New Tiger 4120 Heavy lifter motor testing results

I have been researching motors to use on my copters for a while now. I think I have every spec of every heavily lift motor on the market. I think I looked at every motor from a thrust and efficiency standpoint about 5 times each. What it comes down to is that I have not been pleased with either of my copters ability to carrying my 11 pound payload that consists of my red scarlet with brushless motor gimbal. This coming week I am upgrading the gimbal I fly with the red and that will make things heavier so I really needed to address the motors. With my flat 8 Tiger U5 motor, Tiger 16 inch props combo I was hovering around 62-65 percent depending upon air conditions, more on the 65% range in the current summer air. The 2nd copter with KDE 4014 motors and Tiger 18" inch props X8 combo hovers between 63-66% depending upon air.

Issues that I had to consider.
The MK BL electronics is rated at 40 amps max, probably even a little under that so many of the higher power motors such as U7, newer KDE motors were not even a consideration with the amount of current they draw. Even the U7 420 KV motors were probably borderline of being much.

Why I can't run KDE motors
I would have been willing to install the KDE 4014’s and convert to a more efficient flat 8 along with 16 inch props but it appears that that combo would actually hover higher than what I’m seeing now. It appears that the KDE motors really need the KDE ESC’s to be efficient and if you use other electronics the efficiency goes down significantly. Here’s how I am assessing my information.

My X8 KDE 4014-18 inch prop motor configuration hovered at 64-65% throttle at a flying weight of 26-26.5 pounds. According to the KDE motor specs this combo puts out 2520 grams of thrust at the exact throttle it requires for me to hover. If I remove 15-20% that’s required for the X8 configuration I should “technically” need about 2016-2142 grams of thrust to hover my 26 pound flat 8 copter with everything else being the same but that would not be enough motor, not even close.

KDE does have a 5215 out now that would provide enough lift with 2055 grams of thrust but it draws up to 38 amps of current which is a little too close for the MK electronics safety margin.

So based on what I measured with my 2 different copters that both use the same electronics, same flying weight, same everything else I’m estimating that I need about 460 grams of thrust to make up for the inefficiency of using the KDE motors through the MK electronics. That’s about a 23% loss in efficiency. So it appears to me based on the information and conclusions I came up with that to use KDE motors with the MK electronics requires a significantly larger, heavier motor that consumes more a lot more current thats not compatible with even MK's biggest power boards. It’s pretty hard to make up 466 grams of thrust in a similar size motor package.

Other considered options
Switch to DJI or use the absusive I2C converter with KDE motors and KDE ESC's. In my opinion the I2C converter is not efficient from the feedback I have seen and it has known yaw issues. DJI is another option but I think that option has been pretty well documented.

Tiger 4120 motors.
Tigers 4120 KV motor puts out about 1570 grams of thrust at 50 percent throttle which is about exactly where I need to be considering the actual data I am seeing with the U5 motors. So with "many" back and forth discussions with Michael McVay (thanks again Michael) I have decided to try the tiger 4120 400 kv motors. After seeing the specs for the 4120 400 kv motors I tried to research user experiences and feedback. Guess what? I couldn't find anything. Not even one user that used them. Based on my current Tiger results and assuming that the data matches up I thought they would be a perfect fit. I decided to convert my X8 back to a flat 8 and have 2 flat 8 combos.
Here's some of the negatives I do not like about these motors.
#1. They are heavier than what I am used to running at about 260 grams each. My new flat 8 weights 1.5 pounds more than my U5 flat 8 that is an exact duplicate besides the motor difference.
#2. The bearings are not as smooth as the KDE motors or the Tiger U5 motors.
#3. It uses a goofy bolt pattern that wont bolt up any of the known motor plates out there. I had to modifiy a set of the aliexpress plates I used on my X8 to make them work. About 5 hours of work.
#4. They use the poor C clip design
#5 The bearings do not have as long as a running life as the newer motors, they recommend changing them out around 60 flight hours.

With that said let me get to the nuts and bolts (the results).
These motors perform exactly as expected and I believe I have a winner here.

Settings
I left all adjustments exactly the same, motor timing is carried over at 24 degrees. Nothing has changed.

5D payload testing
Even thought this combination is about 1.5 pounds heavier now, the copter just climbs effortless, and with AH off and the stick at center it just climbs. The hover throttle is around 42% and draws about 58 amps of current. Giving it full throttle it just rockets to the moon and drew 157 amps of power. So its hovering about 38% of its total power so tons of headroom.
Flight time - 18 minutes 7 seconds with 12% reserve left. This is about a 1.5 to 2 minutes less flight time than I was seeing with the U5 flat 8 copter ( but again I am 1.5 pounds heavier now) the weight to power to efficiency trade off is probably not quite enough to make this the right choice for this combination although its certainly close. For the 5D I still prefer the U5 combo for better flying time.

