Long March 3B/E is the biggest launcher of the Long March Family standing 56.33 meters tall with a main diameter
of 3.35 meters and a liftoff mass of 458,970 Kilograms. It represents a recent improvement of the Long March 3B Launcher
that first flew in 2007 and features a larger first stage and boosters than the CZ-3B to increase its payload capability
to Geostationary Transfer Orbit to 5,500 Kilograms and Low Earth performance to 12 metric tons.
Long March 3B features a core stage and four-strap-on boosters and a second stage, all using storable propellants, being topped by a cryogenic third stage. The four strap-on boosters use 37,700 Kilograms of Unsymmetrical Dimethylhydrazine and Nitrogen Tetroxide as propellants. Each of the Boosters is 15.3 meters long and 2.25 meters in diameter. The strap-ons provide 740 Kilonewtons of thrust with their YF-25 engine and are jettisoned after burnout and fall back to Earth. The boosters burn just over two minutes.
The Core Stage of the vehicle features four YF-20C engines that provide a combined thrust of 2,962 Kilonewtons. The stage is 23.3 meters in length and holds 171,800 Kilograms of storable propellants at blastoff. Stage 2 has a burn time of 2 minutes and 39 seconds. The second stage of the Long March 3B also uses Hydrazine and NTO as propellants on its way uphill. The second stage features a YF-22E Main Engine providing a thrust of 742 Kilonewtons as well as four 12kN Vernier Engines. The stage is 10 meters in length consuming 49,000 Kilograms of propellants during flight. It burns for just over three minutes before the third stage takes over.
Unlike the other stages, the third stage of the CZ-3B is powered by cryogenic Propellants. The upper stage of the Long March 3B is powered by two YF-75 Engines - each providing 79 Kilonewtons of Thrust. Third Stage propellants are 18,200 Kilograms of liquid Oxygen and liquid Hydrogen. The Upper Stage has a reduced diameter of three meters and is 12.4 meters long.
For Geostationary Transfer Orbit Missions, the third stage makes two burns with variable durations, the first puts the vehicle in a Parking Orbit while the second raises the Apogee to match Geostationary Altitude.
The payload fairing of the CZ-3B/E is 4.2 meters in diameter capable of hosting large payloads.
On launch day, the rocket went through a 7-hour countdown operation that started with the fueling of the Cryogenic Third Stage with Liquid Oxygen and Liquid Hydrogen – the remaining stages and boosters are filled with hypergolic propellants several days before launch. As the countdown progressed, the launch vehicle was powered up and started functional tests of its telemetry and communications system at L-80 minutes. The flight software is loaded into the computers of the launcher at L-40 minutes followed by a verification of the Guidance & Control System of the vehicle.
Also, the payload air-conditioning system is reconfigured and the purge system of the first and second stage is disconnected for launch. In the final 20 minutes of the countdown, the third stage engine begins its Chilldown Sequence to condition it for ignition. At L-15 minutes, the third stage propellant topping sequence begins followed by the disconnection of the spacecraft umbilical after the satellite had been placed in flight mode.
The telemetry system of the launcher goes into launch mode at L-3 minutes and one minute later, the umbilical arms to the third stage are retracted. 90 seconds before launch, the vehicle is switched to internal power and the control system of the vehicle assumes control of the countdown at L-1 minute. After a final set of systems checks, the engines of the boosters and first stage are ignited at L-0 with liftoff occurring an instant later.
Following its liftoff from the Xichang Satellite Launch Center, Sichuan Province, China’s launch site for Geostationary Launches, the Long March 3B launch vehicle started following its standard ascent trajectory towards GTO.
This flight profile calls for the pitch maneuver shortly after liftoff to align the vehicle with its trajectory to the East. Booster Separation occurs 2 minutes and 21 seconds into the flight followed by first stage shutdown and separation at T+2:39. Debris of the boosters and core stage fall back to Earth and impact downrange from the launch site on China’s mainland. The fairing separates just before the 4-minute mark and also falls back to Earth for a crash landing downrange from the launch site. Around 5 minutes and 45 seconds into the mission, the second stage burns out and is jettisoned.
Shortly thereafter, the third stage ignites on its first burn which is about 4 minutes and 30 seconds in duration ending just after passing 10 minutes into the flight. After coasting in its Low Earth Parking Orbit for 10 minutes and 30 seconds, the third stage ignited again to increase the apogee at the appropriate location which is precisely targeted. The burn begins at about T+21 minutes and is just over three minutes in duration. After shutdown, the third stage performs a re-orientation ahead of spacecraft separation at T+25 minutes and 45 seconds.
This launch was the 176th successful Chinese orbital launch and the 176th launch of the Long March rocket family. It was the 77th orbital launch from the Xichang Satellite Launch Center and the second Chinese launch of 2013 – the first out of Xichang.
