Engine config¶
A new RFM_PowerplantConfig starts with Rated Power, Transmission Limit and Governed RPM at 0. You have to fill those in or the power group won't build. Everything else that controls how the engine behaves (governor, spool, start sequence, temperatures) defaults to the Huey's T53 values, which work fine on other turboshafts too. Change these for your engine:
| Field | What it is | UH-1 (T53) | Mi-8 (TV3-117) |
|---|---|---|---|
| Rated Power | Takeoff power, in watts | 1,044,000 | 1,659,182 |
| Transmission Limit | Max power the gearbox can take, in watts (the total, on a twin) | 820,000 | 1,640,540 |
| Governed RPM | 100 % speed, given as main rotor RPM | 324 | 192 |
| Flight Governor Reference Fraction | Where the governor holds rotor speed in flight, as a fraction of Governed RPM | 1 | 0.95 |
| Idle Ng | Gas generator idle speed, fraction of 100 % | 0.70 | 0.73 |
| EGT Idle / Rated / Limit / Start Limit C | Exhaust gas temperatures. If your engine shows TGT, ITT or MGT instead, use those limits here. | 400 / 610 / 625 / (0 = same as limit) | 700 / 975 / 990 / 780 |
| Nr Max / Min Continuous / Warning Percent | Rotor RPM limits | 104.6 / 90.7 / 92.4 | 101 / 88 / 92 |
| Ng Max Percent | Gas generator red line | 101.5 | 101 |
| Idle Fuel Flow (kg/h), Specific Fuel Consumption (kg/kWh) | Fuel burn | 59 / 0.36 | 165 / 0.36 |
| Starter Ng Rate, Light Off Ng, Starter Dropout Ng | Start sequence | Huey values | Huey values |
| Torque Gauge Full Scale Psi, Bleed Heater/Device Psi | Only for the cockpit gauge | Huey values | — |
| Freewheel Disconnect Inertia | The engine's own spinning parts (power turbine and the gears on the engine side of the freewheel), referred to main rotor speed, kg·m² | 170 | default |
| Main Rotor Inertia, Geared Inertia | Only used to set the spring stiffness when Drivetrain Torsion is on | 3103 / 340 | not used (torsion off) |
| Drivetrain Torsion (group 07) | Shaft wind-up wobble. Single engine and lumped outputs only. | on, 4 Hz, 0.02 | off |
"Referred to main rotor speed" means a part spinning N times faster than the main rotor counts as N² times its own inertia. RFM works out all the engine speeds and inertias at main rotor speed, so the engine-to-rotor gear ratio only matters for the cockpit gauges (Visuals Engine Gear Ratio).
Leave the governor gains, spool times, runaway and stall torque ratios at their defaults unless you have actual engine data. I tuned them to behave sensibly across different engines.
Piston engines (R22, R44, H-34, Bell 47) aren't supported. The engine model is a free turbine turboshaft.
The three RPM numbers have to match: engine Governed RPM = system Governed Rotor RPM = main rotor Nominal RPM. The tail rotor's Nominal RPM has to equal main RPM × the tail branch Speed Ratio (Huey: 324 × 5.108 = 1655, Mi-8: 192 × 5.854 = 1124). The authoring check will flag it if they don't.
Don't know the tail gear ratio? Tail rotors usually run at about the same tip speed as the main rotor, so ratio ≈ main radius ÷ tail radius. That gives 5.6 for the Huey (the real one is 5.1) and 5.4 for the Mi-8 (real is 5.9). Close enough to start with.