Thrust issue

Hello all,

I have built an v-shaped octo-copter, with a 5000mah, 35c, 3s battery, 12gauge wire running from the center out to the arms, where I split the 12 gauge into 4 smaller gauge wires to go to the escs.

I have 10x45props with Motor AC2830-358, 850Kv from 3DRobotics, using 20amp escs. At the time, they were specified to provide 433grams of lift at 50% and 1095grams at 100%.

I have checked and double checked the prop directions, motor directions, and redone the esc and radio calibration.

My copter, all up weighs 3500g. A little heavy, but even with conservative numbers, this suggests I have a factor of two on my thrust.

While I start getting some lift at 50%, I go to 100% throttle and still barely get off the ground. Some basic math suggests I have 8*1095g=8760g of thrust at that point. Even using the more recent specs on the 3dr site of 880g -> 7040g of thrust.

I logged the motor outputs, confirming they go to full power, and suggesting I should be getting plenty of lift.

Could there be something wrong with my power distribution setup? Should I go to 4S? My props have about 1" of clearance between each other, am I losing thrust due to proximity? Soldering together 12 gauge wires, I used a fair amount of solder; is that an issue? I've attached a picture of the 12 gauge wire as it arrives at an arm, and the split into 4 plugs for the escs.

I've looked at other setups, and it seems to me that they are in similar weight/thrust setups. Even the 3DR hexa, using the same motors, takes off with 3000gram all up weight.

Any insight would be helpful.




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