Research worksheet¶
Fill this in before you start building. Honestly, most "why does it fly wrong" problems I've run into came from a guessed number, so it's worth the time. Copy it into a spreadsheet or your own notes and fill in the Your value and Source · confidence columns for your aircraft.
The UH-1H and Mi-8MT columns are what RFM's two templates use, so you can see what kind of number goes there and in what units. They're not defaults to copy.
Field names match the Workbench inspector.
How to use it¶
Priority
| Mark | Meaning |
|---|---|
| ★ | Needed before the first hover. Guess here and every test after it is misleading. |
| ◆ | Needed for believable handling. A labelled estimate is fine to start. |
| ○ | Optional, or only if your aircraft has that system. |
Confidence. Put one of these next to every source:
| Code | Meaning | Example |
|---|---|---|
| P | Published: manual, type certificate, manufacturer data | "TM 55-1520-210-10 fig 6-2 · P" |
| D | Derived: calculated from published numbers (write the calculation down) | "2 × 100 kg × 7.3² ÷ 3 · D" |
| M | Measured on the 3D model in Workbench | "model, skid tube · M" |
| E | Estimate from a similar aircraft or rule of thumb | "scaled from UH-1 · E" |
| ? | Unknown: left at a neutral value |
Later on, when something flies weird, the E and ? rows are the first place to look.
Where to find data
| Source | Good for |
|---|---|
| Type certificate data sheets (FAA TCDS, EASA TCDS), free online, civil types | Rotor RPM limits, engine model and ratings, max weights, CG limits, fuel capacity |
| Operator's / flight manuals (US Army TM 55-xxxx-xxx-10, NATOPS, Russian РЛЭ, civil RFM/POH) | Limits, instrument markings, hover performance charts, fuel, weights, control rigging |
| Maintenance manuals (US Army -23 series) | Rigging angles, gear ratios, blade weights, tire pressures |
| NASA / NTRS technical reports, AGARD, university theses | Rotor blade data, inertias, flight-test derivatives for common types (UH-1, UH-60, AH-1, CH-47, Bo 105, Puma) |
| Jane's All the World's Aircraft, manufacturer brochures | Dimensions, rotor diameters, weights, engine ratings |
| Engine TCDS / manufacturer data | Takeoff, max continuous and one-engine-inoperative power, gas-generator limits |
| Your 3D model (measure in Workbench) | Positions: hubs, CG estimate, gear points, fin and stabiliser, fuel tank |
Convert everything to RFM's units as you go (watts, kg, metres, kg·m²). There's a conversion table in Unit conversions.
A. Layout: decide these first¶
| Data | UH-1H | Mi-8MT | Your value | |
|---|---|---|---|---|
| ★ | Rotor layout (main + tail / tandem / coaxial / other) | main + tail | main + tail | |
| ★ | Number of engines | 1 | 2 | |
| ★ | Landing gear (skids / nose wheel / tail wheel / 4-wheel) | skids | nose wheel | |
| ★ | Main hub type (teetering / articulated / hingeless) | teetering | articulated | |
| ★ | Main rotor direction seen from above (anticlockwise / clockwise) | anticlockwise | clockwise | |
| ★ | Which template to start from (Pick your starting point) | — | — |
B. Weight and balance¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ★ | Empty mass, kg Without crew, fuel, removable weapons. Know exactly what's included. |
Flight Empty Mass | 2360 | 7176.7 | ||
| ★ | Empty CG position, model metres From manual CG stations, or estimate on the model |
Empty Mass Point | model bone COM_UH1 |
native COM | ||
| ★ | Rotational inertia pitch / yaw / roll, kg·m² Estimate: a box of the fuselage's size and mass. Pitch ≈ yaw ≈ m·L²/12; roll ≈ m·(W²+H²)/12. Real values run 20–50 % higher because of the rotor mast and tail. |
