Good afternoon everyone!
First of: I am absolutely blown away by the way our 247D was received by the community. The amount of good wishes, congratulations and praise is overwhelming. I can’t thank you enough for it and I know that the rest of the team feel the same too.
I know that it might seem as if I went radio-silent. While I did have to do some catch-up on my sleep in the last few days, I still read everything that’s being posted here with great interest and I make notes of potential issues and things we could improve upon.
I also want to let you know that I am hopelessly behind my support-tickets, so if you sent me an email over the past few days, be aware that I am getting to it eventually, it’s just that the volume of emails is… a excessive… so it might take some time. Please be patient!
I want to address a couple of issues and try to outline where we are with the add-on.
1. Checklists
I hear you! I’ll be working on some interactive checklists, meanwhile Eric also got started on a PDF version of it. It’s kind of anachronistic, since checklists weren’t “invented” by the 1930s, but I understand how useful they are in this case.
2. Sound issues
We’ll keep working on the sound and a lot of issues that you fine people pointed out are already on our list to fix. Before an update is ready, I’d highly recommend to disable the “headphone simulation” in the audio settings, since it still seems to be causing some issues. And yes, the missing audio for the right flywheel is a bummer…
3. State saving-issues
I’m investigating what’s causing the issues with the state saving. It seems that in some cases the initialization code, which synchronizes the lever position with the internal simvar states, doesn’t always execute correctly. While this issue is unsolved, I’d recommend to wiggle engine distribution dial, the tank distribution dial and the mag switches before flight, to make sure they are set to the right value internally.
4. Starter issues with controllers like Honeycomb
I would highly recommend you create a controller configuration for the Boeing, which doesn’t use any starter-events! It seems that some of you can’t start the engines, because the engine-start events are not called properly and at least sometimes it can be traced down to the controller assignment used.
I’ll try to get to the bottom of this in the next update. The big issue is that I need to catch the right events from firing - and there’s a LOT of events related to starting engines.
5. Documentation
For the update, I will also spend some more time explaining engine management and the damage model.
6. Ts and Ps
This is a big one…
As you know, we’re using our own physics models to calculate temperatures and pressures - among other things. I saw that some of you already dug into the config file and found the extensive parameters for the oil circulation, which should give you an idea of the complexity of the system.
I am confident that the physics behind those calculations is spot on. However, with so many parameters to tune, there got to be problems with it too. It’s the old garbage in-garbage-out issue. Your calculations are only as good as the parameters you feed them with. I do believe that the oil temperatures are currently off the mark. The value displayed on the gauge is in fact Fahrenheit, but as some of you pointed out, the temperature range doesn’t seem to be right. The good news is, that this is merely a matter of scale. From a simulation point of view it makes no difference if the operating range lies between 80 and 110F, or 100 to 150F - it’s just a matter of tuning the parameters to fit the expectations.
A completely different matter is the cylinder head temperature and this is a tough one!
Some of you reported that the cylinder head temperature never seems to go above 100F during cruise, which is a problem that needs to be addressed. The question is, whether or not this is a problem with the simulation, or it is a problem with engine management - I’m quite divided on this myself.
In the real world, things don’t always go as planned and physics can be unpredictable at times. If you see your engine temperatures falling, you’d troubleshoot the problem (leaner mixture, more rpm, more manifold pressure, close oil shutters), however, if nothing helps, you’d come down to land and try to figure out what went wrong.
Obviously the second part - figuring out what went wrong - is quite difficult in the sim and I admit that we didn’t provide you with a lot of tools to trouble shoot.
But there’s also another part to this: sometimes it is simply not possible to operate your aircraft in the current conditions, because it’s not built for it.
It seems that those who experience a low cylinder head temperature with all its consequences, fly relatively fast through relatively cold air. In a way you’re super-chilling the engines doing so. Since the 247D doesn’t have cowl flaps to regulate the engine temperatures, there’s really not much that can be done at this point. The remedy could be: try finding some warmer air, run your engines faster, maybe try flying slower (drop your gear for a while?) or ultimately, land and wait for better conditions.
At the same time, I understand that the parameters for chilling the engine could be way off in our simulation - but the tweaking of such a parameter is not easy. If I decrease the “chill” effect of the wind, you might also have some real trouble keeping your engines cool during climb.
Long story short: I will keep working on those parameters and try to find a better balance between cooling the cylinders and heating them up. However, I would also like to ask you to keep an open mind with the level of simulation. We implemented real-world-physics (oppose to the usual look-up tables), and because of this, you will find yourself situations that can’t be explained easily.
Final thoughts
Once again, I want to thank you all for all the support and love you keep throwing at us. It is a very humbling experience.
We will keep working on this airplane and work through the issues you pointed out and I hope that, with your help, we can make her better and better.
Lastly, please be patient with us! I’m doing my best working through the support tickets, mails and messages, but the day only has 24h.
Much love!
Otmar and team
Wing42