Sao Paulo - The Embraer E195-E2 completed flight flutter test. The aircraft was accelerated at high speeds for the first time to see how extreme aerodynamic forces affect the airframe.
The aircraft, which performed the test is a prototype of the Embraer E195-E2. It was the first, and maybe the last time the aircraft would have been exposed to such extreme flight conditions in its entire life.
Flutter is a dynamic aeroelastic phenomenon which can cause oscillations on the aircraft and if allowed to continue, might grow unbounded and cause structural failure.
Several flights were planned for the campaign. During each flight, test pilots pushed the flight envelope (the range of combinations of speed, altitude, and the angle of attack within which a plane is aerodynamically stable) up to the automated design airspeed.
First, the plane was stabilized at a high flight level around 40,000 feet, then the pilots pushed the aircraft into a dive. As the altitude decreased, the prototype began to accelerate up to the ultimate design speed.
During the campaign, the test plane was forced up to 0.9 Mach which is very close to the sound barrier. At such a high speed, local shock waves are developed on the airframe and the vibration levels in the cockpit increase significantly.
During that time the behavior of the aircraft was continuously monitored online from a telemetry room by using a set of transducers distributed on the entire airplane so that the reaction of associated structures could be analyzed in real-time.
After each flight, engineers analyzed all the data, and clearance was given to the next flight where the airplane would fly at a higher speed. This process was repeated several times until the maximum design airspeeds and Mach numbers have been reached.
This is a highly risky process. Therefore, some risk minimization measures were taken prior to each test.
During the flight flutter tests, the crew wore helmets and parachutes and was ready to evacuate the aircraft promptly in case of any loss of control.
According to the manufacturer, the E195-E2 performed very well during the flight flutter testing and the results found were very close to the theoretical predictions.