Prop Slip Calculator

Formula

To calculate the prop slip:

\[ \text{Slip} = \left( \frac{\text{Theoretical Speed} - \text{Actual Speed}}{\text{Theoretical Speed}} \right) \times 100 \]

Where:

\(\text{Theoretical Speed} = \frac{\text{RPM} \times \text{Pitch}}{\text{Gear Ratio} \times 1056}\)
\(\text{Actual Speed}\) is the speed measured in MPH

What is Prop Slip?

Prop slip is the difference between the theoretical distance a propeller should move in one revolution and the actual distance it moves. It is expressed as a percentage and is a measure of propeller efficiency.

Example Calculation 1

Let's assume the following values:

Actual Speed = 50 MPH
Engine RPM = 5000
Propeller Pitch = 21 inches
Gear Ratio = 1.5

Using the formula:

\[ \text{Theoretical Speed} = \frac{5000 \times 21}{1.5 \times 1056} \approx 66.67 \text{ MPH} \]

\[ \text{Slip} = \left( \frac{66.67 - 50}{66.67} \right) \times 100 \approx 25.00\% \]

The Prop Slip is approximately 25.00%.

Example Calculation 2

Let's assume the following values:

Actual Speed = 60 MPH
Engine RPM = 5500
Propeller Pitch = 23 inches
Gear Ratio = 1.6

Using the formula:

\[ \text{Theoretical Speed} = \frac{5500 \times 23}{1.6 \times 1056} \approx 75.00 \text{ MPH} \]

\[ \text{Slip} = \left( \frac{75.00 - 60}{75.00} \right) \times 100 \approx 20.00\% \]

The Prop Slip is approximately 20.00%.