01. Overview: Beyond Expendable Launchers
While mainstream coverage focuses heavily on crewed orbital missions, the Indian Space Research Organisation (ISRO) is quietly executing a generational shift in structural and propulsion engineering. At the center of this transition are two critical programs: the NGLV (Next Generation Launch Vehicle — codenamed “Soorya”) and the ADMIRE (Autonomous Discretionary Maneuvering Industrial/Experimental) vertical takeoff, vertical landing (VTVL) testbed.
For scale aerodynamic modeling and CAD reconstruction, NGLV represents a complete departure from the strap-on heavy architecture of the LVM3, moving toward a high-fineness-ratio monolithic core designed for booster recovery.
02. Propulsion Shift: The LME-1100 Methalox Architecture
Unlike the hypergolic Vikas engine or solid S200 boosters, the NGLV core stage utilizes liquid oxygen (LOX) and liquid methane ($\text{CH}_4$) in a staged-combustion cycle.
- Engine Designation: LME-1100 (110-tonne thrust class)
- First Stage Cluster: 9 × LME-1100 engines arranged in a central gimballing + outer ring octaweb-style thrust structure
- Upper Stage: C32 cryogenic stage powered by a single CE-20 engine (later transitioning to a methalox upper stage)
- Soot & Reusability Factor: Methane eliminates the coking (carbon soot buildup) associated with kerosene (RP-1), allowing rapid turnaround of turbopumps and injector plates without full teardown.
03. Aerodynamic Control Surfaces for Booster Recovery
To recover the first-stage booster via barge or downrange landing pad, both the sub-scale ADMIRE test vehicle and the full-scale NGLV First Stage integrate three distinct mechanical subsystems rarely seen on Indian launchers:
- Deployable Planar / Lattice Grid Fins: Mounted near the interstage ring to provide high-authority pitch, yaw, and roll control during hypersonic and supersonic atmospheric re-entry.
- Cold-Gas Attitude Control Thrusters (ACS): Positioned at the upper interstage to flip the booster post-MECO (Main Engine Cutoff).
- Pneumatic/Hydraulic Telescopic Landing Legs: Four base-mounted carbon-composite struts folded flush against the lower propulsion skirt during ascent.
04. Reference CAD Scaling Table (Real vs. 1:100 & 1:144 Scale)
For CAD designers and scale engineers building digital twin assemblies, below are the baseline dimensional conversions derived from official VSSC/ISRO structural disclosures:
| Structural Parameter | Full-Scale Baseline | 1:100 Scale (CAD mm) | 1:144 Scale (CAD mm) |
| Total Vehicle Height | 93.0 m | 930.0 mm | 645.8 mm |
| Core Booster Diameter | 3.8 m | 38.0 mm | 26.38 mm |
| Payload Fairing Diameter | 5.0 m | 50.0 mm | 34.72 mm |
| Hammerhead Fairing Taper | 15° Boattail | 15° Constant | 15° Constant |
| Stage-1 Engine Nozzles | 9 × Bell Nozzles | 9 × 6.2 mm Exit Dia | 9 × 4.3 mm Exit Dia |
05. Key CAD Modeling Notes for Lab Iteration v0.1
When modeling the NGLV silhouette in 3D CAD, two geometric features define its visual accuracy:
- The Hammerhead Fairing Profile: Because the payload fairing (5.0 m) is wider than the core booster (3.8 m), the upper stage features an aerodynamic boattail transition skirt to minimize transonic drag and aero-acoustic buffeting.
- Base Heat Shield & Engine Skirt: The 9-engine cluster requires a scalloped metallic thermal protection shield at the base to survive recirculation heating during retro-propulsive landing burns.
Status: Digital blueprint dimensional verification complete. Next log will cover 3D wireframe modeling of the supersonic lattice grid-fin actuator housing.