The Roof is on Fire

[Kobymaru]

It seems KSP got (a lot!) harder.

Consider the following ship:

http://i.imgur.com/OsjXTxF.jpg?1

It is a fine ship, is it not? Well, something is amiss. Namely, the probe core keeps exploding for no apparent reason when reaching Orbit.

Checking the log, it turns out that the probe core actually overheats.

But how?? This is a (almost) perfectly streamlined ship. Also, why would it overheat when I am almost in space, where there is no friction?

Let's turn on the dirty cheating debug-menu: http://i.imgur.com/ljTlJV9.jpg?1

Oh my. That's a lot of bright colors, right here. But how could it get so hot?

Let's check the temps: http://i.imgur.com/gNzQKs9.jpg?1

Wow, that's pretty hot. And it's going up instead of down.

The capsule itself is hotter, but it's going down.

So what has happaned here? Apparently, launching a rocket through the atmosphere produces a *lot* of heat on the parts that face the airstream. In this case, this was the Mk1 command pod.

Since the Pod is connected to the Probe core, the pod heats the core via conductive heat transfer (touching hot things makes you hot as well).

However, the Pod has a much higher heat tolerance than the core, and the core explodes from all the heat it gets from the Pod.

tl;dr: KSP is hard.

ps.: I'm not complaining. I like it that way! Although I will probably never ever turn Quicksave anymore, until I get a good grip on KSP-Physics.

[Starwhip]

You're getting hotter because of radiation from the sun, and heat from other parts seeping into the part in question.

KSP got a helluva lot more complicated in one update.

[Thomas988]

You're getting hotter because of radiation from the sun, and heat from other parts seeping into the part in question.

KSP got a helluva lot more complicated in one update.

True dat! The thermal physics are so complex I don't even know how to build my rockets with them in mind.

[Aerindel]

Funny, I feel like it got a lot easier. It seems almost effortless to get into orbit and parachutes seem massively overpowered.

[Starwhip]

Funny, I feel like it got a lot easier. It seems almost effortless to get into orbit and parachutes seem massively overpowered.

They are. This thing is basically full.

[juanml82]

Well, if they hadn't, I'd just be attaching a lot of them, so I don't see what's the gameplay issue about them

[Hcube]

they are not OP because they have very slow terminal velocity ; ie its not the fact that 1 chute can slow down a full booster slow enough to land it that is the problem.

What makes chutes OP is that you can just open them at like 40km hile re entering at 3500m/s and they will not burn nor tear apart and they will slow you down freaking 25gs very easily. THAT´s what makes the chutes OP

[magnemoe]

Stuff the probe inside an service compartment together with batteries and science stuff. I even have an spare parachute in it. heat shield below.

Activate parachute==safe landing, that is unless you hit the mountains west of KSC.

[NFUN]

they are not OP because they have very slow terminal velocity ; ie its not the fact that 1 chute can slow down a full booster slow enough to land it that is the problem.

What makes chutes OP is that you can just open them at like 40km hile re entering at 3500m/s and they will not burn nor tear apart and they will slow you down freaking 25gs very easily. THAT´s what makes the chutes OP

I hope they fix it in the next update, I feel weird whenever I use the chutes because of this. Force of habit dictates me open asap

[Kobymaru]

You're getting hotter because of radiation from the sun, and heat from other parts seeping into the part in question.

KSP got a helluva lot more complicated in one update.

Actually, the sun has very little to do with it. The radiation flux changes when you put the part in the shade, but not by very much.

True dat! The thermal physics are so complex I don't even know how to build my rockets with them in mind.

Honestly, I kinda like it. It's a new challange. I just wish they would "communicate" it more (maybe in the tutorials?) and provide diagnostic tools for it. It just feels weird to use the Debugging menu for regular ship construction

Funny, I feel like it got a lot easier. It seems almost effortless to get into orbit and parachutes seem massively overpowered.

The only thing that got "easier" is the dV requirement. The engineering complexity definitely got more.

What makes chutes OP is that you can just open them at like 40km hile re entering at 3500m/s and they will not burn nor tear apart and they will slow you down freaking 25gs very easily. THAT´s what makes the chutes OP

I hope they fix it in the next update, I feel weird whenever I use the chutes because of this. Force of habit dictates me open asap

Yeah, same for me. But I have 3 ships with probe cores attached to capsules, and I need to get them down somehow without burning off the core that serves as a link to the only parachute. I guess I'll use that to "cheat" my way down until I figured out a good solution to this.

