how small does a plane have to be to be considered 1/2A? is there a written limit? wingspanwise or weightwise? powerwise? I didn't even know small planes had their own classification...I have been talking with the big boys in the other sections...mabey THIS is where I belong? I love smaller planes, especially nitro powered...

As far as I know, 1/2A refers to the size of the engine which is 0.049 cu inch, so an 1/2A plane would be any that can fly with a Cox 0.049 or equivalent.
It looks like this term has been stretched to a degree to mean any small plane..

I believe that the original definition of 1/2A was all engines less than .050 cubic inch displacement. "Small" as defined by many (including Randy Randolph and Joe Wagner) is .25 or smaller engines, is generally what seems to be the acceptable definition for this forum. There is a group of modelers that also builds 1/4A which is defined as .020 or below. The term goes back to the 50's when small engines started being produced.

Looking at the forum title makes me wonder what 1/8A would be...I didn't think they made anything (in glow anyway) that is that small.
Looks lik my smallest engine is an 'A' then...

All:

Officially, anything with an engine less than 0,050 is 1/2A, then up to 0.15256 (2.5cc) is class A, B goes to 0.299, and C is up to 0.65. A long time ago C was up to 0.50 with D then going on to 0.65.

None of these classes are worried about too much anymore, and most competition classes have thrie own limits and exclusions.

And, as sturmvogel said, 1/4 A is accepted s meaning 0.02 power. Yes, there is also a 1/8A, for the 0.01 engines. But the 1/4A and 1/8A have never been "Official" classes.

Current definitions are very loose, with the 0.061 and 0.074 engines often being included in 1/2A, and some have even claimed 1/2A status for 0.09 and 0.1 engines. I think that's going a little too far, though.

Bill.

William has it right. I consider .051 to .074 as larger engines for ½A models. The same way someone might use a .46 engine in a ".40 size" model.

Hey guys,
Once I read in Model Airplane News that 1/2A wasn't a term for size, but meant either the plane was controlled by elevator and aileron or elevator and rudder. This is what they said in the magazine, beats me. In this article they showed some airplanes that were actually large and considered 1/2A because of there control setup(2ch). They continued by saying that in today's terms 1/2A consists of small planes, but a long time ago 1/2A had nothing to do with size.
I'm not sure what issue this article was in, but I do remember reading it. If you don't believe me then call them up and ask them. Strange but true.

I wonder why someone would make up a story like that??

1/2 A is the size of the engine as mentioned before.

The classification of models by engine displacement seems to me to be more of an issue for competition than for sport flying. After all, who really cares if your sport plane has an .049 engine or an .061? If the chosen sport engine provides the proper amount of power the particular size is not all that important. On the other hand, the .061 is enough larger than an .049 and has the potential for enough more power that in a competitive situtation it would have the advantage.

In the current Academy of Aeronautics rule book the maximum size for 1/2A varies by event:

1/2A freeflight is .000 to .050
1/2A control line speed and racing goes to .0504
1/2A control line combat to .051
1/2A RC pylon to .0519

In my mind, .051 is the upper limit and .061s and larger are as "Bipe Flyer" indicated, larger engines that are close enough to 1/2A to substitute in sport applications.

pipercub1234

I remember that too. It was a letter sent in by a reader who's friend had explained to him how ½A meant "half aerobatic" and was A/E control. The editor's reply explained it properly as the engine displacement.