Empty Inertia + Override Inertia | 17259 / 14639 / 3795 (native used) | 57622 / 54754 / 10013 | ||
| ★ | Usable fuel, kg Litres × 0.8 or US gal × 3.07 for jet fuel |
Fuel Capacity | 637 | 1450 | ||
| ◆ | Fuel tank centre, model metres | Fuel Point | 0, 0.9, −0.459 | 0, 2.1, −0.937 | ||
| ◆ | Max gross weight, kg For checking only; RFM doesn't enforce it |
— | 4309 | 13000 | ||
| ◆ | CG limits fore/aft, metres from datum For checking only |
— | TM chart | РЛЭ | ||
| ○ | Crew body mass override, kg | Live Occupant Bare Mass | (off) | 80 |
C. Main rotor (repeat for each lift rotor)¶
| Data | Goes into (rotor config unless noted) | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ★ | Radius, m (half the rotor diameter) | Radius | 7.315 | 10.644 | ||
| ★ | Number of blades | Blade Count | 2 | 5 | ||
| ★ | Blade chord, m (width) | Chord / Blade Stations | 0.533 | 0.52 | ||
| ★ | Rotor RPM at 100 % | Nominal RPM | 324 | 192 | ||
| ★ | Hub position, model metres | Rotor unit Hub Point / Hub Bone | bone rotor_fx (0, 4.15, 0.04) |
bone v_rotor |
||
| ★ | Spin direction from above | Spin Direction (−1 anticlockwise, +1 clockwise) | −1 | +1 | ||
| ★ | Collective pitch range, deg (lever down / up) and the radial station it's measured at | Collective Min Deg / Max Deg, Pitch Reference Fraction | 0.75 / 11 at 0.75R | 2.667 / 15 at 0.7R | ||
| ★ | Cyclic pitch range, deg (fore-aft / lateral) | Cyclic Long Deg / Lat Deg or Cyclic Kinematics | 12 / 10 | swashplate data | ||
| ◆ | Mast tilt forward, deg | Shaft Tilt Deg | 5 | 4.5 | ||
| ◆ | Blade twist, deg root→tip (negative = washout) | Twist Deg / Blade Stations | −10.9 | +5 inboard → 0 at tip | ||
| ◆ | Root cutout, fraction of radius | Root Cutout | 0.085 | 0.192 | ||
| ◆ | Blade mass, kg (one blade) | Blade Mass | — | 140 | ||
| ◆ | Blade flap inertia, kg·m² per blade (or derive from mass) Estimate: blade mass × R² ÷ 3 |
Blade Flap Inertia / Measured Blade Flap Inertia Kg M2 | 1552 | 4775.84 | ||
| ◆ | Rotor polar inertia, kg·m² Estimate: blades × blade mass × R² ÷ 3, or without blade mass 0.0135 × max takeoff mass × R² |
Output branch Inertia (Power groups, engines and shafts) | 3103 (in combiner) | 19942 | ||
| ◆ | Teetering: flap stop, radians; precone, deg | Flap Stop, Precone Deg | 0.192 / 2.75 | — | ||
| ◆ | Articulated: flap hinge offset, fraction of R | Hinge Offset | — | 0.021 | ||
| ◆ | Articulated: lag hinge offset, fraction of R | Lag Hinge Offset | — | 0.048 | ||
| ◆ | Articulated: flap stops up / down, deg | Rigid Flap Up/Down Stop Deg | — | +25 / −4 | ||
| ◆ | Articulated: lag stops, deg | Rigid Lag Positive/Negative Stop Deg | — | +11 / −13 | ||
| ○ | Articulated: pitch-flap coupling (δ3) | Pitch Flap Coupling | — | −0.5 | ||
| ◆ | Articulated: lag damper, N·m·s/rad (needed: without one the rotor can oscillate) If unknown: 0.35 × blade flap inertia × lag frequency per rev (0.25) × rotor speed in rad/s. The authoring check prints this. |
Lag Damper Nm Per Rad Sec | — | 8000 | ||
| ○ | Articulated: droop-stop release RPM | Centrifugal Flap … fields | — | 108–111 / 95–108 | ||
| ○ | Stabiliser bar fitted? | Bell Bar Enabled | yes | no | ||
| ○ | Airfoil section name and real lift/drag tables | Use Mach Re Airfoil / Airfoil Decks | NACA 0012 built-in | NACA 230-series tables | ||
| ○ | Blade bending / torsion frequencies (per rev) | Group 05 elastic modes | 4 / 6.5 | off |
Quick sanity check. Tip speed = 2π × radius × RPM ÷ 60 should land between 200 and 250 m/s (UH-1 248, Mi-8 214). Yours: __ m/s.