Stuff the probe inside an service compartment together with batteries and science stuff. I even have an spare parachute in it. heat shield below.

Activate parachute==safe landing, that is unless you hit the mountains west of KSC.

I think that's not aerodynamically stable. The center of drag would be in the middle of the construct, and the center of mass would be inside the capsule, so at the top - this would lead to the capsule flipping over. Of course none of it matters, if you just pop the chute at 22km with 2000 m/s. Then all your problems are solved magically.

[Sirrobert]

they are not OP because they have very slow terminal velocity ; ie its not the fact that 1 chute can slow down a full booster slow enough to land it that is the problem.

What makes chutes OP is that you can just open them at like 40km hile re entering at 3500m/s and they will not burn nor tear apart and they will slow you down freaking 25gs very easily. THAT´s what makes the chutes OP

RealChute

[KerbMav]

RealChute

A good mod, yes, but why does its existence preclude reasonable game mechanics of the stock game? If a parachute is the answer to reentry, why do we have heat shields - or a heating mechanic at all?

OT: I too am puzzled how the probe core gets popped after all that speeding through the atmosphere is already over - sometimes upon reaching orbit even the heat shield has been used up by a few percents while still in the decoupler fairing under the pod.

[Commissioner Tadpole]

Heh, after proving that getting to orbit does not mean burning straight up until you're out of the atmosphere, KSP now proves that space is not cold, and that it can be hot as hell.

But do thermometers display an actual craft heat? I have a science lab on Duna's surface with a thermometer, and for whatever reason it reads 233°, and at night. I'm fairly sure Duna's temp is -30°.

[KerbMav]

Heh, after proving that getting to orbit does not mean burning straight up until you're out of the atmosphere, KSP now proves that space is not cold, and that it can be hot as hell.

But do thermometers display an actual craft heat? I have a science lab on Duna's surface with a thermometer, and for whatever reason it reads 233°, and at night. I'm fairly sure Duna's temp is -30°.

Celsius or Kelvin?

[Commissioner Tadpole]

Celsius or Kelvin?

KSP doesn't specify temperature. Just says 233° without a temperature unit. But if it's in Celsius, then Duna's apparently hot enough to boil water. No wonder it's dry...

[Bill Phil]

Celsius or Kelvin?

Kelvin can't be negative...

Anyhow, I had a rocket explode on ascent. Hilariously... But no flames were showing at all. So I didn't know it was burning up.

[DDay2021]

Celsius or Kelvin?

I'm fairly certain that temperatures in KSP are in Kelvin. Just as a reference 373K is boiling point of water, 933K is melting point of Aluminum and 1698K is melting point for steel. So the pods must be made out of something very strong for the 2400K max temp. I've been doing some experiments with heat, I've seen a Mk 1 Command Pod go from 288K to 306K just sitting on the launch pad. I figured it was just solar heating, but the temp does not drop at night.

233 Kelvin is -40C and coincidentally -40F

Edited April 29, 2015 by DDay2021

[Kobymaru]

A little update:

After launch, the craft is still very hot. Trying to reenter right after entering orbit will give you a higher probability of Thermo-death. Do a few orbits for cooldown of the craft before reentering again.

It turns out temperature is STORED along with the save file. This means that you can use timewarp, but you have to WITH the craft during the cooldown period.

Also, it turns out that heating is EXTREMELY sensitive to attitude changes. If you keep your capsule exactly on the retrograde marker during the whole descent, you can prevent the capsule from overheating.

[Bill Phil]

I'm fairly certain that temperatures in KSP are in Kelvin. Just as a reference 373K is boiling point of water, 933K is melting point of Aluminum and 1698K is melting point for steel. So the pods must be made out of something very strong for the 2400K max temp. I've been doing some experiments with heat, I've seen a Mk 1 Command Pod go from 288K to 306K just sitting on the launch pad. I figured it was just solar heating, but the temp does not drop at night.

233 Kelvin is -40C and coincidentally -40F

Again, kelvin can't be negative.

