No idea. All I know is that I seem to have plenty of horsepower to spare. I’ll see if that’s still the case with a 5D Mark III. I think it will be. My next step is to implement the 3rd axis for “follow me” mode (like MōVI’s “majestic” mode). That’ll also be a direct drive, but a larger motor (the 8017).
Finally had a free afternoon to get ‘er back in the air. I have been meaning to get my rubber wheels back on the landing gear, but ever since I got the landing gear extensions from Famous Hobby, I haven’t been able to figure out how to use the wheels. Today I finally figured that out. And I had some really wonderful flights. I even took the big step of flying over the beach, and a little over the water. The copter is handling very well, and while I’m not pushing it that hard, I am seeing so really remarkable stuff. For one, in ambient temperature of 55°F and winds of 10-15mph (with lots of weird turbulence from the cliffs) the copter felt quite controllable. Even PH managed to hold its own against the wind, although it wasn’t super happy. But I would say it was usable. I have to recalibrate my compass and update to MK 2.0.3 firmware, and I think it’ll be better. But the truly amazing thing is that at a AUW of about 19 lbs, look at the BL temps. And this isn’t bad reporting...they felt cool to the touch when I landed. Amazing. Still not sure of flight times, but this flight was 11 minutes, and I landed with no battery warnings and good voltage levels. Just didn’t want to push it, and the wind was whipping pretty good. MK Version: FC HW:2.5 SW:2.02a + NC HW:2.0 SW:2.02a Flight date: 2/4/2014 4:53:36 PMFlight time: 4:53:36 PM - 5:04:40 PM (664 secs, 00:11:04)Batt. time : 660 secs, 00:11:00Elevation(GPS) : 0 15.81 38.255 m (min/avg/max)Altitude(Barom.): -5.25 13.86 36.8 mVertical speed : -2.24 -0.01 3.79 m/sMax speed : 38.6 km/hMax target dist.: 5.6 mSats : 12 13 15Voltage : min. 0, max. 24.8 VCurrent : 0.5 50 85.9 AWattage : 0 1164 1855.44 WCapacity: 9240 mAhMotor1: 0.0 6.5 11.3 A Temp: 11 13 18 °CMotor2: 0.0 6.7 12.3 A Temp: 12 13 17 °CMotor3: 0.0 4.6 9.5 A Temp: 11 11 14 °CMotor4: 0.0 6.6 10.3 A Temp: 12 15 18 °CMotor5: 0.1 6.0 10.2 A Temp: 10 12 16 °CMotor6: 0.0 5.4 10.3 A Temp: 10 15 18 °CMotor7: 0.0 4.0 9.4 A Temp: 11 14 17 °CMotor8: 0.0 8.2 12.9 A Temp: 11 15 18 °CMagnet Field: 104 110 119 % (ok)Magnet Inclination: 51 61 73 degNo errors found
I think they’re 20mm, but 25 would be better. It depends on the width of your wheel hubs. I should have slightly longer ones, and shorter screws. Such is life at the intersection of Rube Goldberg and McGyver.
Just joining this thread thanks... steve. I was advised to upgrade to the double xl but nobody said it won't fit my copter. I just wanted to upgrade to a 6S system with new motors, I wasn't planning on moving batteries around. Does this thread mean I can't mount it under my traditional battery plate? I haven't gotten that far in my rebuild and I'm suddenly nervous.
There are a lot of different options for mounting everything. While you could just get longer spacers, I’ll caution you that 6S batteries weigh a lot more than 4S batteries of the same capacity. As such, you would want to consider whether the added stress they could cause on the various components could cause a disaster in the air should things get a little loose. If you’re running dual batteries (as most of us are), putting both on the same tray should involve some careful analysis. Bottom line: welcome to the frontier. It can get a little weird out here.
Update 11 Feb 2014: I got the 3rd axis Alexmos add-on, and have started the integration process, but now I’m re-thinking my timetable. The reason for that is the teeny tiny power wires (22AWG?) for the 3rd axis expansion board, contrasted to the humongous 8017 motor I have in the yaw cage. Looking at that thing makes me think I’m going to smoke that little board the first time I try and do something ambitious with the gimbal. I also noticed that the spec for the 2-axis board says it’s only capable of 3S or 4S operation, even though I’ve had good results with a 5S LiPo. Makes me think I’m already living on the edge, so to speak. Consequently, I think I’m going to shelve the 3rd axis project until the new 32-bit 6S Alexmos boards are shipping. There are 6S boards now, but it looks like there’s a much better version on the way with more CPU and better integration. Viacopter.eu is accepting preorders for them, and says they’re expected in March. So, back to the airframe. I got the 500mm booms to give me a little more separation, and the weather looks like it’s clearing a bit.
Steve: What's the power requirement for the motor? Remember you only energize three, maybe four, coils on the motor at any one time. The specifications say that the DC resistance for the motor is 18.8 ohms, so, if you're powering it using a 3S LiPo, say, then it's going to draw 0.67 Amps.....not that much for those wires. Obviously that current might increase some, but that's just an "order of magnitude" calculation. Did it fit that hub plate without modification or was it designed for it? (Just wondering if there's any such thing as motor mounting standards....) Andy.
The gimbal is of my own making, starting with a Freefly 2-axis, then augmented using parts sourced from BrushlessGimbals.com and Famous Hobby. The controller I’ve been using is the Basecam/SimpleBGC from Viacopter. That’s where I got the 3rd axis controller, too.
Thanks for doing the math for me, Andy. You know me well. The pan axis cage is available in two flavors from Famous Hobby...one for the 5208-size motors, and the one that I got for the 8017.
Steve if you where to do it all over again , would you go the same route? Do you use any viberation dampners?
To be honest, part of what I was trying to do is learn as I went, and I certainly did that. So would I go the same route? Of course not, because I know more now than I did. But for somebody wanting to get the best performance out of their system, it’s a good thing to go slowly, ask a lot of questions (of yourself and others!), and did I mention go slowly? [edit] I guess to directly answer your question, yes, I am quite happy with where things are. But newer and better (or at least newer) hardware and software is appearing constantly, so that’s a factor, too. And I’ve learned in this field that just when your thoughts sound like “oh, I’m just going to take a quick test flight...it won’t be dark that soon”, it’s time to pack it in and wait until the morning.
My dirty little secret (well, one of the many): http://www.ohmslawcalculator.com/ohms_law_calculator.php Let me know if those motor wires get too hot... Andy.
The refreshing thing about working with a gimbal and power limits is that when wires file for a divorce from their solder pads, things don’t fall out of the sky...they just sort of go limp.
Built a new balancing rig for my gimbals. This one will support a few more KGs than my previous one (made of PVC). BOM: about $35 Edit: I had the gimbal constructed incorrectly in this photo...see this post for the correct configuration.
Steve wouldn't you want to do the balance from the center of the pan motor, assuming that it is centered on the copter when attached?