Tip speed |

RPM X Diameter Inches X .00436 = tip speed (Ft/Sec) |

The normal maximum for a wood prop is 900 Ft/Sec |

2700 X 68 X .00436 = 800 Ft/Sec |

Geometric Pitch |

RPM X Pitch Inches X .000947 = Speed (MPH) |

This approximates the aircraft forward speed. |

2700 X 60 X .000947 = 153 mph |

Blade Angle |

Pitch/Circ. = the arc. tang. = angle (Degrees) |

To find the angle needed at any blade station for a desired pitch. |

Example: 60 pitch, 68 diameter (214" Circ.) |

60/214 = .2804, then arc. tang of .2804 = 15.70 Degrees |