not true in my experience. even though not in contact with the hot surface, the hot air heats the herb very quickly (5 seconds during inhale) to whatever temp the heater is set for. the air flow makes the difference. and maintaining the heater temperature so the air flow doesn't cool the heater.
I'm not sure that experience is the same here? You don't have herb sitting on the heater do you? And your system, as I understand it, is closed loop and has a very fast response time? In FV the screen temperature is not regulated and any air flow cools it.
The point remains, AVB sitting on a screen much hotter than 400F is going to burn.
I think we have evidence in the herb touching the screen shows the screen never exceeded 400F by very much (or we'd have burn). We also see, I think, that the herb not in contact is at best partially vaped by the time that in contact is done without mixing.
I'm still trying to sort out the points FV raised about differences with MFLB. I think there's something to the 'updraft/downdraft' idea. But it's not as simple as it sounds at first (what is?). In MFLB it's true heat is drawn away by airflow, we rapidly lean not to draw too much of the modest heat supply away. However, it's selective about it largely. Much of the air (half) comes through the 'wings' which are not heated. Most of that which actually comes through the trench walls comes from the part not covered by herb and therefore not doing any work anyway. The part we really need, the trench floor under the load, is largely bypassed I think?
I think there's some information in the very large difference in efficiency here. MFLB usually has no trouble vaping a trench or even two on a battery 1/3 the size. So yes, heat is being taken out of the game by convection in the original FV. I'm not sure that does any useful work, however?
Fun stuff, thanks.
OF