Quiet Drones 2026

13:30 Community Impact, Engagement, and Perception 2

13:30 20 mins	Potential of ornithopters for quiet drones Michael Paul Jenkins Abstract: This paper considers the potential of an ornithopter drone as an inherently quieter solution than rotorcraft for purposes such as delivery, monitoring, inspection and filming. It is well known that aerodynamically generated sound increases very rapidly with speed of a blade through the air. The wings of an ornithopter are also its means of propulsion, and in cruise the velocity of the wings through the air is comparable to the velocity of the aircraft itself, so their velocity is approaching the minimum possible. Thus there is the potential for much quieter operation with the low speed wings of ornithopters compared with the high speed blades of rotorcraft. In many cases, what is required is a drone that can both cruise to its delivery or monitoring site, and then hover there. It is pointed out that an ornithopter can be realised that can both cruise and hover and make a smooth and continuous transition between these two flight modes. Such a design is also capable of vertical take-off and landing. A further feature is that the design does not have to use flexible or membrane wings, allowing a durable and fatigue resistant design. Patent applied for.
13:50 20 mins	Building public trust towards drone identification system Ittiporn Chaisit Abstract: Drones or UAVs are becoming more widely used in emergency response, infrastructure inspection, logistics, and the creative industries. However, public acceptance of drones remains uneven, particularly when individuals unexpectedly encounter drones flying nearby. While many people express curiosity, others report discomfort or negative reactions due to concerns about for example privacy, safety, and potential misuse. Meanwhile, public support is generally higher for drones used for societal benefits such as search-and-rescue, medical delivery, and firefighting rather than for leisure or commercial activities. This sentiment difference highlights a need for mechanisms that can foster transparency, accountability, and trust in drone operations. One proposed solution is a drone identification system that enables the public to access key information about nearby drones in real time. Such a system could help address uncertainty by allowing individuals to identify who is operating the drone and for what purpose. However, limited research has investigated how the public perceives this kind of system, what information they expect to access, and whether such transparency tools could meaningfully enhance trust and acceptance. This study explores public perceptions, expectations, and concerns related to a drone identification system through a qualitative focus group methodology. A series of workshop-style sessions were conducted with members of the public, incorporating role-play scenarios that simulate realistic encounters with drones operated by different stakeholders (e.g., hobbyists, commercial operators, emergency services, and government agencies). Participants interacted with draft concepts of a potential identification interface and discussed the types of information they would want to access, how they would interpret it, and how it might influence their trust in the drone and its operator. Preliminary findings suggest that transparency about operator identity and purpose plays a critical role in shaping acceptance, especially in urban and residential environments. Participants emphasised the importance of easily accessible, non-technical information and expressed support for systems that clearly distinguish responsible, authorised operations from potentially unsafe or intrusive activities. This research contributes to emerging discussions on public-centred approaches to drone regulation and demonstrates how identification technologies may be designed to enhance societal trust as drone operations become more prevalent in everyday life.
14:10 20 mins	Psychoacoustic evaluation of propeller designs for a quadcopter drone Renatto M. Yupa-Villanueva, Roberto Merino-Martinez Abstract: Noise emissions pose an important obstacle to the societal acceptance of unmanned aerial vehicles. In particular, for the typical multicopter configuration, the noise emitted by the propellers and their interactions with each other and the airframe, generate the distinctive drone buzzing sound signature. Hence, considerable research has been devoted to studying propeller noise at low Reynolds numbers to inform the design of low-noise drones. Nevertheless, the current state of the art faces two important limitations. (1) Most literature focuses on the study and/or design of individual, isolated propellers, but typically neglects the installation effects of these propellers within a drone airframe. (2) The acoustic evaluation is normally performed with conventional sound metrics, such as the equivalent A-weighted sound pressure level, which fail to capture human hearing