FAT-455 Wing Overheating

[Mars-Bound Hokie]

For those of you who don't know what part I'm talking about, it's this bad boy right here.

Spoiler

• Fuel capacity: 600
• Price: 2,800
• Impact tolerance: 15 m/s
• Maximum Temperature: 1200K
  • Which brings me to this question.

 

Very common in large aircraft like this:

 

If you do know what I'm talking about, then here's the problem. I'm building a 4-engine airliner that can carry up to 36 people (and has a probe core for remote-controlled use). However, whenever I get up to the desired altitude and airspeed (5,000 m MSL at 300 m/s or more), the wings tend to overheat. One of the test runs ended up with a wing exploding, in fact. 

 

• The airliner (first prototype) during its ascent.
  • Neat that it can get past 343 m/s, huh.
• Has Big-S Delta Wings for more fuel and lift.

 

I then added radiators to the cargo bay - as well as some batteries to increase power capacity (and a ladder and some lights for passengers who want to walk inside the plane), and made sure they were on before taking off. However, that was no good as my wings were THIS CLOSE to blowing up after that test. 

 

Any ideas how to prevent the large wings from overheating? I'm thinking about adding some small TCS units inside the cargo area, but I don't know if they'll do any good. I'm also open to ideas regarding flight characteristics (e.g. don't exceed x m/s, stay above y km altitude unless going over a mountain).

Spoiler

P.S. I hate it that the MechJeb aircraft autopilot tends to make the aircraft bounce after turning it on. How can I make it work properly - let's say, by keeping it at 5,000 m altitude - without dealing with the wobble?

 

EDIT: It's the main wing that's overheating. The delta wings have a heat tolerance of 2400K

Edited July 12, 2020 by Mars-Bound Hokie
Clarifying which wing is overheating

[Superfluous J]

You're flying very fast, vet low. Those are 747 wings and just aren't built for it.

[Alex and Drew]

Which wing the delta wing or the main wing overheated?

[Mars-Bound Hokie]

7 minutes ago, Alex and Drew said:

Which wing the delta wing or the main wing overheated?

Main wing. Just edited my OP for clarification.

 

7 minutes ago, Superfluous J said:

You're flying very fast, vet low. Those are 747 wings and just aren't built for it.

Just what specific airspeed/altitude did you have in mind?

Edited July 12, 2020 by Mars-Bound Hokie

[Kaerbanogue]

as mentionned you fly too fast too low, but the FAT-455 and the BIG S-delta wing (which I think iis attached to) have the same Max. Temperature according to ksp wiki. So having one burning up and not the other is quite strange. Are you sure your engine exhaust doesn't heat the wing ?

[Alex and Drew]

I just went mach 3 easily below 5000m with no overheating. My best guess is that the 4 engines are doing the overheating.

 

[Mars-Bound Hokie]

3 minutes ago, Kaerbanogue said:

as mentionned you fly too fast too low, but the FAT-455 and the BIG S-delta wing (which I think iis attached to) have the same Max. Temperature according to ksp wiki. So having one burning up and not the other is quite strange. Are you sure your engine exhaust doesn't heat the wing ?

I will not deny that I might have an issue with how I fly this thing, but I will contest that the two different wing types have the same temperature tolerance.

• The individual wiki pages for the FAT-455 and the Big-S Delta Wing give different temperatures, and they were last updated at least two years after the page you sent.

[Kaerbanogue]

8 minutes ago, Mars-Bound Hokie said:

I will not deny that I might have an issue with how I fly this thing, but I will contest that the two different wing types have the same temperature tolerance.

• The individual wiki pages for the FAT-455 and the Big-S Delta Wing give different temperatures, and they were last updated at least two years after the page you sent.

oh yes indeed, but the page I linked is as recently updated as individual pages so there is a mystery here. maybe just debug your plane close to sun, engines off, and see how the heat is handled

Edited July 12, 2020 by Kaerbanogue
oupsi

[Mars-Bound Hokie]

28 minutes ago, Kaerbanogue said:

oh yes indeed, but the page I linked is as recently updated as individual pages so there is a mystery here. maybe just debug your plane close to sun, engines off, and see how the heat is handled

Kinda easy to keep the engines off when there's no air for them to use, isn't it. Anyway, I tried that and saw the heat gauges only covered the internal radiators.

 

For another test, I flew higher (~9,000 m altitude) and slower (~280 m/s). That seemed to work.

 

So far, so good. Even better, the overheating warning for the FAT-455 wings didn't turn on; only for the internal radiators. I don't know how far this bad boy can go on one take of fuel, and it might take a great chunk of my day IRL to find out - and today's my birthday. Any other suggestions on how I can keep the wings cool enough to not blow up (TCS, fly higher/lower, go slower/faster, add something)?

Spoiler

• Velocity of Kerbin's rotation about its polar axis (~175 m/s)
  • {Circumference = (2*pi*(radius = 600,000 m))} / {1 day = (6 hrs/day * 3600 sec/hr)} = 174.5 m/s

 

[Laie]

On 7/12/2020 at 3:29 PM, Mars-Bound Hokie said:

whenever I get up to the desired altitude and airspeed (5,000 m MSL at 300 m/s or more), the wings tend to overheat.

@Alex and Drew got it already: the problem is the engines. Goliaths tend to overheat, badly, when you take them trans- or even supersonic. It gets better again at higher altitudes, say 7+km.

The FAT-455, on the other hand, has a pretty low heat tolerance, which is probably the main reason why it lights up. The heat gauges turn on when a part reaches a certain percentage of max, and if max is lower, the heat gauge comes on earlier.

My best guess is that the heat is totally non-critical, and that the wing actually acts as a powerful heatsink. The large airliner wing has a lot of surface to shed heat with, after all.