Angara-A5 - Problems
The crisis of 2008-2010 painfully hit the Angara: underfunding of the project postponed the start of flight testing of the rocket from 2010 to 2012, then to 2013 and, finally, to 2014. Nevertheless, despite the lack of resources, the creation of the space-rocket complex continued.
After analyzing the data obtained during the first flight, it turned out that the carrying capacity of the rocket is less than expected. As Russian Deputy Prime Minister Yuri Borisov said in an interview with the Vedomosti newspaper in September 2019, the heavy Angara does not meet the requirements of the main customer, the Ministry of Defense. An example is the refusal of the Ministry of Defense of the Russian Federation at the beginning of 2016 to purchase the Sfera-V communication satellites , for which there was no carrier of suitable carrying capacity.
Since the end of 2014, Russia has formally had “light” and “heavy” Angara. Why weren't these rocket used? There are two main reasons for this. The first is interruptions in the work of the State Research and Production Center named after M.V. Khrunichev because of the transfer of production from Moscow to Omsk, the second - the unavailability of the Vostochny cosmodrome for the launch of "Angara".
The official version of the move, announced a few years ago, said that the problem was welding: the Omsk Polet uses friction welding, which is necessary to create the Angara, while the Moscow plant, where Proton has been made for many years, uses argon-arc welding. Isn't it easier, and most importantly, isn't it cheaper to change the welding method in such a situation? This question did not seem to be of much concern to industry leaders. Another reason for the move, officially announced, is the advantageous location: Omsk is closer to the Plesetsk and Vostochny cosmodromes. But over the years of the existence of Russian cosmonautics, products have been successfully transported both to Plesetsk and to Baikonur.
The established production cycle at the most powerful profile holding in Russia was disrupted, and three large enterprises, numbering about 16,000 people, were withdrawn from its structure (“Proton -PM "in Perm, KBKhA and VMZ in Voronezh). Massive redundancies of personnel were carried out under the auspices of "production optimization" (the most significant loss was production veterans), and production ties were undermined, or even destroyed. Development work was also affected by the move. These changes also affected the cycle for the manufacture and launches of Proton, established over decades (in 2007-2013, the Khrunichev State Research and Production Space Center launched an average of 10-12 Protons per year.
And on the Omsk "Polet", instead of the gradual and phased development of the serial production of "Angara", a super-costly emergency mode was included: the first stage of modernization of the Polet's capacities cost the treasury 7 billion rubles (the galvanic shop alone - 250 million rubles), the second stage - 10 billion rubles, but the process has not been completed yet. And the decision to abruptly transfer production to unprepared areas with untrained personnel not only cost a pretty penny, but also did not give the expected effect: the timing of the production of new Angara missiles is constantly postponed, as well as the launch of its serial production.
The joint Russian-Kazakh project for the construction of a new launch complex at Baikonur, which began back in 2004, came to a halt at the same time, and it was decided to prepare the Angara site on Vostochny. At Vostochny, where the percentage of unfinished construction of the first stage (infrastructure and residential buildings) is extremely high, and 163 criminal cases have already been opened against contractors (109 of which have been brought to court), and the amount of costs for the construction of the "Angarsk" complex is 10 times more than it was in Plesetsk - 300 billion rubles.
The state program also provided funds for the construction of a second launcher at the Plesetsk cosmodrome with all systems and infrastructure for launching the Angara-A5 with KVRB (17.256 billion rubles). Construction had not started as of 2020.
The Angara-A5 suffers from suboptimal mass distribution between stages. Angara-A5 has a very large first stage and small second and third stages. This leads to a decrease in the total characteristic velocity and pyaload. During the development period, only the RD-0124 engine, which was being developed at that time, was available to the designers as the third stage main engine. Its thrust is only 30 tf, which is significantly lower than that of a similarly intended third-stage propulsion system of the Proton launch vehicle. The total thrust of the sustainer RD-0213 and the steering RD-0214 is twice as much - 62.5 tf. As a result, the designers were forced to limit the mass and fuel supply of the third stage, as well as redistribute the mass in favor of the URM-1 package. The operation of a package of five URM-1 with throttling of the engine of the central block leads to the fact that by the end of the operation of the blocks of the first stage, a relatively small amount of fuel, about 70 tons, remains in the central block, which are consumed at the stage of the second stage. For comparison, during the operation of the first stage, more than 570 tons of fuel are consumed, and the third - about 35 tons.
The thrust-to-weight ratio of the first and third stages is very low. The thrust of the engine of the third stage of the Angaru-A5 is half that of the third stage of the Proton. The total thrust of the RD-191 engines at the first stage of the Angara-A5 is also less than that of the lighter Proton - only 980 tf, while 6 RD-275 Proton-M engines have a thrust of 1020 tf (in both cases, the thrust is indicated on the surface of the earth). At the same time, the Proton launch vehicle will deliver a smaller payload (in the latest version of the Proton-Mup to 23.7 t). The low thrust-to-weight ratio leads to the fact that the steps are forced to gain orbital speed longer and climb more slowly to the height of the reference orbit, which directly increases gravitational losses to overcome the force of gravity.
The relatively high dry weight of URM-1 blocks results from the layout of the first / second stage package from the same URM-1 missile blocks of a relatively small size. This leads to a larger area of ??the side walls, and, consequently, a greater mass of the shells compared to a monoblock or three-block layout. Therefore, the mass fraction of the carrier with such an arrangement is obviously worse, which directly affects the energy characteristics and the mass of the payload. The third stage, due to the forced small size, also has a relatively low mass fraction.
The RD-191 engines have a very high dry weight of about 2.3 tons, which is twice as heavy as, for example, two Merlin engines of the same thrust. At the same time, the difference in the value of the specific impulse is relatively small - about 20-25 sec (200-240 m / s). In addition, extremely high pressure and temperature of the working fluid (in fact, hot oxygen) inside the turbopump unit and the RD-191 ducts lead to the threat of ignition of the engine structures with its destruction and emergency termination of the flight. To prevent this, filters with a mesh size of 80 microns, which is equal to the diameter of a human hair, are installed on the fuel lines at the engine inlet. Based on operating experience and accidents with engines of the same family RD-170 and RD-180it was found that aluminum dust grains of just this size are sufficient to initiate a fire in an environment of hot compressed oxygen.
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