I looked and didn't find it in any of their documentation or the forums. But that's ok. I did my own experiment. Tonight I bench tested my Dynon heated pitot tube for the first time. Here are my observations:
The tip of the pitot mast became hot within seconds, and then the heat slowly spread aft. So it looks like the heating element is located at the very tip of the mast. I then let it do its thing for about 25 minutes, more than long enough to reach steady state (also evidenced by the fact that the duty cycle had stabilized). At this point, the tip of the mast was very hot to the touch, with temperature decreasing aft toward the base of the mast, which was only warm to the touch. The 3/16" aluminum tubes were not even warm, couldn't have been more than a few degrees above ambient, if that. You wouldn't know by touching them that the pitot heat is even on. [Sorry I don't have real temp measurements. Didn't have a thermocouple on hand. But these qualitative measurements are more than good enough.]
Given these observations, I now have high confidence that plumbing it with plastic tubing will not be an issue temperature-wise.
BTW, a few other general observations:
The current draw measured about 7.8A when the heating element is on, and about 60mA when the heating element is off.
Once steady state temp was reached, the duty cycle was surprisingly low. The heating element turned on about once a minute for only two or three seconds. Now granted, this is on the bench, with ambient air at room temperature, and no airflow. Under flight conditions the duty cycle should be somewhat higher due to greater rate of heat loss to the airstream. But still I'm surprised at how low it is, at least on the bench.
And overall, my impression of this tube so far is very positive. Well designed, well made, and works well to the extent that I've been able to test it so far. Good job, Dynon!
