RE: F3D? Why don't we have it in the U.S.?
Those numbers are the AMA rulebook designations for different events. 422 is more commonly known as Q40. 424 is Q500 airframes, only no hollow molded wings or tails, with the only approved engine being the Thunder Tiger Pro .40 with an APC 9/6 sport prop. 426 is also Q500 airframes, composites allowed, with the Jett engine specified for the class. There is also 428, which is Q500 with the "long stroke" Nelson and Jett engines, which were getting nearly as fast as some Q40 planes.
The 424 planes are probably around 115 MPH or so, maybe a little more. The 426 planes, around 150. 428, upwards of 170+.
Lots of folks use the Viper by great planes as a 424 plane. It's an ARF, not much work to putting one together, and the TTpro .40 runs right around 100 bucks, so the investment in a race plane is not too bad. Dig around in the forums, there are suggestions for reinforcements, etc, that will make the viper last a little longer by beefing up a couple of weak areas.
Stay safe over there, and by all means, contact me when you're back, I'll let you know when the races are, etc.
And thanks for what you're doing!