im just learning to fly and i have a shuttle challenge with a os 32 in it running 15% nitro with a os-8 plug in it , after about 3 or 4 flights i cant even get it off the ground , i increase the throttle and nothing happens, i fly one flight after another is that to much flying ? do you have to let it set and cool down after every flight? it seems to run fine at first,i have a good smoke trail when i can get it off the ground. thanks for any help

I would venture to say you are just a bit lean on the top end. Try a couple clicks to the left or richer and see if it improves.
You shouldn't have to let the engine cool longer than a refuel job. If you are too lean it could be staying too hot.