I'm looking for some number to use for a heat transfer coefficient of bare wire in still air. but not having much luck. This number just needs to get me into the ball park - I know it would be rather complex to solve with precision. Think of it this way - I have a length of wire dissipating x number of watts across a known surface area - what would the temperature rise in still air be? Just need to know to about +/- 50% .. I will be under 250C of temperature rise - no incandescence. I've seen tables - they are based on unknown safety factors etc... not actual rise and for jacketed/insulated wire. I've got a book ordered that will get me there, but I'm thinking some kind of number must exist. Can anyone point me in the right direction?