could any one tell how the airfoil sections are oriented for swept wing.. if its perpendicular to quarter chord line then what will they do near the leading and trailing edge to complete the shape.. kindly reply..

Have a look at some of the plans on this page -

http://www.unclewilliesplans.com/about39.html

Originally Posted by boss03

could any one tell how the airfoil sections are oriented for swept wing.. if its perpendicular to quarter chord line then what will they do near the leading and trailing edge to complete the shape.. kindly reply..

Its orientated in the direction of flight, that's what the air sees. More or less, ignoring effects of high sweep angles.

Boss, it's been done both ways with decent results.

When swept wings first showed up the norm was to set the airfoil ribs at 90 degrees to the quarter chord line, or near enough to it. This results in a elongated airfoil when seen as a direct "inline" direction. Yet it is how many of the early swept wing jets were built. Even the ribs themselves were angled like that under the skins in many cases.

These days we don't seem to do this as much..... or at all. On our models the airfoils are used with the proper shaped ribs parallel to the aircraft center line rather than angled to be perpendicular to the quarter chord line.

Now looking at the wording of your question it seems like you think this means that the airfoils "S" turn to be inline at the leading and trailing edges and angled at the quarter chord line. Nope, it don't work like that. It's all or nothing. You either go with the airfoil parallel to the aircraft center line or you angle the WHOLE rib to the quarter chord line.

With many of our models the wing is an open frame style. Angling the ribs would produce a lot of wobbles in the flow direction. So we modellers tend to choose the option of the proper name brand airfoil done as ribs which are parallel to the center line of the aircraft.

Thanks for all for your reply... and also there is correction in the question... its not about leading edge and trailing edge.. if section is oriented perpendicular to chord, what they will do near root and tip..
i need this thing because i am going to calculate aerodynamic loads acting on the sweep wing using sectional data available..i am little bit confused while taking section whether it should be along the flight axis or perpendicular to chord..
kindly reply..

Flight axis. What you're talking about is called strip theory and it becomes less accurate the more sweep you have because of spanwise flow.