A J-3 model @ 80" is generally referred to as being a 1/5 th scale Cub. A true accurate 1/5 th scale J-3 would have an 84.8" wingspan. So, at 80" it is really a 19% model, close enough to get called a 1/5 th (20%) scale. Most model kits and ARF's get their scale size number rounded off by the maker and the flyer. This past Monday I had the chance to fly my 1/4 scale J-3 in tandem with another 1/4 scale J-3. My Cub is actually 24% (100" w.s.) and the other was a full 1/4 scale, 25% (106" w.s.). Parked on the ground together or in the air flying together you couldn't tell the 24% from the 25%. Close enough...so the 80" is called a 1/5 th scale.