Day 5 was another challenging day for me as this time my struggles with the glider were not on the ground, but in the air. After missing the start yet once again, I settled onto the course line with just a few other pilots. I was starting to make up some good ground and was just about to catch up with the lead gaggle when I got too aggressive after arriving at cloud base and going on glide. I've been pushing the new glider so that I can find out what the performance limits are. Conditions are pretty mellow here so I've been opening up the trimmers full and going about hafl speed as soon as I'm done climbing and headed out on glide. I was really trying to play catch up and pushed the glider too hard when still under the cloud and kind of rough conditions. The glider frontal stalled strongly and exited with about a 30% crevat on the left side. I was able to counter it ok without stalling the wing but was unable to fish it out with the stabilo or any other lines for that matter. I was forced to stall the glider to get the crevat out and then was back on my way. I lost 3 or 4 hundred feet during the maneuver along with any hope of catching up with the lead gaggle. I hooked up with my good friend BZ from Sitka and we worked our way out to the river after some very low saves and then we both noticed some very menacing weather further down the course line. The task was cancelled at that point and there was no scoring for the day..... By the time we were all packed up a farily strong gust front came through the area, and it poured cats and dogs in Governador Valadares for several hours after.....