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Flow Optimization and Riblets in Air Race – A Review

For 4 years, bionic surface technologies (BST) worked with teams in the Red Bull Air Race more than successfully and helped athletes and their machines with aerodynamic and technical expertise to extraordinary successes over several years. In 2022, well-known stars of the aviation motorsports scene will again perform daredevil stunts in the sky – a reason for us to look back and highlight the benefits of flow optimization and shark skin in the aviation motorsports scene. 

Edge_with_riblets Kopie

Worldwide, 2018. In this year, the Red Bull Air Race took place in seven destinations around the globe. In Abu Dhabi (ARE), Cannes (FRA), Budapest (HU), Kazan (RU), Wiener Neustadt (AUS), Indianapolis (USA) and Fort Worth (USA), the best of the best competed in the famous air sports scene and collected points to be able to hold the coveted trophy in their hands as world champions. 
With only a few points between them, three men shared the podium. Third place went to American Michael Goulian, second place to Australian Matt Hall and first place to Martin Šonka from the Czech Republic. As different as these three men are, they share the secret of their success. 

With the engineers from BST to victory

Šonka, as well as Goulian and Hall, relied on the optimization and aerodynamics know-how at BST. While third-placed Goulian relied on winglets designed by BST to secure a lead of more than 30 points over fourth-placed Frenchman Mika Brageot, Matt Hall equipped his plane with BST’s proven Riblet technology (also known as Shark Skin, note). Czech gold winner Šonka, on the other hand, relied not only on riblets and winglets from BST, but on an entire aircraft: an EDGE 540 V3, which was closely analyzed by BST’s experts in the past and modified to achieve a total efficiency increase of 17%. The aerodynamic modifications to the aircraft itself, as well as the precise fitting of Riblets, were thus instrumental in the victory.

Peter Besenyei (HUN) - Action

Aerodynamic optimization without trial & error

Another step into the past is necessary to understand what exactly helped Martin Šonka to win about 3 years ago:

Budapest, 2015. That year, the team of Hungarian pilot and co-founder of the Red Bull Air Race Peter Besenyei approached the Austrian company. Besenyei’s own participation in the brilliant flying spectacle meant that he was naturally highly interested in getting the maximum technical performance out of his aircraft. A seemingly difficult undertaking, because: the engine and propeller had to be the same on every plane, so there was an apparent equality of opportunity. In order to gain an advantage over the competition, the pilots’ technical teams increasingly used winglets and wingtips to reduce the amount of induced drag.
But, what to do, in addition to standardized engines and propellers, wingtips and winglets can no longer contribute to the decisive seconds between victory and defeat? Redesign aerodynamics from the ground up!

Superlative racing machine thanks to flow optimization

So, the team Peter Besenyei and BST started a project that would soon revolutionize the whole Red Bull Air Race scene. Within just 3 months, based on a Zivko EDGE V3, an aircraft was developed that aimed to be the fastest and most efficient racing machine, and soon excelled in practical tests.

At the start of the project, the task was to decide on a flying machine on which the aerodynamic optimizations would be made. The choice was between the existing aircraft, a Corvus Racer 540, and a second model, a Zivko EDGE V3, both were analyzed using flow simulation. It quickly became clear that the Zivko EDGE was the more aerodynamically favorable model.
However, this initial analysis of the flow was not only used to decide, but also to be able to assess the overall aerodynamics of the aircraft, including unobstructed flows. This allowed several aircraft parts to be highlighted in advance that could be aerodynamically optimized.

One area of the aircraft, that was fundamentally changed, was the engine cowling. Several aerodynamically favorable variants were developed for the engine cooling inlets, which could again be tested for their suitability at various operating points. The position and size of these cooling inlets play a decisive role in the overall aerodynamics of the aircraft. With the optimization of BST, it was thus possible to achieve a better streamline shape of the engine cowling.
The area of the wingtips plays a supporting role in the aerodynamics of an aircraft due to the induced air pressure, but is at the same time delicate for the aerodynamics of the overall system. Here, the exact external conditions to which the wingtips are exposed, such as the limited length of the entire wing, had to be considered. For the wingtips, too, different models were designed and tested for their suitability before the best was selected and the flying machine was fitted with it.

