[Mithrandir]

Another data point.

Today, 90 to 95 degrees outside. Right after a flight, my GP38% internally was exactly ambient. After sitting in the sun, it got to be 105 to 110 degrees internally and that typically took about 5 to 10 minutes to stabilize. (I drilled a .125" hole in the fuse side next to the Rx and stuck a Fluke Temp Meter probe thru that hole, thus measuring air temps the Rx is exposed to)

Very little wind, so no cooling going on when the plane was on the ground.
Not a lot of air getting inside the plane as it is sealed up pretty good.

The internal air is being cooled convectionally through the skins of the model
as it is in flight.

Solid connection in this environment.