Volume: 3 Issue: 1 (2025) Serial Number: 3

Torsion-bar springs remain the dominant primary suspension element in tracked armored platforms of the 30–50 t class — CV90, Puma, K21, Namer, K9 — because they deliver the highest strain-energy density per unit mass of any single-component spring within the geometric constraints of an armored hull (Gomes et al., 2024a). Their dynamic life on cross-country terrain is, however, tightly coupled to two design variables whose individual effects are well understood but whose combined optimum has been only sparsely mapped in the open literature: the shoulder-fillet ratio r_f/d at the spline-to-active-length transition, and the active-to-shoulder diameter ratio D/d. This paper develops a coupled spectral-fatigue framework that combines a calibrated Pilkey-type shoulder-fillet stress-concentration model with the Tovo–Benasciutti spectral correction (Benasciutti & Dirlik, 2021), an ISO 8608 displacement PSD (Lenkutis et al., 2021), and a single-degree-of-freedom wheel-station transfer function, and proposes a new dimensionless Geometric Fatigue-Efficiency Index (GFEI) that couples the stress-concentration penalty, the fillet geometry, the active-length slenderness and the bar mass into a single design-selection scalar. The framework is applied to ten parametric scenarios covering the 33–50 t combat-mass range and is validated against ten synthetic S-N points generated from the published Basquin parameters of five SCOPUS-indexed 2018–2024 fatigue studies on 51CrV4 / SAE 5160 spring steels, achieving Pearson r = 0.580, RMSE = 0.73 decades in log N, and a regression slope of 1.05 consistent with one-decade scatter typical of high-strength spring-steel S-N data (Gomes et al., 2024a; Saklakoglu et al., 2021). Results show that increasing r_f/d from the common-practice value of 0.05 to an optimum of 0.12–0.16 extends the cross-country service life by more than three orders of magnitude in the uncapped Basquin extrapolation, at a bar-mass penalty below 3 %, while lengthening the active length past 2.1 m yields diminishing GFEI gains below 5 % beyond the baseline. The original contribution of the paper is the GFEI index, which condenses the coupled geometric-fatigue trade-off into a single comparable scalar and enables direct designspace screening prior to full FE or field testing.

This article examines the operational effectiveness of 250-gram-class First-Person View (FPV) drones as a precision munition system in urban and semi-urban combat during the Russo-Ukrainian war, drawing on a structured synthesis of operational data released between February 2022 and December 2024. The study proposes and applies a six-dimensional Urban FPV Precision Effectiveness Index (UFPEI) that quantifies performance across target-class versatility, cost-to-kill ratio, electronic-warfare resilience, urban kill-chain latency, operator-training efficiency, and logistical-production footprint. Empirical calibration is performed through three case studies: the defence of Bakhmut (October 2022 – May 2023), the defence of Avdiivka (October 2023 – February 2024), and the Kupiansk–Kharkiv axis operations (2024). The results show that 250-gram-class FPV platforms with commercial-off-the-shelf components achieved a 20– 50% hit-rate band against moving or partially covered targets, with a cost-to-target-value ratio ranging from 1:80 to 1:50,000 depending on target class, and contributed to a documented 60– 70% share of confirmed Russian armoured-vehicle kills during the Avdiivka phase. The integration of FPV strike cycles into the Delta and Kropyva battle-management systems reduced urban kill-chain latency from the early-war baseline of 15–30 minutes to a 2–5-minute operating band by late 2024, while the growth of Ukrainian FPV production from approximately 1,200 units in 2022 to 1.7 million in 2024 demonstrates that the sustainable scaling of a precision munition system at micro-platform scale is possible outside the traditional defence-industrial base. The original contribution of the study is threefold: the proposal of the UFPEI composite metric, the first systematic comparative calibration of FPV urban effectiveness across three major city battles, and the articulation of a second-generation FPV-doctrinal regime characterised by battlemanagement-system integration, tactical unit professionalisation, and sustained production at scale.

