Engine start issues with Bonanza

gaboro

Hello,

I don't know whether I do something incorrectly, or the Black Square Analog Bonanza has some issues, but the engine the does not start as expected (as in the document and in the checklist). This is the normally aspirated version (not the turbocharged, but the turbocharged version might also have problems).

This is 3 problems, all of them are different. I attached videos for all of them, and they were performed in order in the simulation.

The three problems are the following.
(1) Cold and Start, the engine does not start even with the documented procedures if the throttle is slightly more open then almost closed. I believe even if the throttle is almost 50 % (or even if it's 20 %), the engine should start, not only when it's almost closed. https://streamable.com/qxpxtp
(2) Flooded engine, I followed the procedure, and the engine never starts, only if I repair the engine. https://streamable.com/dx8rxf
(3) Hot engine, the engine surprisingly easy to start every time, if the mixture is full and the throttle is almost closed (but not fully). The documentation says that it's very difficult to start a hot engine, and I need to run the fuel pump for a while with closed mixture to be able to start the engine. https://streamable.com/83ckrl

Is there anything wrong I do, or misunderstand the documentation? These three issues are separate, I have different issues with all three cases. Or is there a bug in the software, or somehow the current version of the Flight Simulator doesn't work correctly with the addon?

(The latest version of MSFS installed currently, 1.37.19.3, Premium Deluxe edition, but not every downloadable content is downloaded. The version of Bonanza addon installed is 0.1.1.)

I've also created a ticket with Just Flight.

Thanks for any replies, hope the issue can be resolved (even if the solution is to realize I do something incorrectly).

Black Square

Thank you for sharing those videos. I cannot express how much better it makes the service I am able to offer here when my users take the time to create videos.

Everything seems to be working correctly from your videos. Here is what I see in each scenario:

Since you only ran the fuel pump for the prescribed couple of seconds, there is very little fuel in the cylinders. A correspondingly low throttle setting is required to create the correct fuel-to-air ratio. This might correspond to the bottom 10-15% of throttle travel; however, since you crank the engine several times with the throttle too high to start, some of that fuel is worked out of the engine, thereby further reducing the throttle setting required to start the engine.
This is the hardest one for me to diagnose. I believe there is just still too much fuel in the cylinders to start, and if you continued cranking the engine, or waited several minutes (time acceleration), the engine would start with the procedure you demonstrated.
How long did you run the engine before attempting your hot start, and how long did you let it sit and cool down afterwards? It's very easy to start an engine that was just running. The problem arises when a hot (not warm) engine is left sitting for at least 10 minutes, but less than a couple hours. In this time window, fuel in the lines surrounding the hot cylinders is vaporized, which creates a back pressure that opposes the flow of new fuel into the cylinders for starting. I have programed my aircraft such that if you can hear the engine cooling (metal contracting) ticking sound after shutting down for a few minutes, then you know the engine is susceptible to vapor lock.

I hope that answers some of your questions. Unfortunately, this complexity is difficult to see and understand in my older aircraft, which is why I developed the tablet interface for the Dukes. If you haven't seen it in action, it may also help explain the logic behind the scenes in the Baron and Bonanza, since my engine starting simulations are fairly similar between the two. Let me know if you have any more questions! Always happy to help.

gaboro

Thank you Black Square for making this excellent addon!

I was able to reproduce the correct scenarios, and it looks like the ones I tried in my previous post were the expected outcomes.

I really enjoy the plane, and only see people praising it too!

I'll start with some additional questions, and then I'll write down what I did in this particular case and how they worked.

Is that ok that for flooded engine I was able to start the engine without leaning the mixture, and varying only the throttle?
Not related to this issue: I read somewhere you're working on a similar tablet that Duke currently have: https://community.justflight.com/post/25841 . Is that really true?
Not related: I've read in some places that the state saving has bugs, and that currently you're working on a fix? Is that also true? (I've created a ticket for that very recently.)

About the engine start. It looks like it works as in the manuals. (The environment: normally aspirated Bonanza, EHRD airport, 15 C outside temperature, at mean sea level, standard air pressure, "Clear Skies" weather in July. Propeller high RPM in all cases.)

(1),(2) The cold start and engine flooding case can be handled together. If the auxiliary fuel pump was running high, with full throttle and full mixture with 5, 15, 30, 60 seconds, then the correct throttle starting positions (with full mixture) were 5, 30, 50, 75 % respectively. (The percentages can be seen if the INSTRUMENT DESCRIPTION TOOLTIPS are turned on.) In these cases, it is not possible to start the engine with any other combinations that are listed here: so for example, it's not possible to start the engine if the auxiliary fuel pump was running for 15 seconds, and the throttle (after the fuel pump was turned off) are 5 % or 50 %. So it's pretty good, and very interesting that yes, you have to be careful with the engine.

(3) I was running the engine with 22 IN HG manifold pressure for 4 minutes, the cylinder head temperature went to around 210 C, with cowl flaps open. Then, I turned off the engine for 12 minutes (mixture cut-off, throttle fully closed). And as the documentation says, I was unable to start the engine with the normal cold procedures, but I was able to start it with the hot procedures. Works as expected too. On the other hand, I tried with different combinations, and I was able to start the engine sometimes easily.

Thanks, it really looks like I just didn't understand how the engine works, but I learned a lot.