Definition of AIRFOIL. : a body (as an airplane wing or propeller blade) designed to provide a desired reaction force when in motion relative to the surrounding air.

- Webster's dictionary.

Better to keep it simple, and not try to introduce too much explanation or theory.

Yes, Arvel Gentry is good, and also fun to read.

Another one who studied airflow a lot and wrote about it (but maybe not in English) was the Swedish inventor, turbine-builder and sailor, Frederik Ljungstrøm. He explained the interactions between jib and mainsail, and the turbulence around  masts way back in the nineteen thirties...

Thank you Darren for putting this right.  Good old Newton (plus the phenomenon of viscosity in fluids) must not be forgotten when discussing the lift and drag of aerofoils.

Here is a link to John S Denker’s «See how it flies”, Chapter 3, about Lift and Drag:

http://www.av8n.com/how/htm/airfoils.html

and here is the link to Denker’s start page.

http://www.av8n.com/how/

Denker confirms what NASA writes about this. Many school books on basic fluid theory need to be revised

Arne

Quite correct, sir,  and thank you for the intervention.

Comments please, and members may care to open the debate on any questionable terms here to generate support for their position.

The Glossary Editorial Group presents for the review 
of the JRA membership a rather more complete Glossary 
of Junk Rig terms.

The Glossary can be found by clicking here
The Editorial Group is seeking your input with a view 
to publishing this document on the JRA website for 
the benefit of members and non-members alike. 

A brief note of corrections, clarifications and 
congratulations should be addressed to the Group 
at <jrgeditor@gmail.com>.

Let me finally acknowledge the work of Dave Zeiger, 
Shemaya Laurel and Lesley Verbrugge without whom...