The contemporary European security debate has revived the classical question of how far the progressive professionalization of small armed forces converges with, or diverges from, the civilian society that sustains them. This article examines the longitudinal relationship between military professionalization and the civil-military gap across eight small states of Southeast Europe — Slovenia, Bulgaria, Romania, Croatia, Albania, Montenegro, North Macedonia and Bosnia and Herzegovina — over the period 2014–2023. Two composite, dimensionless country-year indices are proposed. The Military Professionalization Index (MPI) combines the share of professional volunteer personnel, the tertiary-education share of the officer corps, defense expenditure as a share of GDP, a NATO-interoperability proxy and a multilateral-exercise-intensity component. The Civil-Military Gap Index (CMGI) combines the trust differential between the armed forces and civilian institutions, a demographicrepresentativeness distance, a value-orientation divergence measure calibrated on EVS and WVS data, and a recruitment-difficulty indicator. An eighty-observation country-year panel is assembled from SIPRI, NATO Official Texts, the IISS Military Balance, Eurobarometer and Balkan Barometer waves, EVS/WVS rounds and DCAF regional reports. Within-country fixed-effects regression of CMGI on MPI and MPI² yields a negative linear coefficient of – 1.88 (t = –6.84) and a positive quadratic coefficient of +1.35 (t = 7.31), implying a U-shaped relationship with a country-invariant minimum at an MPI threshold of 0.697 (adjusted R² = 0.487). The cross-country Pearson correlation between sample-average MPI and CMGI is – 0.53. Three hypotheses are supported: professionalization narrows the civil-military gap at low-to-intermediate levels of development; the relationship is non-linear and reverses beyond the threshold, consistent with the specialization-divergence thesis; and NATO membership affects the gap primarily through professionalization rather than directly. The principal contribution is the joint MPI-CMGI framework, which renders the professionalization-gap relationship a measurable, panel-comparable quantity and provides the first empirical bridge between the classical civil-military-relations literature and the military sociology of post-modern small-state armed forces in the Southeast European operating environment.

The transition from a logistical pause to a combat manoeuvre represents one of the most underexamined inflection points in armoured-mechanised operations. During a pause, vehicles are dispersed in an assembly area with heterogeneous fuel states shaped by patrol activity, engine idling, environmental conditioning and unequal previous consumption; when the orderto-move arrives, the battalion must refuel and move out within a fixed window that is typically 90 to 180 minutes. This article develops an original formal model of fuel redistribution for a reinforced armoured-mechanised battalion of ninety vehicles across three consumption classes, and compares four redistribution policies (proportional, priority-based, greedy shortest-processing-time, and an optimised lexicographic weighted schedule) under three tanker-fleet configurations (three, five, and eight 15,000-litre tankers). The study introduces the Battalion Refueling Readiness Index (BRRI), a novel composite metric that integrates the share of vehicles meeting their class-specific fuel threshold, the dispersion of the post-refuelling fuel distribution, and the makespan of the refuelling operation. Two hundred Monte Carlo realisations of pre-manoeuvre fuel states yield three principal findings. First, policy choice is decisive in the knife-edge fleet regime: in the small-fleet configuration the priority-based policy outperforms the proportional baseline by 8.7 percentage points of BRRI, whereas in the large-fleet configuration all four policies converge within 0.5 points. Second, the greedy shortest-processing-time rule maximises the headcount readiness rate in constrained fleets (59.4% vs. 50.0% under priority), but does so at the price of elevated dispersion (22.3% vs. 17.3%), which is operationally costly because it leaves heavy vehicles of the main effort below the combat threshold. Third, sensitivity analysis shows that reducing the order-to-move window from 120 to 60 minutes collapses BRRI by roughly half in the small-fleet configuration while leaving the large-fleet configuration essentially unaffected, which identifies tanker-to-vehicle ratio rather than scheduling sophistication as the dominant lever. The original contribution of this article is threefold: the BRRI metric, a transition-specific mixed-integer scheduling formulation distinct from steady-state convoy refuelling problems, and an empirical demonstration that class-priority heuristics dominate in the operationally relevant fleet regime. The results have direct implications for the doctrinal sizing of Class III (Bulk) distribution platoons in small NATO and partner-state armoured brigades.

