Abstract：[Objective] The top-level metrics for evaluating the performance of an aircraft fire-extinguishing mission system include effective drop utilization rate and uniformity. The former refers to the ratio of the liquid collected on the ground within the effective coverage area to the dropped liquid; this ensures that sufficient liquid falls to the effective coverage area on the ground. The latter refers to the average thickness of ground coverage within the effective coverage area; this ensures that the thickness of liquid coverage falling to the effective coverage area on the ground meets the requirements of the firefighting task. However, physical modeling and the top-level metrics decomposition and allocation for fire-extinguishing mission systems have not yet been documented. The current work aims to address a semiphysical and semiempirical model for the top-level metrics decomposition and allocation of large firefighting aircraft fire-extinguishing missions.[Methods] Based on the ground pattern and fraction models by Legendre et al. and Gu et al., respectively, we establish a semiphysical and semiempirical model for the top-level metrics of aircraft fire-extinguishing missions by coupling logical reasoning and theoretical derivation methods. Further, we clarify the quantitative relationship between the top-level metrics and parameters at the design stage (such as the average flow rate and the total amount of liquid dropped) and the planning stage (such as the viscosity of the released liquid, the density of the released liquid, flight velocity, and flight altitude) of the fire-extinguishing mission system. Moreover, the top-level metric decomposition and allocation method is proposed by reversely applying the semiphysical and semiempirical model with a predetermined liquid release performance requirement as the goal. This enables rapid calculation of the range of relevant parameter values at the design and planning stages of the fire-extinguishing mission system, providing a theoretical basis for the iterative upgrade design of existing aircraft models and mission planning.[Results] To validate the effectiveness of the top-level metrics decomposition and allocation method for aircraft fire-extinguishing missions, this study decomposes and allocates the top-level metrics for a typical fixed-wing large firefighting aircraft fire-extinguishing mission system, obtaining the “hatch area” range for the design stage and the “fire-retardant viscosity” and “flight altitude–flight velocity” decision-making planes for the planning stage of the fire-extinguishing mission.[Conclusions] The results indicate that the proposed decomposition and allocation method can, to some extent, guide the optimization design and fire-extinguishing mission planning of the fixed-wing aircraft fire-extinguishing mission system.
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2023, Vol. 63 
