Research report | Survivability of a Propellant Fire inside a Simulated Military Vehicle Crew Compartment: Part 1 - Baseline Study
A number of combat vehicles carry their propelling charges and high explosive filled projectiles inside the crew compartment. Such arrangements give rise to questions about the prospects of crew survival in an unplanned munitions initiation event owing to co-habitation of the crew with an on-board magazine. DSTO has undertaken an experimental study to investigate this concern. A trials structure was developed whereby a range of propelling charge types and storage configurations were initiated in a simulated military vehicle crew compartment. The trials structure was fitted out with simulated personnel instrumented to enable the threats from the thermal, ejecta and pressure environment created by the propelling charge event to be assessed. The trial results indicated that the thermal and ejecta threats posed the greatest risk to crew survival. The effectiveness of a range of hazard mitigation techniques was also assessed and this is addressed in Part 2 of this report.
A number of combat vehicles carry their propelling charges and high explosive filled projectiles inside the crew compartment. To permit the provision of informed advice on future acquisition programs, the Capability Development Group tasked DSTO to investigate the prospects of crew survival in the event of an unplanned munitions initiation event owing to the co-habitation of the crew with an on-board magazine. After initial modelling work indicated that a propelling charge fire would indeed subject the crew to a hazardous and potentially life-threatening environment, a trial was conducted in mid-2010 to experimentally ascertain the survivability of the crew when exposed to such an event.
A trials structure was developed whereby a propelling charge fire was initiated in a simulated military vehicle crew compartment, and simulated personnel were instrumented with a range of heat flux gauges and pressure sensors. This data was then fed into models to predict burn levels and intrathoracic overpressure effects. Threats to crew personnel from ejecta were also investigated.
Three propelling charge module types in four different module configurations were tested over the course of the trial and it is these experiments that are the focus of Part 1 of this report. A range of hazard mitigation techniques were also assessed in the trial. These included: the use of a MIL-STD automatic fire suppression system; personnel clothing configurations; and propelling charge storage tube confinement modification. Part 2 of this report addresses the effectiveness of these hazard mitigation strategies.
The trial results indicated that the thermal and ejecta threats posed the greatest risk to crew survival. In the absence of a fire suppression system, a single propelling charge storage tube event will create a thermal environment that will cause severe respiratory and skin burn damage with a minimal probability of survival and will also pose a sympathetic cook-off risk for other stored munitions in the crew compartment. Ejecta in the form of unburnt propellant grains and/or propelling charge modules posed a life threatening risk to crew for all baseline tests conducted using a storage tube configuration considered representative of that used in a representative military vehicle. While the generated pressure in the crew compartment was found to pose a hazard in certain instances, it was secondary to the thermal and ejecta effects.
An evaluation of the suitability of widely used skin burn damage heuristics, which are based on time-weighted energy absorption and ambient temperature parameters, was also made using burn damage predictions from the transient heat flux measurements collected over the course of the trial.