Very true. These motors are monsters for sure. I really don't have time to be the tests mule to sort the problems out especially when I'm planning on running the Scarlet soon. It would be nice if there was a motor that was just a tad larger than the U5's but I think I need to go back to the U5's and try them with 550 booms and 16 inch tiger props. I think it will be good enough to get by.
I seen this before and recalibrating the ACC and or compass resolved the issue. The motors might be putting out excessive magnetic fields that are throwing off the electronics as well.
Oh yes I did that today and took my time making sure everything was perfect. All motors are aligned properly and I ran each motor individually before I flew and after. They sound fine and everything is lined up. I use metal clamps on the hub and on the motor so that the motor angle won't change.
Some sort of friction make sense for explaining the issue...especially if you sanded the hole just enough to spin free when perfectly centered. Maybe you could get a drill bit that was a little bigger than the hole and give yourself some extra room. Here is what I am having made up for U7s - the photo is the 3D printed one next to the mounts I got yesterday (same as yours). Notice the larger center hole and slightly longer distance between the frame clamp holes so there is room for the center shaft and to get clear access to the bolts. This is the non-press not version to be opposite of the press nut version in a coax set up. Popping out a press nut leaves you with a 4.4mm hole for a 3mm bolt. A washer or bushing of some type might have worked too, but since I am having them cut from a sheet of carbon why not make them fit perfect...I also widened the arcs on the side so the 53mm bottom of the U7 did not hang over the edges at all. Hope you get it sorted out today. Did you post it somewhere for Holger to comment on as well - he could certainly address any issues with the brushless.
Here's the GPX file from the longest run I did yesterday. I won't be doing any testing any time soon as its snowing and going to be very cold all week.
Hey Dave, it looks like you’re using metallic hex screws to secure the power distribution board. I am using nylon screws because I’m concerned about conductivity. Is that unnecessary? It certainly looks like there’s no circuit traces that run through those areas, but call me superstitious...
I didn't want to trust it with nylon bolts (even though I'm using nylon standoffs- LOL). I don't think thats a problem because it runs great with the U5's and there's no components close enough to the head of the bolt.
I think I’m going to stick with the nylon parts. The PDB isn’t really a stressed component, and the BL pigtails serve to anchor the board pretty firmly in place.
Michael I compared the CS motor plates that I got from Quadrocopter that I use for the U5's and they are very similar to the plates for the U7's in that the center hole is very close to the size of the motors shaft. It's a tight fit but they work perfect. I"m using lots of 222 on the threads of the bolts and I can't see how the motor can be moving around the plate. Obviously it can't hurt to drill out the center hole a little bit just to see. I did post this on the MK site and emailed Holger as well.
It looks like Holger agrees with me. http://forum.mikrokopter.de/topic-post503106.html#post503106 Maybe some bad vibrations that disturbe the Gyro-Signals on the FC?Or the wrong vibration dampers under the FC? Either too weak or too stiff.
Dave out of interest is your fc mounted on Vibration dampeners? i cant see it in your photo? http://www.quadrocopter.com/Vibration-Dampeners-M3x15_p_135.html
Yes I'm using the rubber standoff's as well as plastic stand off's on top of them just like in Andy's video.
I talked to Quadrocopter today and they believe the U7's need to be timed differently. They also believe that the active breaking needs to be turned off and that the U7's need a 17" prop. That would be fine for a co-ax but not for a flat 8 so I'm sticking the U5's back in.
I was planning on giving some U7s a try by this weekend...I'll definitely take a closer look into things before I put anything up in the air. Was planning a coax, but maybe I'll try a flat until we know more about how well it works with the new MK. I could also see if they perform any differently on a different FC and with a different motor mount (assuming I get the new ones cut by the weekend).