Looking at used planes. I understand the .40, .60, 27% etc. What I don't understand is the 1.20, 1.60 scale. Can someone fill me in what how big these planes generally are?

The distinctions can get rather blurry; especially with the several excellent 1.20 two strokes available today.

With the 3D guys hanging 1.60s on a model that would fly fine with a .61 (and telling everybody about it), things can get even more confusing. And the so-called "tweeners" are in a class by themselves. These are slightly-larger-than quarter-scale aerobatic semi-scalers that are "between" large glow engine and small gasoline engine size. The Goldberg Yak (77" ) and H9 Extra 260 (78" ) are good examples of this.

IOW, your best bet is to ask advice regarding a specific model. Not trying to be obtuse, but that's the way I see it...[sm=drowning.gif]

When someone speaks of a 27% scale plane, that indicates the ratio of the size of the model to the size of the full scale plane. Thus, a 33% plane is one-third scale size.

When someone speaks of a .40, .60, 1.20, or 1.60 size plane, that indicates the engine size (in cubic inches.) Thus, a .61 size plane is designed, roughly, to balance correctly and fly suitably with a 10cc engine.

Best wishes,
Dave Olson

Planes advertised as "40 -size" are planes designed to fly on "40" sized engines. This means the engine has 0.4 cubic inches of displacement. (or 6.5 cc's). Trainer planes in this size are about 4 or 5 foot wingspan and weigh 5 or 6 pounds. a "60-size" plane is designed for motors (glow engines) of 0.6 cu inches displacment. Perhaps another foot larger and 6 or 7 pounds weight. a "1.20" plane / engine is targeting an engine with 1.2 inches displacement. These would typically weigh in around 8 - 10 pounds.

Somewhere around this size, the engine manufacturers begin to use the metric system. Especially gasoline engines. So you will see a 35 cc gasser. This is the same size as a 2.10 glow engine (about 16 cc per cu inch). And the planes in this size are often quoted as a percentage of their full-scale counterparts. So a 25% scale plane is one-fourth the size of the full sized plane.

For aerobatic planes such as Edge, Extra, Cap, a 35% plane would typically fly with a 100 cc engine and weight 28 pounds. A 40% scale would typically fly with a 150 cc motor and weigh 35 pounds.