Russia’s MC-21 tested for reverse thrust behavior

This thermal image shows the flows of air from the MC-21's engines in thrust reversal as the aircraft is braking on the runway (Photo by TsAGI)

Russia’s Central Aerohydrodynamic Institute (TsAGI), located in Zhukovsky outside Moscow, has completed thrust reversal tests on a mock-up of the Irkut MC-21 narrowbody aircraft powered by Pratt & Whitney PW1400G engines. The institute conducted the tests at the request of Irkut Corporation, which leads the development of the new airliner.

The tests were intended to appraise the safe operating conditions, and establish the engine stall margin, with the thrust reversers engaged. The results of this study will be used in preparations for the flight tests, which are set to begin in the spring of 2017. The MC-21 will be initially flight-tested with PW1400Gs. The Russian-made option — Aviadvigatel PD-14 is expected to be installed at a later stage.

TsAGI was testing the thrust reversal mode in a full-scale wind tunnel. The tests simulated the aircraft landing and braking on the runway with the thrust reversers engaged. The experiments provided information about the thrust-reversing effect on the aircraft’s controls, its stability and controllability, including in case of system and engine failures in the braking phase. The researchers identified potential ways to prevent re-ingestion of fuel vapors into the air intakes, and proposed measures to ensure reliable engine operation in reverse thrust.

The tests were based on TsAGI’s in-house approach, which relies on the use of weight and aerodynamic measurements and also on advanced optical and thermal imaging methods for air flow visualization, says Alexander Chevagin, who heads the institute’s propulsion aerodynamics research department. This approach allows for a detailed analysis of how the air flows around the airframe in different engine operation modes, and depending on the runway speed after landing.

TsAGI is actively involved in the MC-21 testing program. In October this year, the institute completed the second phase of flutter tests on a dynamically similar model of the airliner. TsAGI is now assembling a second MC-21 prototype, to be used for static testing.