Radiators

[locustgate]

I'm wondering when I need a radiator, so far I know that if I have an LV engine I need a radiator?

[Randazzo]

In stock the LV-N is the biggest heat monster, yes, though other engines (if you need to burn them long enough) can generate a ton of heat as well. Since the heat is still turned off (as far as I know) for ISRU and such, engine heat and/or heat from being exposed to the Sun will be your primary concerns.

[Reactordrone]

They're also useful on reentry. Throw a few small radiators on the sides of the ship and the heat indicators will hardly show up. Much lighter than a heat shield as well.

[locustgate]

They're also useful on reentry. Throw a few small radiators on the sides of the ship and the heat indicators will hardly show up. Much lighter than a heat shield as well.

I thought they only removed internal heat (from engines) and not external heat from reentry.

[Reactordrone]

I brought a three man lander back from Minmus that had three small radiator panels and it barely got hot during reentry. The temperature indicators for the solar panels showed up briefly and then went away as I got into thicker atmosphere. Might have to do more tests to see if very low melt temperature parts like the goo pods will survive.