Confusing cabin heating on the Turbine Duke
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I absolutely love the beautiful schematics on the tablet - much more fun to control the temperature when you can see all the elements at work.
A thing I first noticed when flying up high in cold air, is that the cabin heat schematics on the tablet might be a bit misleading/confusing? Have checked the pdf manual and video, but can’t really make it make sense.
To give a rundown of my understanding:
Cold air gets in only through the ram air duct and cooling can be done by the AC evaporator. Of course the cold air around the plane will have a big effect up high, cooling the plane. (wonder if it can still get some cold air to mix in when the ram air valve is closed, or how the automation handles temperature control - will have to do another flight to look at that)As I am flying the turbine duke, the combustion heater is disabled, so hot air is provided from the bleed air only, with manual valves to select how much this bleed air is cooled down by intercoolers. The air from this is supposed to enter the cabin air plenum and then the fan blower passes the air over the evaporator and the disabled combustion heater to ducts in the cabin.
The video emphasises how, when flying, air can only enter through these two paths
First thing that confused me was that there would often be a clear heat gradient along the disabled combustion heater, with the left side getting hot first – before the plenum where the hot air from the bleed system is supposed to enter.
Perhaps a smaller air volume means that temperatures in the ducting will generally be faster to change. Still, with how it is described and looks on the schematics, hot air first coming out the ducts and then working its way back to hot bleed air inlets certainly looks confusing.
I see a valve further down the left ducting, which changes position according to heat demand. If there is hot air entering here somehow, it could perhaps also explain the “backwards” flow of hot air, but no documentation seems to suggest that.Doing further debugging/testing on the ground I tried shutting down the pressurisation air from either side to see if that could teach me anything further.
When I shut of both, the cabin was unable to pressurise as expected. Turning the heat on however, the cabin still heats up despite the bleed air being blocked! Changing the intercooler valves doesn’t make a difference any longer when this is done.
So is there another unmentioned source or path for the heat, some bug in the code, or some workaround where the turbine duke gets some heat injected at the combustion heater?
Or is it perhaps just me missing something obvious?Sorry for the long post. Always difficult to "describe confusion" so I included everything.
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I don't even want to tell you how many hours and lines of code it took to fix what looked like a simple problem here... That's okay, because I wouldn't be proud of my products unless I put in the effort to fix everything like this when my users share them with me!
The Turbine Duke's heating system will now behave as expected. The only thing I didn't fix was that the heat duct heats or cools faster than the plenum. It's not really. It just looks like it, because they have different smoothing constants in the visualizer's code. Just tell yourself that the lower thermal mass of the duct causes it to change temperature faster, just as you suggested above.
Anyway, thank you for pointing this out! Whenever I have to put a lot of work into fixing something like this, it always results in a much more accurate simulation, which makes me smile.
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Nice!
It is fantastic to see how dedicated you are to get everything working perfectly. Also in a case like this, where many users might never notice that anything is wrong.
Makes it much more satisfying to dive deeper into the systems, when you know that the dev is not just aiming for having the basics "look kind of right", but actually wants to simulate the underlying systems properly.
