The RD-93MS turbofan engine is a critical component of the experimental Strizh demonstrator, as Russia makes strides in developing its next-generation supersonic civil aviation technologies. This powerplant is an adaptation of a well-established Russian military aviation engine for a different purpose: to showcase the technologies necessary for future supersonic passenger aircraft. UEC-Klimov of the United Engine Corporation developed it in collaboration with the Zhukovsky Research Center, TsAGI, and the Central Institute of Aviation Motors (TsIAM).
The Strizh program includes evaluating an integrated propulsion system that has been specifically engineered to meet the aerodynamic and acoustic requirements of civilian supersonic flight. The configuration uses two RD-93MS engines, each connected to a flat jet nozzle with an oblique cut and a specially developed air intake. Ground testing has verified the engine’s thrust characteristics meet the technical specifications established for the demonstrator.
RD-93MS: Adapting an established engine for a new application
The RD-93MS is a member of the RD-93 engine family, which UEC-Klimov originally developed for military aviation. The Chinese FC-1/JF-17 fighter aircraft are powered by the RD-93. Its development provided UEC-Klimov with experience in compact turbofan propulsion for high-performance aircraft.
For Strizh, however, the requirement is different. This requires changes to the installation arrangement and exhaust configuration. Accordingly, the RD-93MS has been modified to operate with a specially designed exhaust nozzle and specialized air-intake apparatus. The engine must receive air from the intake under necessary conditions, and the nozzle must manage the exhaust flow. The resulting assembly must function as a unified system.
The reported tests confirm compliance with the demonstrator’s thrust requirements, which is a critical distinction. They do not, in isolation, demonstrate the readiness of a production supersonic passenger aircraft or establish the engine’s ultimate performance across all flight conditions.
Why Strizh uses two RD-93MS engines
The Strizh demonstrator is currently under development to examine various technologies for a future Russian civil supersonic aircraft. The proposed upper-fuselage positioning of the propulsion system is one of its most significant features.
The Strizh configuration differs from traditional aircraft installations because the engines are typically located on the upper portion of the airframe, rather than beneath the wings or alongside the rear fuselage. The purpose of this arrangement is to mitigate the intensity of the sonic boom reaching the ground and to affect the propagation of shock waves around the aircraft.
The propulsion system’s engineering requirements are also influenced by the engines’ positioning. The engines must receive air through specifically engineered inlet ducts, and the exhaust must be directed in accordance with the aircraft’s aerodynamic layout.
TsAGI has been responsible for investigating these aerodynamic and propulsion-integration challenges. Before conducting wind tunnel experiments, its engineers developed and produced models of the air-intake devices and exhaust nozzles.
Under the tested conditions, the air-intake characteristics exceeded the standard reference values, as stated in the institute’s December 2025 announcement. The Strizh demonstrator also demonstrated acceptable pressure losses associated with the flat jet nozzle. Full-scale ground testing of the adapted RD-93MS engine was later conducted on the basis of these results.
Flat nozzle introduces a different engineering challenge
The flat jet nozzle with an oblique cut is one of the most distinctive features of the RD-93MS installation. This is not simply a change in external appearance. To accommodate the aircraft’s upper-mounted engine arrangement, the nozzle must regulate the exhaust flow as part of the propulsion system’s aerodynamic design.
Circular exhaust nozzles are the norm for conventional fighter-engine installations. In contrast, the Strizh program is dedicated to studying a flat configuration that can be seamlessly incorporated into the demonstrator’s airframe architecture.
The development is especially pertinent because the nozzle geometry can significantly impact acoustic behavior, exhaust-flow characteristics, and thrust recovery. Rather than optimizing a single characteristic independently, engineers must maintain a balance between these factors.
The nozzle was produced through a combined process that included laser sintering, welding, and milling. This manufacturing method was chosen to generate the necessary structural characteristics and geometry.
The flat nozzle with an oblique cut is a first in domestic aviation practice, according to TsAGI. Before the engine underwent ground testing, its aerodynamic characteristics were initially examined using experimental models in wind tunnels.
The results are significant because a nozzle that functions properly in isolation must also function accurately when connected to the engine and integrated with the aircraft’s air-intake system. The Strizh program is designed to verify the entirety of this arrangement, rather than individual components.
TsAGI creates a system to mitigate aircraft noise
Another critical component of the RD-93MS development is noise reduction. Supersonic passenger aircraft encounter two distinct acoustic challenges: the sonic boom associated with supersonic flight and the noise emitted during takeoff and landing.
The Strizh program uses unique engineering methodologies to resolve these concerns. The purpose of the upper-mounted propulsion arrangement is to explore methods for mitigating the sound impact of the sonic boom. In the interim, TsAGI has created a specialized noise suppression system to mitigate the noise produced by the engine’s exhaust jet during takeoff.
During the ground testing phase, the system was installed on the flat nozzle. Its objective was to mitigate the acoustic intensity of the exhaust stream during high-thrust operating conditions associated with takeoff.
This is particularly significant for civilian aviation, as the availability of supersonic aircraft at existing airports can be influenced by community exposure and airport noise restrictions.
Ground testing confirms the engine’s thrust performance
The completion of ground-based engine testing at UEC-Klimov was the most significant milestone in the RD-93MS development. The tests were conducted in collaboration between UEC-Klimov and TsAGI specialists as part of the Sivil-2025-TsAGI research program.
TsAGI subsequently reported that the research phase had yielded various noteworthy results, such as the successful wind-tunnel investigations of the intake and nozzle arrangements, the manufacture of the flat nozzle, and full-scale ground testing of the engine with noise suppression.
Numerous Russian aviation organizations are involved in the Strizh program. TsAGI coordinates the demonstrator’s technological development, while UEC-Klimov develops and adapts the engines. TsIAM contributes its expertise in aviation propulsion research. The Zhukovsky Research Center coordinates government-sponsored research programs.
The next challenge is to convert these ground-test results into an operational flight demonstrator.