Ever notice that buzz in the sky?
That’s a drone, a device we’re seeing more and more, making a noise we’re hearing more and more.
So, what’s up with the sound drones make and how can we make it less of a bother?
We’re going to check out what makes drones sound the way they do and how new tech could help quiet them down.
If you’ve ever asked yourself “What’s that buzz? while a drone is flying overhead, this is a question that many of us are now asking.
Let’s dive in to understand why drones make noise, how it affects us, ways to reduce it, and what we might expect in the future.
What Sound Do Drones Make?
The sound of a drone can vary based on its model and the distance from which you’re hearing it.
Drones produce a high-pitched buzzing or humming noise, akin to a swarm of bees or a distant lawnmower. This is the sound of the propellers spinning at high speed to generate lift. Drones can produce noise levels between 70 to 80 decibels, which is comparable to a vacuum cleaner or a busy road.
Some models, like the Mavic Mini 2, are quieter, producing around 64 decibels of noise. However, the perceived loudness can decrease as the drone moves farther away or higher in altitude.
How a drone is being used can also affect its sound.
For instance, quadcopters, are usually quieter than others since they use less power to stay up.
The main noise from drones happens when their propellers spin, usually between 100 to 300 times per second for small drones.
Other sounds might come from the motors and vibrations in the drone’s body.
Remember, the sound can change depending on the drone’s design and use.
how loud is the sound of a drone?
When you hear a drone, it can be as loud as a vacuum cleaner, usually around 70 to 80 decibels.
The loudness of the drone can change though, based on things like
- How big it is
- How many motors it has
- How big the propellers are
- How fast they spin
- Where it’s being flown
| Device | Average Noise Level (decibels) |
|---|---|
| Drone | 70 to 80 |
| Vacuum cleaner | 75 to 85 |
| Television | Around 70 |
| Refrigerator | 30 to 50 |
| Quiet Air conditioner | Under 40 to 60 |
| Washing machine | 40 to 80 |
Smaller drones, like the ones some people have at home, are usually quieter than big ones used in industry. An interesting thing about drone noise is that it’s high-pitched, which can make it more annoying than other sounds that are just as loud. As a drone gets higher up or farther away, it does get quieter.
| Drone Model | Decibel Level (dB) |
|---|---|
| Mavic Mini 2 | 64 |
| Mavic Platinum | 70 |
| Spark | 74 |
| Mavic Air | 76 |
| Phantom 4 Pro 2.0 | 76.5 |
| Mavic Pro | 79 |
| Phantom 4 Pro | 81 |
Some drone makers, like DJI with their Mavic Mini 2, have worked to make drones that are quieter, with noise levels as low as 64 decibels.
So, drones can be pretty loud, usually around 70 to 80 decibels, but how loud one is can depend on a lot of different things, including the kind of drone and where it’s being flown.
What factors affect the noise level of a drone?
In this section, we’ll unravel the key factors that contribute to the noise made by drones, from their propellers and motors to their flight configurations and operating conditions.
Understanding these elements can provide insights into why drones sound the way they do and how their noise can potentially be reduced.
Propellers
The noise a drone makes is influenced a lot by its propellers. Propellers come in different sizes, shapes, and materials, all of which can affect the noise level. Small propellers have to spin faster, which makes more noise. Bigger propellers can spin slower, which is quieter. The way a propeller is shaped and how many blades it has can also change the noise it makes.
Electric Motors
Another big part of a drone’s noise is its electric motors. Some drones have brushless motors, which are usually quieter and more efficient than brushed motors. How the motor is put into the drone and whether it’s enclosed or not can also affect the noise it makes.
Flight Controller Setup
The settings of the flight controller, like the motor speed and how the propellers are angled, can also influence the noise level of a drone. Changing these settings could help make the drone quieter.
Frame
The frame of the drone, or its body, can play a part in the noise it makes. Vibrations from the motors and propellers can go through the frame and add to the noise. If the frame is well-designed, it can help keep these vibrations and the noise down.
