The real trick in flat foam -for outdoor practice --is a bit different than what you see offered by the commercial guys --
first -get the strongest , lightest motor and battery setup- My next setup is a 2100 TP yellow stripe 3 cell and a 11x.5.5 Electric prop APC prop on a Hacker A20/20L
I have the small 34 s motor and the A20/22L -which really are the best in these sizes I have seen and we have doon various outdoor setups
next up will be just about 375 squares - a real receiver ( good range ) such as my JR 910 PCM with case removed in a piece of shrink tubing (not shrunk!)
servos - 241 JR for good resolution .
Then make certain all linkages are dead tight -just like any good pattern plane .
The plane must be stiff -no floppy twisty setup .
all up weight should be about 16 ounces .
we use small CF tubes to stiffen wing -then use a single brace rod under wings -like the Shocky flyers use .
Anyway - you have to really get the throws and expos right and fly at a bit higher speed than the 3D stuff.
You also have to learn to fly in closer than the usual pattern distances .
It really is good training and fun.
So This is our setup for a low cost outdoor electric pattern plane - which will take a beating and give lots of GOOD practice time -in a park.
You can easily triple (and then some) the cost going to a converted larger " ARF w/electric" pattern bird.