Saved from subsidence a few years ago, this test center of the Office of Aerospace Research (Onera) reproduces continuous or gusty winds at speeds exceeding the sound barrier. It is now running at full speed with almost full bookings for the next four to five years.

Here, models of Rafale, new reactors or wings packed with sensors can be exposed for hours to air currents of up to Mach 12, or nearly 15,000 km / h. Objective: to measure pressure resistance or acoustics.

The challenges of the decarbonization of civil aviation as well as the race for new military projects fueled by the war in Ukraine have filled the order book of the Modane wind tunnels and, more generally, that of Onera which, upstream of the tests, conducts all kinds of research projects.

In 2022, the Office broke its own record for orders, which amounted to €162.9 million (+7% compared to 2021), including €59 million for the Directorate General of Armaments (DGA) alone and €15.6 million for the Directorate General of Civil Aviation (DGAC). About a third of customers come from abroad, mostly from Europe but also from South Korea for example.

"Even more indispensable"

During a rare press visit to the heart of the S1 wind tunnel, voices resonate in a giant hose with a diameter of 24 meters and 400 meters long. It is hard to imagine that here roars winds of up to Mach 1, or more than 1,000 km / h, speed at which no human being would survive.

S1 is one of four wind tunnels at the Modane site. This set is considered unique in the world because of the wide range of aerodynamic tests offered, but also because it is exclusively powered by hydraulic energy, thanks to two dams.

A wind tunnel at the Office of Aerospace Research site in Modane, Savoie, March 17, 2023 © JEFF PACHOUD / AFP

"There is not ONE missile of the nuclear deterrent force that has not passed here," says Bruno Sainjon, director general of Onera. "In these times when both civilian and military sovereignty has regained importance, (the site) has become even more indispensable," he said.

"Here we are working on the next generation (of nuclear missiles, editor's note) with a superramjet much more complicated, but which will allow us to go much much faster," he adds.

The new military programming law "forces us to go back into activity in many areas such as combat aeronautics," explains for his part the delegate general for armaments, Emmanuel Chiva, in one of the "veins" (corridors, editor's note) of test. "The new Rafale standards that will have to carry different armaments must, for example, be treated in the wind tunnel," he said by way of example.

The different components of the SCAF, the Future Combat Air System launched by France, Germany and Spain around a common aircraft, will also be tested here.

- Real versus digital -

For the DGAC, the tests focus on "how to profile the planes, to build them, to limit the noise effect that this has on the residents," details Damien Cazé, Director General of Civil Aviation.

In the era of supercomputers and numerical simulations, the Modane centre, a former spoils of war recovered from the Austrian Alps by the Allies after 1945 and revived in the Maurienne valley, paradoxically finds a second wind.

A wind tunnel of the Office of Aerospace Research (Onera), in Modane (Savoie), March 17, 2023 © JEFF PACHOUD / AFP

"Everyone is starting to do hypersonic wind tunnels (from Mach 5, editor's note). At some point, there are effects that we cannot simulate with the computing power and techniques we have today," Chiva said.

"Digital technology is not everything, especially on new forms of aircraft (...) you have to review everything on the experimental side," says Sainjon.

According to him, even the United States, which once wanted to abandon this kind of facilities, returned to it with, in the early 2000s, a reinvestment for NASA alone estimated at 600 to 700 million dollars.

© 2023 AFP