What means overheat ?

[Mr_Auto]

1. Is it just warns of the engine explosion? or means something else? like using more fuel?

2. What is overheat? engines or fuel tank? i was searching information about overheat and find this "The Mainsail engine will overheat when running on full thrust and placed below a Jumbo tank, but when below two functionally identical X200-32 tanks it will not. I have no idea what causes this."

2b. Why smaller fuel tanks slows down overheat?

Edited June 27, 2013 by Mr_Auto

[pebble_garden]

1. If you overheat past a certain amount, the engine will explode. (The overheat is shown by a red temp bar next to the fuel bar.) I don't know if the probability of an explosion rises with the amount of overheating, or if it's just a threshold thing. I recall reading the devs planned to do more with this functionality in the future. In practical terms, I've found that you can run a Mainsail attached to a single orange tank at 1/3 overheat without any problem, for at least a couple of minutes.

2. Each fuel tank dissipates a little heat from the engine. A big orange tank doesn't dissipate enough heat by itself, but in-line with a small tank the two can keep up with a Mainsail engine at full power. It's not exactly *realistic* but it makes a crazy kind of Kerbal sense.

Actually I take that back a bit. Now that I think of it, the SR-71 Blackbird used to run its fuel through a network of little pipes under the hot skin of the aircraft on its way to the engine, as a clever way to preheat the fuel while doing double-duty as a coolant. Oh those brainy engineers.

PS The Blackbird also used that fuel as the fluid for the hydraulic systems. JP-7, I believe it was called (link). Nasty stuff!

PPS A further note: I've used a Mainsail attached to a single orange tank at about 70% power with no problem. It'll reach about 1/3 overheat, and I've never experienced an explosion at that level. But as the rocket climbs the overheat slowly reduces, even though the throttle remains steady. I'm not sure if that's a function of changing atmospheric pressure, or something to do with the fuel tank emptying. Something to ask a dev!

Edited June 27, 2013 by pebble_garden

[RocketPilot573]

1. Yep, once the "overheat" bar fills up all the way then the engine will explode.

3. That's just a bug that's been around for a while.

[KrazyKrl]

1.) Already sufficiently answered by the other replies.

2.) You can think of the fuel tanks as "heat sinks" that conduct heat away from a heat source.

2b.) It's probably because they have no current value of something like "thermal dissipation." So what ends up happening, is that a large tank, and a small tank have the same thermal dissipation values. So a large tank has, say, 500 Joules/second of dissipation; but so does EACH small tank. So the thermal cooling rate is double, when it shouldn't be. It is technically a bug, but it's due to the game still being a work in progress.

[Capt'n Skunky]

The bug with the mainsail overheating the big orange fuel tank has to do with how heat dissipation is done. The engine will look to the center of mass of parts connected to it and disapate heat based on the distance. The problem is the big orange tank has it's CoM so far from the engine it's not disapating heat properly causing the engine to over heat and explode.

This can be fixed in two ways. One, don't run the mainsail at full throttle too long and secondly, use a smaller tank connected directly to the engine.

Cheers!

Capt'n Skunky

KSP Community Manager

[Tw1]

I read that the orange tank is insulated, and that makes it get hot easily. It works if you apply kerbal-logic.

[allmappedout]

The bug with the mainsail overheating the big orange fuel tank has to do with how heat dissipation is done. The engine will look to the center of mass of parts connected to it and disapate heat based on the distance. The problem is the big orange tank has it's CoM so far from the engine it's not disapating heat properly causing the engine to over heat and explode.

This can be fixed in two ways. One' date=' don't run the mainsail at full throttle too long and secondly, use a smaller tank connected directly to the engine.

Cheers!

[b']Capt'n Skunky

KSP Community Manager

I never knew that was how it worked, thanks Skunky! Presumably that means that were you to, for no reason whatsoever, want to run a mainsail attached to the jumbo orange tank sideways, using the radial attachment thingamybobbits, presumably that would solve the issue? (and leave you with a crazily shaped craft?)

[Mr_Auto]

Ok, so i shouldn't be afraid about overheat bar? the only dangerous thing is engine explosion when the bar it's full?

[Dkmdlb]

I regularly run mainsails at 95% power with the overheat bar almost to the edge for minutes at a time with no problems.

[Mr Shifty]

Ok, so i shouldn't be afraid about overheat bar? the only dangerous thing is engine explosion when the bar it's full?

I believe the Deadly Re-entry mod introduces damage to the engines if they're run too hot too long, but the stock game only cares if it's all the way full.