[1.0.4]Thermal bug at eve landing attempt

[Kourou]

So I built an eve lander that is able to return from ~2500m, and tried to land it in version 1.0.4. With a veeery shallow reentry path and Airbrakes, it survives the new reentry heat relatively safe, maybe even at 110%. But every time, when I'm already quite slow and the ship is cooling down again, the "bottom right" of my Aerospikes explodes due to overheating and destroys everything.

As this happens every time with this setup and is easy to recreate, I could track down that it is not even the atmospheric heating, but absurd Radiation values even with already 1600K Skin temp, so I'm absolutely sure this is a bug.

Did I miss something? Is this a known issue? Any workaround known, or do I just have to disable Convective Flux as well as Radiation in the debug menu to land Jeb safely?

[Foxster]

Got more pictures, say one on the pad or VAB?

[Jouni]

It looks like you're flying too low and/or too fast.

Added a factor to simulate the switch from laminar to turbulent flow (in layman's terms, if you're going too fast too low, you get a massive boost to heating). That corrects so steep reentries are in fact deadlier than shallow ones.

The switch from laminar to turbulent flow is (mostly?) based on the product of speed and air density. According to the numbers in your screenshot, your lander is quite close to the region, where the switch happens during a Kerbin reentry. Basically this is not a bug, and you just need to lose more speed in the upper atmosphere.

[Kourou]

Here's the Lander rendered in the VAB:

Originally Posted by Jouni

It looks like you're flying too low and/or too fast.

Originally Posted by 1.0.3 changelog

Added a factor to simulate the switch from laminar to turbulent flow (in layman's terms, if you're going too fast too low, you get a massive boost to heating). That corrects so steep reentries are in fact deadlier than shallow ones.

I saw this "turbulent" effect for all other parts too, not pushing it anywhere dangerous. But only this one Aerospike suddenly gets so insane Rad Flux, it explodes as hit by a stone with 1.6km/s.

Val and me just double-checked it - the turbulent switch is still handled by Conv Flux:

Picture was taken only split-seconds before Rapid Unplanned Disassembly Event:)

[Foxster]

You could try replacing the shock cones (draggy) with nose cones. Should get less heat in that area.

[Jouni]

I saw this "turbulent" effect for all other parts too, not pushing it anywhere dangerous. But only this one Aerospike suddenly gets so insane Rad Flux, it explodes as hit by a stone with 1.6km/s.

I didn't mean the visual effect. I meant the change in reentry heating in 1.0.3, which increases the heating by a factor of 100x in a matter of seconds, if you descend too fast without losing enough speed.

[Signo]

This is surely a "too low too fast" issue.

I had the same problems with Eve in 1.0.4. The only way I found to overcome this is to simply use engines to burn and slow down.

Unluckily I can not provide you with a "scale" on this because I had different results based on the drag&shape of the different tries.

There is unluckily no way to avoid turbulent convection as far as I know apart from slowing down. (we should install a wind tunnel @KSC...)

It might seem weird but on Eve heat is easy to avoid, turbulent convection is not.

[windows_x_seven]

Did you put radiators on the parts? Apparently they blow up quite easily.

If not, you most likely came in too fast and/or too low, where the temperatures will be a lot higher.

- - - Updated - - -

Also, you might want to strut the lander's 2.5m to 1.25m adapter with the capsule! That will prevent a lot of wobble!

[Signo]

You will not go fast enough to generate enough heat to need radiators, you will explode a lot earlier due to turbulence generating the heat spike that the radiators can not absorb.

[selfish_meme]

You could try replacing the shock cones (draggy) with nose cones. Should get less heat in that area.

Apparently according to red iron crowns testing the shock cones are the most aerodynamic cones and even work backwards mounted on Rapiers to reduce drag.

[Foxster]

Apparently according to red iron crowns testing the shock cones are the most aerodynamic cones and even work backwards mounted on Rapiers to reduce drag.

Err, yes, except it doesn't need any intakes.

[Michaelo90]

Err, yes, except it doesn't need any intakes.

So what? It's still less draggy than any nosecone.

[Foxster]

So what? It's still less draggy than any nosecone.

I'm not sure why you think that. If he used 'Advanced Nose Cones - Type A's instead then they would have 1/3 the max/min drag and 1/5 the angular drag.

Edited July 6, 2015 by Foxster

[NathanKell]

Um...you do realize that max/min drag numbers have not mattered since .90? That's why KSP doesn't display them ingame.

[Foxster]

Um...you do realize that max/min drag numbers have not mattered since .90? That's why KSP doesn't display them ingame.

What drag number in the cfg should we look at, cos all the drag numbers are bigger for a shock cone than a nose cone, no? Edited July 6, 2015 by Foxster

[NathanKell]

None of the drag numbers in the cfg mean anything, unless there's an explicit DRAG_CUBE defined as cargo bays have.* Drag is now based on part shape and size. Look in PartDatabase.cfg for the drag numbers.

The first six triplets are for X+, X-, Y+ (forwards for a stack part), Y-, Z+, Z-. In each triplet, the first number is the area, the second is the drag coefficient, the third is depth at the widest point.

*Also if there's a ModuleDragMultiplier, as parachutes have, then drag is multiplied by that number when the part is in that state.

I suggest you look in this thread for more information on the drag model in KSP 1.x.

http://forum.kerbalspaceprogram.com/threads/119108-Overhauls-for-1-0

[Foxster]

None of the drag numbers in the cfg mean anything, unless there's an explicit DRAG_CUBE defined as cargo bays have.* Drag is now based on part shape and size. Look in PartDatabase.cfg for the drag numbers.

The first six triplets are for X+, X-, Y+ (forwards for a stack part), Y-, Z+, Z-. In each triplet, the first number is the area, the second is the drag coefficient, the third is depth at the widest point.

*Also if there's a ModuleDragMultiplier, as parachutes have, then drag is multiplied by that number when the part is in that state.

I suggest you look in this thread for more information on the drag model in KSP 1.x.

http://forum.kerbalspaceprogram.com/threads/119108-Overhauls-for-1-0

Ah, yes, I remember that now. I suppressed it I think because it was just too hard to understand. Still is.

Did some testing and it is quite correct that the thing with the lowest drag of that size is indeed the shock cone intake. Who would have thunk?