Blades

[nikolakis]

Hellow to every one!!

Im new here and my english level isn't high so forgive me for eny mistakes 

Im from Greece and Im making the final project for the university. I have to construct 3 blades ( Naca 4415). I try to calculate the chord width at each station of the blade. Does any one know the equations for the chord, angle β and angle φ?

What's more, how can I post an image? (I want to show what exactly am looking for)

Nick

[DamonHD]

You can post the image(s) as attachment(s), see below where you enter the text.

I hope you're not asking us to do your coursework for you!  B^>

Rgds

Damon

[SparWeb]

A very good place to start looking is on the website of Hugh Piggott.  He has built numerous wind turbines, and he is an excellent teacher.  On his website www.scoraigwind.com  you can find a lot of information about the blades.  Look particularly for "blade carving" and "blade aerodynamics" because he has written a page or two about the very question you ask.

Also - there is a chance, small chance but not a zero chance, that some of his material has been translated into greek.  I know it has been translated into french and italian, so maybe some  ΓpΣΣk  translation exists.

[nikolakis]

No, I just want a little help.

Thank you for the site. Im good reader, but Im not so good in writting    Im going to look at this!!

[nikolakis]

Hi,

Finally I found a way to calculate the chord and angles along a blade!!

I'm looking now for lift and drag (coefficients) data over a range of Re numbers of NACA 4412 airfoil. Does any one know where can I find that. I have searched everywhere even at NASA site but I can't find for a range of Re.

Thanks

[Flux]

Years ago I had a book with all the NACA sections and their lift/drag curves.

I can't remember what it was called and I don't have it any more but let's hope someone else can help you. This information has been available so it probably still is if you can find it.

I seem to remember that the one you mentioned and a lot of similar ones have very similar curves and the best lift/drag occurs at about 4 deg.

Flux

[piglet2]

Check this:

http://airfoils.worldofkrauss.com/foils/793

[SparWeb]

The real authority on the NACA airfoils would be NACA themselves.  Their research is available online, but I'll save you the trouble of searching:

Summary of Airfoil Data
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092747_1993092747.pdf

Hmmm...  it turns out the file is 38 MB!   

This is better:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091689_1993091689.pdf

Table IIc on the second-last page is exactly what you need.  Even the Reynolds number is in the right range.
The column for CL is evident in the table, and I just checked the text, you can use his figures "Cc" as "Cd" for drag coefficient.  Close enough.


If you expect to be investigating many different airfoils in the future, or want a very detailed understanding of them:

Abbott, Ira; Von Doenhoff, Albert, Theory of Wing Sections, Dover press.
It's a classic.

[nikolakis]

Thank you SparWeb. It is what exactly Im looking for!!!!!!!