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Propeller airflow and tip speed calculator

Pitch speed, tip speed, Mach number, static thrust and shaft power of a propeller — from RPM or from motor KV and battery.

Calculator author: @s_prudak Discussion in Telegram

1. Propeller geometry

Diameter, pitch, blades and flow efficiency

Quick presets (diameter × pitch): 10.0×4.5″ (254×114 mm)
in
in
Theoretical advance per revolution:
Number of blades (B)
85%
Stall 50% Slip 15% Ideal 100%

2. RPM and powertrain

Enter RPM directly or calculate it from KV and battery

rpm

3. Environment (speed of sound and density)

Airflow speed (pitch speed)

Real estimate (with slip):
/
Theoretical (ideal 100%): ·

Blade tips (tip speed)

Linear tip speed (π × D × n):
/

Final propeller RPM

Frequency: Blade pass:

Static thrust and power estimate

|
Thrust: Efficiency:
Disc area

Mach zones at the blade tips

  • < 0.65 Mach Optimum for efficiency and low noise
  • 0.65 – 0.85 Mach Noise, growing losses
  • > 0.85 Mach Wave crisis / blade failure

Engineering formulas:

  • Vflow = Pitch(m) × (RPM / 60) × ηslip
  • Vtip = π × D(m) × (RPM / 60)
  • Mach = Vtip / (331.3 × √(1 + T/273.15))

Configuration comparison table (propeller + rotation)

Save different builds (motor, battery and propeller) to compare them side by side

Saved configuration Propeller Source / RPM Flow (real / theoretical) Tips (tip speed) Mach number Static thrust / power Action

Thrust and power are an empirical estimate from the pitch/diameter ratio, not a measurement: check them on a test stand before relying on them.