Second lift rotor (tandem, coaxial, intermeshing only)¶
| Data | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|
| ★ | Second hub position, model metres | — | — | ||
| ★ | Its spin direction (normally opposite the first) | — | — | ||
| ★ | Its shaft tilt and any sideways splay, deg | — | — | ||
| ◆ | Differential collective for pitch (tandem) or yaw (coaxial), deg at full stick/pedal | — | — | ||
| ◆ | Differential lateral cyclic for yaw (tandem), deg at full pedal | — | — | ||
| ○ | Rotor overlap (tandem) or vertical spacing (coaxial), m | — | — |
D. Tail / anti-torque rotor¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ★ | Radius, m | Tail rotor config Radius | 1.295 | 1.954 | ||
| ★ | Blades | Blade Count | 2 | 3 | ||
| ★ | Chord, m | Chord | 0.2136 | 0.27 | ||
| ★ | Tail rotor RPM at 100 % (or the gear ratio to the main rotor) If unknown: ratio ≈ main radius ÷ tail radius |
Nominal RPM + tail branch Speed Ratio | 1655 (× 5.108) | 1124 (× 5.854) | ||
| ★ | Hub position, model metres | Rotor unit Hub Point | −0.375, 3.685, −8.459 | bone v_tail_rotor |
||
| ★ | Pitch range, deg (full one pedal … full other) | Collective Min Deg / Max Deg | −10.5 … 18 | −7.833 … 20.5 | ||
| ★ | Thrust direction (follows from the main rotor spin, Rotor units) | Shaft Axis | 1, 0, 0 | −1, 0, 0 | ||
| ◆ | Pitch at centred pedals, deg | Control map bias or yaw curve | 0.5 of range | 0.428 of range | ||
| ○ | Cant angle (UH-60 style), deg | Shaft Axis tilted up | 0 | 0 | ||
| ○ | Ducted (fenestron)? | (not modelled; see Other layouts) | no | no |
E. Engines and drivetrain¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ★ | Engine model (turboshaft only; piston engines aren't supported) | — | T53-L-13B | TV3-117VM | ||
| ★ | Takeoff power per engine, W (shp × 745.7) | Rated Power | 1,044,000 (1400 shp) | 1,659,182 | ||
| ★ | Transmission limit, W (total) | Transmission Limit | 820,000 (1100 shp) | 1,640,540 | ||
| ★ | Main rotor RPM the governor holds | Governed RPM, Governed Rotor RPM | 324 | 192 (flight 95 %) | ||
| ◆ | Max continuous and one-engine-inoperative power, as fractions of takeoff (twins) | Normal / Contingency Power Limit Fraction | 1 / 1 | 0.876 / 0.989 | ||
| ◆ | Ground idle gas-generator speed, % | Idle Ng | 70 % | 73 % | ||
| ◆ | EGT (or TGT / ITT / MGT): idle / max continuous / limit / start limit, °C | EGT Idle / Rated / Limit / Start Limit C | 400 / 610 / 625 / — | 700 / 975 / 990 / 780 | ||
| ◆ | Rotor RPM limits: max / min continuous / low-RPM warning, % | Nr Max / Min Continuous / Warning Percent | 104.6 / 90.7 / 92.4 | 101 / 88 / 92 | ||
| ◆ | Gas-generator red line, % | Ng Max Percent | 101.5 | 101 | ||
| ◆ | Idle fuel flow, kg/h | Idle Fuel Flow | 59 | 165 | ||
| ○ | Specific fuel consumption, kg/kWh | Specific Fuel Consumption | 0.36 | 0.36 | ||
| ○ | Engine output shaft RPM at 100 % (for the gauge ratio) | Visuals Engine Gear Ratio | 20.37 × rotor | |||
| ○ | Power-turbine inertia referred to rotor speed, kg·m² | Freewheel Disconnect Inertia | 170 | default | ||
| ○ | Accessory drag (pumps, generators), N·m at rotor | Common Accessory Torque Nm | 120 | default | ||
