The Turkish aviation industry is proving its engineering maturity in 5th generation fighter jet production in the laboratory before taking to the sky. TUSAŞ has rolled out the Full-Scale Static Test (FSST) aircraft, produced within the scope of the National Combat Aircraft KAAN project, which is an exact structural twin of the flight version. Although the first flight of a fighter jet is the most spectacular moment for the public, for global aviation authorities, the real victory is won in these static test centres where the aircraft's structural limits are pushed. This process, where TUSAŞ engineers essentially perform a flight simulation on the ground using over 200 hydraulic pistons and 5,000 sensors, constitutes the greatest safety barrier for KAAN to safely open its flight envelope.
Modern fighter jets are subjected to immense aerodynamic loads on their airframes while operating at supersonic speeds and under high G-forces. The only way to ensure these loads will not tear the aircraft apart in the air is to bend, pull, and pressurise it with unimaginable forces on the ground before it ever flies. The FSST programme initiated by TUSAŞ is not just a strength test but also constitutes the verification of the design, the correlation of the digital twin with physical reality, and the legal evidence for the international certification infrastructure.
Mechanical Orchestra: Aviation Simulation on the Ground
The full-scale static test rig has a complex engineering architecture that applies massive forces from different angles to every point of the aircraft. TUSAŞ built a special system for this challenging test. The test rig features over 200 high-capacity hydraulic pistons operating in synchronisation with a closed-loop control system.
However, these immense forces must be distributed homogeneously, like aerodynamic drag in the air, without damaging the aircraft's surface. For this, engineers use over 300 specially designed load pads and a whiffletree mechanism. This hydraulic piston orchestra, working in perfect harmony, brings the harshest manoeuvres and wind resistances down to earth, effectively testing the maximum limits to which pilots might push the aircraft in the future.
The system not only bends the aircraft from the outside but also stresses it from the inside. The cockpit is pressurised from within to simulate the pressure differential at high altitudes, verifying the strength of the fuselage panels. Similarly, the internal fuel tanks are filled with air or liquid to measure structural resistance to internal pressures.
The Aircraft's Nervous System: A 5,000-Channel Data Network
The heart of the static test is the massive measurement infrastructure that instantly converts the millisecond structural responses of the aircraft's frame to the applied forces into digital data. TUSAŞ teams have equipped KAAN with what is essentially a nervous system to monitor its structural integrity:
- Strain Gages: Approximately 5,000 strain gages were placed on wing roots, fuselage joints, and critical load-bearing surfaces. These sensors produce millions of data points by measuring microscopic elongations and stresses in the metal and composite materials.
- LVDT Sensors: Linear variable differential transformer sensors physically record how much the aircraft flexes (deflection) under load, from wing tip to root, tracking structural deformation millimetrically.
- Load Cells and Pressure Sensors: These instantly verify, via the closed-loop system, whether the hydraulic pistons are applying precisely the required tonnage of force to the aircraft.
Risk Management and the Ultimate Load Test
These tests, involving thousands of tonnes of force, inherently carry significant risk. A millisecond loss of synchronisation between pistons or an unforeseen local yield could destroy the multi-million dollar prototype within seconds. To manage this risk, TUSAŞ employs a staged and extremely slow loading method. The system automatically stops tests within milliseconds if predetermined load limits are exceeded.
The two most critical phases of the test are the Limit Load and Ultimate Load verifications. The limit load represents the highest force the aircraft might encounter during its operational life. However, the real test occurs during the Ultimate Load phase. KAAN's structure is tested under 1.5 times the limit load force, proving the aircraft's safety margin.
Perfect Correlation of the Digital Twin with Reality
The live data obtained from these tests is instantly compared with the Finite Element Model (FEM) prepared in the computer environment. The correlation of the responses between the digital twin in the virtual environment and the physical aircraft proves that the aircraft's design is flawless.
KAAN's full-scale static test aircraft is effectively performing the most challenging and potentially fatal flight mission without moving a single millimetre on the ground. TUSAŞ's ability to perform these tests with its own infrastructure declares to the global arena that Türkiye has established an end-to-end, fully independent aviation ecosystem for 5th generation fighter jet production and certification, requiring no external assistance whatsoever.
