Propeller Tip Speed Calculator
Determine Propeller RPM Redline

Would you like to know how fast your propeller tips are traveling? Enter some different combinations of prop diameter and RPM setting below to find out. Note: Ambient temperature is needed to determine the speed of sound for a particular day.  The speed of sound varies according to air temperature.

Try different temperatures then you will see just how much the speed of sound can vary.

This calculator can be very useful when trying to determine the ideal propeller speed reduction ratio.  You may want your propeller to reach its redline (.88 to .92 mach) at the same time your engine reaches its maximum rpm limit, its redline.  To calculate this ratio, divide the maximum prop rpm, as you have determined by using this prop tip speed calculator, into the maximum engine rpm.

REMEMBER, .88 to .92 mach is a redline.  This is NOT the most efficient tip speed range for your propeller to operate.

This calculator is provided courtesy of P. Ponk Aviation.  Visit their website at www.pponk.com. 

USE THIS CALCULATOR AT YOUR OWN RISK

 
Over .92 mach the airflow begins to detach from the propeller which decreases efficiency and dramatically increases noise. To improve performance and public relations you should consider reducing RPM so your tip speed will be below 0.92 mach.

To convert MPH to feet per second multiply by 1.4667.  To convert feet per second to MPH multiply by 0.681818.  If you have a propeller speed reduction unit (PSRU) divide your gear ratio (i.e. 2.58) into the maximum engine RPM (i.e. 6800 rpm) to determine your propeller RPM (i.e. 2636 propeller RPM).

To determine how fast your propeller can theoretically push or pull you through the air at a given rpm and pitch, multiply your propeller's pitch in inches (usually measured at 75 percent of the prop disk radius) times the RPM.  Then multiply that figure times .000947 which gives you your speed in miles per hour.  Then multiply this figure by .85 if your aircraft is reasonably aerodynamically clean or by .80  or .75 if your aircraft is somewhat "draggy".  This last operation compensates for propeller slippage and some aircraft drag.  The end result should be a reasonably accurate estimate of your aircraft's airspeed potential.  Use this process to help determine the amount of propeller pitch you need for your particular aircraft.

If you want the quietest and most efficient propeller propulsion system, select a prop configuration (and reduction drive ratio) that will keep the tip speed for your cruise rpm at or below 700 feet per second or 475 mph.  Above this speed "compressibility" of the air in front of the prop leading edge begins to occur which begins to rapidly degrade the performance of your propeller.

The pitch selection guide below uses pitch in inches and does not include prop slippage.  It shows the "theoretical airspeed."  To convert degrees of pitch as measured with a protractor go to the page linked here and use the converter to find your blade pitch in inches.
Degrees Pitch to Inches Pitch Converter


Pitch Selection Reference Guide

Prop RPM
Cruise Air Speed 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500
220                       106 101 97 93
210                     106 101 96 92 89
200                   106 100 96 92 88 84
190                 106 100 96 91 87 84 80
180               106 100 95 91 86 83 79 76
170             106 100 94 90 85 82 78 74 72
160           106 100 94 89 84 80 77 73 70 68
150         106 99 93 88 83 79 75 72 69 66 63
140       106 99 92 87 82 78 74 70 67 64 62 59
130     106 98 92 86 81 76 72 69 65 62 60 57 55
120   106 97 91 84 79 73 70 67 63 60 58 55 53 51
110 106 97 89 83 77 73 68 65 61 58 55 53 51 48 46
100 96 88 81 75 70 66 62 59 56 53 50 48 46 44 42
90 86 79 73 68 63 59 56 53 50 48 45 43 41 40 38
80 77 70 65 63 56 53 50 47 44 42 40 38 37 35 33
70 67 62 57 53 49 46 43 41 39 37 35 34 32 31 30
60 58 53 49 45 42 40 37 36 33 32 30 29 28 26 25
50 48 44 41 38 35 33 31 29 28 26 25 24 23 22 21
40 38 35 32 30 28 26 25 23 22 21 20 19 18 18 17
30 29 26 24 23 21 20 19 18 17 16 15 14 14 13 12
20 19 18 16 15 14 13 12 12 11 11 10 10 9 9 8
10 10 9 8 8 7 7 6 6 6 5 5 5 5 4 4

This reference guide is courtesy of www.culverprops.com

Prop RPM
Cruise Air Speed 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900 4000 4100 4200
220 89 86 83 80 77 75 73 70 68 66 65 63 61 60 58 56 55
210 85 82 79 76 74 71 69 67 65 63 62 60 58 57 55 54 53
200 81 78 75 72 70 68 66 65 62 61 59 57 56 54 53 51 50
190 77 74 72 69 67 65 63 61 59 57 56 54 53 51 50 49 48
180 73 70 68 66 63 61 59 58 56 54 53 52 50 49 48 46 45
170 69 66 64 62 60 58 56 54 53 51 50 49 47 46 45 44 43
160 65 64 63 58 56 55 53 51 50 48 47 46 44 43 42 41 40
150 61 59 57 55 53 51 50 48 47 45 44 43 42 41 40 39 38
140 57 55 53 51 50 49 46 45 43 42 41 40 39 38 37 36 35
130 53 51 49 47 46 44 43 42 40 39 38 37 36 35 34 33 33
120 49 47 45 44 42 41 40 38 37 36 35 34 33 32 32 31 30
110 45 43 41 40 39 37 36 35 34 33 32 31 31 30 29 28 28
100 41 39 38 36 35 34 33 32 31 30 29 29 28 27 26 26 25
90 37 35 34 33 32 31 30 29 28 27 26 26 25 24 24 23 23
80 32 31 30 29 28 27 26 26 25 24 23 23 22 22 21 21 20
70 29 27 26 25 25 24 23 22 22 22 21 20 19 19 18 18 18
60 24 23 23 22 21 20 20 19 19 18 18 17 17 16 16 15 15
50 20 20 19 18 18 17 17 16 16 15 15 14 14 14 13 13 13
40 16 16 15 15 14 14 13 13 12 12 12 11 11 11 11 10 10
30 12 12 11 11 11 10 10 10 9 9 9 9 8 8 8 8 8
20 8 8 8 7 7 7 7 6 6 6 6 6 6 5 5 5 5
10 4 4 4 4 4 3 3 3 3 3 3 3 3 3 3 3 3

This reference guide is courtesy of www.culverprops.com


HOVERHAWK