Quiet Props: Comparing the Obeka low -noise props to the original DJI props for the Mavic Pro

Don’t have time to read the details and theories? Here are the quick links to what you want to know:
Tools used
Data
Drone Flight Theory
Video
Results

I’m a private pilot and have been building and flying model aircraft (sUAS) for decades.
I haven’t seen any reviews on DJI Mavic Pro quiet props that I really liked.  So when I was presented with the opportunity to test Obeka’s quiet prop for the Mavic Pro, I was very excited to do it.

For this evaluation I did visual inspection, weight, RPM/Power, and sound level, all of which allowed me to make what I feel are accurate conclusions.

  • I tried to make the tests as fair and accurate as possible.
  • I mounted my sound meter to a tripod so it would be at the same spot and angle for each flight.
  • I created autonomous flight paths so I could fly the same position flight path and speed for each flight.

Tools I used

Test Data

  • Prop Weight
    • Stock: 34 gm average per prop. Total 29.35 gm
    • Obeka: 52gm average per prop. Total 26.09 gms
  • Average Hover Decibel
  • Average Hover RPM
    • Stock: 570
    • Obeka: 440.
  • Average Hover Power as per DJI Go4. Visible in “Sport Mode”.
    • Stock: 25.5%
    • Obeka: 23.5%
  • Balance was as good as the balance of the stock Mavic props which are very close.

Drone Flight Theory:

The flight controller on these drones varies the RPM by what you are telling the drone to do. When in hover the controller spins the motors at whatever rpms it takes to keep the drone at a steady altitude and position. Something every full-sized aircraft pilot knows that most DJI drone pilots may not is that the air-conditions affect the performance of your wing/prop. Flying in Cheyenne Wy at 6000 feet above sea level the air is generally much thinner than here in Mount Dora Fl at sea level. So, the Mavic’s controller will have to spin the props faster to hover in Cheyenne than it will in Mount Dora. Spinning the props faster generally means more noise and shorter flight times.

More than altitude affects the density of the air. Weather plays a big part of it. Air Pressure, Air temperature, and even humidity. When the temperature goes up the air density drops. Flying airplanes in North Las Vegas there where days the air at the 2600ft elevation had a density altitude of nearly 6000 feet.

video

 

My Conclusions:

The Obeka props have an obvious shape difference and in spite of their less weight they are bigger and have more surface area. A prop is basically a wing. Generally a wing with more surface area creates more lift but at often at the penalty of more drag which would mean that the motor may have to work harder to spin it at speed.

The increased lift causing the rotors to spin at a lower RPM creates less noise but also a lower pitch noise so it doesn’t sound as much like a bunch of angry bees.

Lower RPM to spin the lighter more efficient props should slightly increase flight times.

Prop RPM, Flight Performance, flight time/battery life are effected by wind as well as the ever changing air conditions. When you fly your drone in the cool morning air, the motors will not have to work as hard to generate the lift needed—as compared to flying in the hot afternoon air, which means your props will make more noise in the afternoon, and your batteries are not likely to last as long.

Used to make video:

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