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Chart of HP vs RPM for APC props?

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Chart of HP vs RPM for APC props?

Old 12-04-2013, 04:57 PM
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RC_Fanatic
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Default Chart of HP vs RPM for APC props?

Anyone have a chart that shows HP absorbed by different APC props as a function of rpm? I'm looking for props from say 10x5 to 16x10. I think I recall seeing a graph of this a long time ago.

Yes, for the techie types, I know it will vary with temperature, altitude and the phase of the moon but I think I can deal with those issues!
Old 12-09-2013, 12:52 PM
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Hi!
Why would you like to know that???
Old 12-09-2013, 01:25 PM
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Originally Posted by jaka View Post
Hi!
Why would you like to know that???
The first answer is that I am an engineer and thus always curious! The second is that I have a few engines I would like to compare and to see the effects of different mufflers and any other odd ideas that come to mind. Yes, I could build a dynamometer but that seems more effort than is justified by my curiosity.

Why do you ask?
Old 12-12-2013, 04:48 PM
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Several years ago my club built a simple torque tester just to find out what different props did with a number of different engines. EVflyers.com the info is still posted on the site but as I recall they didn't have a lot of the smaller props. At that time most of the people were going to bigger planes and DLE and other gas engines from China were just getting popular. I can understand Jakas question, most of us just tach different props on an engine then fly the plane to see how we, the pilot likes the way the prop works on the engine plane combo. If you phoned or emailed a manufacture like APC they may have the info you want on hand or know of a site with the info? I would think that over the years there own engineers would have done the testing and have the info you want?
Old 12-13-2013, 12:22 PM
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Du-oh! The APC web site has all the data I could use, and more! Just need to plug it into a spreadsheet.
Old 12-13-2013, 04:31 PM
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Or just read it and forget about it like most of us. Numbers just give you a starting point then it requires real world testing. It's why most of us have a big box of props in different lengths and pitch. Once I find the prop that will fly the plane the way I like it to fly I buy several of them, balance them and just toss them into my flight box. Take a look at John Buckners prop wall when he posts photos. No hobby shop I have ever been in has a selection like that!! Each engine and air frame will fly differently using the same size prop so there is no one size fits all.
Old 12-13-2013, 05:29 PM
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Originally Posted by Gray Beard View Post
Or just read it and forget about it like most of us. Numbers just give you a starting point then it requires real world testing. It's why most of us have a big box of props in different lengths and pitch. Once I find the prop that will fly the plane the way I like it to fly I buy several of them, balance them and just toss them into my flight box. Take a look at John Buckners prop wall when he posts photos. No hobby shop I have ever been in has a selection like that!! Each engine and air frame will fly differently using the same size prop so there is no one size fits all.
Are you familiar with the term "preaching to the choir"? I do understand the concept of fitting the prop to the plane to the intended mission. I was never intending to imply that this was an effort to get around that process. Read post #3.
Old 12-18-2013, 12:24 PM
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Originally Posted by Gray Beard View Post
Or just read it and forget about it like most of us. Numbers just give you a starting point then it requires real world testing. It's why most of us have a big box of props in different lengths and pitch. Once I find the prop that will fly the plane the way I like it to fly I buy several of them, balance them and just toss them into my flight box. Take a look at John Buckners prop wall when he posts photos. No hobby shop I have ever been in has a selection like that!! Each engine and air frame will fly differently using the same size prop so there is no one size fits all.
Having a couple spare props in the flight box is good insurance. I have never broken a prop for which I had a spare at the field. The only ones that break are those with no spare.

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