YF-1


The YF-1 was a Chinese liquid rocket engine burning N2O4 and UDMH in a gas generator cycle. It is a basic engine which when mounted in a four engine module forms the YF-2. It was used as the basis for developing a high altitude version known as the YF-3.
Some authors state that it was a direct copy of С.2.1100/С.2.1150 La-350 booster engine developed by Isayev OKB-2. What is known is that the engine development had great trouble with combustion instabilities and it took a long time to have a reliable combustion.

Versions

The basic engine has been used since the DF-3 rocket and has been the main propulsion of the Long March 1 orbital launch vehicles.
While the basic engine was used multiple times, it was only used as a single engine for booster application. It is usually bundled into modules of multiple engines.
The relevant modules for first stage application are: