Dynamics of Unmanned Aerial Vehicles

The 'monocopter' is a type of #micro #aerial #vehicle (MAV) largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. Overall, the vehicle weighs 69 grams, achieves a maximum lateral speed of about 2.37 ms−1, an average power draw of 9.78W and a flight time of 16 min with its semi-rigid wing. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. The proposed craft accomplishes a controllable flight in 5 degrees of freedom by using only one thrust unit. It achieves altitude control by regulating the force generated from the thrust unit throughout multiple rotations. Lateral control is achieved by pulsing the thrust unit at specific instances during each cycle of rotation. A closed-loop feedback control is achieved using a motion-captured camera system, where a hybrid Proportional Stabilizer Controller and Proportional-Integral Position Controller are applied. #research #paper: https://lnkd.in/gbtUTExx #authors: Shane Kyi Hla Win, Luke Soe Thura Win, Danial Sufiyan, Shaohui Foong #robotics #engineering #quadcopter #drones #innovation #technology

Frequency Escalation in UAV Systems – Transmissions in the 7.5–12 GHz Band Recent observations indicate a clear upward shift in the radio spectrum used by unmanned aerial systems (UAS). Traditional ranges for command and video links — 300 MHz to 7.2 GHz — are now heavily saturated. Consequently, more UAVs are operating within the 7.5–12 GHz band, entering the centimeter-wave (SHF) domain rarely used by small and medium-class drones. Field reports confirm analog video transmitters above 8 GHz, marking a significant departure from the standard 2.4 GHz and 5.8 GHz bands. Operating higher enables avoidance of interference and greater data throughput, especially for HD and 4K video with minimal latency. This, however, demands high RF precision and antenna stability, as even minor detuning degrades link performance. Frequencies above 7 GHz mean shorter wavelengths, faster attenuation, limited obstacle penetration, and strict line-of-sight requirements. Maintaining stable connections requires high-gain directional antennas, increased transmitter power, or airborne relay UAVs to sustain long-range links despite terrain masking. Operation in the 8–12 GHz range allows wider bandwidth and lower latency but requires advanced RF filtering, thermal stabilization, and high-linearity amplification (LNA/PA). This raises system complexity while reducing detectability. Most current detection and counter-UAS (C-UAS) systems cover up to ~7 GHz. Thus, new UAVs may operate beyond detection. Analog modulation at these frequencies generates non-standard spectral signatures not recognized by common RF classification algorithms. To adapt, infrastructures must expand spectrum monitoring to at least 12 GHz, update RF signature libraries, upgrade analyzer firmware, and test jamming effectiveness in the 8–12 GHz range. The ongoing upward shift in UAV frequencies marks a new phase in unmanned architecture, emphasizing adaptability, dynamic channel allocation, and resilience in contested electromagnetic environments. The spectrum itself has become a battlefield — one where superiority depends on intelligence, agility, and precise spectrum management.

What happens when a stealthy flying wing meets tight stability margins, and flight controls built on #imperfect #models⁉️ By the mid-1990s, unmanned aircraft were already well understood from a flight mechanics standpoint, with programs such as the D-21 having demonstrated high-altitude unmanned flight decades earlier. What RQ-3 #DarkStar set out to explore was more demanding: the integration of low observability 📡, long endurance, and a high degree of automation within a flying-wing configuration, where stealth, aerodynamic coupling and #limited #control #authority dominate the design space. Technically, DarkStar relied on an unconventional airframe optimized for radar signature reduction, supported by fully automatic flight from takeoff to landing, satellite command and control data links, and sensor integration under severe size and weight constraints. These choices pushed the vehicle into take off regime where aerodynamic #model #fidelity and #robust #control law design were not just important, but mission-critical. The loss of the prototype in April 1996 exposed the consequences of getting that balance wrong. Shortly after rotation, the aircraft pitched up aggressively, entered a stall, and crashed, not due to structural or propulsion failure, but because the flight control laws, modified shortly before flight, were insufficiently robust to modeling errors in the low-speed, high-angle-of-attack regime of a flying wing, leading to an unstable airframe–control interaction. Although later redesigns improved stability, the program was cancelled in 1999 as costs rose, performance fell short, and alternative platforms such as Global Hawk demonstrated greater robustness and operational margin. DarkStar’s lasting value lies in its technical lessons: controllability and model accuracy are as decisive as stealth, with early failures often shaping the control and verification philosophies of aeronautical programs. #avgeek #control #modelbaseddesign

