In addition to Saurabh's advice, here is some more information:
Getting correct aerofoil shapes with coro can be difficult. The sweetest aerofoil for you airplane can be a matter of trial and testing, and the results are only available once the plane is in-flight (most of us do not have wind tunnel testing equipment
)
Here are some things to keep in mind when doing aerofoils:
1. Two components (in conjunction) are required to make planes fly properly, the vertical lift and the horizontal speed, always complementing each other within a specified window.
2. Most coro wings use a single spar (SPAD based designs) and hence mimicking perfect numbered aerofoils can be very difficult. Making a rib based design in coro is equally difficult. One probably has much simpler choice of choosing between a flat, symmetric and semi-symmetric only; The first thing to decide is what kind do you want. Choose flat for slow flyers and trainers, semi-symmetrical for sport trainers and symmetrical for aerobatic trainers that go very fast.
3. Thicker aerofoils provide more lift, but the thicker an aerofoil, the slower the plane goes (because of larger drag). This is only applicable to a limit after which additional drag can cause all types of chaos, including large drop in lift. So racer etc tend to have thinner aerofoils while slowflyers can have thicker aerofoils.
4. So, the second thing one needs to look at is the aerofoil thickness. This is determined as the percentage of the thickest aerofoil section (which will be at the spar for SPADS) to the chord of the wing. thin aerofoils can be of the order of 10-12% whereas thick ones can go upto 16-18% at times...but a 'fit' needs to be achieved. Something greater than 12% should work. It should not necessarily mean that you start with an 18% foil, the plane might just not fly
Hope that helps
GS