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3 or 4 blade props?
Ok, Tony,
That makes sense. Is there a formula for calculating a prop's thrust? rpm vs hp? Given 21" pitch and the current 3 blade a 21" diameter (stainless steel) 21?R²(0.66)=19.0250?R²(0.80) it doesn't work out exactly. If the formula doesn't display in the newsgroup, I will try a different venue. Thanks, Capt Frank Tony Thomas wrote: First of all, normally a 4 blade prop will have a smaller diameter than the 3 blade to compensate for the extra blade surface. You want to go with the same pitch prop. The 18 will be way too small a prop and will travel less and be less efficient than the 21. Stay with same pitch which is inches of travel forward per revolution (in theory not compensating for slip). A 4 blade will have less slip at lower rpms than a 3 blade which is why it will be more efficient at cruise. |
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