Engine stopping too quickly after setting mixture to cutoff?

[gulredrel]

Hello,

Don't know i this is a bug or not. Anyone else also noticed, that the engine stops too soon after going to cutoff on the mixture lever?

Going to cutoff there is still fuel in the fuel lines which will be sucked into the carb and cylinders slowly stopping the engine, also propeller and rotating mass in the engine will have quite an inertia coming to a stop more slowly. ED's P-47 with the same engine stops much more slowly.

The sudden stoppage also appears when switching the mags to off. I had no luck being in low idle to do a mags grounding check with going mags off and immediately on again which should result just in a short drop in RPM and recatching of the engine ignition (also working in P-47).

If necessary I can create trk and record a video of what I mean.

Please see her real engine stopping at around 5:25 in the video.

Thanks

Jens

[Art-J]

Yup, it's impossible not to notice that, although I suspect it's just a low'ish priority WIP aspect of engine simulation. I wouldn't mind, however, seeing animation extended somewhat in the future to more accurate levels for such a big prop, as the real vids like the one above show.

[CF104]

On 7/11/2025 at 2:26 PM, gulredrel said:

Hello,

Don't know i this is a bug or not. Anyone else also noticed, that the engine stops too soon after going to cutoff on the mixture lever?

Going to cutoff there is still fuel in the fuel lines which will be sucked into the carb and cylinders slowly stopping the engine, also propeller and rotating mass in the engine will have quite an inertia coming to a stop more slowly. ED's P-47 with the same engine stops much more slowly.

The sudden stoppage also appears when switching the mags to off. I had no luck being in low idle to do a mags grounding check with going mags off and immediately on again which should result just in a short drop in RPM and recatching of the engine ignition (also working in P-47).

If necessary I can create trk and record a video of what I mean.

Please see her real engine stopping at around 5:25 in the video.

Thanks

Jens

Slowly stopping the engine at fuel cutoff just isn't a thing with pressure carburetors. When I worked on aircraft with pressure carbs, the cutoff of fuel was definitely under 2 seconds. When going to cutoff, the engine will momentarily lean out causing a quick audibly perceptible rise in RPM and this doesn't take very long. Once the fuel is no longer being supplied by the pressure carb, the engine should coast to a full stop in about 5-7 seconds.

I haven't tested the shutdown timing myself but I will on my next flight.

Here is a video from the cockpit showing the cutoff procedure. Probably not a -1D but it's a R-2800 nevertheless.
 

Regards,

John

[-Rudel-]

Hi, we'll look into this 

[Art-J]

@CF104 I'm quite sure OP's comment is not about  engine reaction time to lever being pulled to cutoff, but more about how fast the prop comes to a stop. There's some inertia in this big prop and, looking at vids of restored 3-blade Corsairs, it takes between 8-9 seconds for the prop to stop. In module right now, the complete animation finishes in half of that time.

Not a deal breaker issue, but something worth tweaking a bit in my opinion.

[CF104]

4 hours ago, Art-J said:

@CF104 I'm quite sure OP's comment is not about  engine reaction time to lever being pulled to cutoff, but more about how fast the prop comes to a stop. There's some inertia in this big prop and, looking at vids of restored 3-blade Corsairs, it takes between 8-9 seconds for the prop to stop. In module right now, the complete animation finishes in half of that time.

Not a deal breaker issue, but something worth tweaking a bit in my opinion.

If you reread the OP's post, it was a 2 part comment. First about the fuel cutoff time and the second about the inertial coast down. Both of which I covered in my reply.

Not a deal breaker as you say.

Cheers,

John