| ○ | Start sequence: light-off and starter cut-out Ng, % | Light Off Ng, Starter Dropout Ng | 12 / 40 | default | ||
| ○ | Torque gauge full scale at the transmission limit (100 for a % gauge) | Torque Gauge Full Scale Psi | 50 psi | — |
F. Airframe aerodynamics¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ◆ | Forward drag, equivalent flat-plate area, m² Light 1–1.5, medium 2–3.5. Some NASA reports list it as "f". |
Fuselage Drag Area Z | built-in | 3.134 | ||
| ◆ | Side and top projected areas, m² (measure on the model) | Fuselage Drag Area X / Y | built-in | 125 / 127.6 (fitted) | ||
| ◆ | Fuselage size: half width / height / length, m | Aero Half Extents | — | 1.25 / 1.6 / 5 | ||
| ◆ | Cabin aerodynamic centre, model metres | Fuselage Point | 0, 1.4, −0.5 | 0, 2.51, −0.59 | ||
| ◆ | Tail boom centre, model metres (if modelling it separately) | Tail Boom Point | 0, 1.95, −4.95 | 0, 3.29, −7.52 | ||
| ◆ | Vertical fin: area m², span m, centre | Fin Config, Fin Point | built-in, 0, 1.83, −5.49 | 1.3 m², 0, 3.79, −12.67 | ||
| ◆ | Horizontal stabiliser: area m², span m, installed angle deg, centre | Stabiliser Config, Stabiliser Point | built-in, 0, 2.66, −7.79 | 2 m², 2.7 m, −6°, 0, 3.42, −10.74 | ||
| ○ | Sideslip → roll moment coefficient | Body Roll Moment Coefficient | 0 | 58.9 | ||
| ○ | Moving stabilator / elevator schedule | Control-linked incidence (airspeed schedules not supported) | UH-1 linkage | fixed | ||
| ◆ | Wings, second fin, endplates, rudders: area m², span m, centre, angle | Flight Extra Surfaces | — | — |
G. Landing gear¶
Skids¶
| Data | Goes into | UH-1H | Your value | Source · conf. | |
|---|---|---|---|---|---|
| ★ | Cross-tube attach points, body side and skid side, model metres | Support Body Attach / Skid Attach | front 0, 0.59, 1.74 → 1.23, 0.02, 1.74; rear 0, 0.56, −0.59 → 1.23, 0.06, −0.59 | ||
| ★ | Skid runner centre, length, tube size, pitch/yaw | Contact area Center, Length, Half Width/Height, Pitch/Yaw Deg | main 1.4, 0, 0.8, 2.9 m long; front and rear lips | ||
| ◆ | Support stiffness, N/m (≈ static load on that support ÷ desired compression) | Spring Rate | front 100,000 / rear 200,000 | ||
| ◆ | Support damping N·s/m, travel m | Damper, Max Travel | 10,000 / 0.2 | ||
| ○ | Skid friction static / sliding | Custom Skid Static / Kinetic Mu | 0.5 / 0.35 |
Wheels¶
| Data | Goes into | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|
| ★ | Strut top and axle points for each gear leg, model metres | Strut Body Attach, Axle Center | nose 0, 0.87, 2.25 → v_wheel_F; mains ±1.19, 2.50, −1.60 → v_wheel_bL/bR |
||
| ★ | Tire radius, m | Tire Radius M | nose 0.298 / main 0.433 | ||
| ★ | Strut travel, m | Max Travel M | nose 0.165 / main 0.36 | ||
| ◆ | Static load per strut, N (from weight and CG) → preload and spring | Preload N, Spring Linear N Per M | nose 8,437 / 187,487; main 12,485 / 106,780 | ||
| ◆ | Compression in the model's rest pose, m | Bind Compression M | nose 0.109 / main 0.218 | ||
| ◆ | Tire stiffness, N/m | Radial Stiffness N Per M | nose 604,124 / main 539,191 | ||
| ◆ | Steering: which wheel, pedal-linked or castering, max angle | Steering Mode, Max Steer Deg | nose, pedal-linked | ||