 

Like the wingtips, the cockpit of the aircraft was specially optimized for racing conditions. Together with several smaller optimizations, such as the drag shoes, it was thus possible to optimally increase efficiency and speed. By using flow simulation, it was thus possible to achieve an overall increase in efficiency of 13% without any trial and error. Positive side effects were also the reduced fuel consumption and the associated Co2 emissions, but also better handling of the aircraft at higher speeds.

The use of Riblets

It wouldn’t be a product from bionic surface technologies if it didn’t get an exclusive application of the well-known, iridescent foil, which has meanwhile demonstrated its capabilities on large passenger aircrafts, on wind turbines or racing cars.
Before application, the Riblets were also analyzed with the help of a flow simulation. This has the advantage that various Riblet structures could be tested in advance, and the best mixture applied to optimally reduce frictional resistance. By applying these micro- and nanostructured surfaces, which are modeled on nature, to flow-relevant parts of the aircraft, a further 4% increase in efficiency could be assured.
The finished racing machine, which was specially manufactured and covered with Riblets, celebrated its premiere in Budapest on July 4, 2015. On this day, Peter Besenyei from the backfield was able to fly 6th place and thus showed how important and useful the aerodynamic optimization of airplanes is.

Detail

Not just a few podium places, but many

The statistics on the successes of the pilots in connection with the products of BST speak a clear language: the company was an integral part of the Red Bull Air Race since 2015 and consistently supported various international teams with their knowledge around the Shark Skin and the optimal aerodynamics of aircraft.

Since the beginning of the cooperation with Hannes Arch in 2014, not a year went by without at least 2 winners putting their trust in the know-how of BST’s engineers – and this until the last race in 2019.

 

Thus, bionic surface technologies records 51% of all victories with their collaboration and 49% of all podium finishes. In addition, succeeded in 2018 a personal record when all races were won. With its world-renowned Riblets, BST has been responsible for 3 out of 5 world championship titles and 3 vice world championship titles between 2014 and 2019. 

 

1.       Place

2.       Place

3.       Place

Total Races

2014

2

1

0

24

2015

2

0

0

21

2016

4

5

2

24

2017

2

6

6

24

2018

8

5

4

24

2019

2

2

3

12

Total

18

18

15

129

The year 2022 - hope for further successes

Even if a sad anniversary is approaching for the Red Bull Air Race – after all, the last one took place two years ago on September 08, 2019, in Chiba, Japan, before it was abandoned due to “lack of public interest” – there is reason to rejoice: even in 2022, one does not have to do without daredevil and spectacular stunts of well-known greats of aviation motor sports on the sky.
Building on the legacy of the hugely popular Red Bull Air Race, World Championship Air Race hopes to bring back the fastest, three-dimensional motorsport on the planet but create a challenging environment where competitors embrace the latest technological developments in Green Power and Advanced Aerial Mobility to push the envelope of the global aviation revolution.” the Fédération Aéronautique Internationale FAI announces on its site www.wcairrace.com the new concept with four different classes under the name World Championship Air Race.

So we can continue to be curious!

In memoriam of Hannes Arch

Hannes Arch, who died in a serious helicopter crash in 2016, was the first pilot ever to put his trust in the expertise of bionic surface technologies and celebrated great successes with the support of BST. Hannes Arch was also the first Red Bull Air Race pilot to celebrate victories with Shark Skin. The technical and human discussions with Hannes were formative for the development of ever better racing machines. He was an incredible person and an even better pilot. Both, his flight maneuvers and his friendship will always remain unforgotten for us.