Electric Ducted Fan (EDF) Thrust Calculator & Powertrain Sizing
Compute static thrust, lip suction augmentation, disk loading, and DC bus current based on 1D actuator disk momentum physics and validated wind-tunnel empirical data.
Propulsion Input Controls
ISA ρ=1.225 kg/m³
YTF-60 Industrial Heavy-Lift
Standard EDF Thrust & Power Sizing Benchmark Table
Direct reference data for electric ducted fans across standard rotor diameters (250mm to 1900mm) at sea-level standard atmosphere (ISA, ρ = 1.225 kg/m³).
| Diameter (mm) | Power (kW) | DC Bus (V) | Static Thrust (kgf / N) | Exit Velocity (m/s) | Thrust/Power (kgf/kW) | Matched Propulsion Model |
|---|---|---|---|---|---|---|
| 250 mm | 5.5 kW | 96 VDC | 16.5 kgf (162 N) | 52 m/s | 3.00 kgf/kW | YTF-Custom 250 |
| 420 mm | 12 kW | 150 VDC | 34.0 kgf (333 N) | 56 m/s | 2.83 kgf/kW | YTF-Custom 420 |
| 600 mm | 22 kW | 400 VDC | 60.0 kgf (588 N) | 58 m/s | 2.73 kgf/kW | YTF-60 Industrial Ducted Fan |
| 850 mm | 38 kW | 600 VDC | 115.0 kgf (1,128 N) | 62 m/s | 3.03 kgf/kW | YTF-Custom 850 |
| 1200 mm | 50 kW | 600 VDC | 200.0 kgf (1,961 N) | 64 m/s | 4.00 kgf/kW | YTF-200 Aviation Thruster |
| 1900 mm | 120 kW | 800 VDC | 500.0 kgf (4,903 N) | 66 m/s | 4.17 kgf/kW | YTF-500 Heavy-Lift Unit |
| 1600 mm (High PR) | 600 kW | 800 VDC | 1,000 kgf (9,807 N) | 82 m/s | 1.67 kgf/kW | YTF-1000 Megawatt Propulsor |
Aviation Ducted Fan Powertrain Sizing Process
A deterministic four-step engineering procedure for matching electric propulsion to heavy-lift multi-rotors and eVTOL architectures.
Establish MTOW & Thrust-to-Weight Margin (T/W)
Determine all-up gross weight including payload, structure, and batteries. For industrial multi-rotors, target a baseline T/W of 1.4:1 to 1.6:1 for gust margin; for high-altitude or dynamic sling operations, target 1.8:1 to 2.0:1.
Allocate Multi-Rotor Fan Geometry & Disc Area
Divide total thrust by the number of propulsors (quad, hex, or octo configuration). Check vehicle frame envelope limits. Calculate required disk area A = π(D/2)² to ensure disk loading remains below 140 kg/m² for efficient hover.
Incorporate Shroud Lip Suction & Tip Clearance Benefit
Account for duct lip suction T_lip = (0.20 to 0.35) × T_total in static hover. Verify that tip clearance ratio δ/R is under 0.25% (0.8mm–1.2mm) to suppress tip-leakage vortex (TLV) and maintain high Figure of Merit.
Select High-Voltage 400V–800V DC Architecture & Thermal Margin
For units above 20kW, size voltage to keep phase current below 150A. High-voltage 800V SiC architecture reduces wiring harness weight by up to 64% and ensures continuous hover without stator overheating.
Common Engineering Pitfalls in Ducted Fan Sizing
Critical mistakes often made when transitioning from hobby EDFs or open propellers to industrial UAVs.
Mistake 1: Ignoring Duct Shroud Lip Radius
Using a sharp or thin inlet lip causes immediate flow separation at the intake edge during static hover, destroying 25% of potential lift and causing blade stall.
Always ensure an elliptical inlet lip profile with contraction ratio r_lip/D > 0.08 to sustain attached streamline contraction and forward suction.
Mistake 2: Specifying Low Bus Voltage (<100V) on 50kW+ Systems
Attempting to run 50kW at 48V or 96V creates currents exceeding 600A–1,000A, causing prohibitive I²R thermal runaway and massive copper cabling deadweight.
Transition to 400V–800V DC architecture for all propulsors above 20kW to slash conductor weight by up to 64% and maintain cool inverter operation.
Mistake 3: Excessive Blade Tip Clearance
A blade-to-shroud radial gap greater than 1.5% of diameter allows high-pressure exhaust to bleed backward into the suction zone, forming massive tip-leakage vortices.
Use high-rigidity CNC carbon composite duct shells to maintain strict radial clearance below 0.25% (0.8mm–1.2mm).
Fluid Dynamics & Sizing Equations
Actuator Disk Momentum Theory with Shroud Suction Integration
Where ρ is standard air density (1.225 kg/m³), A is rotor disk area π(D/2)², and P is aerodynamic power transferred to the fluid column.
In hover conditions, high streamline contraction over the high-curvature intake cowl induces forward negative static pressure, contributing 20% to 35% of total static lift.
A production ducted fan achieves a Figure of Merit (FM) of 0.74 to 0.78, with inverter and PMSM motor efficiency combined at 90% to 94%.
Tip Clearance Rule: Keep blade radial tip clearance <= 0.8% of diameter to suppress tip-vortex losses and preserve lip suction advantage.
Disk Loading Trade-off: Higher disk loading (>120 kg/m²) increases compact packaging and high-speed efficiency at the cost of hover power consumption.
Thermal Headroom: High-current continuous hover requires ram-air stator cooling to prevent NdFeB permanent magnet demagnetization.
Altitude Density Derating & Forward Speed Transitions
How air density changes with altitude and how cruise velocity shifts aerodynamic power requirements.
| Operating Altitude | Air Density ρ | Static Thrust Derate Factor | Extra Power for Same Thrust |
|---|---|---|---|
| Sea Level (0 m) | 1.225 kg/m³ | 100% (Baseline) | 0% (Nominal) |
| 1,000 m (3,280 ft) | 1.112 kg/m³ | 95.2% | +4.9% |
| 2,000 m (6,560 ft) | 1.007 kg/m³ | 90.5% | +10.3% |
| 3,000 m (9,840 ft) | 0.909 kg/m³ | 85.9% | +16.1% |
| 4,000 m (13,120 ft) | 0.819 kg/m³ | 81.4% | +22.5% |
While open propellers experience severe stall and flutter at high advance ratios, ducted fans benefit from cowl internal diffusion. However, at forward speeds V > 25 m/s, ram drag on the inlet lip and changed blade relative inflow velocity reduce the static shroud augmentation. Transition analysis requires aerodynamic pitch matching or variable pitch blade scheduling.
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