Prather Prop ratio

[Hotrods]

I searched around and cannot seem to find what Prather props based there ratio on. Does anyone know for sure? Best I can figure it is based on 1.6 🤷🏼*!**♂️

[Peter A]

Prather Prop Chart

Prop# Diameter Pitch
215 40.6mm (1.60") 2.5"
220 43.7mm (1.72") 2.6"
225 46.7mm (1.84") 2.8"
230 48.3mm (1.90") 3.0"
235 50.8mm (2.00") 3.2"
240 53.8mm (2.12") 3.3"
245 57.2mm (2.25") 3.5"
250 58.4mm (2.30") 3.6"
255 61.0mm (2.40") 3.8"
260 64.0mm (2.52") 3.9"
265 66.3mm (2.61") 4.0"
270 69.6mm (2.74") 4.2"
275 74.9mm (2.95") 4.3"
280 78.7mm (3.10") 4.5"

[fweasel]

Thanks Peter, that's a good list to have. Don't think I've ever seen them all in one list.

[plinse]

My brain runs in metric so my list looks slightly different, all collected from an onlineshop and copied in Calc.
They all have different pitch factors, looks like they were all made in similar style but not equal. This is also something you can experience quite easily changing from 215 to 220 for example. They have lots less difference in speed and power consumption then the diameters suggest.

Still I run the Prather a lot as I strictly prefer steel propellers over beryllium. I balance my propellers myself so I either go for Prather or DrProps RTR but I don't try to protect myself against Beryllium grinding dust as such protection always has leaks.

Typ Dia Pitch Faktor Aufnahme
215 40,46 63,5 1,57 3/16
220 43,69 66,04 1,51 3/16
225 46,74 71,12 1,52 3/16
230 48,26 76,2 1,58 3/16
235 50,8 81,28 1,6 3/16
240 53,85 83,82 1,56 3/16
245 57,15 88,9 1,56 3/16
250 58,42 91,44 1,57 3/16
255 60,96 96,52 1,58 3/16
260 64,01 99,06 1,55 3/16
265 66,29 101,66 1,53 3/16
270 69,6 106,68 1,53 1/4
275 74,93 109,22 1,46 1/4
280 78,74 114,3 1,45 1/4

(edit: Sorry in editing the table looks better then in posted format, the lines can be read actually...
But the main interest why I posted the second list is showing the pitch factors that change from 1,45 to 1,6:)
Typ Faktor
215 1,57
220 1,51
225 1,52
230 1,58
235 1,6
240 1,56
245 1,56
250 1,57
255 1,58
260 1,55
265 1,53
270 1,53
275 1,46
280 1,45

[Hotrods]

I was coming up with the same ratio in pitch you have presented, thank you for helping me conform the results. Have a great day!

My brain runs in metric so my list looks slightly different, all collected from an onlineshop and copied in Calc.
They all have different pitch factors, looks like they were all made in similar style but not equal. This is also something you can experience quite easily changing from 215 to 220 for example. They have lots less difference in speed and power consumption then the diameters suggest.

Still I run the Prather a lot as I strictly prefer steel propellers over beryllium. I balance my propellers myself so I either go for Prather or DrProps RTR but I don't try to protect myself against Beryllium grinding dust as such protection always has leaks.

Typ Dia Pitch Faktor Aufnahme
215 40,46 63,5 1,57 3/16
220 43,69 66,04 1,51 3/16
225 46,74 71,12 1,52 3/16
230 48,26 76,2 1,58 3/16
235 50,8 81,28 1,6 3/16
240 53,85 83,82 1,56 3/16
245 57,15 88,9 1,56 3/16
250 58,42 91,44 1,57 3/16
255 60,96 96,52 1,58 3/16
260 64,01 99,06 1,55 3/16
265 66,29 101,66 1,53 3/16
270 69,6 106,68 1,53 1/4
275 74,93 109,22 1,46 1/4
280 78,74 114,3 1,45 1/4

(edit: Sorry in editing the table looks better then in posted format, the lines can be read actually...
But the main interest why I posted the second list is showing the pitch factors that change from 1,45 to 1,6:)
Typ Faktor
215 1,57
220 1,51
225 1,52
230 1,58
235 1,6
240 1,56
245 1,56
250 1,57
255 1,58
260 1,55
265 1,53
270 1,53
275 1,46
280 1,45

[RaceMechaniX]

I believe the nominal pitch ratio as cast is supposed to be 1.5. The numbers above validate this.