RC India

hello der all,
                 I am making one slow flyer as m new to this hobby. But m confused which air foil i must use. Either go for flat base or any other??????
Wing span is 80cm & fuselage is 60cm(75% of wing) length. Nothing has been decide yet for power system.M using coro as plane's material.
The basic design is attached here.

under cambered wings are slow fliers but making them is tough..... second option is to go for flat base with >12% thickness.

Flat-1 to Flat-3
These airfoils are popular for Trainers and Slow flying aircraft.  Flat-2 and Flat-3 are thinner versions of Flat-1.


Clark-Y
If there is an all time favorite, this is it.  The Clark-Y has been used on countless models from the J-3 Cub to modern Electric powered warbirds.  Jim Young and Jim Ryan (Ryan Aircraft) are big fans of the Clark-Y.  If you want a Semi Symmetrical airfoil, and you haven't a clue which one to use, the Clark-Y is a great choice!

hey thanks but Clark-Y profile is possible to make by using coro & one thing m designing it on CAD sofware (Creo) so any software in which i can derive Clark-Y profile & put it in creo??
DWG/DXF conversion can work so i can put it in creo.

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 :D)

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

long story cut short, the plans should mention the dimensions unless you're diverging.

ok will go for that
i think will go for flat base air foil
is der any airfoil generator software
or
how to calculate profile
is there any method

Rajesh,

1. SMS lingo is not allowed on the forum. Sooner or later, some mods will be after you so please take care and edit your post.

2. There must be a plethora of softwares available. A google search should help. Like I said, if you're doing a coro spad, your best bet would be go with a flat with over 12% thickness. You might be able to design the best airfoil on a software but cutting it in coro is a pain, and very difficult.
Hope that helps.
GS

It seems you are going in for a 40 size trainer in Corro

Just build a Debonair

The free plans are on http://spadtothebone.net/freeplans.htm

You need to modify it as in

http://www.rcindia.org/self-designed-diy-and-college-projects/spad-debonair-(modified-from-plans)-built-flown-successfully/

It is an excellent and forgiving trainer

I so agree with Rai sir