Advanced EDF Thrust Inputs
Formula Used
The calculator combines momentum thrust, pressure thrust, useful jet power, and aircraft weight checks.
- Fan area:
A = π × D² / 4 - Electrical power:
P = V × I, when voltage and current are entered. - Useful jet power:
Puseful = P × fan efficiency × (1 - duct loss) - Momentum thrust:
Tm = ṁ × (Ve - V0) - Pressure thrust:
Tp = ΔP × A - Total thrust:
Ttotal = (Tm + Tp) × number of fans - Thrust-to-weight:
TWR = Ttotal / (mass × g) - Static disk estimate:
T = (Puseful × √(2ρA))^(2/3)
How to Use This Calculator
Enter fan diameter, power, efficiency, duct loss, and aircraft mass first. Add voltage and current when bench data is available. The calculator will use voltage times current before the direct watt field.
Enter measured mass flow or exit velocity when you have test data. Leave both blank when you want an estimated static thrust value. Use inlet velocity above zero for moving-air checks. Add static pressure only when you know the outlet pressure difference.
Press the calculate button. The result appears below the header and above the form. Review thrust, thrust-to-weight ratio, safety margin, loading, and efficiency. Then export the result as CSV or PDF.
Example Data Table
| Fan Size | Power per Fan | Efficiency | Duct Loss | Model Mass | Use Case |
|---|---|---|---|---|---|
| 50 mm | 450 W | 62% | 10% | 950 g | Small sport jet |
| 70 mm | 1200 W | 68% | 8% | 2500 g | Medium EDF jet |
| 90 mm | 2600 W | 70% | 7% | 5200 g | Large scale jet |
Engineering Article
Why EDF Thrust Matters
An electric ducted fan model depends on clean airflow. The fan must pull air through the inlet. It must also push that air through the outlet. Thrust comes from the change in air momentum. A pressure difference can also add force. Good thrust is not only about motor watts. It also depends on duct shape, fan size, battery voltage, blade design, and outlet area.
Power and Airflow Balance
More power can raise thrust, but the gain is not perfectly linear. Small fans often need high rpm. That can increase noise and heating. Larger fans usually move more air at lower velocity. They may give better static pull. The right setup depends on aircraft weight and flight style. A fast jet needs strong exit velocity. A heavy model needs enough static pull for launch and climb.
Efficiency and Duct Loss
Fan efficiency describes how much input power becomes useful air power. Duct loss reduces that useful power. Sharp inlet lips, blocked intake paths, rough ducts, and poor exhaust tubes can reduce thrust. A smooth inlet improves flow. A clean thrust tube can help velocity. Even a strong motor may perform poorly if the duct is restrictive.
Using the Results
The thrust-to-weight ratio is a key design guide. A gentle sport model may fly with modest ratio. A strong jet launch needs more margin. A safety factor helps compare available thrust against required thrust. Power loading shows how many watts are used for each newton of thrust. Disk loading shows how hard the fan area is working. Use the chart and exports to compare setups before buying parts.
FAQs
1. What is EDF thrust?
EDF thrust is the force made by an electric ducted fan. It comes from accelerating air through a duct and nozzle.
2. Is static thrust enough for aircraft design?
Static thrust is useful for launch checks. Flight performance also depends on speed, inlet flow, drag, and exit velocity.
3. Why does duct loss matter?
Duct loss reduces useful air power. Poor inlets, rough surfaces, bends, and blocked intakes can lower real thrust.
4. Should I enter mass flow?
Enter mass flow when you have measured data. It makes the momentum thrust result more direct and realistic.
5. What thrust-to-weight ratio is good?
Many sport EDF models need more than 0.7. Fast launches and vertical performance need higher ratios.
6. Why is voltage under load important?
Battery voltage drops during operation. Loaded voltage gives a better power estimate than fully charged resting voltage.
7. Can this replace bench testing?
No. It is a design estimator. Always confirm final thrust, current, temperature, and battery behavior with safe bench testing.
8. Why include a safety factor?
A safety factor protects against losses, weak batteries, hot weather, measurement errors, and imperfect duct installation.