And reentry heat is pretty darn hot...

[WWEdeadman]

I'm fairly certain that temperatures in KSP are in Kelvin. Just as a reference 373K is boiling point of water, 933K is melting point of Aluminum and 1698K is melting point for steel. So the pods must be made out of something very strong for the 2400K max temp. I've been doing some experiments with heat, I've seen a Mk 1 Command Pod go from 288K to 306K just sitting on the launch pad. I figured it was just solar heating, but the temp does not drop at night.

233 Kelvin is -40C and coincidentally -40F

I'm pretty certain temperature on KSPs thermometers is °C. For multiple reasons: Kelvin doesn't have the "°" "degree" * thingy, it's just K as a unit, and Kelvin can't be negative. Then again, I had the thermometer show -432° back a few versions, which would be about 200 degrees under absolute zero (0 K = -273.15°C) (picture here: http://puu.sh/hvjni/e65ec1c4d6.jpg )

But yeah, The readings I had in 0.90 were the same on the in-game "display" of the thermometer as they were for the °C value deadly reentry added to the right-click menu. So I'm fairly certain about the °C thing.

* EDIT: Then again, the "°" doesn't show up in the screenshot I posted, so it could be K, apart from the fact it is negative, and Kelvin can't be negative...

[turkwinif]

Quoting the changelog in the 1.0 blogpost: "- All game temperatures changed from ‘Kervin’ to proper Kelvin."

So now all temperature readings on the thermometer should be in Kelvin. I haven't been able to download KSP 1.0 due to internet data limitations, do thermometers in version 1.0 go below 0?

[KerbMav]

Kelvin can't be negative...

I know.

Was suggesting that his memory of Duna being -30° might be correct but the new reading having switched to another unit.

But do thermometers display an actual craft heat? I have a science lab on Duna's surface with a thermometer, and for whatever reason it reads 233°, and at night. I'm fairly sure Duna's temp is -30°.

[DrD]

they are not OP because they have very slow terminal velocity ; ie its not the fact that 1 chute can slow down a full booster slow enough to land it that is the problem.

What makes chutes OP is that you can just open them at like 40km hile re entering at 3500m/s and they will not burn nor tear apart and they will slow you down freaking 25gs very easily. THAT´s what makes the chutes OP

Exactly. They should just make it so above a certain speed chute tears off. Perhaps in a certain range it could be a chance thing.

I thought that was the whole idea of drogue chutes, they can open at a higher speed.

I haven't seen anyone post about Duna landings with new chutes.

[X-SR71]

I haven't been able to download KSP 1.0 due to internet data limitations

Really dude? The update is only like 150mb. Haven't you got 150mb data left on your plan to spare?

[mikegarrison]

So what has happaned here? Apparently, launching a rocket through the atmosphere produces a *lot* of heat on the parts that face the airstream. In this case, this was the Mk1 command pod.

Since the Pod is connected to the Probe core, the pod heats the core via conductive heat transfer (touching hot things makes you hot as well).

However, the Pod has a much higher heat tolerance than the core, and the core explodes from all the heat it gets from the Pod.

This is a real engineering phenomenon: thermal soakback. I'll give an example.

In a jet engine, the combustor is where all the burning happens. Combustors are made of super high temp alloys (usually nickel-based). But the fire inside is still hotter than the combustor wall can survive. So the wall is cooled by airflow. Also, heat gets into the fuel injectors and fuel manifold (because they are physically attached). And that heat is carried away by the fuel.

So what happens when the engine is shut off? Well, the airflow stops. And the fuel flow stops. That's what was carrying away all your heat. Fortunately the flame stops too. So the combustor wall has no more heat coming in, which means it slowly cools down. But it cools down by radiating and conducting and convecting the heat away. Well, that means the heat goes from the combustor and into the fuel injectors and fuel manifold. Since no more fuel is flowing, they get hotter after the engine is shut down. A lot hotter. So much hotter, that you have to worry about them coking up the fuel that is still sitting in the manifold.

And insulating them only makes the problem worse, because the heat soaks in but can't get back out. That's what space is doing to your rocket. Vacuum is a great insulator, and the heat is conducting from the hot parts to the formerly cool parts. With vacuum being such a good insulator, it just builds up there. Real world problem that is showing up now in KSP.