I have been researching the C.G. range for the KR2S and have some interesting findings.
I found that you can make a conservative approximation by assuming a trapezoid shape and it appears that Ken Rand did this for the KR2. I found a website that has a simple online calculator...the critical factors are root chord, tip chord and sweep. I was surprised to find that overall length doesn't have much impact on the range. http://www.nasascale.org/howtos/mac-calculator.htm A KR2S with a 29.125 inch tip chord will have a MAC of 39.33 inches as opposed to what is in the manual for a KR2 with a 36 inch tip chord. The 8 to 16 inch range in the manual looks to be a bit conservative for the KR2...which is a good thing for the KR2S. The interesting thing is what sweep can do to you. The airfoil profiles for the AS5048 have about an inch less sweep than the KR2S plans...and that moves the C.G. range forward a little. If you make the front surface of the outboard wing front spar parallel to the center section instead of the rear surface, it reduces the sweep about an inch...and this might move your acceptable C.G. range a little forward. Play with it...you might be surprised...and as usual, your mileage may vary. https://sites.google.com/site/mykr2stretch/ https://sites.google.com/site/mykr2stretch/parts-for-sale
