A progressive solid rocket motor development campaign focused on performance, reliability and advanced propulsion research

The Nebula Program consisted of four successive motor iterations (Nebula I, II, III and IV). Nebula is a lating word meaning “fog”, a common weather phenomenon at Lleida-Alguaire airport. Each one was designed to validate new concepts, improve manufacturing methods, and push the limits of in-house solid propulsion technology. Every stage provided valuable data that guided the next generation of development.

The Mission Purpose

Nebula was created to:

Advance Cosmic Research’s expertise in solid rocket motor design
Improve combustion efficiency and structural reliability
Validate simulation tools with real test data
Optimize manufacturing and assembly processes
Explore high-thrust motor concepts for future launch vehicles

Nebula I – First Validation Stage

The first Nebula campaign focused on understanding manufacturing tolerances, ignition behaviour, sealing systems and instrumentation integration.

Main findings

Identified the importance of precise grain geometry
Improved grain fabrication procedures, implementing ammonium nitrate–aluminium propellant technology for the first time
Tested thermal behaviour of nozzle and structural components
Evaluated pressure sensor integration and sealing methods
Detected opportunities for better insulation and sealing performance
Confirmed the need for higher-pressure testing to achieve full combustion efficiency

Nebula I laid the foundations for all future developments. It established manufacturing procedures, validating instrumentation, and providing the first experimental data used to characterize and calibrate the propellant combustion models.

After a previous failed test in a previous iteration (Nebula 0), in March and April of 2019, Cosmic Research performed some more static motor tests to evaluate the performance of the Nebula I motor. The test bench included temperature and pressure sensors and a load cell. The Nebula-I is a 1:10 simile of Bondar’s actual otor.

Nebula II – The Bridge to Nebula III

Nebula II was conceived as an intermediate step between the first prototype and a larger high-performance motor.

Main Objectives

Replicate future large-motor geometry at reduced scale
Validate a full-aluminium structural design
Reduce weight while maintaining safety margins
Improve thermal modelling
Confirm structural resistance of critical threaded and closure components

Nebula II successfully generated new combustion and structural data later used in the design of Nebula III.

Nebula III – High-Thrust Ambition

Nebula III represented the most ambitious stage of the program: the development of an ultra-high-thrust solid motor intended to become one of the most powerful amateur solid motors in Europe.

Highlights

Engineered for record-level thrust performance
Optimized grain geometry developed using newly created in-house design software
Improved manufacturing through a large capacity pressing system, allowing larger grains and fewer grain segments
Incorporated lessons learned from Nebula I and II and validated combustion models from previous campaigns
Designed as the intended propulsion system for the Bondar launch vehicle.

Nebula III marked the transition from experimental prototypes to large-scale propulsion systems. Although the motor did not reach its expected performance levels during testing, the campaign generated valuable data that enabled a comprehensive review of combustion, thermal and structural behavior.

Nebula IV – Diagnostics & Future Improvements

Nebula IV focused on engineering review and root-cause analysis after partial performance issues detected during previous tests.

Areas Investigated

Nozzle geometry optimisation
Grain-to-nozzle spacing
Ignition system tuning
Chamber pressure operating range
Thermal protection quality
Internal gas flow behaviour
Erosive burning effects
Simulation model corrections
Propellant consistency
Grain bonding integrity

Nebula IV transformed test anomalies into engineering knowledge, defining the path toward safer, more efficient future motors.

Outcomes

The Nebula Program became a major internal milestone in Cosmic Research propulsion development. Through iterative testing and continuous improvement, it strengthened our capabilities in:

Solid propulsion engineering
Thermal and structural analysis
Test stand operations
High-thrust motor design
Data-driven development methodology

Mission Collaborator

Aeroports de Catalunya provided the infrastructure that made the Nebula test campaigns possible. By granting access to suitable testing facilities at Lleida–Alguaire Airport, they enabled the safe execution of static firing tests.