1. Basic information
YF-115 is a high-altitude oxygen-rich afterburning cycle liquid oxygen kerosene engine developed by the Sixth Academy of Aerospace Science and Technology. It forms a series with the YF-100 engine and is widely used in my country’s new generation launch vehicle. According to vector control capabilities, YF-115 is divided into YF-115F (one-way swing in front of the pump), YF-115G (two-way swing in front of the pump ±5°), and YF-115H (no swing capability). Subsequent improvements include YF-115B and Tianhuo-11.
2. Core parameters
(1) Structural parameters
length
quality
combustion chamber
Number of turbine pump rotors
Nozzle area ratio
2.325 m
540 kg
1
1
88
(2) Performance parameters
Thrust (vacuum)
Specific impulse (vacuum)
combustion chamber pressure
Thrust to weight ratio
180 kN
3349 m/s
12 MPa
36
3. Development experience
In 2002, while developing the YF-100, my country started the program demonstration and engineering design of the YF-115 using its breakthrough liquid oxygen kerosene supplementary combustion cycle engine technology. In 2005, YF-115 successfully conducted its first gas generator-turbine pump joint test. In 2006, the YF-115 successfully underwent complete machine testing. In 2012, YF-115 completed the preliminary prototype development and entered the sample development stage. In April 2013, the YF-115 was installed on the second stage of the Long March 6 and successfully conducted a hot test run. On August 29, 2014, four YF-115 machines were installed in parallel on the second stage of the Long March 7, and the power system test of the second stage of the Long March 7 was successfully conducted. On September 20, 2015, YF-115 successfully made its first flight mounted on the Long March 6 rocket.
4. Installed application
Long March 6: The second stage of the Long March 6 is 2.25 meters in diameter, equipped with one YF-115, has a double-swing engine, and does not have a secondary start.
Long March 6A: The second stage of the Long March 6A has a diameter of 3.35 meters and is equipped with a YF-115 engine. The engine swings in both directions to provide control torque. During the secondary two-start mission, the engine was replaced with a YF-115B.
Long March 6C: The second stage of the Long March 6C has a diameter of 2.9 meters. It is equipped with one YF-115 engine at one start. The engine swings in two directions to provide control torque. The theory supports secondary ignition. The YF-115B engine is used when the secondary ignition is supported.
Long March 7: The second stage of Long March 7 has a diameter of 3.35 meters and a length of 15.445 meters. It is equipped with two non-swinging YF-115s and two double-swinging YF-115s, with a total thrust of 720 kN (73.47 tons) and a thrust-to-weight ratio of 0.73.
Long March 7A: The second stage of the Long March 7A has a diameter of 3.35 meters, with 2 non-oscillating YF-115s and 2 double-swinging YF-115s.
Long March 12: The Long March 12 has a diameter of 3.8 meters and is equipped with two YF-115Bs. The engine has double swing and can be started twice.
5. Evaluation
As a vacuum-improved engine, the YF-115 nozzle area is relatively conservative and the specific impulse is unsatisfactory. Among my country’s new generation of medium-sized launch vehicles, the capacity of any rocket equipped with YF-115 is much lower than that of similar rockets that do not use YF-115. However, it is an important product for my country’s early exploration and practice in the field of afterburning cycle technology. , YF-115 has accumulated valuable high-pressure afterburning cycle engine design, manufacturing and testing experience for our country, making our country the second country to fully master the liquid oxygen kerosene high-pressure afterburning cycle engine technology, filling a gap in the upper stage power of my country’s new generation rocket at that time, and replacing the traditional plan of the old Long March rocket’s second-stage main engine plus a touring engine.
