Re: JB & Prop Pitch Measuring Method
Actually south of Hooty (in Texas), there is a place called Coastal Propeller which has the computerized tool I mentioned. The pitch measurement takes only a minute or two. Usually it's
free. But if you guys prefer to pay for it, I'm sure Mike there will take your money.<br /><br />If you're truly interested in measuring the propeller's pitch correctly
yourself, here is one crude suggestion.<br /><br />Place your prop face-up on a flat surface (aft faces of the blades up). Draw a reference line along the face of one of the prop blades, along its center from hub to tip. Then measure out from the center any convenient distance (preferably 70-75% blade length) and make a tick mark. This will be your radius measurement. Draw a transverse line across the blade face, at right angles to the radius line, through the radius tick mark. Take a straight-edge and lay it on this transverse line so that its bottom edge runs off the prop blade and just touches the flat surface or table top. Place a carpenter's square against the straightedge anywhere along the high side. Note the vertical height from the table top at that point. This will be your height measurement. Measure the base, the distance along the table top from the point of the straightedge, on the table, to the bottom corner of the square. This will be your base measurement. Then use the pitch formula.... Pitch = 2 pi x Radius x Height / Base.<br /><br />This method is hard to measure with, and gets less accurate with more complex blade designs, but it will get you close. After doing it a while you will find ways to refine your measuring techniques.<br /><br />Or, here are some other suggestions....<br /><br />
http://homepages.apci.net/~michalak/15mar03.htm#Propellor Pitch <br /><br />
http://www.soinc.org/wristuff/pgagerh.pdf <br /><br />
http://rcboat.com/febtech.htm <br /><br />
http://marlongofast.tripod.com/models/pitchGtxt.htm <br /><br />
I think I'll check Harbor Freight and see if they have one of those computerized tools that Forktail is talking about. Probably don't cost more 'en $25-$30.
Hooty......13.95-ebay.....BIN!!!!
No need for the sarcasm Hooty and Walleyehed. Obviously you both realize that tool is about $60,000 and can't be bought through a mail order sale catalog. <br /><br />But I must admit I laughed too when I saw you using the measuring tape that way.
