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The Soyuz-2-3 launch vehicle would serve as an intermediate step between Soyuz-2 and Soyuz-3 launch vehicles in the effort to upgrade the oldest family among Russian space boosters. The concept of the Soyuz-2-3 emerged during 2005, when RKK Energia settled on the Soyuz-based rockets as a launch vehicle for the prospective Kliper orbiter. The Soyuz-2-3 would be capable of launching a "light" version of the Kliper spacecraft, as well as the unmanned cargo container within the Parom orbital tug system.
Like the Soyuz-3 launcher, the Soyuz-2-3 apparently borrowed body dimensions for the 1st and 2nd stages from the Avrora (Aurora) project -- a short-lived commercial venture aimed to launch the Soyuz-based rockets from Christmas Island in the Indian Ocean.
The first stage, traditionally comprised of four conical strap-on boosters, would be equipped with a brand new RD-0155 engine developed by KBKhA design bureau in Voronezh and burning a mix of kerosene and liquid oxygen.
The top section of the 2nd stage (also known as "core" or a "sustainer" stage) would have a cylindrical shape with the constant diameter, as oppose to conical shape in the earlier versions of the Soyuz rocket. It would enable the core stage of the Soyuz-2-3 to carry as much as 40 tons more propellant in comparison to the core stage of the Soyuz-2. (In March 2007, TsSKB Progress said that a 50-ton increase in propellant load would be achieved with a larger diameter core stage.)
Like Avrora, the second stage would be equipped with the modified NK-33 engine, inherited from the ill-fated N1 rocket, developed during the Moon Race between the USSR and the United States in the 1960s.
The NK-33-1 engine would be able to develop up to 200 tons of thrust (from 150 tons in the N1 rocket) and it could be gimbaled up to 15 degrees, eliminating the need for steering thrusters, traditionally present on all booster stages in the Soyuz family.
Despite these improvements, the Soyuz-2-3 would be a less radical upgrade of the family than the Soyuz-3 booster, since the former would not employ liquid hydrogen on the third stage.
Proponents of the Soyuz-2-3 and the Soyuz-3 projects argued that it would be the cheapest way to produce a launcher of this class. They promised to use the existing cache of as many as 70 units of NK-33 engines left from the N1 program, to build initial batch of Soyuz-2-3 rockets. Later, profits from commercial use of the vehicle would be re-invested to jump-start mass production of NK-33-1 engines.
As of June 2005, the preliminary design of the Soyuz-2-3 project was expected to be completed at TsSKB Progress by the end of 2005 and "working documentation" to be produced during 2006. As of 2006, the project was expected to be completed by 2012.
During the Dvigateli 2006 show in April 2006, Sergei Tresvyatskiy, the director general of OAO SNTK Kuznetsov, promised to initiate test firings of existing NK-33-1 engines in mid-2007.
A Russian 15-year Federal Space Program, adopted in 2005, allocated 4,000 million rubles for the Rus-M development program, which encompassed upgrades of the Soyuz family. It envisioned the development of a launch vehicle with the capability of launching 11 tons into the low-Earth orbit, during 2007-2010; and a vehicle with the 15-ton capability to the same orbit and 3.4 tons to the geostationary orbit during 2010-2015.
At the beginning of 2006, RKK Energia and TsSKB Progress agreed to a three-stage development plan for the Soyuz-2-3 project. The first version of the rocket would carry 11 tons into circular orbit delivering, commercial and military satellites. In the second development phase, the payload would be increased to 13 tons, thanks to the introduction of the RD-0155 engine on the first stage. This would enable the vehicle to carry the "light" version of the Kliper. Finally, during a third phase, the payload would grow to 15-16 tons and above, giving the rocket enough power to launch the "heavy" version of the Kliper.
Russian military apparently also expressed interest in future upgrades of the Soyuz family. On June 5-6, 2006, the commander of Russia's Space Forces, Colonel General Vladimir Popovkin visited TsSKB Progress to discuss the issue with the organization's management, a regional edition of the Kommersant daily reported. On March 2, 2007, the Soyuz-2-3 project became the central theme of discussions with the Chairman of the Russian Duma (Parliament) Boris Gryzlov, who visited TsSKB Progress with an entourage of regional officials and subcontractors.
A long-promised demo test of the NK-33 engine finally took place on June 2, 2008, in the presence of a number of high-ranking civilian and military officials from Moscow. The engine successfully fired for 266 seconds. Still, Designer General at TsSKB Progress, Ravil Akhmetov, told RIA Samara news agency that the idea of reviving the NK-33 engine within the Soyuz-2-3 project faced skepticism among some officials.
Around 2007, as an intermediate step toward the development of the Soyuz-2-3 rocket, TsSKB Progress proposed the Soyuz-1 vehicle, which utilized a single core stage without traditional strap-on boosters on the first stage.
By 2011, the progress made on the Soyuz-1 project apparently revived hopes for the eventual development of more powerful rockets retaining the basic Soyuz architecture, but equipped with NK-33 engines. In April 2011, a circa 2007 model of the Soyuz-2-3 launch vehicle with five NK-33-1 engines on the first and second stages re-appeared at the Russian exhibit in Vienna dedicated to the 50th anniversary of Yuri Gagarin's historic mission. At the time its first launch was projected in 2014. (487) In the meantime, the head of TsSKB Progress, Aleksandr Kirilin, told a local newspaper that a nearly completed Soyuz-1 upgraded with standard strap-on boosters could have increased its payload from 3 to 10 tons. Other variations of the rocket could bring the payload mass up to 16-17 tons, Kirilin said. He described the Soyuz-2-3 vehicle as a possible stepping stone toward the new-generation Rus-M rocket. (486)
On August 1, 2011, NPO Energomash disclosed that at the meeting of its Scientific and Technical Council, NTS, three days earlier, top propulsion experts in the nation had reviewed proposals for the RD-193 engine intended for the "prospective versions" of the Soyuz rocket. Such designation possibly hinted that the proposed powerplant derived from RD-191 -- the engine originally developed for the Angara family of rockets.
Known specifications of the Soyuz-2-3 and Soyuz-3 rockets (as of 2006):
*Mass of the Kliper spacecraft in the 200-kilometer circular orbit with the inclination of 51 degrees.
**Mass of the Kliper spacecraft with emergency escape engines and the launch vehicle adapter.
Written and illustrated by Anatoly Zak; last update: August 3, 2011
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The Soyuz-2-3 launch vehicle, with a cargo container (left) and the "light" version of the Kliper spacecraft (center), as compared to the Soyuz-3 rocket (right), proposed to carry a "heavy" version of the Kliper. Click to enlarge Copyright © 2006 Anatoly Zak
A heavily redesigned version of the Soyuz-2-3 rocket, which was first displayed around 2007, and then resurfaced in 2011.