# Pitch vs angle

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#### Protech Racing

##### Well-Known Member
Anyone have a quick chart for using angle to match my pitch? 56x28 prop. What should the angle be at 75%?
Thanks, MM

#### Dana

##### Super Moderator
Staff member
The angle $$\beta$$ at any radius R is:

$\beta = arctan(\frac{pitch}{2*\pi*R})$

Last edited:

#### pwood66889

##### Well-Known Member
Yeah, picky ol' bugger...
And isn't arctan = Cosine divided by Sine? Too many years away from being a junior in high school... :-(

#### Dana

##### Super Moderator
Staff member
Yeah, picky ol' bugger...
And isn't arctan = Cosine divided by Sine? Too many years away from being a junior in high school... :-(
Any units you want, as long as it's consistent.

#### Swampyankee

##### Well-Known Member
Pitch and radius have to be in the same units (inches, meters, feet, furlongs, whatever). The angle returned from arctan will be in radians or degrees, depending on how your calculator's set. In a spreadsheet, it will return radians.