A visual and sound question....

[Guest BobL]

I have a freeware general aviation twin. The engine and propeller (both the sounds and the visual presentation) achieve ignition almost as soon as I hit the starter. I want to retard the ignition so that the propeller visual and sound are retarded.Said another way, from both a visual presentation and a sound presentation, I want the aircraft engine/propeller combination to 'crank' through several blades before the engine actually starts.Is this easily accomplished? How/where do I start.BobL

[Guest Douglas K]

Bob,You need to decrease the normalized starter torque, found in the aircraft.cfg file (piston_engine) section. (See below)The method for changing this is easy, but it can take some time to get things just right. I don't usually pay much attention to the startup and shutdown, but fooling around with the MS C-172 just now, I found that a value of about 0.06 seems right as far as cranking time is concerned. I also increased the idle rpm friction scalar to 1.7 to slow the prop animation on startup and shutdown, and then I increased the idle rpm mechanical efficiency scalar to 1.7 to keep the engine running at idle with the increase in friction. (Shown in bold below) (piston_engine)power_scalar = 1.0 //Piston power scalarcylinder_displacement= 90.0 //Cubic inches per cylindercompression_ratio= 8.5 //Compression rationumber_of_cylinders=4 //Number of cylindersmax_rated_rpm= 2700 //Max rated RPMmax_rated_hp= 180 //Max rated HPfuel_metering_type= 0 //0=Fuel Injected, 1=Gravity Carburetor, 2=Aerobatic Carburetorcooling_type= 0 //0=Cooling type Air, 1=Cooling type Liquidnormalized_starter_torque= 0.03 <--changed to .006 //Starter torque factorturbocharged= 0 //Is it turbocharged? 0=FALSE, 1=TRUEmax_design_mp= 0 //Max design manifold pressure, (inHg)min_design_mp= 0 //Min design manifold pressure, (inHg)critical_altitude= 0 //Altitude to which the turbocharger will provide max design manifold pressure (feet)emergency_boost_type= 0 //0=None, 1=Water Injection, 2=Methanol/Water injection, 3=War Emergency Poweremergency_boost_mp_offset= 0 //Additional manifold pressure supplied by emergency boostemergency_boost_gain_offset= 0 //Multiplier on manifold pressure due to emergency boostfuel_air_auto_mixture= 0 //Automixture available? 0=FALSE, 1=TRUEauto_ignition= 0 //Auto-Ignition available? 0=FALSE, 1=TRUEmax_rpm_mechanical_efficiency_scalar= 1.0 //Scalar on maximum RPM mechanical efficiencyidle_rpm_mechanical_efficiency_scalar= 1.0<--changed to 1.7 //Scalar on idle RPM mechanical efficiencymax_rpm_friction_scalar= 1.0 //Scalar on maximum RPM frictionidle_rpm_friction_scalar= 1.0<--changed to 1.7 //Scalar on idle RPM frictionAll aircraft for MSFS are not created equal though, so you will have to play around with your piston twin using the above method as a guideline until you have what you want.Also, prop MOI can affect how fast the prop spins up when starting, and how quickly it stops on shutdown. It is also found in the aircraft.cfg file in the (propeller) section, but you shouldn't change it too much as it will affect propeller rpm changes and engine operation.

[Guest BobL]

That worked great...Thanks so muchBobL