Commercial Rockets

LONG MARCH (Chángzhēng, 长征) — “classic” models — China, 1970

The Chinese have put many different rocket models under this one name — so many that I’m going to put the newer ones in a separate article. Here we will look at models 1 through 4.

These older Long March rockets burn hypergolic fuel, like the Proton. Model 1 was a rather small rocket — they added a third stage to a ballistic missile (Dōng Fēng 4) and got a capacity of about 0.3 tons to low orbit, with which they launched their first two satellites. They quickly moved on to a more serious rocket, and used the Dong Feng 5 as a starting point. It was originally called the Fēng Bào (风暴), which means Storm, but then got dubbed Long March 2, with the name change coinciding with a move to a new manufacturer. The success record was poor at first but improved with revisions. Model 2A could lift 1.8 tons, 2C could lift 2.4, and 2D (which was lengthened) did 3.1 tons. These use four gimballed engines on the first stage, and one with a large nongimballed bell on the second, with separate little vernier rockets for steering.

Then for the 2E, they added the feature which has been characteristic of China’s heavier rockets ever since: four liquid fueled side boosters with one engine apiece, doubling the thrust and bringing the LEO capacity up to about 9 tons. The smaller 2C and 2D models remain in use to this day, along with the 2F which replaced the 2E.

The Long March 3 is similar to the 2 but with a hydrogen-burning third stage added, while at the same time shortening the second stage relative to the heavy version used in the 2. Again, models 3A, 3B, and 3C all remain in active use. This is used mainly for geosynchronous orbits. The 3C uses two side boosters instead of four; the different models are basically just optimized for different payload weights. The 3B has its own variations: 3B/E and 3B/G, with lengthened first stages and side boosters which made their first appearance in the 2F. There is also a 3C/E using the lengthened stages. I think the short stages are now dropping out of use, except in the lightweight Model 4. This is an upgrade which omits the side boosters and uses small upper stages — the second is even shorter than the one used in the 3, and the third is a small hypergolic one rather than the hydrogen burner. Models 4B and 4C are in use.

All of these rockets essentially form a single modular system, mostly built around a single engine, the YF-20. One in each side booster, four in the core stage, and one with a large bell (plus a small vernier engine) in the second stage. Only the third stages use a different engine.

At times these rockets have had a much poorer reliability record than their American and Russian competition, and have sometimes killed bystanders in downrange areas, yet now they claim a streak of 75 consecutive successful launches, from 1996 to 2009. In 2003 a Long March 2F, now dubbed “Shénjiàn” (神箭, Heaven Arrow — a reference to ancient gunpowder rockets which were commonly attached to arrows), carried China’s first astronaut — er, taikonaut — into orbit. It was a punishing ride because the rocket’s vibration was exceptionally harsh. They’ve managed to reduce it since then. (The 2E was even worse; it was retired after it shook a couple of satellites apart.) Later, a 2F/Shenjian launched a small orbital habitat, and then another was able to rendezvous with it.

China has recently started developing a much more modern range of rockets which burn kerosene and hydrogen — some of them quite large. These continue to use the Long March name but are covered in a separate article in the “modern era” section. Of these, model 7 is the one which retains the classic design while modernizing the propulsion. Model 6 is smaller, and model 5 is larger. But despite the obsolescence of models 2, 3, and 4, all three remain in heavy use, with a combined launch cadence which sometimes exceeds that of SpaceX, let alone Roscosmos.

Long March 2F: mass 464 t, diam 3.3 m (7.8 at base w/o fins), thrust 6500 kN, imp 2.8 km/s, type Gd, payload 8.4 t (1.8%), cost $15M/t?, record 139/4/10 (8 crewed).
Long March 3B/E: mass 459 t, diam 3.3 m (7.8 at base), thrust 5900 kN, imp 2.8 km/s, type Gd, payload 12 t (2.8%), cost $6M/t?, record 128/0/6.
[Show stages] (LM 2 and 3)
Stage name L-45 L-186 L-86 (LM-2) * L-54 (LM-3) H-18 (LM-3) * Yuanzheng
Role (pos) count booster (S) ×2|4 core (1) upper (2) upper (2) kick (3) kick (3|4), opt
Diameter (m)   2.25   3.30   3.30   3.30   3.30
Liftoff mass (t) 48.5 199    91   52   19.2
Empty mass (t)  4.0 13.0  4.8  2.8  0.9
Fuel mass (t) ~14.3  ~60    ~27.1  ~15.5  ~3.0
Oxidizer mass (t) ~30.2  ~126     ~59.1  ~33.7  ~15.3 
Fuel type UDMH UDMH UDMH UDMH hydrogen UDMH
Engine YF-20C YF-21C
(20C ×4)
YF-24E (22E +
23F vernier)
YF-24E (22E +
23F vernier)
YF-75 ×2 YF-50D
Power cycle gas gen gas gen gas gen gas gen gas gen ?
Chamber pres. (bar) 71   71   71   71   38  
Ox./fuel ratio   2.12   2.12   2.18   2.18   5.10
Thrust, vac max (kN) 810    3300     830    800    160     6.5
Thrust, SL initial (kN) 740    2960    
Spec. imp, vac (km/s)   2.83   2.83   2.97   2.97   4.30   3.09
Total imp, vac (t·km/s) 491    513    255    147    78.4
Long March 4C: mass 250 t, diam 3.3 m, thrust 3000 kN, imp 2.6 km/s, type Gd, payload 4.2 t (1.7%), cost $12M/t?, record 79/0/2.
Stage name L-176 L-36 L-14.5
Role (pos) count core (1) upper (2) kick (3)
Diameter (m)   3.30   3.30   3.30
Liftoff mass (t) 188    37.4 15.5
Empty mass (t) 12.3  2.0  1.0
Fuel mass (t) ~56    ~11.1  ~4.6
Oxidizer mass (t) ~119    ~24.3  ~9.9
Fuel type UDMH UDMH UDMH
Engine YF-21C
(20C ×4)
YF-24E (22E +
23F vernier)
YF-40B rs
Power cycle gas gen gas gen gas gen
Chamber pres. (bar) 71   71   46  
Ox./fuel ratio   2.12   2.18   2.14
Thrust, vac max (kN) 3300     800    101   
Thrust, SL initial (kN) 2960    
Spec. imp, vac (km/s)   2.83   2.97   3.00
Total imp, vac (t·km/s) 485    105    43.4