Skyroot Aerospace has achieved a critical milestone in the integration campaign of its Vikram-1 launch vehicle, with the successful assembly of the lower inter-stage structure connecting Stage 1 and Stage 2.

Unlike a conventional inter-stage, which primarily serves as a mechanical load-bearing shell between propulsion segments, the Vikram-1 inter-stage has been designed as a multifunctional systems bay.

It provides a protected environment for key avionics, navigation and safety-critical electronics, as well as housing retro-propulsion hardware, sensors, and the pyrotechnic or pneumatic separation mechanisms needed to execute precise stage detachment during ascent.

This multifunctionality makes the inter-stage a hybrid structural and subsystems module—ensuring effective mass optimisation while reducing the spacecraft’s overall complexity.

The structure itself is fabricated entirely out of advanced carbon composite materials, which contribute high stiffness-to-weight ratios and superior vibration-damping characteristics, essential for both efficiency and survivability under the high dynamic loads experienced during first-to-second stage transitions.

With the integration phase now complete, Skyroot Aerospace has equipped the inter-stage with all its required subsystems, including wiring harnesses, separation actuators, thermal shielding elements, and sensor suites that will monitor vibration, acoustic, and load conditions during flight.

Of special note is the retro-propulsion assembly integrated within the unit, which is designed to ensure clean separation between the stages by creating a slight counterforce that minimises structural re-contact or debris hazards.

Precision sensors mounted in the inter-stage will continuously feed data into the vehicle’s avionics core, enabling near real-time adjustments during the crucial staging event. This highly integrated approach ensures that the performance of stage separation—a historically sensitive and mission-critical phase—achieves maximum reliability and predictability.

The completed structure has now advanced to its next qualification phase: installation on a dedicated vibration test bed. This test campaign will replicate the intense dynamic environments that the inter-stage will encounter during actual flight, including random vibrations, low-frequency oscillations, and coupled loads reflecting motor ignition and thrust decay profiles.

The tests will verify not only the structural integrity of the carbon-composite shell but also the resilience of the avionics, separation systems, and retro mechanisms embedded inside. This vibration validation is critical to ensuring that no hardware failures or inadvertent triggers threaten the sequencing of multiple subsystems during ascent.

Once cleared, the inter-stage will be further subjected to thermal cycling, shock separation tests, and system-level integration rehearsals, before being finally mated with Vikram-1’s fully integrated Stage 1 and Stage 2 propulsion units.

This progress marks a significant forward step in Vikram-1’s developmental roadmap, showcasing Skyroot Aerospace’s engineering depth in building indigenous small satellite launch vehicles capable of modular, reusable, and efficient operations.

The inter-stage’s advanced integration represents not just a structural link between propulsion stages, but a highly sophisticated subsystem command hub that underpins the stability, safety, and success of India’s first privately-developed orbital-class rocket.

The vibration tests now underway will form a decisive qualification milestone, ensuring that Vikram-1 remains on track for its planned flight debut while setting the foundation for scalable next-generation Skyroot launchers.

IDN (With Agency Inputs)