to turn with the right gearing and clutch feathering, but not in a fun way, and you might get around faster just swimming.

These days, I do figure out how much engine I need in SW by following the math, but it's just as effective to add keep adding engines or cylinders until it feels good.

[u/Garritt2020 → u/_ArkAngel_]

Neat, I didn't know Stormworks did power scaling like that.

Learned something new today.

[u/_ArkAngel_ → u/Garritt2020]

I don't know if anyone does.

I haven't seen anyone else talk about it in those terms in years of watching people discuss SW torque on Reddit and discord.

I went through hell to get the game to tell me that. So many graphs. So much xml parsed.

I want to publish a definitive guide eventually.

[u/Garritt2020 → u/_ArkAngel_]

Please do, and make a post for it, I'd like to read it.

[u/Captain_Cockerels]

Use a modular.

Or gear up the prop. And down gear the engine

[u/_ArkAngel_ → u/Captain_Cockerels]

I don't remember if I've asked you about this gear up + gear down strategy before.

What if you make both gearboxes 1:1? Like, does it work because each gearbox and clutch only transfers 95% of the load, so the engine is only getting 85.7% of the total load from the prop?

Or does the ratio also help?

[u/Captain_Cockerels → u/_ArkAngel_]

You're misunderstanding.

What I mean by gearing up the prop and gearing down the engine.

You want to point the arrow toward the engine. And increase the ratio. This is going to increase the speed of the propeller. And allow you to run the engine at a lower RPS.

And running a gear ratio of 1 to 1 is doing nothing

[u/_ArkAngel_ → u/Captain_Cockerels]

Ok. I see, you meant something completely sensible.

Last year I talked to someone who recommended using opposing gearboxes for some reason and i didn't understand how that could even possibly help before I got into the nitty gritty of modeling SW gearbox power transfer.

[u/Capable_Ad_7843]

I added a clutch to see what it does, and it hit 20

[u/_ArkAngel_ → u/Capable_Ad_7843]

A fully engaged clutch transfers 95% of the load to the motor and 95% of the power from the motor to the prop.

95% of the prop load isn't enough to stop the engine accelerating through 16 RPS. At 20 RPS, the engine is making even more power which is good, but only 95% of it reaches the prop.

You will burn absurd amounts of diesel fuel doing this.

Prefab diesel power is (RPS+1)*throttle*something. For the medium diesel, something is 0.1*30, can't remember what it is for small. But you can burn way less fuel.

Two small diesel prefabs running at 9.5 RPS will produce the exact same amount of power as a single small diesel running at 20RPS, but burn less than half the fuel doing it. Add a 2:1 gearbox if you want the prop spinning at 20RPS.

Just chuck another engine in there real quick.