I need some help from someone who's better at mathematics than me.

Is there a formula I can use to increase the wing area of a model to a specific desired area? For example if I want to increase a models area from say 250 square inches to 350 square inches can I input both those values and come up with a multiplier for the span and chord that will give me the desired area?

I hope this question makes sense.

Divide 250 into 350 to get the ratio of areas, then take the square root to get the scaling factor.

350/250 = 1.4

sqrt(1.4) = 1.18 or 18% larger linear dimensions

Multiply all the linear dimensions (chord, span, etc) by 1.18 and your airplane will be 40% bigger in area.

Brett