September 30, 2013
Credit: Beijing Aerospace Propulsion Institute
Chinese engineers are proposing a Moon rocket more powerful than the Saturn V of the Apollo missions and matching the payload of NASA's planned Space Launch System (SLS) Block 2, the unfunded launcher that would put the U.S. back into super-heavy space lift.
Drawing up preliminary designs for the giant Long March 9 launcher, Chinese launch vehicle builder CALT has studied configurations remarkably similar to those that NASA considered in looking for the same capability: to lift 130 metric tons (287,000 lb.) to low Earth orbit (LEO). One of the two preferred Chinese proposals has a similar configuration to the design finally adopted for SLS Block 2, though the takeoff mass for both CALT concepts, 4,100-4,150 tons, is greater. On that measure, at least, China wants to build the largest space launcher in history.
Preliminary work is underway for the intended engines. At the Xian Space Propulsion Institute, engineers are certainly planning and probably doing risk-reduction work for a kerosene-fueled engine, apparently called YF-660, that would be comparable to the 690 tons thrust of the Saturn V's F-1. The Beijing Aerospace Propulsion Institute, meanwhile, is working on critical technologies for a 200-ton-thrust liquid-hydrogen engine that would be used for the first stage of one launcher design and for the second stage of both. That engine is apparently called the YF-220.
Comparison with current launchers and engines highlights the scale of China's ambitions: Whereas U.S. SLS engineers are aiming at a 10% increase on the throw weight of the Saturn V and would use mainly familiar propulsion technology, CALT's super-heavy launcher would have 10 times the throw weight of anything that China now has in service, and would be four times bigger than even the largest rocket it is developing—the Long March 5. The YF-660 engine would be five times as powerful as the biggest engine China has so far built, one that has not yet flown.
The Chinese industry is seeking permission to begin developing a Moon rocket. Studies encompass payloads as low as 70 tons to LEO, says an industry official, suggesting that China may follow the SLS concept by first building a smaller launcher adaptable to enlargement.
Possible Long March 9 configurations were shown two years ago. At the International Astronautical Congress held here Sept. 23-27, CALT published main specifications (see table). One of the two concepts, Scheme A, would have four YF-660s mounted in the core first stage and one in each of four side-mounted boosters. In Scheme B, most of the takeoff thrust would come from four solid-propellant boosters, each generating 1,000 tons of thrust, while four YF-220s would be mounted in the first stage. That adds up to 4,800 tons, but the specified total is 5,000 tons, suggesting that the solid-propellant booster engine, the YF-220 or both will generate a little more than the thrust attributed to each individually. The designation of the YF-220 may hint at its real thrust target.
“I don't find much to criticize in their approach, and a lot to like,” says an experienced U.S. space engineer.