I flew good today; until the 'last flight.' First flight was good. Had a crosswind and ran off the runway when I landed but other than that it was a very smooth landing. On the second flight, I wanted to practice landings, so I took off and flew a couple of laps. I was going to do a loop, then come around and land. The engine died in the loop but I had plenty of altitude to bring it around for a deadstick landing. I still cannot figure out exactly what I did wrong, but I must have given right aileron when it needed left; and I smacked the runway pretty hard. The fuselage looks OK but the wing appears to be hurt pretty bad. I'll strip off some covering in the next few days to see how big the repair job will be.