New Platinum Props Tested

[sar104]

Higher pitch = More load on the motor = motor heat,up to the point of failure,if it's too much! You can easily see the diffrence in pitch, in the video.

Are you suggesting that increasing the pitch increases the power dissipated by the motor without increasing its thrust?

 

[ykwarks]

flew around as i normally due and came back in sports mode full forward all the way from 2miles away, my motors were just slightly warm. it’s 90+ degrees here, but not much wind the mavic has to resist to. stock configuration. will try testing again on a windy day.

 

[Ron_Dog]

Are you suggesting that increasing the pitch increases the power dissipated by the motor without increasing its thrust?

NO! Increasing the pitch,only increases the power if the motor is able to stand the high current draw at full throttle. Increasing the pitch,at a lower RPM ( or motor KV) will get better flight time. Look at the KV of the motors on bigger drones. They amost all run a 900KV motor or less,with big 12-14 inch props. I think DJI's "tweak" to the esc's was to try and reduce the rpm's of the motors? Time will tell? I fly my MP hard (at full throttle 95% of the time it's in the air),and with the stock props the motors come down "warm" at best.

 

[sar104]

NO! Increasing the pitch,only increases the power if the motor is able to stand the high current draw at full throttle. Increasing the pitch,at a lower RPM ( or motor KV) will get better flight time. Look at the KV of the motors on bigger drones. They amost all run a 900KV motor or less,with big 12-14 inch props. I think DJI's "tweak" to the esc's was to try and reduce the rpm's of the motors? Time will tell? I fly my MP hard (at full throttle 95% of the time it's in the air),and with the stock props the motors come down "warm" at best.

OK - so your point is that the higher pitch props generate more thrust per RPM (as expected), but that therefore at any given RPM the motor is working harder. In a simple hover that's fine, since that is roughly a constant total thrust (equal to the weight of the aircraft) situation, but if the RPM limit is not reduced, then at max RPM the motor is generating more thrust with the new props, working at higher power, and therefore will get hotter. That seems reasonable.

The DAT files include ESC temperature and motor current draw, so it should be simple to check if that is happening. I've ordered some of the new props so I'll run some tests.

 

[kona]

How did DJI ever come up with the bizarre conversion from 1 db to 60% savings?

1% is not equal to 60%. At least not in the reality I live in.

 

[lolo780]

OK - so your point is that the higher pitch props generate more thrust per RPM (as expected), but that therefore at any given RPM the motor is working harder. In a simple hover that's fine, since that is roughly a constant total thrust (equal to the weight of the aircraft) situation, but if the RPM limit is not reduced, then at max RPM the motor is generating more thrust with the new props, working at higher power, and therefore will get hotter. That seems reasonable.

The DAT files include ESC temperature and motor current draw, so it should be simple to check if that is happening. I've ordered some of the new props so I'll run some tests.

What firmware are you on? With .900 I don't see any esc temp data.

 

[lolo780]

Do u mind sharing some pics when u do this of how u do it?
In my head i imagine the mavic would fly more efficiently forward with the motors tilted a little forward as it would be more aerodynamic

I meant 20 deg aircraft pitch, but I do tilt the motors to help forward flight by shimming between the aluminum motor base and the plastic arm.

 

[sar104]

What firmware are you on? With .900 I don't see any esc temp data.

It's been there as far back as I've looked. Are you looking at the aircraft DAT files?

 

[sar104]

How did DJI ever come up with the bizarre conversion from 1 db to 60% savings?

1% is not equal to 60%. At least not in the reality I live in.

DJI is claiming a 4 dB reduction. In acoustic power space, dB is given by 10log₁₀(P/Pᵣ), so a 4 dB reduction is equal to a power ratio of 2.5 - i.e. P = 0.4Pᵣ which is a 60% reduction.

 

[lolo780]

It's been there as far back as I've looked. Are you looking at the aircraft DAT files?

DAT files. Under -- ESC -- there's no data.

 

[sar104]

DAT files. Under -- ESC -- there's no data.

I have no idea what you are looking at.



And for a listing of all the fields that are decoded: Mavic Pro .csv Column Descriptions

 

[cderoche]

It looks like I burned out 1 of my Esc's. My last flight was fine, which was stock configuration. Today I try to fly and I get "1No.ESC Error" and aircraft cannot take off due to the error. The new props definitely put more load on the motors. Perhaps I damaged it with a previous flight. I did fly with heavy batteries 2 flights earlier, but last 2 flights were stock and I had no issues. Only today when I attempt to do another flight did I get the error.

Man what a bummer!
Just ordered a big 4000mah LiHV Multistar pack and MaxxUAV battery mod adapter... planned on also adding the new props.... maybe I still can use the new props but with just the stock battery only. I wonder though, even with only stock battery on board, I have my firmware modded for more speed, wonder if that is too much for these props?

