Trying to make something a little more compact than my last design-still haven't had that one in the air-snow and cold!! Anyway I have a 550mm octo with 240mm plates turning 12" props. Working on getting the pixhawk setup now. Bought a 3d printer so I printed all y won motor spacers and tube clamps. The main housing clamps are 5 degree up angle and notched for the arms. mounting holes on bottom for 60mm wide tubes or 62mm gimbal mount
Those are DJI 2212 motors pushing the 12-38 props. ecalc shows no problem and I put both the red and black motors on my test scan to check heat problem. Full throtle for 4 minutes got the motors up to 120 deg. with both 11x4.7 and 12x3.8 with almost identical watt and thrust readouts. I don't figure these will run at full throttle very often. ecalc puts it at about 35 mph and im looking for stable video.
The design is like a Chinook with about 50% overlap. It would run with multiple motors out. This one can handle up to 13" props and the big one up to 20"
AUW without battery is 1575g
The motor mount is also notched and I am using my custom CF motor mounts that are 100% separated from the arms with goromets. They can be adjusted for tension and I just flew them on my 680 with a DYS gimble and Canon dslr and the picture is very stable.
I have motors and folding arms for making a larger version 300mm body, using 3508-380 motors and 17"+18" props to test. mounting holes for 60 and 155mm mounting tubes, 62mm and 100mm gimble mounts. I have the CF plate to router the big octo
I also designed and printed a set of Hex mounts like the Tarot 680 but with 5 degree of up angle on all the arms that I will be putting together next. I have the plates designed like the octo but 280mm instead of 300(same design as the ones pictured below
Any input welcome. Weather starting to get a little better and hhopefully in the next month I will be flying all this stuff I have been designing.
I think the only concern I see right off the bat are the motor mounts. I am not sure if you designed them to break if you crash, They look weak (thin) and possibly weakened with the weight reducing cuts you made.
I guess lift efficiency is also a concern in your frame design but that is a trade off, the ability to change prop and motor size is probably worth the 15% (just a guess) waste.
Incorporating 3D parts is genius and gives you plenty of ideas to mess with, you gave me an idea for angled motor mounts.
The motor mounts will be 2.5mm thick here and are 3mm on my big ones which I have had 3-4 crashes with the 3mm mounts on my Tarot 680 style hex and only cracked one and broke a few CF propeller. I accidentally used a 3mm cutter on these and was suppose to be a 2mm so they are a lot smaller than they should to be. Easy to beef up when I cut the next ones. These are fine for my tests tho.
I have been using these mounts for a while. They are mounted in rubber so flex some anyway. I tested with a out of balance prop and was pretty impressed how much they dampened the vibration compared to rigid mounted of same design. My big hex and octo have them. My folding hex had milled tube mounts at the motors to give a 5 degree angle on the end of strait arms.
I was thinking lift efficiency would be better than a +8 or x8 and it could not get any smaller. With them so close you could run with multiple motors out. I will play with this.
Time will tell.
Off topic - which brand/model 3D printer did your buy?
I am interested in getting a 3D printer as well.
Just bought a HK fabrikator when they were on black friday sale. Works pretty good and i have made a lot of items so far. Still working on the right heat combination tho
I have the controller (ArduCopter), gps and landing gear installed. Tested all the motors and Tomorrow I plan on my first video ever of testing it out. Suppose to get up to 40 degrees here so hopefully not 15 mph winds.
If all goes well I will build the larger version shortly with 3508's, 17" and 18" props-to test for endurance and heat. 300mm diameter plates with aluminum folding arms. using a Pixhawk on this one. It will be a 800mm design able to take up to 20" props (8) and the arms will be 225mm long so 16mm tube should be more than strong enough. I might be selling this one when its done.