Aerospace Technic and Technology

The article examines light sport aircraft (LSA) with a maximum take-off weight (MTOW) up to 600 kg as targets for hybrid powertrain integration and the quantitative boundaries of such hybridization under the stringent regulatory and mass constraints inherent to this aircraft class. The goal of the article is to formalize the mass and aerodynamic constraints of hybridization for the LSA class with a fixed MTOW of 600 kg and to justify selecting the serial Bristell LSA aircraft as a platform for the subsequent conceptual design of a hybrid powertrain. The tasks to be solved are: to conduct a systematic review of publications from 2015 to 2026 on hybrid-electric propulsion and to identify the research gap for the LSA class; to propose a classification of light aircraft with MTOW ≤ 600 kg by features relevant to the mass-energy balance; to perform a quantitative comparison of six serial LSA models using the mass efficiency metric η_m; to formalize the mass balance equation for an aircraft with a hybrid powertrain under a regulatory-fixed MTOW; to establish an upper mass increase bound through linearization of the stall speed equation compatible with the V_S0 ≤ 45 kts restriction; to justify the hybrid system architecture and the realistic range of the degree of hybridization H_P; and to select a specific serial platform using a formalized suitability criteria system. The methods applied include: systematic literature review with quantitative extraction of unresolved tasks; comparative analysis of flight performance characteristics of serial LSAs based on manufacturer data; analytical modeling of the aircraft mass balance; linearization of the stall speed equation for small mass perturbations; structured analysis of the EASA CS-LSA and FAA 14 CFR Part 1.1 / ASTM F2245 regulatory frameworks; multi-criteria suitability assessment of the platform. The results obtained: the mass efficiency metric η_m for six serial LSAs lies in the range 0.410–0.517 with a spread of 10.7 percentage points, equivalent to ≈ 64 kg of payload; for the Bristell LSA (EW = 325 kg, η_m = 0.458) with full fuel tanks of 120 L the available mass budget for the hybrid superstructure is only 18 kg, while with 60 L fuel it reaches 62 kg; linearization of the V_S0 equation establishes for this platform an absolute upper mass increase bound Δm_max ≈ 56 kg (a constraint inactive for aircraft with MTOW > 900 kg); the realistic degree of hybridization is H_P = 0.087…0.214 ≈ 0.1…0.25, significantly below H_P = 0.3…0.5 typical for general aviation aircraft; the parallel hybrid architecture has been selected as the only one compatible with the regulatory requirement of a single non-turbine engine; under the four suitability criteria K1–K4 the Bristell LSA achieves a score of 4/4 and is selected as the platform for subsequent research stages. Conclusions. For the first time for the LSA class with MTOW ≤ 600 kg a closed system of mass-aerodynamic hybridization constraints has been constructed, comprising: the mass balance equation Δm_hyb ≤ 105 − m_fuel; the linearized stall speed constraint Δm_max ≈ 56 kg; a formal definition of the H_P range through the regulatory MTOW limit; and the CS-LSA-based justification of the parallel architecture. Scientific novelty lies in identifying and formalizing the V_S0-specific dominant constraint for the LSA class, inactive for larger aircraft and not considered in previous studies, as well as in the methodology of multi-criteria selection of a serial platform for subsequent hybrid powertrain development under fixed MTOW conditions.

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