I'm looking to see if anyone or any group has compiled a matrix of what reasonably works for different engines in the .049 to .061 range.  My limited gut feel is:

Cox Baby Bee class - 50 squares to 125 squares
Cox Medallion class - 100 squares to 150 squares
Cox TeeDee class - 100 squares to 175 squares
NV/Norvel .049 class - 150 squares to 200 squares
NV/Norvel/AP Wasp .061 class - 175 squares to 225 squares

Obviously there is the issue of what the engine application might be.  Again, my gut feel for this first guess is that the first three might be for sport 1/2A flying, while the last two, maybe the last three would be for 1/2A light to moderate stunt flying.

Looking for information and correction.  Thanks!

Jim Howell

The upper end engines look about right, but the Babe Bee/ Golden Bee should be about 125 to 150 sp.in. And the others blended in appropriately.

Of course it depends on how hard you plan to fly the model. Level flight, loops and lazy eights on the one hand, or a precision pattern on the other end of the scale.

Look at the available kits to see what works.

Motorman, Larry,
Thanks for the responses.  I'll put this on a note and stick it on the wall of my workshop.  Since all my previous  1/2A C/L flying was done 55+ years back, my vague memory of puting a Baby Bee on all the Goldberg, and hollow log models seemed to have affected my "gut feel" on the small end.

Back then, the "how hard" factor was mostly for fun and amazement that I could actually do this.  Three years of Christmas gift Cox and Wen Mac plastic ARF failures predisposed me to believe that 1/2A stuff was unflyable.  Once I built that Ringmaster and Fox .35 and learned a smidgen about C/L flying, I decided that balsa did fly better than plastic and that I could build them.  Then building and flying the Goldberg, Scientific, and cobbled up flying wings with a BB stuck up front was sheer pleasure.

I'm pretty sure that this time around, the flying will desired to be flown much harder!
Jim Howell
Huntsville, AL