 

[victor_lim]

tempted to try, my launch always attract crowd

 

[Pablo]

tempted to try, my launch always attract crowd

My launch always brings all the boys to the yard, and they're like, it's better than yours. **** right it's better than yours.

I can teach you, but I have to charge.

 

[dscline]

If the motors are getting hotter then either they are being cooled less or they are working harder, since heat dissipated in the motor should be a monotonic function of power output.

Not necessarily. In a DC motor, speed is proportional to voltage, and torque is proportional to current (and power is torqueXspeed, or voltsXcurrent). Since the thrust should be the same (takes the same amount of thrust to hover, or fly at X speed), power should be roughly the same. We know the motors are spinning at a lower speed (if nothing else, just by the tone), so if power is the same, applied voltage will be lower, and current higher. It's the higher current that is likely the primary cause of the higher heat. The sine wave ESCs on the platinum probably help this situation. If I had to guess, I'd bet the MPP with the new props runs at lower motor temps than the MP with the new props.

If they are actually working less hard then the heat generated in the motor should also be less, not more.

The props might be more efficient, but putting the motors in a less efficient range.

 

[tracer bullet]

It looks like I burned out 1 of my Esc's.

You had more than one battery installed, right? And so a heavier load than stock?

I am thinking so, and am impressed with that thread, just wanting to be sure the new prop didn't fry the ESC on an otherwise stock Mavic. Because if it did that's kind of a big deal for people swapping props.

I've read all the posts in this thread and may have missed it but didn't see for sure.

 

[Ron_Dog]

OK - so your point is that the higher pitch props generate more thrust per RPM (as expected), but that therefore at any given RPM the motor is working harder. In a simple hover that's fine, since that is roughly a constant total thrust (equal to the weight of the aircraft) situation, but if the RPM limit is not reduced, then at max RPM the motor is generating more thrust with the new props, working at higher power, and therefore will get hotter. That seems reasonable.

The DAT files include ESC temperature and motor current draw, so it should be simple to check if that is happening. I've ordered some of the new props so I'll run some tests.

Yes it should! I will be looking forward to your results! I don't think I'll be selling off my current model any time soon. The claimed 3 minutes of extended flight time,will most likley be more like 90 seconds,in the real world. Their statment is for no wind conditions,and I'm not sure if I've ever got to fly in those conditions? But I'm pretty sure I haven't! I've either been flying into a headwind,or flying with a tailwind 90% of the time. I've never got the promised 27 minutes of flight time from my current MP,so I suspect the new model is "over rated" as well. I might be able to get 23-25 minutes of flight,but that would deplete my Lipo battery below 20%,and that's something I try to avoid,as it is extreemly hard on lipo's to be discharged past 80%,and really shortens the life span of the battery's! I suspect DJI is lowering the RPM of the motor,through the esc's to achieve the same thrust/lift as the original model,but at a reduced rpm,thus keeping the current draw the same,or a little lower. As mentioned in their notes (no wind) makes a big diffrence too,but finding those conditions to fly in, will be very few,and far between. Motor condition will also come into play,as some will have lot's of hours on them,compared to newer one's with less time on them (bearing wear). It will be intresting to say the least!

 

[sar104]

Not necessarily. In a DC motor, speed is proportional to voltage, and torque is proportional to current (and power is torqueXspeed, or voltsXcurrent). Since the thrust should be the same (takes the same amount of thrust to hover, or fly at X speed), power should be roughly the same. We know the motors are spinning at a lower speed (if nothing else, just by the tone), so if power is the same, applied voltage will be lower, and current higher. It's the higher current that is likely the primary cause of the higher heat. The sine wave ESCs on the platinum probably help this situation. If I had to guess, I'd bet the MPP with the new props runs at lower motor temps than the MP with the new props.


The props might be more efficient, but putting the motors in a less efficient range.

Agreed in general, but I thought that motor speed was entirely controlled by pulse-width modulation in these motors, not DC voltage. And motor speed appears to correlate with current, not voltage. Am I missing something?

 

[Ron_Dog]

I have to admit, I've never seen this much excitement over a plastic injected prop! LOL! Simple test,install the props,fly check the motor temp! If the motors are hot,your "over proped",if the motors are normal temp,your ok! Put the graphs,slide rulers,and calculators up and go fly!

 

[Ron_Dog]

Agreed in general, but I thought that motor speed was entirely controlled by pulse-width modulation in these motors, not DC voltage. And motor speed appears to correlate with current, not voltage. Am I missing something?

View attachment 22630

Yes you are! A increase in voltage will result in a increase in motor RPM,at any setting. Ask the racing drone guy's why they run a 4 S lipo as opposed to a 3 S battery! Raising the voltage will increase the RPM of any electric motor. Take a cheap motor (brushed) and use a single C cell battery,then check the RPM! Now add another cell (in series) 2 batterys,and check the RPM again! It will increase in RPM's! Basic electronics. What I would have liked to seen, was a battery with more capacity. PWM does control motor speed (throttle),but a higher voltage will produce a higher speed at any throttle setting.