How Loud Are Drones? How to make Drone Quieter? (2021)

How Loud Are Drones

How Loud Are Drones? Continue reading the guide below for more information.

You might be thinking about buying a drone but are concerned that its noise will make your neighbors unhappy.

The sound produced by most hobby drones is 80dB, which is similar to a loud vacuum cleaner. A small hobby drone’s sound is louder than a vacuum cleaner and can travel further and without walls.

How Loud Are Drones?

How Loud Are Drones (1)

Drones can be very loud in terms of their noise volume. There is also a correlation between the distance a drone is flown from the observer and the drone’s perceived volume. We need to know how loud a drone can be heard. This unit of volume is called the decibel.

A decibel refers to the intensity of sand. It is also abbreviated as dB. Because sand is very sensitive, the dB scale can be quite large. Normal hearing people can hear everything, from the slightest touch to the skin to the roaring of an airplane’s engine. Logarithmic scales are used to measure decibels. It increases by 10 points for every unit of increase.

Here is a table with different dB levels to help you understand the decibel levels relative to everyday sounds.

Decibel levels

0 dB, which is the softest sand that the human ear can hear, is almost inaudible. This is similar to a leaf falling onto the ground. Your hearing will be damaged if you are exposed to sand above 140 dB. Long-term exposure to loud noises of 85 dB or more can also cause damage to your hearing.

dB level everyday example drones at this dB level
10 normal breathing
20 watch ticking
30 whispering nearby
40 quiet library
50 refrigerator working
60 quiet traffic noise
70 Washing machine working DJI platinum, DJI spark
80 morning alarm clock Phantom 4 pro, Mavic air, DJI Mavic pro
90 subway train
100 Machinery/pneumatic drill
110+ car horn/jet engine from about 100 m

As you can see, noises can quickly reach dangerous levels. Your hearing will be protected if you reduce the time spent listening to loud noises. The drones can be heard at levels between 70 and 80 decibels. This noise level is close to 85 dB, which can cause ear damage. Drones are designed to fly far from you, so it is unlikely that you will be exposed to loud drones for long periods.

Read also: How To Stop Drones From Flying Over Your House?

Why Drones Are So Loud?

Although the motors make a lot of noise, the propellers are the primary reason they are so loud. The drone’s propellers are what create the high-pitched noise you hear. Drones cause this annoyingly high pitch noise. There are three main reasons.

The shape of your blade.

Noise is also influenced by the turbulence a propeller’s blade or propeller creates. The more aerodynamic a propeller’s blades are, the less noise they will make. DJI spent a lot of time redesigning its propellers to create “low-noise propellers.”

Pitch of the blade.

A blade’s pitch is another reason it may make more noise. Pitch refers to the angle at which the blade cuts through the air. This creates lift. You can increase lift by increasing the pitch. However, more drag will cause more noise.

The blade’s diameter or surface area.

This determines the surface area of the blade. The propeller with a smaller surface area will require the blades to spin faster to produce more lift. This creates more sound. The sound it makes is closely related to the speed at which the blade turns. The frequency of a blade turning is directly related to the pitch.

To create the same lift, if there is a lot of blade surface, it doesn’t have to turn fast. Because the blade rotates slower, it makes less noise. Helicopters make a low, thud sound instead of making a high-pitched noise.

What can I do to make my drone quieter?

What can I do to make my drone quieter

Drones can be kept in the air, so there is no way to stop them from creating noise and displace air. We are talking about excess energy required to move air and create thrust. The volume of a drone can only be reduced in two ways:

Absorb the sound generated: There are several products that claim to reduce drone noise while hovering. This method balances air displacement and absorbs the sound waves produced by propellers whipping through the air. Many drones do not use this approach, so third-party accessories are required to absorb the sound.

Changing propeller shape and morphology: Because the propellers or motors generate the most noise, many manufacturers can modify the propellers’ surface textures and shape to reduce noise. Although there are mixed reviews about this method, it is quite affordable to buy stealth propellers.

These are two ways to reduce drone noise.

Increase the number of rotors

Each rotor must displace less air to keep the drone in the air, so each motor must work slightly less. NASA’s 2015 prototype drone was designed to eliminate drone noises during flight.

NASA’s drone had eight motors, which means each motor could work at slightly different speeds per minute. This results in smaller harmonics being generated than if there were only four propellers and reduced the frequency spectrum.

Frequency spectrum spreading is a technique that allows for the precise control of many propellers by an electronic control unit. It was almost impossible to hear the drone at 30 m when it was being flown.

This drone is perfect for parcel delivery.

Bigger slower propeller

It comes down to the fact that larger propellers can move more air than smaller propellers. Each motor does not have to produce the same amount of thrust. People have found that a larger propeller reduces the noise frequency, which is also less irritating.

Aftermarket propellers can be purchased for almost any drone. This can affect the noise level. The thrust factor for creating vertical lift will be increased by increasing the propeller diameter.

Reduced RPM propellers will cause more stress on the motors, leading to increased demands on the internal components. This means that you always get a return on your investment when you change the propellers.

Sand down the surface

You will often find logos or other information embedded into a commercially available drone.

You can remove any molding marks from a drone by simply using 800 or 600 sandpaper. Then, gently rub the surface to correct the shape.

The propeller’s plastic is usually a reinforced nylon composite. It is difficult to damage. You don’t have to sand down propellers or risk your drone being thrown off balance. Instead, you can rub each propeller the same amount of times. You can also rub each propeller for the same time.

Buy low noise propellers.

There are many aftermarket low-noise propellers. You can find low noise quick-release propellers at any retailer, such as Amazon. There are a few ways they can work.

  • They reduce the number of revolutions per minute.
  • Stealth propellers have a smooth surface.

Stealth propellers can reduce noise levels by around 3.5 dB and increase revolutions per hour by approximately 20%. Super-efficient, smooth blades can also have the side effect of allowing for longer flight times and up to 14% more hovering.

This approach has the advantage that you don’t need to adjust your drone settings to achieve optimal performance. You don’t need to make any setting adjustments. You need to take the old propellers off and replace them with the new stealth propellers. The DJI Mavic Air will adjust everything. You could adjust the gain to get better performance if there was a software upgrade.

Propeller shrouds

You can also buy what is called a shroud. Dotterel, a company that makes noise-reducing and safety shrouds for drone propellers, has created one. They dampen the sound of the drone’s air interacting with its body, arms, and other parts.

The safety shroud absorbs noise from the ground and then reflects it up. Because it is made from acoustic materials, certain frequencies are absorbed into the shroud’s core.

Conclusion

You now have a better understanding of the effects of drone noise and how to reduce it. We hope you found this article helpful. Please share it with others who may need it. We appreciate you taking the time to visit Staaker.com. We are grateful for your support.

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