In June 2026, the DGA measured the radar signature of a Rafale F4 at Bruz—thirteen years after the last such campaign. The key factor at stake: the distance at which radars can detect it.
An American F-35 returns a radar echo equivalent to an object measuring 0.01 to 0.02 square meters. A fighter jet without special treatment returns an echo five to one hundred times larger. Since 2022, Ukrainian surface-to-air batteries have demonstrated the cost of a poorly managed signature. The Rafale’s signature has never been made public; it has just been re-measured, angle by angle.
First test in thirteen years
In June 2026, a Rafale F4-standard aircraft was suspended in mid-air at Bruz, on the outskirts of Rennes. Oriented and re-oriented to face a platform bristling with antennas—which visitors are forbidden to photograph—the aircraft was observed from every angle. The DGA (French Defense Procurement Agency) conducted a campaign there to evaluate its radar signature: the echo it reflects back to the radars illuminating it.
Reporting to the Ministry of the Armed Forces, the DGA manages French armament programs and evaluates defense technologies before they enter service. It conducted these tests at a facility named SOLANGE, part of its Information Superiority center (DGA-MI) located at the Bruz site. The Rafale tested was an F4-standard model—the aircraft's most recent version—with each standard bringing new sensors and weaponry to the armed forces. The last campaign of this kind took place in 2013.
Advances in hostile radar capabilities
Since February 2022, Ukrainian surface-to-air defenses have shot down some of the most modern Russian aircraft in their fleet. These losses have influenced how Western military planners assess the cost of entering defended airspace.
Over the same period, the number of radars has proliferated, and the range of wavelengths they emit has expanded. Long-range surveillance radars operate on long wavelengths, while fire-control radars use short wavelengths. Shapes and coatings that reduce the radar echo against one type of wave are less effective against another. Consequently, a signature considered acceptable in 2013 no longer yields the same result when facing a sensor network that scans across multiple wavelengths and cross-references the data.
The DGA assesses what the military calls "survivability"—an aircraft's ability to penetrate a defended zone and exit it safely. Radar signature determines a specific parameter here: the distance at which a hostile sensor locks onto the aircraft.
The DGA facility that swallows a fighter jet
SOLANGE is a cylindrical structure measuring 58 meters in diameter and approximately 40 meters in height. The acronym stands for *Système orientable lourd pour aéronefs et gros engins* (Heavy steerable system for aircraft and large vehicles).
A fighter jet enters the facility full-scale and in its operational configuration, without needing to be dismantled first. Elsewhere, engineers measure scale models and then extrapolate the results to full size—a process that entails a margin of uncertainty. An official document from the Ministry of the Armed Forces describes the facility as a "radar signature measurement base unique in Europe."
The nEUROn combat drone demonstrator also underwent testing in this facility. At the same time, the June 2026 campaign utilized the ED2EN laboratory—located at the Bruz site and dedicated to digital electronic warfare. The data recorded on the test unit informs the development work on airborne jamming equipment.
Why nothing must touch the aircraft
The sensor receiving the echo cannot distinguish the wave's point of origin. A wave reflected off a wall arrives with the same signal characteristics as one reflected off the aircraft, thereby skewing the readings. For this reason, the walls and ceiling of the SOLANGE facility are lined with thousands of pyramid-shaped electromagnetic absorbers; their geometry traps stray waves rather than reflecting them.
DGA engineers aim to replicate conditions approximating "free space"—that is, actual flight—within an enclosed space measuring 58 meters in width.
For the same reason, landing gear resting on the ground or a metal mounting frame would produce a spurious echo that could not be distinguished from the aircraft's own signal. Hence the Rafale suspended in mid-air.
The aircraft is then observed from multiple angles. Viewed head-on, from a front-quarter angle, from below, or from the rear, a fighter jet does not return the same radar echo; the difference between these values spans orders of magnitude.
The figure no one confirms
Radar Cross Section (RCS) is expressed in square meters and describes the amount of energy an object reflects back to the transmitter illuminating it. It reveals nothing about the aircraft's physical size. A fighter with a wingspan of nearly 11 meters can have a lower RCS value than a metal sphere measuring just a few tens of centimeters across. The shape of the airframe and the cavities exposed to radar waves—air intakes being the primary example—matter more than the aircraft's overall volume.
