The developers of "Angara" fear that rocket engines may destroy the rocket at the start

Representatives of NPO Energomash stated that the engines of the Angara rocket RD-191 have a design defect that could lead to the destruction of the carrier at the start. The report was prepared by NGO experts for the Korolev Space Readings in Moscow, as reported by Vedomosti.

The problem, according to rocket scientists, is directly related to the package arrangement of the first and second stages of the engine. Thus, the four blocks of the first stage surround the side of the second. The engine of the central unit should operate for a long time under reduced pressure (throttling), in the mode of 30% of the nominal thrust value.

But in this case, low-frequency oscillations are generated in the Angara engine, which can "lead to the appearance of resonance and destruction of the launch vehicle design."

In order to solve the problem, the designers added a special valve to the engine. True, this decision does not always work. “It has been established that this method allows to significantly reduce the amplitude of oscillations,” but “on individual engine instances a manifestation of low-frequency oscillations is observed when operating in low modes, from which it can be concluded that the effect of using a three-position valve can be different on different engine instances” the report says.

The problem of eliminating low-frequency oscillations will have to be addressed, and in the near future. The fact is that mass production of the rocket is scheduled for 2021. The new carrier must replace the Proton missiles. "Angara" are considered representatives of the environmentally friendly family of launch vehicles of different classes. The family includes both light missiles and carriers with increased payload.

Until now, Angara was launched only once, in 2014, when the Angara-A5 heavy rocket was launched. The second launch, scheduled for 2016, was postponed to the end of 2019.