Assuming AD-1's been redesigned, I wonder if we're looking at a slimmer booster rocket signifying a potentially lower range/altitude variant. Not sure what would be the rationale for that though.
The other possibility is that some major stride was made in solid-fuel chemical composition, resulting in lesser quantity of fuel needed to achieve same kinematics as before, hence a thinner & lighter booster is enough.
The other possibility is that some major stride was made in solid-fuel chemical composition, resulting in lesser quantity of fuel needed to achieve same kinematics as before, hence a thinner & lighter booster is enough.










