I didnt know this, but I am suprised its easier to hit an eagle. I would have thought that would have been designed to have a smaller heat sig than a big fat cobra. Interesting.
Just for reference, my almost fully upgraded Cobra tends to run around 40 degrees, depending on what I'm doing. I've seen that go as low as 35 at times, though not often.
Shes a big ship, compared to an Eagle, Viper or even a Sidewinder. There's a lot more hull there, so I imagine it's a lot easier to dissipate heat, which may account for why they run cooler than some of the smaller ships.