As probligo said it "And that is very often what did happen". It takes LOTS of short engine runs and study followed by learned bits of minor trim changes to set up a high powered free flight model. And Disaster is a companion constantly waiting at your shoulder during the testing.

Steve-kerry has some good points but I don't think you need to reduce the dihedral as long as you limit the rudder throw and size. Besides, the reduced dihedral will ruin the roll out if you choose to follow the "minimal disturbance" form of "radio interferance". You'll need a faithful free flight planform for unassisted climbs and rollouts.

As far as engine size to model size goes I suspect for a 25 to 30 you'll want a 600 or so sq inch wing area. The rest will scale apporpriatley with the span coming in at around 55 to 60 inches or so. But this is assuming you chose a HOT engine. The Satelite 1000's normally fly with a formula 1 Torp 40, or Nelson 40 as a minimum. Rossi 60's running on pen bladders (aka speed engines) are not unheard of either although these hotter engines also show up on 1100 to 1200 sq inch monsters as well.