Yeah, Henri's article is interesting.
Seems like the DF-31AG's main improvement is its cross-country TEL and a longer ranged missile (visible through the structural reinforcements on the launch tube as required by higher pressue propellants).
Unlike its older DF-31A , which is placed on a semi-trailer 1S1-31A , which is pulled by a road tractor, this new DF-31AG uses a 16 × 16 Tractor-Erector-Launcher (TEL) Thus its off-road capability.
The launch tube has several circular reinforcements, suggesting more pressure during missile take-off. Changes in the propulsion system, at least for the 1st stage, could have been implemented. It is therefore not excluded that a new type of propellant of the N-15 family, which develops a specific pulse (ISP) higher than that of HPTB and NEPE used in the other ICBMs of the world.
It is probably for this reason that this new variant of Chinese mobile ICBM is called DF-31AG, which should read DF-31A (改), where 改 (Gaï) means "Modified" in Chinese.
While the propulsion system of the missile seems to have evolved, there is no indication that its size has changed. The DF-31 and its extended range version DF-31A are mono-ogive ICBMs, the first and second stage of which measure 2 meters in diameter and 1.4 meters for the third stage. The maximum effective range of DF-31A is 12,500 km.
Based on the first available elements today, it is believed that the DF-31AG would bring the following gains over previous versions:
-Improve the off-road capability of the carrier, therefore its mobility and survivability
-Increase the range of the missile at a lower cost, by changing its engines and reducing the structural mass
Therefore, the DF-31AG would be a project to upgrade the existing DF-31 and DF-31A to a more advanced standard without fundamentally changing the design. It is unclear, however, whether it is the DF-31B whose existence was revealed by the Americans after its shooting of September 25, 2014 .
To be continued.
Maybe this warrants a DB entry; DF-31AG with 6749 nmi instead of 6074 nmi of the DF-31A.