A modeling friend asked me about carving props and mentioned he was interested in trying one. He flies mostly FAC scale events, so I though it appropriate to contribute something here. The biggest starting hiccup with props is to figure the block size after deciding on the prop diameter, pitch and shape. I've carved a few blocks that were a bit too narrow to contain the blades that I wanted. So I decided to write a spreadsheet that would help design a block that would let me get my prop.
I have supplied two versions, one for Excel 2010 and one for older versions, 2003.
To use it, design your prop, choosing diameter, pitch, max blade width and radius for max blade width. Then guess a block width. Something a bit smaller than the max blade width is a good place to start. Enter these values in the shaded cells of the spreadsheet and it will calculate all sorts of parameters. The block shape is the kind with a fixed width in the outer 40% of the blade. The spreadsheet lists ten block chords that can be compared to the blade shape to see if the initial block is wide enough. If there isn't much margin to adequately cover the blade, a second guess for block width can be entered and a new set of chords examined. When the blade fits, you then can lay out the block to get the right triangular shape for the inner part of the block and the right curves on the sides of the block where it has constant width.
I'll be interested in reading comments about the calculator.
Ray
Received on Fri Aug 19 2016 - 11:01:34 CEST
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