Operating Environment
Where and how a drone is being flown can also change its noise level. If a drone is high up or far away, it’ll be quieter.
So, a drone’s noise level can be affected by its propellers, motors, flight controller setup, frame, and where it’s being flown. By thinking about these things, it’s possible to design and set up a drone to make less noise.
How To Reduce The Noise From Drones
In this section, we’ll delve into various methods that can help reduce the noise produced by drones.
These include adjusting drone components, changing flight settings, and considering the operating environment.
Do’s
- Use larger propellers, as they need to spin slower and produce less noise
- Consider using propellers made from materials or designs that reduce noise
- Use brushless motors, which are generally quieter and more efficient than brushed motors
- Adjust flight controller’s settings to optimize noise reduction
- Design or choose a drone with a well-structured frame that can minimize vibration
- Fly your drone at higher altitudes and further distances to reduce perceived noise
Dont’s
- Don’t use small propellers, they need to spin faster and produce more noise
- Avoid using standard propellers without any noise reduction features
- Avoid using brushed motors, they are less efficient and can be louder
- Don’t leave your flight controller’s settings on default if noise is a concern
- Avoid drones with flimsy frames that allow vibration to increase noise
- Don’t fly your drone at low altitudes near listeners if noise is a concern
Implementing these changes can make a significant difference in the noise generated by your drone, leading to a more pleasant drone-flying experience for everyone involved.
how noise-cancelling propellers Drone work
Noise-cancelling propellers are a fascinating aspect of drone technology designed to reduce the buzzing sound typically associated with these devices.
They function through various strategies, including biomimicry, structural modifications, and even active noise cancellation.
Let’s explore each of these in detail.
Biomimetic Propellers
Biomimetic propellers take inspiration from nature, specifically the silent flight of owls. By integrating leading-edge serrations into the propeller design, like those seen on owl feathers, these propellers suppress noise and increase thrust. An example of this is the sawtooth propeller, which can reduce noise by up to 4.73 dB.
Toroidal Propellers
Another innovative design is the toroidal propeller, which features a closed-form, twisted-doughnut shape. This shape minimizes the air vortices (whirling air currents) created at the tips of the blades and strengthens the propeller’s overall stiffness. As a result, the high-pitched noise associated with drones is reduced without sacrificing thrust.
Blade Twist
Adjusting the blade twist angle, or the angle at which the propeller blades cut through the air, can also reduce drone noise. Through computer simulations and experimental measurements, researchers have found that twisted propellers can significantly decrease noise by suppressing the vortices at the trailing edge of the propellers.
Active Noise Cancellation (ANC)
Active Noise Cancellation (ANC) is a technological solution for reducing drone noise. It works by analyzing the noise waveform produced by the drone’s propellers, creating a similar but opposite wave function, and using this as an “anti-noise” signal. When combined, the original noise and the “anti-noise” cancel each other out, effectively reducing the perceived noise.
Serrated Gurney Flaps
Serrated Gurney flaps are a recent innovation that merges two noise-reduction strategies. The Gurney flap is a trailing-edge structure on an airfoil, and serration is a low-noise design technique. This combined structure increases propeller lift per unit rotation speed and decreases propeller rotation speed, which in turn minimizes noise.
These techniques, either used individually or in combination, can significantly reduce the noise made by drone propellers. However, their effectiveness can vary depending on factors like the drone’s design, size, and operating conditions.
Drone Sound Changes with Distance and Altitude
The sound of a drone changes with both distance and altitude due to how sound travels in the air. When a drone moves further away from you, horizontally (side to side) or vertically (up and down), the noise it makes seems to decrease.
This change happens because sound travels through air, and as the drone moves away, the sound has to travel a longer distance, becoming less strong by the time it reaches your ears.
