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H.Zwakenberg

What type of propeller to use on a pusher aircraft!

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Hi Group,

 

currently I'm building an IBIS canard, a two-seater which will be powered by either an AeroVee or a Jabiru. Both engine sport appr. 80HP at around 3300 RPM. The max. speed will be around 115-120 Kts.

 

My question: I'm thinking about what prop to use. Since a pusher prop only sees 'dirty' air, I assume that it's no use to mount a propellor with modern laminar sections.

Does anyone has experience or pointers to information sources about this topic? As I'm based in Europe, noise emission (or better: the reduction thereof) is very important too...

 

bye

Hans

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Try this little calculator

 

It worked out almost exactly on my Long

 

http://www.culverprops.com/pitchselection.htm

 

Rick

 

Hi Rick,

 

thanks a lot for that URL, very useful!

 

While it answers the eternal question about what pitch to select, my other concern isn't addressed there. I assume that since pusher props see dirty air, laminar sections don't make sense for this application. This leaves the more conventional sections. I'd like to design/carve my own prop and am somewhat at loss about what airfoil sections to use for this specific application.

 

You wrote that the calculator worked out almost exact on your LongEze. Could you please write a few words about what deviations you discovered?

 

thanks!

 

bye

Hans

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Hi Hans

 

Ok I'll try

 

I have a Great American prop made 20 years ago. It is a 62" x 62"

 

Right around 2750 rpm I'm "indicating" 144 Kts

 

I could not tell you that it is a laminar flow. It appears that the pitch changes from the hub to the tip. It tapers, there is no question about that.

 

I also have a BT climb prop, 64 x 60 I definately get better take off performance but lose about 5kts on the top end. Roughly that is.

 

Yes there is some dirty air but you would be surprized what a little 1.5 meter prop does on the back of one of these things. I worry more about stones and the like kicking up into the prop more than I do about the dirty air.

 

Rick

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Hi Rick,

 

thanks a lot for that information. I dug up another prop calculation resource on the internet. You can find it on: THIS SITE

 

It's a Java-based software, either running inside your browser (JavaScript) or downloadable on your computer (Java). I'm going to try this out the next weekend.

 

take care,

Hans

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Hi Group,

 

My question: I'm thinking about what prop to use. Since a pusher prop only sees 'dirty' air, I assume that it's no use to mount a propellor with modern laminar sections.

Does anyone has experience or pointers to information sources about this topic? As I'm based in Europe, noise emission (or better: the reduction thereof) is very important too...

 

bye

Hans

Hans,

Newton Propelors in the UK. Wood, customer designed, excelent for your VW and the price, think about € 400,-. Worked very well for my Pottier. Don't mention my name;)

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