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Case Study

High Five for High-G-Turn Riblet & simulation in Air Race

Branche

Air Race

Customer

Diverse

service

Riblet Engineering

Task

Improvement of aerodynamical efficiency by modifications on the aircraft

solution

Riblet engineering, Riblet design and application of Riblets on the wings

benefit

Functionality of Riblets of different production methods; Feedback for production and data retrieval

Projectdetails

It’s thrilling, it’s supercharged and only the best pilots qualify to compete in a sport billed as “the world´s fastest motor sport”. Air sport enthusiasts will not only be familiar with the name of Peter Besenyei, the “Godfather” of motor air sport, but also with audacious men like Hannes Arch (†), Michael Goulian, Matt Hall, Martin Šonka and Vito Wyprächtiger who went down into the annals of history of air racing winning world championship titles and vice world championship titles. And there is one common denominator: They all relied on BST´s know-how on flow optimization and Riblets when putting on a brilliant show in the skies with maneuvers that take your breath away. No doubt, flying the pylons at 50 feet above the ground floor at extreme speeds and performing a few High-G-Turns needs extremely skilled pilots and the will to get the maximum technical performance out of the aircraft. The High-G-Turn is a maneuver that allows the pilot to make a sharper turn than normal while the aircraft will lose a substantial amount of speed. Therefore, the potential risk of a High-G-Turn lays in stalling. Using a High-G Turn too long can cause the aircraft to enter a stall when an aircraft’s angle of attack increases beyond a certain point, at which the lift begins suddenly to decrease. 

Figure 1: What it takes to fly in the Red Bull Air Race

Edge_with_streamlines Kopie

Figure 2: Simulation & Riblets on a racing air craft

In the worst case this can cause a loss of control. However, a High-G-Turn is an eye-catching showpiece in the context of air racing and a true aeronautical masterpiece. In the Red Bull Air Race World Championship an elite group of pilots was engaged in a battle of technology and skill but at the same time those world’s fiercest competitors were committed to the advancement of safe aircraft piloting through refined technology and professionalism. That`s where we at BST came into play. The challenge was set: We had to enhance the aerodynamical efficiency and to increase the stability of the aircraft. 

 

By numerical CFD simulation and Riblet engineering we designed the optimal Riblets for the application on the wings. So various Riblet structures could be tested in advance to select the best to reduce frictional resistance. By applying those micro- and nanostructured surfaces, which are modeled on nature, to flow-relevant parts of the airfoils, a 4% increase in efficiency could be assured and even more important, safety aspects on High-G-Turns were addressed. Riblets ensure safer flight maneuvers as they reduce the risk of stall while performing a High-G-Turn. It´s a well-known physical phenomenon that at high speeds when the angle of attack is too steep, the boundary layer detaches from the airfoil and the flow tears off. The aircraft loses lift and starts to spin. Due to the tailor-made Riblets on the wings the flow continuous for much longer and the separation starts later. Therefore, we calculated the applicable flow dynamics for minimizing the risk of stall and to postpone the separation of the flow by adding Riblets on the wings.

Outcome

We at Bionic surface technologies GmbH enhanced the aerodynamical efficiency to improve the flight safety during High-G-Turns considerably by applying Riblets. As a result, the separation of the flow starts later and the risk to enter stall lowers.  The aerodynamical optimization done by BST gave the pilots not only a technical advantage over the competitors but ensured their safe return to earth from their adventures to the skies.