Calculate propeller pitch speed, tip speed, tip Mach number, advance ratio, and pitch angle for RC, drone, aircraft, and boat propellers.
Propeller pitch is the theoretical distance a propeller would advance in one revolution if there were no slip — like a screw threading into wood. A 12×6 propeller has 12 inches diameter and 6 inches pitch, meaning it theoretically advances 6 inches per revolution.
This calculator computes the theoretical pitch speed (MPH, knots, m/s), tip speed and Mach number, pitch angle at 75% radius, and advance ratio. Tip Mach number is critical — when the blade tips approach Mach 0.85-0.9, compressibility effects cause dramatic efficiency loss and noise.
Preset buttons cover RC model aircraft (2-blade 12×6), multirotors (10×4.5), full-scale Cessna (75×56), and boat propellers. The calculator handles both inch and millimeter inputs. A pitch selection guide helps choose the right pitch for hovering vs speed applications.
Whether you are selecting a propeller for a drone, tuning an RC racing plane, or analyzing a Cessna 172's constant-speed prop, this tool provides the key performance parameters.
Propeller selection requires balancing pitch speed, tip Mach, thrust, and efficiency. This calculator provides the key parameters for informed selection.
It is indispensable for RC hobbyists, drone builders, and aircraft/marine engineers optimizing propeller performance. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation.
Pitch speed = Pitch × RPM (distance per minute). Tip speed = π × D × RPM / 60. Pitch angle at r: θ = atan(P / (2πr)). Advance ratio: J = V / (n × D). P/D ratio = Pitch / Diameter.
Result: Pitch speed = 54.5 mph, tip speed = 128 m/s, Mach = 0.37
Pitch speed = 6/12 ft × 8000 = 4000 ft/min = 45.5 mph. Tip: π × 1ft × 8000/60 = 418 ft/s = 128 m/s. Mach = 128/343 = 0.37 (safe).
Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.
Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes
Use concise notes to keep each section focused on outcomes. ## Practical Notes
Check assumptions and units before interpreting the number. ## Practical Notes
Capture practical pitfalls by scenario before sharing the result. ## Practical Notes
Use one example per section to avoid misapplying the same formula. ## Practical Notes
Document rounding and precision choices before you finalize outputs. ## Practical Notes
Flag unusual inputs, especially values outside expected ranges. ## Practical Notes
Apply this as a quality checkpoint for repeatable calculations.
Pitch is the theoretical advance per revolution. Actual advance is less due to slip — typically 10-30% for aircraft props and 20-40% for boat props. Efficiency = actual advance / pitch.
Low pitch (like low gear): more thrust, less speed — good for hovering, climbing, heavy loads. High pitch (like high gear): less thrust, more speed — good for cruise, racing.
When blade tips approach the speed of sound (Mach 0.85+), shock waves form, dramatically increasing drag and noise while reducing thrust. Keep tip Mach below 0.85.
J = V/(nD) where V is airspeed, n is rev/sec, D is diameter. It determines the operating point on the propeller efficiency curve. Peak efficiency is typically at J = 0.5-0.9.
Larger diameter increases disk area and theoretical efficiency (momentum theory), but also increases tip speed, weight, and ground clearance requirements. The optimum balances these factors.
P/D ratio compares pitch to diameter. Low P/D (0.3-0.5) = high thrust, low speed (tugboats, copters). High P/D (0.8-1.2) = low thrust, high speed (fast boats, cruise aircraft).