That's just the engine mass, there's still the mass of the rocket body.That's 6.25% dry mass, that's crazy! In comparison space shuttle SRBs are 15.4% dry mass (91 ton out of 590 ton gross).
A solid rocket motor with a carbon fibre body? That just screams ICBM. DF-51?That the engine is referred to as "sharpened sword" also hints at military applications, if there was any doubt.
With SRBs I don't think there's such a thing as "mass of engine vs mass of tankage", the whole vessel is kind of the engine and has to stand up to the pressure. 160 tons is quotes as the mass of the whole thing, casing nozzle and fuel, and 150 ton is quoted as the fuel mass so dry mass is 10 tons?
No DF51, because based on China’s naming police, DFAB, A means Number of rocket segments. It’s possible for DF45, not 51