Drones are becoming part of life for most people, and I cannot stress enough how important they are due to their many applications. Therefore, the noise that emanates from drones can in some situations limit their functionality, making it essential to find ways to minimize it. But, what can you do to make your drone quieter?
To make your drone quieter, try equipping it with noise-reducing propellers. You can also introduce larger, slow-spinning propellers, which will most likely work for most drones. Finally, you could invest in noise-reducing propeller shrouds.
Drones can be annoying with their low but continuous noise. In some cases, a drone can resemble a swarm of bees, with a similar fear-inducing effect. Minimizing the noise may not be a must, but at times, it is necessary, especially when you are trying to record audio. In this article, we explore more about different methods you can try that will make your drone quieter.
Ways to Make Your Drone Quieter
Even relatively small drones weighing about 20kg are usually 40 decibels quieter than sizable civil aircraft. However, the process of making any drone quieter is the same, and the best way to minimize the noise is by dealing with the hardware. Typically, the drone’s noise comes from the parts of the drone, so it makes sense why you should focus on the various parts of the drone.
» MORE: Do Drones Record Sound?
Most times, the propellers contribute to the noise level the most; therefore, your drone will produce little to no noise if you can successfully address the propeller noise. Different people recommend various approaches to noise reduction on the drone. So I will guide you on some of the various simple techniques that have been working for many people.
1. Install Large Slower Propellers on the Drone
If you have been working with small propellers, they typically do not displace as much air with each turn, which indirectly contributes to the production of more noise. Larger propellers are capable of replacing more air when operating, which means they do not need to rotate as fast as the small propellers to maintain the drone in the air. A large propeller will fly through the air a few times per second less than a small one.
At 500 feet above sea level, large propellers are most likely to be silent. However, they may not eliminate the noise altogether, but they will lower the noise frequency to a more manageable level. When a drone’s propellers spin slowly, it produces lower decibels; hence the sound frequency is reduced and also has an easier time moving through the air.
2. Invest in Propellers that Make Less Noise
Since propellers are the leading cause of noise in drones, why not invest in some that have a much lower noise level? There are several different types of low noise propellers on the market. However, the kind you choose should match the drone model.
Low noise propellers work in different ways, all aiming at reducing the noise of the drone in flight. The primary method is by minimizing the number of revolutions per minute. Usually, when a drone propeller rotates faster, it produces the most noise, which is what low noise propellers tend to fix.
One great propeller I work with is the stealth propeller which is best known for its smooth surface. This propeller reduces the noise of the drone to close to 2.5dB. It reduces its revolution per minute by 20% hence the noise reduction. However, this propeller may affect the drone’s overall flight time because of its slow rotations.
You are only taking off the old propeller and fixing on the new one on the brighter side. So, you need not alter the settings of your drone for the drone to perform well.
3. Use Noise Reduction Shrouds
Dotterel, which specializes in drone noise reduction, has been working on noise reduction shrouds, and they work perfectly. The coverings help reduce the noise that comes up when the blades contact parts of the drone, such as the arms and body. Shrouds contain some nanofiber sound dampening materials which absorb noise from the drone. When the nanofiber captures the noise, they direct it upwards, so as not to reach people on the ground.
The proof from these shrouds is that they were able to reduce the drone’s noise by 6 decibels. But now they are capable of reducing it up to 10 decibels. Apart from reducing the noise, they also offer protection to the drone propellers. Shrouds can work well on any drone, but there are different models intended to serve specific types of drone.
4. Adjust the Propeller to Reduce the Noise
The design and shape of your drone will determine how quiet the aircraft can ultimately be. Manufacturers are now incorporating advanced computer software to create more silent acoustic signature propellers to make the drone noise softer. The Northwest UAV already has such a propeller that produces little noise and resembles a bat wing.
Companies usually twist the shape of the propellers, and through this, they manage to get the acoustic signature to drop by maybe 60% or even more. For instance, the DJI Mavic Pro incorporated the “raked wingtip” to reduce drone noise. Currently, different aftermarket companies are examining other ways that will reduce the noise from drones because not every design suits every drone.
5. Use More Motors on the Drone
If your drone wing is large, you can add in more motors. The engines enable the drone to be propelled more efficiently. With several small quiet motors, your drone will produce much less noise than when you fit it with fewer larger motors.
If you fit the drone with small motors, know that their RPM functionality will be different for each. There can be the production of small harmonics at times, unlike when there is only one motor that brings out a single frequency. The electric control unit controls the many propellers that produce the single frequency spectrum.
6. Adjust the Main Rotors to Reduce the Noise
Nowadays, most drones come with a revolutionary blade design which comes in handy in noise reduction. The case is different if you are using old drone designs. Usually, older drone models have electric motors that make the main engines produce a lot of noise.
To fix this, install a motor glider in the drone. Then adjust the drone settings to maybe slow or medium speed, and it will automatically produce less noise when functioning. You can incorporate this method with other ways that help to make the drone quieter so that you may be able to make better videos.
7. Sand Down the Surface of the Propellers
Other people recommend this method to reduce noise from drones, which has been working for many. Usually, drone propellers from a specific manufacturer carry the logo of that manufacturer. To reduce the noise, try to remove the logo and smoothen the surface using sandpaper. The drone will be propelled much more smoothly, producing less noise.
I remember one time I was flying a popular drone which had some raised logo marks on it. The propeller was therefore not smooth and would produce a lot of noise. Usually, the edge needs to be as smooth as possible, and you should not cause any scratches. I tried using sandpaper to make the edge smooth, and it really helped to reduce the noise level quite a bit.
If the shape of the blade is not in a smooth form, it contributes to the noise the propeller creates. But, if the blade is wide, flat, and smooth, it will most likely produce little to no noise. Also, most times, thin blades make more noise when the edge is in motion than thick blades.
Ensure that before flying the drone, you clean up the propellers. Also, ensure that you remove any scratches that it may have after flights. Moreover, it is essential to regularly balance the propellers to reduce the voice and frequency of the noise they produce. If all these efforts do not work well, replace the propeller with a large slow one.
8. Create Your Own Propellers
If all the methods above fail to work, another better option is creating your own propeller that fits your drone. It is not easy to maneuver through this option, especially if you lack the right skills and knowledge of creating a propeller. Also, a DIY propeller is likely not to be as strong as commercial ones, so you need to follow the correct procedure and ensure that you are not making any mistakes.
If you know about manufacturing a propeller, ensure that you match up the frequency of the propeller to reduce the noise significantly. Also, ensure that the propeller matches the size you are about to replace. Here is a video of someone creating a homemade propeller.
Drones help in so many ways in our lives, and they’ll be even better if they can produce less noise. If your drone makes a lot of noise, try incorporating the above methods. But keep in mind that a completely silent drone is probably impossible.
Image Source: Autel Drones