At 60mm wide, that’d be really tight according to my measurements. I’m not sure I’d be comfortable with the mounts I have. My motors (Avroto 3515) are way smaller.
Thanks again for the measurements - here are the ones of the motor, the beveled bottom width and a 50mm measurement compared to the approximate spot the frame clamp would attach to the mount. The press nuts (if left on) would be to the outside of the 50mm marks. I think I could still get a hex key straight down on one side and an open end box wrench to tighten up a nylock if I took out the press nuts. Very close though......wish there was something else out there to purchase instead of having to design and have made. I think it is not a bad idea to put 2 clamps on each side instead of one - especially if running as a coax.
I’m not sure I understand. Do you mean using a total of 4 pairs of boom clamps to hold each pair of motors? And how would you use them? That would be complete overkill IMHO. I had a near-death experience with the first coax build I did where the consensus was that one of my pairs of motors slipped on the boom, and caused an uncontrolled yaw. So the second pass I used aluminum boom clamps and had no such incidents. But those U7 motors are really powerful, and I wonder about the “weak link in the chain” phenomenon. I’d be concerned about the CF booms and the center plates. I wonder if you might be better off with aluminum booms, or thicker CF booms, or square booms, as well as a somewhat more solid center hub system. After all, you’ll have horsepower to spare with those motors.
Michael, With the taper of the motors, providing clearance, I think that moving away from the SHCS and just using a regular hex head M3 or M4 bolt and nyloc nut would work well, just come at the bolt from the side with an open ended spanner on the nut and bolt after removing the press nuts. then youn don't need the access from the top of the nut to get an allen key in. Cheers Chris
I recall Casey at QC telling me that he'd laid a CF boom between two Pelican cases and then stood on the center of boom and it held his weight....not sure what that is, but, guessing, 110 - 120 lbs. If that's correct, then the motor could generate upwards of 800 lbs of thrust. Then as you say, the lump moves down the snake, and you start worrying about the amount of torque that the hub plates and boom clamps can withstand. Andy.
@Steve: I was thinking about using 2 clamps on each end of the motor mount instead of one. Essentially just putting them side by side. My thought was that in the off chance that one slipped the other could certainly hold in place. Since there is twice the amount of motor torque on a coax set up I was simply trying to prevent a pair of motors from ever slipping. The metal clamps seem really strong and far less likely to slip - I can not really slide one or twist one at all - even when the bolts are loose. This was just an idea to help prevent an unexpected slip or twist of a pair of motors...probably overkill but the weight penalty for a couple extra clamps seemed like a good trade off. And, since right now each motor uses 2 clamps (in a flat octo), so by doubling them up (side by side) for a coax there really is no extra weight compared to a flat octo anyway. No evidence that this is necessary - and would need to have them custom made anyway - but the U7s are really big with a lot of thrust. @Chris: Good point. I bet that would work.
The Famoushobby ones are 58 mm from the inner edges of the press nut diagonally they are 63mm from the center of the holes diagonally. I think they will work because the U7's are approx 53 mm at the bottoms of the bell then flare out so I think they will work just barley. I have a picture for comparison. Below is a roll of tape that just happens to be a hair over 60mm so this is what it will look like.
I think if you use metal clamps on the booms and a set on the hub plate you shouldn't have any slippage at all. With the plastic clamps yes they will most likely slip I could twist the plastic clamps arm force. When trying it with the metal ones they wouldn't budge. I think if the torsion force is that great I think the boom would shear first.
I have received the MK Double Quadro XL power board, and it's a beast! Here are some photos. A couple thoughts... I'm wondering if there might be some wisdom in desoldering the main LiPo pads and running them separately to the two "Quadro" boards independently. I suppose if there were two Flight Control boards, too, then maybe we'd actually have some redundancy (assuming the copter could fly on 4 motors...which is definitely possible in an X8 config). The pads have four small solder dots on one side, but not on the other. I wonder what the purpose of the dots is? I can't wait to get started putting this together. Bummer I forgot to order the bullet connectors for the pigtails. Sigh. :/
HI Steve, Running a power lead to each ring individually is not recommended. The four dots are just some pre-tinning that is done during the assembly. Greetings, Adam
My plan is to directly solder two 12AWG leads to the end of the main LiPo wires and make an integral splitter. I always run dual main flight batteries, and I plan to run them on outriggers (see the beginning of this thread) so I believe eliminating one potential point of failure (the EC5 connectors on the splitter I use now) is A Good Thing. Assuming my soldering skills are OK, that is. And should I elect to run a single battery, I can just leave one end of the splitter empty (maybe I'll make a null plug to keep around just for that reason).
HI Steve, We did something similar, however ours was more of a graft. A second set of wires grafted into the existing main power lead into the board. Our heavies are all running 2x lipos (4S/6S), the more capacity, the better. Greetings, Adam
Interesting. I need a little more length, so I'm going to split 'em at the end like a regular parallel splitter.