I am working on a hexacopter using 12 motors in a coaxial configuration but connecting the motors with a y connection. I have been reading everything I can about coaxial motors and the configurations. With the design I am doing i was thinking on doing a dihedral top 6 motors and strait bottom wondering if the air flow will cause the bottom motor to work too hard because the airflow will not be in a direct line. Thought it might be worth a try but if there is any suggestions otherwise or someone has already tried this with bad results I would be happy to hear. I am using 12, DJI e300 motor-esc's that I have. With all the talk about the bottom motor just pushing air that is already sped up and possible losing ??% efficiency thought it might be worth a try. It will put a large amount of air from the top motor outside of the bottom flow and also cause the bottom motor to actually work to push the air down?
Right now I am working on new upper-lower plates from cf for a hex with 6-4108 480kv and 15-5.5 on a turnigy hexacopter frame just making the plates approximately 8" across flats and changed to 330mm cf tubes, making more room for everything. I have a cnc router table that I am cutting the plates with and the designs will be done this weekend.
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Do not intend to be rude but that is how real twin rotor helicopters work.
Do not forget to have top rotor turning in opposite direction to lower so you loose torque effect , in your photo above top rotors turn say clockwise then lower anti clockwise. If you wish you could put top rotor(dark ble) above lower (light blue) and keep quad shape
Keith
Finally getting back to this one. I have the plates designed and ready to cut out and the motor arms ready to be built. this will be a different design with 2 props side by side on a tee with the motors from one arm above and the next below with about a 30 percent overlap between motors from arm to arm. Don't know if I will put (2) 2212 motors on a single esc or 2 esc's on a single input. I'll be playing with that as soon as I finish testing my octo
How is this build going? Building a hexa coaxial myself, although a different setup...
Getting a little busy around home. I am hoping to keep up with some writing on the projects I am working on. I have 3 different designs going right now plus upgrading my gimble to encoder motors( I designed the mounts for both encoders and pots for single yaw input too).
After considering this 12 motor design and a whole lot of time on ecalc I decided to go a different route that is 4 motors less and a lot more time in the air with about about the same capacity. Designed a octo with every other motor upside down so it has 8 arms, 18" props and only 900mm frame, 300mm dia. plates. Less expense then the 12 and about the same frame size as a x8 but the motors only overlap about 35% instead of one on top of the other-chinook like. hopefully gaining some power.
It looks like 2 motors next to each other can go out and still land safely-this I will test soon. I have built a small version of it with 2212 motors and 12" props that I am just about ready to take to the air.turned out all teh tube clamps on my 3d printer with the arm mounts 5 deg. up angle. the motor mounts are mounted in 4 rubber grommets and adjustable. The plates are 240mm dia. and tubes are 165mm with notches in the tubes and tube clamps so they lock in place vertical always. It can hold up to a 40mm dia. motor and handle 8-13" PROPS. Real compact but has rigid arms, my full size octo will have 3508-380 motors and fold down arms. I am starting with with 17" props. I have all the parts on hnad and the plate designs are ready for the cnc table when I can get to it!
Here's the design of the small octo.
Very strong and compact, even with the plastic tube clamps. Its only a 570mm frame, not bad for 8-12" to 13" props.
I used 16mm aluminum for the arms, CF is much easier to cut the mounting notches in.
All 8 motors are CCW for it to work properly.
Middle picture shows the vibration dampened motor mounts. Can have tension adjusted and they qork quite well.