2018 Winter Semester Flying Robot Project Team A Article 3December 05, 2018


Our team has been making octocopter. Last week, we assembled CFRP pipes and PLA joints into outer frame of octocopter.
This octocopter seems to be octahedron, (so, personally, I call it as coptahedron) so that outer frame consists of 12 edges and 6 vertices. In order to make frame light and rigid, we chose 4 CFRP pipes whose outside diameters are 2 mm and inside diameters 1 mm and which are 1 m long. Then, we cut those pipes into 330 mm long (actually, some pieces were less than 330 mm because of cutting width) to make 12 relatively short pipes. Those pipes were prepared as octahedron’s edges.
These pipes don’t stick to each other so that we needed joints which connect these pipes and arrange them so that they form octahedron. We thought that making these joints from PLA resin was the best, designed shape of joints and manufactured additively with 3D printer. At first, we set the diameters of the holes of the joints 2.3 mm which 2 mm pipes pass through but we found that 3D-printing was more rough than we thought. Then, we reconfigured the diameters to 3 mm and that the pipes get to fit easily.
Then we duplicated these joints. Since the 6 joints and the 12 pipes were prepared, we assembled these parts into the outer frame. The pipes were not so distorted so that cutting error seemed to be acceptable.
Now we are waiting for brushless motors and propellers. Actually, we estimated that total weight of “coptahedron” will be over 800 g and because of the direction of propeller, the max thrust per propeller need to be almost the same as the total weight. Then we searched for brushless motors and found particularly powerful one. We are looking forward to mount these motors and propellers and show you “equipped” picture of octocopter next time.

Nozomu Terao
そして今はブラシレスモーターとプロペラが届くのを待っています。実のところ、“コプタヘドロン”の総重量は800gを超えると想定されており、プロペラの向きのためプロペラ1個当たりの最大推力は機体の総重量とほぼ同じくらい必要です。そこで私たちはブラシレスモーターを探し、特に強力なものを見つけました。次回ではモーターとプロペラを取り付け、 “装着済み”の姿をお見せするのを楽しみにしています。

寺尾 望