Unlocking the dynamics of flight requires a keen understanding of #aerodynamics, especially when it comes to designing #helicopters ... Do you know how do engineers visualize airflow dynamics while a helicopter is in flight❓The answer, could be found in this rare video, where a Chinook is used as a tracer dispersant system, while a chase aircraft records images of the flow field. Edit (this could also be a blade icing test) Here are some of the most used in-flight aerodynamic #flow #visualization 👀✈️ techniques: 1️⃣ Flow Tracers: they are usually small, lightweight tracers that are attached to the helicopter's surface or release them into the airflow. These tracers, often in the form of smoke or dye, provide a visual indication of airflow patterns around the rotor blades, fuselage, and tail. By observing the movement of these tracers in real-time, you can gain valuable insights into airflow behavior during actual flight conditions. 2️⃣ Onboard Cameras 🎥: Miniature cameras mounted on the helicopter's exterior, in a chase aircraft, or inside the cockpit capture high-resolution footage of airflow interactions. These cameras offer a unique perspective, allowing engineers to analyze airflow phenomena such as vortex shedding, boundary layer separation, and wake turbulence. The recorded footage provides data for refining aerodynamic designs and optimizing helicopter performance. 3️⃣ Surface Pressure Sensors: Sensitive pressure sensors placed strategically across the helicopter's surface measure variations in air pressure caused by airflow. By mapping pressure distributions in real-time, you can identify areas of high and low pressure, indicating regions of favorable lift or increased drag. This data helps refine aerodynamic dataset and improve overall flight efficiency. 4️⃣ Microphone Arrays 🎤: microphone arrays installed around the helicopter can detect changes in airflow acoustics, such as blade-vortex interactions and turbulent noise. By analyzing these acoustic signatures, you can gain insights into rotor performance and aerodynamic efficiency. This information can guide the optimization of rotor blade designs to minimize noise and enhance performance. 5️⃣ Computational Fluid Dynamics (CFD) Modeling : While not conducted in real-time during flight, CFD #simulations play a crucial role in understanding and predicting aerodynamic behavior. By inputting flight parameters into sophisticated computer models, you can simulate airflow around the helicopter and analyze performance metrics such as lift, drag, and stability. These simulations complement in-flight observations, providing a comprehensive understanding of aerodynamic phenomena. #AvGeek #HelicopterDesign #Aerodynamics #Engineering #Innovation #FlightVisualization"
Ken McGinnis
6mo
Look like a ice test.
Rodney, in this case I think we’re looking at an icing test underway - now if rotor aerodynamics is complex, then, when icing on the blades is involved, a whole lot of additional physics comes into play!
Mario Asselin
6mo
I believe they are doing in-flight icing. https://nara.getarchive.net/media/right-side-silhouette-of-a-ch-47-chinook-helicopter-equipped-with-a-helicopter-17a610
Wayne Devereux
6mo
This is the Army's HISS. It is decades old, doesn't simulate all icing conditions (specifically not the new SLD ice) and the aging platform is difficult to maintain. But it is the only airborne icing tanker operating for USA Gov't. Several years ago I studied HISS, and other older and small commercial designs, for NASA GRC while researching a newer airborne icing tanker architectures and various platforms for SLD icing tests. We settled on using the venerable S-3B Viking operated by NASA GRC (donated after U.S. Navy sundown). Our studies were limited to modeling and simulation, but the S-3B platform was perfect and our system architecture would have truely modernized airborne icing qualifications. Unforetunately, NASA was comparing SLD icing simulation methods, and the relatively inexpensive airborne tanker concept lost out to building a new multimillion dollar vertical icing research tunnel at Glenn. I'm not sure if it ever got built. But had our design been approved, you'd have been seeing a Viking up there instead of the Chinook.
The video likely depicts an In-Flight Icing (IFC) test evaluating the effectiveness of an anti-icing lubricant on rotorcraft. While CFD tools are crucial for simulating icing scenarios, they currently lack the capability to generate high-fidelity ice shape data required for accurate analysis and improvement of icing mitigation systems. Therefore, experimental testing remains indispensable for enhancing these tools and ensuring their reliability in real-world scenarios. (P.S. FAA Title 14, Code of Federal Regulations Part 25 [Airworthiness Standards: Transport Category Aircraft] Appendix C for aircraft and Part 29 for rotorcraft are used as icing standards for manufacturers.)
Sihong Yan
6mo
This is not flow visualization. What the Chinook carries is known as Helicopter Icing Spraying System (HISS). https://gallery.vtol.org/image/GY8J0
Will Gibbons
6mo
Good for icing too
Jacques Gatard
6mo
You can also do 3D PIV (particle image velocimetry) measurements within a wind tunnel. This was already done at the ONERA F1 low speed wind tunnel in the early 2000s... By synchronizing the laser flashes with the rotor angular position, we have accumulated thousands of high-precision 3D velocity vectors in the wake of the rotor, thus creating a huge database used as a calibration basis by complex 3D nonstationary CFD Codes. Those measurements have been done at different rotor settings, including some that would never have been possible in real flight :). The results have been published in: A. Le Pape, Gatard J, Monnier JC. Experimental investigations of rotor-fuselage aerodynamic interactions using a helicopter powered model. Palaiseau: ONERA; 2005. Report No: ONERA-TP04176. Arnaud Le Pape, Blanche Demaret, Pierre Spiegel, Marie - José Martinez
EI OAD Airbus Icing Network at Airbus
6moAre you sure that it is not a blade icing test!