Does anyone know where I can get a chart that shows the recomended prop sizes for different size engines. Both 2 and 4 stroke.

I've got one on my old web page. Click here (http://home.merlin.mb.ca/~kmartel/propcht.html) to go there.

BTW, welcome to RCFlying.Net!

Thanks a ton. That's exactly what I was looking for. Again thank you.

I started working with one of those charts last summer. I found that the chart needs real world rpm numbers at full throttle with any given prop to get accurate information.

Prop recommendations should be taken as just that, recommendations. Play around with different sizes to find the optimal prop for what your're trying to do. Remember that different props will result in different flight/thrust characteristics. A general rule of thumb is that a lower diameter/higher pitch prop will result in more speed, while a higher diameter/lower pitch prop will result in more vertical.