| ◆ | Brakes: which wheels | Braked | mains | ||
| ○ | Tire friction longitudinal / lateral | Mu Longitudinal / Lateral | 0.75 / 0.75 |
H. Controls and systems¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | Source · conf. | |
|---|---|---|---|---|---|---|
| ★ | Control sign conventions: which way each control moves the blades (from rigging data or just test it) | Rotor signs, control maps | — | — | ||
| ○ | Stability augmentation / autopilot: channels (heading, attitude, altitude, speed) and their authority, % of control travel | Category 10B | none | AP-34B, 20 % | ||
| ○ | Force trim on which controls | Category 09 | no | no | ||
| ○ | Swashplate tilt range and linkage coefficients | Rotor unit Cyclic Kinematics | — | long −5…+7.5°, lat −4.2…+4°, D1 1.7, D2 1 | ||
| ○ | Hydraulic servo rates / limits (leave unlimited if unknown) | Category 11 | off | off |
I. Performance data (for checking, not for input)¶
These don't go into any field. They're what you check RFM against on the test card. Write down the weight, altitude and temperature each number is for.
| Data | Your value | Source · conf. | |
|---|---|---|---|
| ★ | Hover torque or power at a known weight, in and out of ground effect No data? Hover power ≈ W^1.5 ÷ √(2 × 1.225 × πR²) ÷ 0.7 watts, W in newtons |
||
| ◆ | Hover ceiling IGE / OGE at a known weight | ||
| ◆ | Max level speed and cruise speed with power setting | ||
| ◆ | Max rate of climb | ||
| ○ | Autorotation descent rate and best glide speed | ||
| ○ | Fuel burn at cruise, kg/h |
J. Model and game integration¶
| Data | Goes into | UH-1H | Mi-8MT | Your value | |
|---|---|---|---|---|---|
| ★ | Rotor hub bones / pivots | Rotor unit Hub Bone / Hub Point | rotor_fx |
v_rotor, v_tail_rotor |
|
| ★ | Wheel / skid bones | Strut/tire PointInfos | v_ground_contact_* |
v_wheel_F, v_wheel_bL/bR |
|
| ◆ | Rotor slot names and spinning child bone | Visuals Main/Tail Slot Name, Rotor Child Bone | RotorMain, RotorTail, v_rotor |
— | |
| ◆ | Animation graph variables for gauges | Visuals Bindings | torque / Ng / EGT carriers | — | |
| ◆ | Sound loop names (_LP) |
Visuals Sound Loops | built-in set | — | |
| ○ | Seven damage hit-zone names | Damage bridge Zone fields | Engine_01, Gearbox_01, Driveshaft_01/02, RotorMain, RotorMain_Shaft, RotorTail |
— | |
| ○ | Weapon slot names and weapon indexes | Store Vanilla Slot Name, Weapon Slot Index | GunnerLeft/Right, pods 0/1 |
— | |
| ○ | Reaction per round, N·s: guns positive, self-propelled rockets negative (rail/tube friction only) | Store Recoil Impulse Per Round Ns | door guns 10, Hydra 70 pods −20 | — | |
| ○ | Suspension / steering / wheel-spin signal names | Strut/tire … Signal | skid slots 1–4 | suspension0–2, steering0, rotation0–2 |
Before you start building¶
- Every ★ row has a value and a source.
- Everything is in RFM units (W, kg, m, kg·m², RPM).
- Tip speed check passes (section C).
- Main RPM × tail ratio = tail RPM.
- After the first spawn, the
[RFM-LINT]authoring check reports 0 warnings, or you know why each one doesn't apply. - Every E and ? row is marked, so you know what to come back to when tuning.