RuAviation

On October 29, 2025, thrust reverser tests of the PD-8 engine were conducted on the SJ-100 prototype aircraft (serial no. 97003, test registration 97023) at Ramenskoye Airfield in Zhukovsky. The primary objective of these tests was to assess the reverser’s performance across different wing flap configurations, according to the press service of United Aircraft Corporation (UAC).

“In Zhukovsky, the SJ-100 aircraft with serial number 97003 underwent its first PD-8 engine thrust reverser test. Thrust reversal is a technology that redirects engine thrust opposite to the aircraft’s motion to assist in deceleration. Modern airliners widely use this function to reduce speed and stop on the runway,” the statement reads.

The PD-8 engine, developed by Rybinsk-based UEC-Saturn, features a modified thrust reverser design compared to the Franco-Russian SaM146 engine. Instead of the conventional bucket-type reverser, it employs a lattice-type system, which enables faster and quieter operation, improving braking efficiency during the landing roll.

In the SaM146 engine, two large bucket doors rotate to block the main airflow and redirect it forward, generating reverse thrust. In contrast, the PD-8 moves the outer section of the nacelle rearward, opening a composite aerodynamic lattice that redirects airflow from the cold bypass forward while simultaneously blocking the direct exhaust.

The PD-8 reverser is quieter because the lattice cells distribute airflow evenly and redirect it smoothly, reducing turbulence and noise. Its main advantage is improved braking efficiency: the lattice system aerodynamics allow more precise and powerful redirection of the airflow, maximizing reverse thrust and reducing landing roll distance. A lattice-type electrically actuated reverser was first implemented in Russian aviation gas turbine engines on the PD-14.

According to Dr. Yuri Barzilovich, Professor of Technical Sciences, in the article “Efficiency of Thrust Reverser Applications” published in the Scientific Bulletin of the Moscow State Technical University of Civil Aviation, thrust reversers dissipate approximately 14% of energy on dry runways, while wheel brakes dissipate about 60%. In emergency situations, such as system failures or landings on wet or icy surfaces, the reverser’s contribution can rise to 70% of the total energy dissipation.

Before October 29, 2025, SJ-100 prototypes performed landing roll braking without engine thrust reversers. Wheel brakes, including autobrake modes (LOW, MEDIUM, MAX), pedal braking, or Rejected Take-Off (RTO) procedures, provided deceleration. The autobrake system engages immediately after touchdown, reducing aircraft speed without additional crew input.

Certification procedures for the SJ-100 require demonstration of a full stop without using thrust reversers. Therefore, reversers are not mandatory for type certification but serve as an additional safety feature in operational use. Landing and braking distance calculations are based on the performance of the primary braking system without thrust reversers.

In operational conditions, aircraft encounter various landing scenarios, including wet or slippery runways, increased landing weight, or suboptimal brake conditions. In such cases, thrust reversers provide an additional factor for reducing landing roll. Flight experience shows that while certification data form the basis, real-world operations demand consideration of multiple variables.