Version: 1.5.27.0
Frequency: Consistently
Severity: High
Context: Mounted and community
Similar MSFS 2020 issue: Same behaviour in FS2020
Bug description:
When using legacy tables and correct torque values, propeller RPM can be controlled through the prop_power_cf table very well, except when the pitch is between -5 and 5 degrees. At that point, the propeller RPM seems to only be affected by the engine torque. So unless the shaft torque table is adjusted to extremely high values or we override it through code, the engine will underspeed.
This causes a problem when aircraft taxi in beta range, as angles around 0-5 degrees are usually “discing” positions, where the engine produces zero thrust and is critical during taxi and reverse.
The images below show the wild change in RPM in a stabilised engine. The torque is nearly identical, the only thing that changes is the RPM that goes from 400 at 5 degrees, to 700 at 6 degrees.
Note that going below 5 degrees doesn’t change RPM at all, it remains the same until we cross -5 degrees. Under that, tables work fine again.
