How to find cog and do setup


New member
Getting back to the hobby again, I'd like to do what I did not manage when i was ~15 in ~1990: flying (and be able to control) my Graupner ASW 22.
The plastic fuselage is less white now, and might be weaker than it used to be. I've replaced the rudder and elevator servos and swapped the standard aileron servo in the fuselage with 9g servos in each wing.
Unfortunately I can't find the plans from the original kit, neither pdfs on the internet.
Can I assume that the cog is somewhere around where the airfoil is thickest?

Finding the correct angle on the horizontal stabilizer is also challenging. There used to be a template for this, but this is also gone. I guess this should be level when the plane is balanced, but then again: it's difficult to get the plane balanced when I'm not sure where the cog is.
Any suggestions?


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Legendary member
A good rule of thumb to find the CG is 25-33% of the full wing chord back from the leading edge of the wing, which usually ends up where the wing is thickest.


Site Moderator
Staff member
Nose heavy planes fly poorly, tail heavy planes fly once.

Start with CG at 25%, of the mean average cord. On a rectangular wing, the MAC is easy to calculate, it’s more difficult on a swept back wing.


Master member
Cg will be at the front carry through spar, more or less ( which is why they put it there). I believe the t tail should be set a bit nose down, about 1/16" from your picture with the bottom of the wing being level


New member
Thanks for your comments. I'll trim as you suggest and do a few glide tests.
Looking forward to get this plane back in the air again.