Kiwiprops™

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Pitch Conversion º to "


Pitch Conversion Table - Normally calculated at  ~ 70 % of the diameter for feathering type propellers

All feathering propellers have flat blades to ensure minimum drag when sailing with no rotational forces. Normal propellers have progressive pitch with the pitch angle increasing towards the blade root to accommodate the slower circumferential speeds from the smaller diameters and target equal loadings across the blade. Thus to find an equivalent pitch in inches it is necessary to integrate over the diameter.

Empirical experience would indicate that on a 16.50" nominal diameter ( = 17" @ the tips ) Kiwiprop unit with a pitch setting of 21º  (deg) equates to a traditional pitch setting of  ~ 12 to 13 inches.

Obviously for a larger diameter the same pitch setting will produce a higher equivalent pitch. Thus it is much simpler to operate in a " degrees of pitch " regime for all feathering type  propellers. The table below allows conversion for a given diameter from degrees of pitch to an estimated traditional inches of pitch.

 

Diameter "      18º  19º    20º    21º    22º    23º    24º 
14.00  9.5 10.0 10.5 11.0 11.5 12.0

12.5

14.50 9.9

10.4

10.9 11.4

11.9

12.5

13.0

15.00 10.2 10.7 11.3 11.8 12.4 12.9

13.4

15.50 10.5 11.1 11.7 12.2 12.8 13.3

13.9

16.00 10.9 11.5 12.0

12.6

13.2 13.7 14.3
16.50 11.2 11.8 12.4 13.0 13.6 14.2

14.8

17.00 11.6 12.2 12.8 13.4 14.0 14.6

15.2

18.50 12.6 13.2 13.9 14.6 15.2 15.9

16.5

19.50 13.3 14.0 14.7 15.4 16.1 16.8 17.4