ONTO THE LONG MARCH 5

The idea of a new generation of launch vehicles goes back more than 20 years. The decision to proceed with a manned space program in 1992 was linked to a new fleet of launchers. In 1992, at the International Astronautical Congress, Xiandong Bao of the Shanghai Electromechanical Equipment Research Institute outlined in A Modular Space Transportation System a new launcher system able, in different variants, to lift a range of payloads of up to 20 tonnes at the top end. His baseline study marked China’s move away from nitric fuels and to larger-diameter rockets of more than 3-m diameter, and the concept of the launcher family in which different combinations of stages are clustered to send smaller or larger payloads to orbit [8].

In the event, development of the new fleet of launchers would take a long time and, for the Shenzhou and Tiangong programs, China would rely on its existing Long March fleet. A Mir-class space station, though, would require a much heavier rocket capable of putting at least 20 tonnes into orbit. From the beginning, this was called the Long March 5 project in the West and eventually it acquired this name in China itself. From an early stage, the Chinese made it clear that it would be built in multiple versions, from light to heavy, and that it would form the backbone of the launcher fleet to at least 2050. They also took the decision, as did Russia, of phasing out toxic launchers in favor of more environmentally acceptable fuels (kerosene or hydrogen with liquid oxygen).

To kick off the project, the government allocated project 863 funding to develop some of the critical technologies necessary. Project 863 money was focused on the new engines, cost containment, and the achievement of reliabihty. During their earher shopping visits to Moscow, the Chinese had been unable to persuade the Russians to part with the designs of the huge RD-170 engine used on their Energiya rocket, although they were allowed to buy its upper-stage RD-0120 engine (they bought three: one for testing, one for taking apart, one for spare).

At the 2000 International Astronautical Congress, Wu Yansheng and Wang Xiaojun presented A Prospect over the Development of Long March Vehicles in the Next Decade, reporting progress on the design. They outlined the Long March 5 as a 55-m-tall rocket using liquid-hydrogen and liquid-oxygen main engines, flanked by four large strap-ons, weighing up to 800 tonnes, with a lift-off thrust of up to 1,000 tonnes and able to place 23 tonnes in low Earth orbit or send 11 tonnes to geostationary orbit. The next iteration became available not long thereafter, when the February 2001 Aerospace Magazine presented the dimensions of the rocket. The stage would have diameters of 2.25 m (called the K2), 3.35 m (the КЗ), and 5 m, depending on the number of lower stages used and the length of the upper stage. The capacity of the launcher grew to 13 tonnes to geosynchronous orbit and 25 tonnes to low Earth orbit, where it settled. It would be kerosene-fuelled for the lower stages (120 tonnes’ thrust) and hydrogen-fuelled for the upper (50 tonnes’ thrust). Two years later, officials set program targets of a reliability of 98.5%, commercial prices 30% lower than the Long March 3, and a launch preparation period of 15 days.

The CZ-5 program obtained governmental approval in June 2004 and development was assigned to the China Academy of Launcher Technology (CALT).

In 2007, the dimensions were given at 5-m diameter, 59.4 m tall, weight 643 tonnes, thrust 825 tonnes. The first cargo would be the 9-tonne Feng Yun 4 metsat. Later figures were given of a lift-off mass of up to 790 tonnes and lift-off thrust of up to 10,680 kN.

Two new engines were required. Although inspired by the now aging YF-20 design, they were larger and more powerful, with oxygen-rich staged combustion cycle engines. These were a 120-tonne-thrust liquid-oxygen and RP-1 kerosene YF – 100 engine for the first stage and a 50-tonne liquid-oxygen and liquid-hydrogen YF – 77 engine for the upper stage. The YF-100 engines were to have a thrust of 1,179 kN and a specific impulse of 305 sec while the YF-77 hydrogen engine was to have a thrust of 540 kN and a specific impulse of 432 m/sec. Their development took over 10 years. In 2012, the YF-100 was successfully tested at the 7103 factory of the Academy of Aerospace Liquid Propulsion Technology (AALPT) in Xian to 20,000 revolutions a minute for 200 sec, reaching a temperature of 3,000°C, and delivery of the first production YF-lOOs began. Its high-pressure staged combustion cycle engine made China only the second country after Russia to master the technologies

Long March 5 (left), compared to the powerful but Line drawing, showing clearly the thinner Long March 3 series on its right. Courtesy: Paolo importance of the strap-on boos – Ulivi. ters. Courtesy: Mark Wade.

involved. Finally, the CZ-5 design was frozen, with up to six variants (Table 10.8). In each case, the core stage and second stage are 5 m wide.

Various different letters were given for the different models. The D is the largest beast, for 10 YF-lOOs will fire together at lift-off: two main-stage engines, with four strap-ons, each with two engines, its 784 tonnes comparing to the American Delta IV (760 tonnes) and Atlas V (956 tonnes) and Europe’s Ariane 5 (733 tonnes). While primarily intended to launch large space station modules, at the Zhuhai air show in 2009, China specifically identified the CZ-5D version as a rival to Europe’s Ariane 5, able to put two satellites into 24-hr orbit simultaneously, compared to Ariane’s one large and one medium. First launch was set for 2014. In 2012, the first pictures were published of CZ-5 production, welding, and assembly.