Overheating due to re-entry drag - inside service bay

[paul23]

Well simply put, is it normal stuff constantly explodes & overheats inside the service bay (1.25m)? Isn't the service bay supposed to protect equipment from re-entry heat?

[Foxster]

Yea, they are pretty buggy.

They often don't protect the items they are supposed to and they sometimes shake themselves to bits for no good reason.

Hopefully they will have had the bug-fix wand waved across them in 1.0.5.

[InterCity]

Tough luck, you've been visited by a bug.

Try mounting a heat shield underneath it, it may or may not help - if it's in the shielded area of the heat shield there could be less heat.

[Kerbart]

Well simply put, is it normal stuff constantly explodes & overheats inside the service bay (1.25m)? Isn't the service bay supposed to protect equipment from re-entry heat?

As much as this is apparently a bug, if your service bay isn't protected by a heat shield, wouldn't it be normal to expect thing to overheat eventually? Your talking about 1 or 2mm sheet metal at best after all, that doesn't have a lot of heatshielding capacity.

[paul23]

As much as this is apparently a bug, if your service bay isn't protected by a heat shield, wouldn't it be normal to expect thing to overheat eventually? Your talking about 1 or 2mm sheet metal at best after all, that doesn't have a lot of heatshielding capacity.

Same could be said of anything. But actually yes it would reduce heating a LOT, since the drag force (and thus the heat flow) doesn't touch the internal equipment. So the heat of the internal equipment should only increase due to convection - which I suppose a protective environment does try to prevent to it's internals.

So in the end the internal equipment should only heat up so much as the internal temperature of the bay. - My question is: do the larger bays protect?

And otherwise: what point is there in using a cargo bay if it's not for aerodynamics?

[mabarry3]

Pretty sure it's the same for all cargo bays/units. Here's a picture of me re-entering in a plane; the cluster of hot items in the middle of the plane are items inside my cargo bay. While the bay does somewhat protect them, it doesn't do nearly the job you'd expect it to. But it's certainly a lot more aerodynamic/aesthetic to place it inside rather than just sitting out.

[Brainlord Mesomorph]

I have to disagree, bug wise, hot things transfer heat to things that are attached to them IRL thermodynamics.

if the bay's skin is hot enough, logically things inside would hot too, not as hot as quick. not from friction, because they are bolted to a hot metal bulkhead,

EDIT: when you use the nukes, they get hot, and transfer heat to the fuel tanks above them, which then transfer heat to whatever is attached to them (usually radiators).

Edited November 8, 2015 by Brainlord Mesomorph

[paul23]

Problem is: the internal things got hotter than the bay's internal temperature. Way hotter.

[Brainlord Mesomorph]

max temp for the bay is 2900 degrees

max temp for average science experiment is 1200.

so even if the bay only transfers half its heat to the payload, the experiments are red-lining way before the bay does. The heat of an oven doesn't harm t he oven, but can burn the food.

Also the experiments have no place to transfer heat to, so it builds up. the bay is bleeding off heat to both ends and to the payload.

Edited November 8, 2015 by Brainlord Mesomorph

[Starhawk]

AFAIK the cargo bays only protect things that are attached to the nodes at the front and back and parts that are connected to those. Anything attached to the sides of the cargo bay does not appear to be occluded from drag or heating.

Not sure about the service bays since I rarely use them.

Happy landings!

[paul23]

max temp for the bay is 2900 degrees

max temp for average science experiment is 1200.

so even if the bay only transfers half its heat to the payload, the experiments are red-lining way before the bay does. The heat of an oven doesn't harm t he oven, but can burn the food.

Also the experiments have no place to transfer heat to, so it builds up. the bay is bleeding off heat to both ends and to the payload.

The internal temperature of the service bay stays around 400 Kelvin...

[Brainlord Mesomorph]

The internal temperature of the service bay stays around 400 Kelvin...

if you say so. (where does it say that?)

I've been spending the last several days dealing with heat from the nukes slowly seeping everywhere and then blowing up RCS tanks halfway accoss the ship, So it seems logical to me that a payload bay only can provide so much heat protection to the payload.

[Starwaster]

AFAIK the cargo bays only protect things that are attached to the nodes at the front and back and parts that are connected to those. Anything attached to the sides of the cargo bay does not appear to be occluded from drag or heating.

No, that's not true. Cargo bays protect things that are surface mounted as well. All it cares about is whether the item is enclosed in the cargo bay's invisible bounding box.

It is possible of course for a surface mounted item to be seen as outside the box if it's right on the edge and the item's positioning puts its center on the outside.

[paul23]

if you say so. (where does it say that?)

I've been spending the last several days dealing with heat from the nukes slowly seeping everywhere and then blowing up RCS tanks halfway accoss the ship, So it seems logical to me that a payload bay only can provide so much heat protection to the payload.

Kerbal engineering redux as well as the internal data display this.

[Starhawk]

No, that's not true. Cargo bays protect things that are surface mounted as well. All it cares about is whether the item is enclosed in the cargo bay's invisible bounding box.

It is possible of course for a surface mounted item to be seen as outside the box if it's right on the edge and the item's positioning puts its center on the outside.

Interesting. That has not been my experience. I have seen heating of items both attached to the insides of cargo bays (but clearly inside the bay visually) as well as to the surfaces of parts in front or behind the cargo bays axially. In both of these cases, the parts should be protected but are subject to unanticipated heating. I believe that they were also experiencing drag as well, but I may be mistaken on that point. The heating was clear however.

When the Gigantors were removed from the cargo bay walls and attached to a tank which was axially attached to the cargo bay's inside node, no heating was evident.

Happy landings!

[Pecan]

Lots of bad luck with cargo/service bays of all sizes and shapes here, to the extent that I'll often use fairings instead.

FWIW, node-attached battery gets very hot (and might explode) inside a closed spaceplane pod on the way up :-(

Still haven't worked out if these things do anything but Kraken-call and add mass.

[magnemoe]

I have to disagree, bug wise, hot things transfer heat to things that are attached to them IRL thermodynamics.

if the bay's skin is hot enough, logically things inside would hot too, not as hot as quick. not from friction, because they are bolted to a hot metal bulkhead,

EDIT: when you use the nukes, they get hot, and transfer heat to the fuel tanks above them, which then transfer heat to whatever is attached to them (usually radiators).

Yes, i have had an probe core gotten destroyed by overheating from LV-N after the burn was complete as the heat continued to rise in the front of the tug after the burn.

Direct reentry heat will overheat vulnerable parts very fast, the transferred heat is much slower

- - - Updated - - -

Lots of bad luck with cargo/service bays of all sizes and shapes here, to the extent that I'll often use fairings instead.

FWIW, node-attached battery gets very hot (and might explode) inside a closed spaceplane pod on the way up :-(

Still haven't worked out if these things do anything but Kraken-call and add mass.

The radial batteries can not handle much heat, neiter does the small probe cores, RTG or science instruments. the tiny and huge solar panels

The in-line batteries is more capable here. same is the large probe cores.

[Pecan]

...The radial batteries can not handle much heat...

Which is why one would have expected that inside a closed cargo bay, away from the sides, behind a fuel tank, behind a cockpit that they'd be just a little bit protected from the heat. That they don't do any better than being bolted to the outside is what I mean by not having any luck with cargo bays.