Red Scarlet - Brushless motor gimbal testing
I switched gimbals and tested the heavier setup. It was like night and day difference with the U5 flat and KDE 4014 X8 combo. The power for hover is exactly where it needs to be. I am hovering around 52% pulling about 77-78 amps. After observing it for a few minutes at hover I started moving around and doing hard yaw's and it was perfect, no motor restarts or errors. I then lowered the copter to about 15 feet off the ground and gunned it. The throttle response was tremendous and went up to 207 amps. One motor went as high as 33 amps, and the rest stayed in the high twenties which is better than I could have hoped for. So the copter hovering at 78 amps is about 38% of the maximum current its drawing which is exactly what I hoped for.
Flight time - 13 minutes 30 seconds leaving 10% reserve. I probably would have gotten about 14 minutes plus had I not done the full throttle test. On average I was seeing about 15-16 minutes flight time with the U5 copter. So I have lost about a minute or slightly more of flight time but again keep in mind these new motors add about 1.5 pounds to the copter. Motor temperatures are very good. In humid 80% weather the motors were barely warm where the U5's would be hot to the touch. The trade off for more power and head room significantly outweigh the slightly less flight time.

Conclusions
I have a really good motor to fly my red Scarlet combo. I have a lot of head room, and the copter isn't working hard at all to maintain hover or even going forward at a pretty fast pace if needed. I will use the Tiger 4120 flat 8 copter with red payloads and the U5 flat 8 copter for 5D payloads. I just wish the KDE motors worked as efficiently with the MK electronics like the Tiger motors do. I prefer the quality of the KDE motors but I just can't enough power.

Here's the GPX summary of both flights, I can't attach the GPX files because they are over 2meg in size. But I have them for anyone that wants to look.

Flight date: 8/17/2014 12:29:34 PM
Flight time: 12:29:34 PM.0 - 12:43:10 PM.8 (816 secs, 00:13:36)
Batt. time : 810 secs, 00:13:30

Start Lat./Lon. : 40.397073 / -80.0789573
Elevation(GPS) : 0.096 10.08 77.516 m (min/avg/max)
Altitude(Barom.): 2.25 13 81.4 m
Vertical speed : -3.68 -0.01 13.33 m/s
Max speed : 17.4 km/h
Max target dist.: 29.9 m
Max distance/LOS: 99.4 m / 99.9 m

Sats : 10 11 12

Voltage : min. 21.1, max. 24.2 V
Current : 0.5 80 207.5 A
Wattage : 11 1796 4399 W
Capacity: 18003 mAh

Motor1: 0.0 9.5 25.0 A Temp: 34 37 43 °C
Motor2: 0.0 10.4 29.0 A Temp: 31 39 46 °C
Motor3: 0.0 8.5 24.0 A Temp: 32 37 43 °C
Motor4: 0.0 11.7 30.0 A Temp: 34 41 44 °C
Motor5: 0.0 9.8 23.0 A Temp: 35 39 44 °C
Motor6: 0.0 10.0 24.0 A Temp: 35 43 46 °C
Motor7: 0.0 6.7 19.1 A Temp: 39 41 45 °C
Motor8: 0.0 11.4 33.0 A Temp: 32 40 47 °C

Magnet Field: 100 103 107 % (ok)
Magnet Inclination: 64 68 79 deg

Errors / warnings:
FC-Flag "LowBat" (5) occured 496 times!


Flight date: 8/17/2014 12:06:46 PM
Flight time: 12:06:46 PM.2 - 12:24:58 PM.8 (1092 secs, 00:18:12)
Batt. time : 1087 secs, 00:18:07

Start Lat./Lon. : 40.397099 / -80.0790122
Elevation(GPS) : 0.001 12.89 26.711 m (min/avg/max)
Altitude(Barom.): 0.8 15.34 29.05 m
Vertical speed : -1.59 -0.03 3.77 m/s
Max speed : 17.2 km/h
Max target dist.: 24.5 m
Max distance/LOS: 207.6 m / 208.9 m

Sats : 11 11 12

Voltage : min. 21.3, max. 24.2 V
Current : 0.5 58 69.3 A
Wattage : 11 1325 1663.2 W
Capacity: 17711 mAh

Motor1: 0.0 6.7 9.5 A Temp: 30 33 38 °C
Motor2: 0.0 7.8 12.2 A Temp: 28 35 41 °C
Motor3: 0.0 6.1 8.4 A Temp: 30 34 39 °C
Motor4: 0.0 8.7 12.3 A Temp: 32 36 40 °C
Motor5: 0.0 6.9 8.9 A Temp: 33 37 42 °C
Motor6: 0.0 7.4 11.1 A Temp: 32 38 42 °C
Motor7: 0.0 4.3 6.9 A Temp: 36 38 43 °C
Motor8: 0.0 8.5 14.5 A Temp: 30 36 42 °C

Magnet Field: 102 103 106 % (ok)
Magnet Inclination: 63 68 79 deg

Errors / warnings:
FC-Flag "LowBat" (5) occured 458 times!

 

Thanks Michael. To be honest I have no idea. It would be a nice upgrade if its available. As far as the motors go with motor tests on the bench and with the observations of the sound from the flights and the observations of the frame there appears to be no vibration and everything is smooth as before.

 

Steve there's no doubt that if you want to get the best results from the KDE motors you have to run their speed controllers. It's like trying to pick up performance by putting a big camshaft in an engine without upgrading the heads or exhaust (or tuneup). You bring up an interesting observation about the differences in motors. Pole count could definitely be a contributing factor. I saw the video demonstration that they did on the bench compared to the Tiger U7 motor. Response was absolutely like night and day.