Angara (rocket family)

History

After the dissolution of the Soviet Union, some launch vehicles required components from companies now in Ukraine, such as Yuzhnoye Design Bureau and Yuzhmash. The main Soviet spaceport, Baikonur Cosmodrome, was located in Kazakhstan, and Russia faced difficulties negotiating its use. In 1992, the decision was made to develop a new entirely Russian launch vehicle, named Angara, to replace vehicles built outside the country and ensure Russian access to space without Baikonur.

The vehicle was to use the partially completed Zenit-2 launch pad at Plesetsk Cosmodrome and be able to launch military satellites into geosynchronous orbit, which Proton could not do from Plesetsk. Several companies submitted bids, and in 1994 Khrunichev, the developer of Proton, was selected. The commercial success of Proton over the next two decades helped Khrunichev, as the Angara project faced funding difficulties from the cash-strapped Russian government.

Khrunichev's initial design used a modified RD-170 for first stage propulsion and a liquid hydrogen second stage. By 1997, the hydrogen stage was abandoned for kerosene, and the RD-170 was replaced with a modular design powered by the new RD-191, a single-chamber engine derived from the four-chamber RD-170. In late 1997, the Russian government approved the design. By 2004, the design had taken shape.

In 2008, NPO Energomash reported the RD-191 was ready for manufacturing. In January 2009, the first completed Angara first stage was delivered to Khrunichev. The first flight test was scheduled for 2013, and in 2013 the first prototype arrived at Plesetsk.

Vehicle description

The core of every Angara rocket is a module called the URM-1. For the Angara A5 version, four extra URM-1s are strapped on as boosters. Each URM-1 gets its power from a single RD-191 engine, which burns kerosene and liquid oxygen. This engine is a single-chamber version of the four-chamber RD-170, originally built for the Energia rocket.

The RD-191 can reduce its thrust to at least 30%, which lets the core URM-1 save fuel until its booster companions separate. Inside the URM-1, the liquid oxygen tank sits on top, followed by a section holding flight control and telemetry gear, with the kerosene tank below. The bottom houses the propulsion bay, which includes engine gimbal hardware for steering and small thrusters for roll control. The second stage, called the URM-2, uses a single RD-0124A engine, also burning kerosene and liquid oxygen.

This engine is very similar to the RD-0124 used on the Soyuz-2's second stage. For the Angara A5, the URM-2 has a diameter of 3.6 meters. The Angara 1.2 variant will use a smaller second stage powered by the RD-0124A, with a diameter of either 2.66 or 2.9 meters. Neither the Angara 1.2 nor the Angara A5 for low orbits uses an upper stage.

For higher orbits like geostationary transfer, the Angara A5 can use the Briz-M upper stage, which burns toxic propellants, or eventually a new cryogenic stage called KVTK, which uses liquid hydrogen and oxygen. The Blok D stage is also being looked at for launches from Vostochny.

Variants

The smallest Angara is the Angara 1.2, consisting of one URM-1 core and a modified Block I second stage. It has a lift-off mass of 171 tonnes and can deliver 3.8 tonnes to a 200 km × 60° orbit. Its maiden orbital launch took place 29 April 2022. A modified Angara 1.2, called Angara 1.2PP, made Angara's inaugural suborbital flight on 9 July 2014, lasting 22 minutes and carrying a 1430 kg mass simulator.

It weighed 171,000 kg and used a URM-1 core and a partially fueled 3.6 m-diameter URM-2. The heavy lift Angara A5 consists of one URM-1 core, four URM-1 boosters, a 3.6 m URM-2 second stage, and an upper stage (Briz-M or KVTK). Weighing 773 tonnes at lift-off, it delivers 24.5 tonnes to a 200 km × 60° orbit, and 5.4 tonnes to GTO with Briz-M or 7.5 tonnes with KVTK. In the A5, the four booster URM-1s operate at full thrust for about 214 seconds, then separate; the core throttles down to 30% after lift-off, then throttles back up after booster separation and burns for another 110 seconds.

The first A5 test flight was on 23 December 2014, the second on 14 December 2020, and the third on 27 December 2021, but the Persei upper stage test failed. The Angara 1.1, using a Briz-KM second stage with 2 tonnes capacity, was cancelled as it fell into the same payload class as Soyuz 2.1v. The Angara A3, with one URM-1 core, two URM-1 boosters, the 3.6 m URM-2, and an optional upper stage, has no current plans for use but could replace Zenit.

Related projects

The Naro-1, a South Korean rocket, used a first stage based on the Angara URM-1, powered by the lower-thrust RD-151 engine. Its debut on 25 August 2009 failed, though the first stage performed correctly. A second attempt on 10 June 2010 also failed when contact ceased 136 seconds after liftoff, and the review board could not agree on why. The third launch on 30 January 2013 succeeded in reaching orbit.

Did You Know?

• Production of Universal Rocket Modules and Briz-M upper stages takes place at the Khrunichev subsidiary Production Corporation Polyot in Omsk.
• In 2009, Polyot invested over 771.4 million RUB (about US$25 million) in Angara production lines.