aspects, such as tonality or amplitude modulations, which are crucial when analyzing drone noise. To address this gap, acoustic measurements were conducted in the anechoic chamber of the Faculty of Applied Sciences at Delft University of Technology using a commercial DJI Mavic 3 Enterprise quadcopter during hovering. Two experimental configurations were considered: one with the drone equipped with four standard off-the-shelf propellers and another with four low-noise propellers. Both propeller designs feature the same diameter. Measurements were obtained using a phased microphone array and a sound level meter. To perform the psychoacoustic comparison between both configurations, the recorded signals are analyzed using sound quality metrics, including loudness, sharpness, tonality, roughness, and fluctuation strength, computed with the open-access Sound Quality Analysis Toolbox (SQAT). The end goal of this study is to attribute potential differences in sound quality metrics to differences in propeller geometry to promote perception-influenced design practices.
14:30 20 mins	Links Between Engine Design Parameters and Noise Perception: First Results from an Interactive App David Straub, Rahman Al Mahmudur, Carla Bubeck, Clémence Dubois, Susanne Bartels, Stephen Schade Abstract: We developed a mobile app enabling the psychoacoustic analysis of noise from new generations of aircraft. The method aims to identify links between engine design parameters and the perception of their noise. On the engineering side, the noise emissions of distributed electrified propulsion systems depend on the design, configuration, number and position of several individual propulsors. Thus, acoustic effects such as interference, modulation and shadowing might significantly impact on noise characteristics. On the listener’s side, the specifics of the human auditory system introduce more complexities to the perception of this noise. As a result, reactions of acceptance or annoyance to a sound are not only associated to mere physical metrics (such as maximum sound pressure level) but also to psychoacoustic metrics (such as fluctuation strength and sharpness). Previous work outlined the development of a mobile app that allows a large and diverse number of people to, firstly, set the engine parameters; secondly, listen to the corresponding auralised sound; and thirdly, rate it using a standardised questionnaire. Here, we present preliminary results from workshops in an educational context: quantitative ratings of different configurations, validity and usability metrics, and qualitative participant feedback.
14:50 20 mins	Wildlife responses to drone noise: an integrated approach for single- and dual-drone flights Saadia Afridi Abstract: Drones are increasingly being deployed to study wildlife; however, growing evidence indicates that drone noise and presence can alter animal behavior and confound ecological data. Few studies have quantified how acoustic exposure affects the observed behavioral responses of wildlife. Here, we present a field-based protocol that integrates in-situ real-time acoustic monitoring with standardized behavioral scoring to identify species-specific disturbance thresholds in African megafauna. In Ol Pejeta Conservancy, Kenya, we monitored how ﬂight altitude, singular or dual drone ﬂights, and ﬂight path affected plains zebras (Equus quagga) and reticulated giraffes (Giraﬀa reticulata). We conducted single and dual drone ﬂights at 75 m to 20 m altitude with two DJI quadcopter drones (Mavic 3Pro and 3T). A linear microphone array at ground level recorded drone noise, and observers used a detailed ethogram to log vigilance and escape behaviors. Drone noise declined predictably with increasing ﬂight altitude, while dual-drone operations introduced a disproportionate increase in acoustic exposure. This increase was non-linear and reﬂected overlapping rotor harmonics and prolonged exposure rather than a simple doubling of noise. Bootstrapping of behavioral scores showed a robust directional effect, with dual-drone ﬂights producing mean disturbance responses approximately 3 points higher than single-drone ﬂights (95% bootstrap CI: 2–4). Behavioral responses differed between species. Zebras showed consistent, qualitatively dose-dependent increase in vigilance and displacement behaviors below approximately 50 m, particularly during dual-drone operations and in mixed-species herds. Giraffes primarily exhibited prolonged head-up vigilance without ﬂeeing. These findings provide preliminary, context-specific disturbance indicators for the species and open savannah habitat studied and show how coupling real-time acoustic measurements with behavioral observations enables a more mechanistic interpretation of drone disturbance than behavioral data alone. This approach moves beyond simple altitude-based assumptions and supports the evaluation of emerging operational configurations, such as multi-drone ﬂights.

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