Jack Norris books on propeller design & theory of flight

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Martti Mattila

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Feb 24, 2021
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One Ytube video showed a man starting a VW conversion with homemade prop. One commented that he would´n fly behind homemade prop.
Than how about a homemade food will he eat that. This is my latest using Birch/ Cherry 60 by 28 inc. I haven´t decide yet the tip form, round or square but it is a narrower at the tip than I usually do. This is a well running forum it shows pictures before posting, well done.
 

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Gorothan

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Sep 28, 2022
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Tomorrow never comes! Sunday does though, so I got it done today. Here is Jack Norris's practical guide to prop design. Enjoy!
I'm wanting to build a prop for my moster 185 paramotor. This guide makes it sound like you have to be too precise to be able to do it by hand without a prop duplicator (like within a tenth of a degree using the blade chord line. Is that the case or is it possible to get it close enough by hand? Seems to me you can take off that much by sanding a bit too much on one side.
 

Jay Kempf

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People carved props by hand with spoke shaves, protractors and shirt cardboard templates for decades. Never heard of it being a limitation. Now that you can get a CNC machine for $200 and free software to do CAD/CAM as well as better adhesives seems you should be able to do fine. A paramotor isn't trying to be the fastest thing on 35hp.
 

Marc W

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Mar 31, 2017
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Colorado
I read a comment by a professional prop maker. He said, it is hard to make a really good prop, but it is also hard to make a really bad prop. So whatever you make will probably work even if it isn't perfect.
 

TFF

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The guy that use to do prop carving at Oshkosh, used an electric chainsaw to rough out the prop. He would carve out 8-10” per demonstration in about 5 minutes, then he would say, “Any questions?” The shock of it being so fast poured the questions out.

Stations marked and good templates and time is all you need. If you are good, you can carve a prop in a day or two. First prop might take a couple of weeks, and that should probably be a practice. It actually is pretty amazing once cutting the marked areas, and it does magically make a propeller. Forcing yourself to take your time takes patience.
 

Jay Kempf

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CNC allows near perfect symmetry. That's harder to get by hand. That is also why it is better to make a mold and a hub and make individual blades using the same method.
 
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agpilot24

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Oct 9, 2020
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I built a prop from scratch for a very large r/c aircraft. I first read a book and a lot of online stuff, then just got to carving. It was a 36”x20”. I made templates, and overthought it to death, but ultimately, I had to make big wood pieces into many small wood pieces….cutting away everything that didn’t look like a propeller.
Halfway through, I wasn’t convinced it would work out, but eventually it turned out symmetrical, balanced, and looked like a propeller! This was in about 2002 or so, I was building this prop to donate to a project built by a college kid in Wisconsin, a 50’, yes fifty foot span model built from pink foam(from Home Depot), appropriatly named “Floyd”. It did fly.
 
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