Can't get much simpler than this one by KansasCloud: http://www.rcgroups.com/forums/showthread.php?t=1051242
Plans are on page 3 post #33. It's 33 inch span. I would say that a 24" span is a bit small for a trainer, things happen faster the smaller one goes, and it's harder to tell when "it" starts happening. My now 7 yr old grandson flew my 30" span Trainer1 last summer a couple of times. Hope to get him soloing this year. The T1 is a good trainer, although it was set up for brushed J250 motors and nimh packs, so needs a longer nose to balance right with lightweight brushless motors and Lipos. These are both quick/simple builds, but if you are up for a more complex build, then tony65x55's Tuffy is a good one. Another one that's a bit more whimsical is the BluBeagle by Gene Bond. All good trainers and long build threads so most all the questions have been answered somewhere in them.... Enjoy and let us all know how it goes!
bingo, Wil's found the tuffy thread!