Assembled the first Long March 5 airframe. Credit: CASC

It is not unusual for complex development programs to slip. But delays do not usually mount as steeply as they have for Long March 7. In March 2012 the rocket, China’s future workhorse space launcher, was supposed to be about 20 months away from flight. Three years later, that first launch is still at least 10 months away.

Work on Long March 5, meanwhile, has progressed as far as assembling the first airframe; engines have apparently not been installed. That launcher, the largest of the three in China’s new family of carrier rockets, will also be ready for flight in 2016, while the smallest, Long March 6, should lead its siblings with a first liftoff in the middle of this year.

In one configuration, Long March 7 is designed to throw 13.5 metric tons (29,800 lb.) to low-inclination low Earth orbits; it will replace the larger versions of the current Long March 2, 3 and 4 series. It may also become China’s manned launcher, replacing Long March 2F.

The largest version of Long March 5, the one that has been assembled, is supposed to throw 14 tons to geostationary transfer orbit, while Long March 6 has variously been credited with a throw-weight to Sun-synchronous polar orbit of 500 kg (1,100 lb.) or more than 1 ton.

The latest schedule for the three rockets, which are under development together because they share airframe modules and engines, was given by Tan Yonghua, president of the Academy of Aerospace Propulsion Technology (AAPT). Tan is probably happy to discuss the matter because the Long March 7 delay is unlikely to be the fault of his organization. AAPT is providing the engines, which have long been confirmed as mature and ready for service.

“The Long March 7 and our most powerful rocket, the Long March 5, will make their first flights next year, and they will also use the new engine,” the China Daily quotes Tan as saying. The engine is the 120-ton-thrust YF-100. Its development was completed before 2012, when series production of the engine began. So it has been waiting at least three years for its first flight on one—any—of the new launchers. Long March 6 will provide the occasion.

The core of the first Long March 7 airframe in testing. Credit: SASAC

The launcher family is made up of three airframe modules, in varying lengths. Two of the modules—3.35 meters (11 ft.) and 2 meters in diameter—are powered by one or two YF-100s, burning kerosene with liquid oxygen. Those two modules serve as core first stages for Long March 6 and 7 and boosters for Long March 7 and 5. The 5-meter-dia. Long March 5 core modules burn liquid hydrogen with liquid oxygen.

Tan’s schedule for Long March 5 and 6 confirms an Aviation Week report from December, but at that time it appeared that Long March 7 would make its first flight in 2015. Late last year, the airframe of the first Long March 7 had been built, but the engines had not been installed. Before that, the developer and manufacturer, the China Academy of Launch Vehicle Technology (CALT), overcame difficulties that had arisen in the propellant supply system (but not in the engines) by making more than 10 changes to the Long March 7 design. It appears, then, that some new problem may have emerged to push the first flight into 2016.

The schedule has slipped by a total of more than two years during the three years of program execution.

The first airframe underwent tests at a launch site that was not in the Chinese interior, says China Aerospace Science and Technology Corp. (CASC), the country’s main space industry organization. Since the airframe traveled by sea, that site was presumably the new launch base on Hainan. The tests were successful, says CASC, apparently referring to a set of evaluations that late last year were expected to verify compatibility of onboard and off-board systems.

The airframe was built at Beijing, the home of CALT, and at a new space manufacturing base at Tianjin.

CALT is also developing Long March 5. Sibling organization Shanghai Academy of Spaceflight Technology (SAST) is handling Long March 6, which has been expected to be the easiest of the three to develop, because it is the smallest and simplest.

An official photograph of the first Long March 5 (see photo) shows the 5B version, the most powerful, featuring two core stages and four boosters of the largest diameter.

The core modules of the first Long March 5 were being built late last year, by which time the boosters were ready. The next step was to be assembly of the complete airframe without engines. That appears to be the stage that has now been reached. The photograph of the airframe, shown on China Central Television, reveals no sign of the engines.

“Whole-rocket” tests have been conducted successfully on the assembled launcher, says CASC.

In February, the Xinhua news agency reported that the program had completed a ground test on the power system of the Long March 5.

CALT, SAST and AAPT are parts of CASC, which is the main manufacturer for the country’s space program.  Aviationweek

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