This is due to a concept in acoustics, where drones are considered “point sources” of sound. For such sources, the noise level drops by about 6 decibels every time the distance from the source is doubled.
To give you a practical example, a study at Cranfield Airport in the UK discovered that the peak noise levels from various unmanned aerial vehicles (UAVs), or drones, flying at heights of 100 feet and more, fell within 50 to 60 decibels.
This is comparable to the noise levels you would hear in a busy office or a restaurant.
So, whether the drone moves higher into the sky or farther away across a field, the noise it generates becomes quieter to a listener. This also means that if you’re flying a drone in a wide-open park, it would sound quieter than if you were flying it in your backyard.
So, remember, if you want your drone to be less noisy, try to fly it at a higher altitude or further away.
Are there any regulations around drone noise?
Drone noise is a topic of increasing concern as drone usage continues to rise worldwide. Governments and aviation safety organizations are working to regulate and control the noise levels produced by drones.
Here’s a look at how drone noise is regulated:
European Union (EU)
In the European Union, the European Union Aviation Safety Agency (EASA) has established guidelines for measuring the noise level of drones. These guidelines aim to help drone manufacturers and governmental bodies ensure that drones do not create too much noise that could disturb people or wildlife.
The guidelines apply to drones that are used in what are called ‘specific’ category operations.
These operations include a range of activities such as package deliveries, powerline inspections, bird control, mapping services, aerial surveillance, and roof inspections.
However, it’s important to note that these guidelines are voluntary, meaning they aren’t enforceable rules that drone manufacturers must follow for their drones to be certified.
Brazil
In Brazil, the National Civil Aviation Agency (ANAC) has plans to discuss noise requirements for drones in the years 2023-2024.
While exact plans haven’t been released yet, the initiative shows a growing interest in managing and regulating drone noise levels.
United States
The United States is also making strides in addressing drone noise.
The Federal Aviation Administration (FAA) is investing resources to better understand the acoustics of emerging technology aircraft, including drones.
They’re developing what are called ‘Rules of Particular Applicability’ (RPA) as a temporary solution for noise certification for new aircraft designs, including drones.
In summary, while specific regulations can vary from country to country, efforts are being made globally to address and regulate drone noise. As drone technology evolves and becomes more prevalent, it is likely that drone noise regulations will continue to be refined and expanded.
Conclusion
In conclusion, drones produce a high-pitched buzzing or humming noise caused by the rapid spinning of their propellers. The sound level can range from 70 to 80 decibels, similar to that of a vacuum cleaner or a busy road.
The noise can vary depending on the drone’s model, size, propeller design, and flight conditions.
While smaller drones tend to be quieter, advancements in technology have allowed some manufacturers to develop quieter models with noise levels as low as 64 decibels.
Various factors contribute to the noise level of a drone, including the propellers, electric motors, flight controller setup, frame design, and operating environment.
By considering these factors and implementing noise reduction techniques such as using larger propellers, brushless motors, and optimized flight controller settings, the noise produced by drones can be significantly reduced.
Innovative approaches to reducing drone noise include biomimetic propellers inspired by silent flight in owls, toroidal propellers with a twisted-doughnut shape, and blade twist adjustments.
Additionally, active noise cancellation technologies, such as analyzing and countering the noise waveform, as well as using serrated Gurney flaps, have shown promising results in reducing drone noise.
The sound of a drone changes with distance and altitude due to the way sound travels through the air. As a drone moves farther away or higher up, the noise becomes quieter due to the increased distance the sound has to travel.
Regulations regarding drone noise are being developed in various countries, with guidelines and voluntary measures being implemented to ensure drones do not create excessive noise that may disturb people or wildlife.
As drone technology continues to advance and become more prevalent, it is expected that further research and refinement of drone noise reduction techniques and regulations will take place. Ultimately, efforts are being made globally to address and mitigate the noise generated by drones, aiming for a more harmonious integration of these devices into our daily lives.
