M-V

While the Mu-3 series were based on a 1.41 m diameter first stage, the new M-V -I use a new first stage. It is 2.51 m in diameter and much more powerful. It enable the doublement of the payload mass in LEO. This M-14 stage is 13.7 m long with over 70 tons propellant in 2 segments. The motor burn profile is designed for a relatively short, high-thrust burn. The action time is 85 seconds (web time 51 seconds). The second stage M-24 has the same diameter and  including over 30 tons solid fuel. It makes use of the FIH (Fire In the Hole) technology. It is linked to the first stage by a mesh structure and ignited at separation between first and second stage. The third stage M-34 is 2.2 m in diameter and including 10 tons propellant . The first and second stages use maraging steel cases and CFRP nozzles (Carbon Fiber Reinforced Plastic). The third stage uses a carbon fiber-epoxy case and a CFRP nozzle. The first stage uses the movable nozzle thrust vector control (MNTVC) system. The second-stage pitch and yaw attitudes are controlled by the liquid injection thrust vector control (LITVC). The fairing is made  of honeycomb sandwich shell with CFRP face plates. The fairing encloses the payload and the third stage. Mu-V1 can place 1.8 tons in low orbit at 240 km or 1.215 tons in GTO.

Three years have passed since the last operation of M-V-4, than the 2nd stage motors and kick motors were newly developed. Introduced as part of the M-V-II rocket improvement plan, the M-25 TVC (the second stage thrust vector control) is an attitude-control unit using MN (Movable Nozzle) TVC in place of conventional LI (Liquid Injection) TVC to improve thrust performance. Different from LITVC, there is no exhaustion due to overuse or leak of liquid propellant with MNTVC. The stage M-25 (the 2nd stage rocket and 1st/2nd stages joint) weighing about 40 tons.