Kerbal Space Program Megathread V1

[fr0stbyte124]

I made a graph.


X is the mass of the ship excluding engines. I don't know what a reasonable range would be so I plotted it out to 300 whatever units. Y is the ratio of nuclear vs ion final velocities with 2.25 tons of fuel, also not included. Wouldn't have changed the results significantly if I did.

Turns out, the two engine types have equal speeds at around 80-82 mass units, and after that, ion becomes ever-so-slightly more efficient, but nothing like the boost nuclear gets before 80 units. At 300 mass units, Ion is just 22% faster.
If there is interest, I can graph this for 30 engines, too.

[Pat22]

I made a graph.


X is the mass of the ship excluding engines. I don't know what a reasonable range would be so I plotted it out to 300 whatever units. Y is the ratio of nuclear vs ion final velocities with 2.25 tons of fuel, also not included. Wouldn't have changed the results significantly if I did.

Turns out, the two engine types have equal speeds at around 80-82 mass units, and after that, ion becomes ever-so-slightly more efficient, but nothing like the boost nuclear gets before 80 units. At 300 mass units, Ion is just 22% faster.

22% is a lot

Also, yes, try it for 30 Ion engines.
In case you need the info: 30 Ion engines produce 15 units of thurst, weigh 7.5 and consume fuel at 3.6 units per second, which means they'll empty that same 2.25tons of fuel in 3906.25 seconds.

[Prototype]

Get rid of the ion, use more boosters

[Pat22]

Get rid of the ion, use more boosters

Boosters aren't even worth attaching to my initial takeoff stages.

[Tau]

Get rid of the ion, use more boosters

Boosters aren't even worth attaching to my initial takeoff stages.

Obviously you haven't seen the Thor SRB from KW Rocketry.

[Pat22]

Get rid of the ion, use more boosters

Boosters aren't even worth attaching to my initial takeoff stages.

Obviously you haven't seen the Thor SRB from KW Rocketry.

I don't use mods, so no, I haven't.

[fr0stbyte124]

Here is the graph for 30 ions. Turns out the differences in force and burn duration cancel each other out, so the only changing factor becomes weight. If you didn't mind snail acceleration, one ion engine would be most efficient of all of them.


Nuclear: 75.63s burn. Ion, 401.8s burn.

Nuclear is still more efficient for tiny ships, but now they have to be < 14 mass units. At 300 mass units, ion is now 31% better.

[Pat22]

Here is the graph for 30 ions. Turns out the differences in force and burn duration cancel each other out, so the only changing factor becomes weight. If you didn't mind snail acceleration, one ion engine would be most efficient of all of them.


Nuclear: 75.63s burn. Ion, 401.8s burn.

Nuclear is still more efficient for tiny ships, but now they have to be < 14 mass units. At 300 mass units, ion is now 31% better.

I'll stick with 30. It accelerates by 100m/s in about 7 minutes, that's pretty good for me.

[Pat22]

I do need to improve my current prototype though. If it's facing then sun then all is good and well, but in any other case, some of the solar panels don't get any sunlight and don't produce any power so the engines run out of power.

[fr0stbyte124]

In case you need the info: 30 Ion engines produce 15 units of thurst, weigh 7.5 and consume fuel at 3.6 units per second, which means they'll empty that same 2.25tons of fuel in 3906.25 seconds.

Hold on, one of these numbers is wrong, then. You said 120 ion engines consumes 2.5 tons of fuel in 100.45 seconds. Why is 1/4 the engines lasting 39x as long? That puts the consumption rate of 120 ions at 140 units/second.

[ACH0225]

I do need to improve my current prototype though. If it's facing then sun then all is good and well, but in any other case, some of the solar panels don't get any sunlight and don't produce any power so the engines run out of power.

Shit-ton of thermals?

[Pat22]

In case you need the info: 30 Ion engines produce 15 units of thurst, weigh 7.5 and consume fuel at 3.6 units per second, which means they'll empty that same 2.25tons of fuel in 3906.25 seconds.

Hold on, one of these numbers is wrong, then. You said 120 ion engines consumes 2.5 tons of fuel in 100.45 seconds. Why is 1/4 the engines lasting 39x as long? That puts the consumption rate of 120 ions at 140 units/second.

First, I said 2.25 tons of fuel.
Each individual engine burns it at 0.12 per second.
So 30 engines is 3.6
120 engines is 14.4
2.25 tons of Xenon is actually 14062.5 units of Xenon. So 30 engines consume it in 3906.25 seconds. 120 engines consume it in 976.56 seconds.

...strange... I don't know how I got 140/s for 120 engines...

[Pat22]

I do need to improve my current prototype though. If it's facing then sun then all is good and well, but in any other case, some of the solar panels don't get any sunlight and don't produce any power so the engines run out of power.

crap of thermals?

You need six thermals to fully power a single ion. It's not exactly the best way to go.

[Pat22]

Bah, I really need a low-orbit refuelling station for SSTOs.

Although, that does almost defeat the purpose of SSTOs.

[Prototype]

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