A purpose-built stealth aircraft like the American F-35 falls within the 0.01 to 0.02 m² range. A conventional fighter typically remains above 0.1 m², sometimes reaching up to 1 m². Anything exceeding 2 m² falls into the category of bombers.
Engineering estimates, reported in early 2026 by a defense-focused media outlet, place the Rafale’s minimum frontal signature—the value measured head-on, the angle at which a fighter approaches a surface-to-air missile battery—between 0.05 and 0.1 m². Neither Dassault Aviation nor the DGA (French Defense Procurement Agency) has released an official figure. The aircraft sits somewhere in the middle: far less stealthy than the F-35, yet significantly more so than an untreated fighter.
Sukhoi has filed a patent estimating the Su-57’s frontal RCS at between 0.1 and 1 m²—the range of a conventional fighter—even though Moscow markets the aircraft as a fifth-generation stealth fighter. The DGA measures radar returns in a controlled indoor environment, whereas manufacturers typically publish only estimated ranges.
What the measurement determines for SPECTRA
An aircraft with a known radar signature—mapped angle by angle—can determine the distance at which specific radar types will begin to detect it. Data gathered via the SOLANGE facility is used to set this detection threshold within the Rafale’s electronic warfare system, which then triggers countermeasures. Reacting too early would effectively reveal the aircraft's presence to a radar that has not yet locked onto a target.
Developed in partnership with Thales, MBDA, and Safran, SPECTRA detects hostile radar emissions and counters them with jamming and false returns designed to create phantom targets. The aircraft determines its position within the electromagnetic environment without emitting signals itself, thereby avoiding detection by the very systems it is monitoring. Dassault Aviation refers to this approach as "active stealth."
Lockheed Martin took a different path with the F-35, opting for passive stealth designed into the airframe from the outset: an airframe geometry calculated to deflect radar waves and internal weapon bays that eliminate the need for under-wing stores.
In 2022, the Ministry of the Armed Forces decided against developing a Rafale F4 variant dedicated exclusively to electronic warfare—modeled on the US Navy’s specialized EA-18G Growler—deeming the capabilities already integrated into SPECTRA to be sufficient.
On January 12, 2026, Dassault Aviation acquired an equity stake in the French start-up Harmattan AI by participating in a $200 million funding round.
Six months later, on July 13, the two companies issued a joint statement announcing the successful collaborative flight of a Rafale F4 and a drone equipped with NAMIB, their new electronic warfare system. The drone detected and then located an advanced surface-to-air defense system before transmitting the data to the fighter jet, in a simulated engagement scenario within contested airspace. No official source specified the exact nature of the munition that might have been employed during this simulation.
Detection was performed by the drone, not by the Rafale’s own sensors. The SOLANGE facility measures the radar cross-section (RCS) of an airframe itself, rather than data reported to the fighter by a third-party platform.
The "Super Rafale" will undergo testing at the same facility.
The European FCAS (Future Combat Air System) program—a joint initiative involving France, Germany, and Spain to develop a successor to the Rafale and Eurofighter—stalled in 2026.
Dassault Aviation is now discussing a stealthy "Super Rafale" developed independently, paired with a combat drone dubbed "Neuron NG"—a derivative of the demonstrator whose signature has already been measured by the DGA at the Bruz facility. The manufacturer projects this system will be ready by 2045.
Knowing the radar cross-section (RCS) makes it possible to calculate the exact distance at which a specific radar will detect the aircraft; consequently, these measurements are classified data. No manufacturer would entrust such measurements to a foreign partner. Designing an airframe with a lower radar signature than the F4 variant therefore requires a domestic facility capable of verifying results at full scale, as well as engineers trained to operate it.
Thirteen years separate the 2013 campaign from that of June 2026. Dassault Aviation projects a nineteen-year timeframe leading up to the target date it has set for the Rafale’s successor. /END
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