We are excited to share our latest work on downwash modeling for drones, published in IEEE Robotics and Automation Letters! PDF: https://lnkd.in/dd8TEYkH Video: https://lnkd.in/dydmArdf We present a computationally efficient model for estimating the far-field airflow caused by quadrotors in hover and slow flight. This is important as drones are becoming integral to applications from agriculture to public safety, and understanding the aerodynamic disturbances is critical. We show that the combined airflow from quadrotor propellers can be well approximated as a turbulent jet beyond 2.5 drone diameters below the vehicle. Our model relies on classical turbulent jet theory, which removes the need for expensive CFD simulations. We also demonstrate the model's effectiveness in multi-agent scenarios, reducing altitude deviations by 4x when compensating for the downwash of another drone when passing below. Curious? Check out the paper! Reference: "Robotics meets Fluid Dynamics: A Characterization of the Induced Airflow around a Quadrotor" IEEE Robotics and Automation Letters, 2025 PDF: https://lnkd.in/dd8TEYkH Video: https://lnkd.in/dydmArdf Kudos to Leonard Bauersfeld, Koen Muller, Dominic Ziegler, Filippo Coletti! University of Zurich, UZH Innovation Hub, UZH Department of Informatics, European Research Council (ERC), AUTOASSESS, Switzerland Innovation Park Zurich

Happy to share a new Vertical Flight Society JAHS article, developed in collaboration with Dr. James Baeder and PhD canidate Paulo Arias, on the flight dynamics and control of a transitioning quadrotor biplane tailsitter. Results investigate the bare-airframe dynamics, as well as closed-loop, minimum-time transition strategies for both climbing and "flat" transitions. Article can be found at: https://lnkd.in/eTX6DsvM Alfred Gessow Rotorcraft Center University of Maryland University of Maryland - A. James Clark School of Engineering University of Maryland Department of Aerospace Engineering University of Maryland Research #rotorcraft

🌆✈️ Proud to share our latest publication—a joint effort between the research groups of Dr. Ryan Paul and Dr. Kursat Kara at the School of Mechanical and Aerospace Engineering, Oklahoma State University: 📘 "Urban Wind Field Effects on the Flight Dynamics of Fixed-Wing Drones" By Zack Krawczyk, Rohit K. S. S. Vuppala, Ryan Paul, and Kursat Kara As drones begin operating in complex urban environments, the unpredictable nature of urban turbulence—especially near tall structures—poses serious challenges to stability and safety. 🔍 What's new in this work? We integrated: - High-fidelity urban wind fields from Large Eddy Simulations (LES) - With real-time flight dynamics models and Ardupilot-based control laws - Supported by a compact vortex lattice aerodynamic solver for arbitrary fixed-wing configurations 💡 Key Insight: High g-loads on the drone align with sudden spatial changes in Turbulent Kinetic Energy (TKE), revealing how even brief gusts can endanger low-altitude urban flight. 🎯 This research lays the groundwork for safer #AdvancedAirMobility (#AAM) systems, enabling risk-aware design and operation of delivery drones and similar vehicles in cities. 📄 Read the paper: https://lnkd.in/gVZEPg8R 📌 This work was partially supported by the National Science Foundation (NSF) under Grant No. 1925147. #AAM #AdvancedAirMobility #UrbanAirMobility #FlightSafety #Drone #LES #CFD #Turbulence #FlightDynamics OSU MAE OSU CEAT Oklahoma State University