On August 5-7, 2020, Yuzhnoye SDO successfully completed final development tests of the liquid jet system (LJS), installed on the upper stage of the Cyclone-4 launcher, developed by Yuzhnoye SDO and manufactured by PA Yuzhmash.

Testing involved 2️ phases:

▪️ August 5 – main test firings, implementing near-flight low-thrust liquid motor firing cyclogram;

▪️ August 7 – additional test firings, accumulating firing cycles of the low-thrust liquid motors and LJS as a whole.

During the tests each of ten low-thrust liquid motors, that liquid jet system consists of, totaled around 40 000 burns, and total running time of each equaled around 2000 s.

These tests finalized the complete cycle of the ground development testing of the Cyclone-4 upper stage liquid jet system, finalizing the verification of performance capability of the selected structure and its units within the specified operating conditions and their compliance with the basic specifications from the Requirements Specification.

As a recap, Cyclone-4 upper stage LJS is an actuating device of the flight control system and it is designed to:

  • calculate an ascent trajectory and ensure a required accuracy of injection;
  • create steering effort for angular stabilization of the stage in the unpowered portion of flight;
  • create steering effort in roll channel in the powered portion of flight;
  • build longitudinal overloading to provide settling of propellants at the main engine inlet prior to starting;
  • provide attitude of the stage required for spacecraft separation;
  • provide attitude of the stage prior to de-orbiting;
  • stabilize stage prior to de-orbiting;
  • deorbit stage using working and warranty fuel supply up to propellant depletion.

What makes the Cyclone-4 upper stage LJS one of a kind is that it is not equipped with its own propellants storage and supply system. LJS low-thrust liquid motors are fed directly from fuel lines at the main engine inlet, thus decreasing the mass of stage by more than 6️0️ kg.

Completion of testing the Cycone-4 upper stage liquid jet system lays the groundwork for development of new jet systems for the advanced launch vehicles of in-house design.