My new MK heavy lift copter project

HI Todd

I read that your copter is 12.5 pounds. My copter is 14.5 pounds with my big QP batteries. I think your payload should be close to mine but it depends on which red accessories you are going to use and your lens choice. For example I just use the Scarlet brain, a SSD card with the SSD module and a prime lens. I power the camera up with a lipo that already is powering my stabilization to help save weight. This gives me a payload of 10.5 pounds. Your Movi should be close to my weight as I use one BL motor for each axis. If you plan on using red volt batteries and the remote side module or a zoom lens it will be heavier. I can tell you that with a flying weight of 23.75 pounds using 15 inch props my throttle at hover was around 70%. With the larger 16 inch props and a flying weight of 24.5 pounds it knocked it down to 60%. Had I kept the 23.75 pounds it probably would have been around 57-58%. I haven't even had a chance to try the Tiger props which I believe the 5.4 pitch will help even more over the 5.0 pitch.

I also think that the U5's are right on the border line of what they can effectively handle weight wise because when I added just 2.5 pounds for a total weight of 27 pounds my throttle at hover shut up to 70% even with the larger props 16X5 props.

What I would do if I was you I would try to keep your Red accessories light as possible and once you are fully assembled weigh the copter. Then convert the pounds to grams and divide by 8. That's how much trust you will need to maintain hover. See where that number falls on the chart with your motor-prop combination. If you need more than 1400-1500 grams of thrust per motor its probably too much for the U5's. Tiger doesn't give data on 17 props probably because they found them to not be any more efficient than 16's.

 

I got my new 16X5.4 tiger props mounted and ready to test with the 10 pound load. It will be interesting to see the differences between hover throttle. Testing later this morning weather permitting.

 

I was able to do a flight test with the 16X5.4 props. Comparing them to the Xoar 16X5 props at the same 10 pound payload in very similar temps proved hardly any difference. The Xoar 16X5 props needed me 62.2% hover throttle. I averaged 100 data points of throttle with AH off to come to this number. With the Tiger 16X5.4 props I had a 61.7% hover throttle. Flight time is about identical at 18 minutes at total flight weight of 25 pounds. The only difference between tests is that is way rather windy today with the Tiger props, I would say a good 10-12 mph wind with 20 mph gusts verus absolutely no wind with the xoar props. This might have an effect on these numbers and I will retest when its calm.

Current numbers are about the same where I averaged 65 amps with the Xoar props and 62 amps with the Tiger props. Max amps were 83 with the Xoar props and 85 with the Tiger props.

Next up are tests with the red camera.

 

I'm using 6S 10,000 mah Quadropower batteries. I'm landing with 21.6 volts / 3.6 per cell.

 

Here ya go.

 

I made a couple changes to my setup. I shortened the booms 1 1/8" inches so that I can fit the copter with my props and gimbal in my trunk all in one piece. Doing this I was a little concerned that the shorter distance between props would be an issue for flyability. I then borrowed (stole) Steve Maller's idea about the 2 battery tray's and put the batteries out on booms 3 and 7. I just did a test flight without a gimbal like you see below and man what a difference in stability. The lower center of gravity of the batteries really helps stabilize the copter much better especially with these big heavy batteries. If I carried the copter from vertically you could really feel like it wanted to flip over. I had heavier winds today and normally the copter can be a little tippy but this was a major improvement with a huge exclamation point! I try moving the GPS above the Flight control board so that the flight control board isn't completely open and exposed.



Next up I"m going to remove the Ipower 5108 motors with belt drive and try bigger Tiger GR85 brushless motors on my tilt and pan.

 

HI Andy

I shamelessly copied/Stole what Steve did for his X8. I took a regular set of boom clamps that have the press nut top part on it and then drilled holes through my plates. I measured everything up so that the thin carbon fiber strip plates with the press nuts are exactly center on the plate. I use metal clamps on everything now (except landing gear) so this was no exception so I used metal clamps instead of plastic ones. So after I drilled and mounted all the hardware I took a small carbon fiber tube and slipped it through the clamps. I double checked to make sure everything was squared and centered. I then hot glued not only the top of the plate like you see below, but also the one side of the clamp that bolts closed to the plate. I did this to make it easy to take the battery plate on and off the tube easily. I found it very awkward trying to fuss and install all the hardware on the ground without the hot glue holding the parts in place. So now not only is the center of gravity better but now the batteries don't move around from side to side they are solid tight because I have two straps on them (one on each side) instead of one strap right in the middle. Even though the velcro on the bottom helps, the 2 straps for each battery really help hold it in place better.

BTW: I am a firm believer that the GPS and Compass need to be higher than any wiring and part of the interference many experience is because the lipo cables are as high or even higher than the compass. That's why Holger is about to start selling external compass sensors and mounts. Steve's been running his setup with the GPS right on top now and he's not experiencing any issues.

 

Since I have lots of room in the center hub now I removed the GPS assembly from boom 1 and moved it above the FCB just like Mikrokopter comes with stock. I also installed my new Power board with the cooling fins in between the board for just a little extra protection during the hot summer. First thing I did was recalibrate the compass. I then flew the copter with a 10 pound plate for simulated load and the flying in PH was a little wobbly compared to previous flights. As it turned out I had a lot of GPS interference errors. So it appears Andy is right and the GPS is too close to my lipo wires.

 

HI Andy

It might be the motor wires but never the less its not going to work so its going back to its normal spot. Yes I spray painted one set of landing gear last year when I was experimenting with using it as a tail right behind boom 5. Now I"m just using it as a landing leg.