First, to expand on Jeff Anderson's comment above, the first thing that I notice here are the dimensions of the motor. Assuming that a "30 cm loop" is made from about 60 cm of rubber, knotted at the ends, and knowing the density of Tan Super Sport rubber, I'm guessing that your loop is nowhere close to the maximum of 2 grams allowed by the rules. (around 1.2 g maybe?) So the first thing you can do is to use a longer loop so that your motor is as close to 2 g as possible. If the 80 winder turns you mentioned were put into a 1.2 g motor, you could expect about 120 turns or more on a 2 g motor.InfiniCuber wrote:
Well, my plane seems to be climbing all right, but it doesn't climb very high. I've snapped several rubber bands like a .081 30 cm loop broke many times after about 80 or so winds on a 15:1 winder. So getting more turns is becoming difficult. Also, the knots that show up once wound hit my motor stick and when they hit it mid-flight, it shakes the plane a bit (you can hear the plastic covering shake).
You also talk about knots. Are you stretching the rubber out to around 4-5 times its rest length when you start to wind, and gradually shortening this distance as the wind progresses? If not, you should try this, as it can reduce the tendency to form the knots you are observing, and allows you to pack more turns, and therefore more energy into the same piece of rubber.
Finally, you indicate that your plane doesn't climb as well as you'd like. Without knowing more details, I'm guessing that maybe the rubber is too narrow for the prop you are using, as speculated by others in this thread. The rubber delivers the greatest torque at the beginning of the flight, but the torque quickly decreases, especially if you are using a loop that is shorter than than the maximum allowed. So the duration of the climb may be shorter than you need for these reasons. What is the torque when you are at maximum winds, and what is the torque after you back off to launch?
Back to the rubber size, as hinted at by others, there is an optimum size for a given plane/prop combination. Thinner rubber will give you more winds for a given mass motor, but more winds isn't a guarantee of longer flights. One of our planes is currently flying best on a 2 gram loop of rubber cut to 0.105", which results in a loop about 14" long (includes 2 o-rings). This gives us way fewer turns than you could put onto a narrower loop, but the prop has a fairly high pitch, and the results are pretty good. Our best flight in a 19 ft. ceiling is currently 3:28.
So I hope that this helps.