CG rules still apply to pattern planes...The only difference is they are more tolerant of CG changes.....

If the CG by the designer is where you have that's a great starting point...Ivan was and still is a great flier and has designed some great flying planes.....Trust his advice on CG.....you may like it a little more aft or a little more forward...for taste.....

As for all the talk about Center of Pressure on the wing....I'm a mechanical Engineer and I can tell you your not going to calculate a center of pressure on that wing!

I also seriously doubt you are at 50% of the MAC...maybe 50% of the root cord but not 50% of the Mean Aerodynamic Cord (MAC).


You don't need not worry about the CP on the wing...and you don't really need to worry to much about the percentage of MAC....

The calculations will work for our models so I won't say that they are garbage...but in practical application they mean didily squat!

Making the numbers come are not going to make you fly better...and putting the Planes CG per the numbers is nothing more than a one time exercise that you are going to change right away......Most pattern models are not designed around these principles anyway.....they are designed by trial and error....Not only that but at the reynolds numbers we are flying at the rules are very broad and the results from the proper calculations have a very very broad range...we are talking like 10% of the wing cord difference...The important part is the feel not the numbers....So drop the idea of the numbers they mean squat!

I can tell you from experience run the CG Ivan has on the plans.....We flew tons of these planes back in the early 90's and the CG is on or close to his recommendation.

Just my opinion...If you still want the numbers I'm sure someone can tell you how to calculate the stuff....but be aware the C of P is not the only thing you need to worry about...Reynolds number...What speed is the plane flying at? Air density? Incidence....total weight of the model...and on and on....Not to mention what air foil is on the model?

Do you know the air foil....? You need that before you can even venture into the world of aerodynamics....

Its a lot more practical to just stick it on the CG on the plans and tweak from there.....

Good Luck
Troy Newman