This article evaluates the evolution of civilian control over the armed forces in Bulgaria across two decades of North Atlantic Treaty Organization (NATO) membership (April 2004 — April 2024), combining a longitudinal institutional analysis with a structured regional comparison. The study develops an original composite indicator, the Civilian Oversight Completeness Index (COCI), which aggregates seven dimensions of civil control — parliamentary oversight, executive–ministerial balance, judicial autonomy over military justice, intelligence oversight, defencebudget transparency, media and civil-society engagement, and procurement transparency — each scored on a 0-to-10 scale using coded indicators drawn from NATO host-nation assessments, DCAF peer reviews, Transparency International Defence Index data, V-Dem and Varieties-ofDemocracy micro-variables, Bulgarian National Audit Office reports, and a systematic reading of 124 parliamentary-committee transcripts. The empirical analysis yields three principal findings. First, Bulgaria's aggregate COCI score rose from 4.2 (2004) to 7.3 (2024), a gain of 3.1 points that places Bulgaria in the upper-middle tier of Central and Eastern European NATO members but clearly below Slovenia (8.1), Slovakia (7.6) and Romania (7.4). Second, the institutional progress is highly uneven across dimensions: parliamentary formal powers, executive civilianisation, and budget transparency advanced by more than 3.5 points each, whereas judicial autonomy over military justice, intelligence oversight, and procurement transparency improved by only 1.6, 1.1 and 1.4 points respectively, producing a pronounced dimensional-disparity index of 0.47. Third, the gap between formal and substantive civil control in Bulgaria — captured by the COCI versus the Bertelsmann Transformation Index (BTI) substantive-democracy score — stands at 1.2 points in 2024, compared with 0.4 in Slovenia, 0.5 in Slovakia, and 0.8 in Romania, indicating the largest institutional-substantive gap in the regional peer group. The article interprets these findings through a political-institutionalist lens and argues that Bulgaria exemplifies a trajectory of accelerated formal compliance combined with retarded substantive democratisation, in which NATO accession pressure consolidated formal oversight architecture but left three residual deficits — parliamentary depth, intelligence autonomy, and procurement transparency — only partially addressed. The article concludes with policy implications for NATO enlargement conditionality, for the Allied Centres of Excellence agenda on resilient governance, and for the prospective security-sector-reform trajectories of non-member Western Balkan states

Disinformation operations have become a persistent feature of the Western Balkan security environment and are increasingly treated, in both NATO doctrine and regional strategic documents, as an asymmetric instrument of pressure targeting the cognitive rather than the material layer of the defence system. This article examines the empirical link between the intensity and coherence of disinformation operations and the evolution of public confidence in the armed forces across five Western Balkan states — Bosnia and Herzegovina, Serbia, Montenegro, North Macedonia and Kosovo — over the period 2016–2023. A composite Disinformation-Cohesion Transfer Index (DCTI) is proposed, combining the per-capita volume of tagged military-relevant narratives, social-media platform penetration, a HerfindahlHirschman thematic-coherence measure and a per-capita refutation-intensity term from regional fact-checkers, anchored to a cohesion baseline derived from Gallup World Poll and Balkan Barometer data. A forty-observation country-year panel is assembled from the EU East StratCom Task Force database, the DFRLab case catalogue, regional fact-checker outputs, social-media penetration statistics and public-opinion waves; four case studies — the 2016 Montenegro coup-attempt cluster, the 2018 Prespa Agreement referendum, the 2021– 2022 BiH secession-rhetoric spike, and the 2022–2023 Kosovo license-plate and Banjska crisis — are analysed in depth. Within-country fixed-effects regression of the change in military confidence on log DCTI and its one-year lag yields a negative contemporaneous elasticity of –10.9 pp per log unit, a weaker positive first-lag coefficient of +4.7 pp per log unit consistent with a recovery pathway, and an adjusted R² of 0.66 across thirty-five country-year transitions. Three hypotheses are supported: disinformation intensity is non-trivially linked to militarycohesion erosion across the five states; thematic coherence amplifies the impact of raw narrative volume; and refutation intensity below a country-specific threshold is associated with non-linear erosion of public trust in the armed forces. The principal contribution is the DCTI framework, which renders asymmetric disinformation pressure on military cohesion a measurable, panel-comparable quantity and provides a first empirical bridge between the hybridwarfare and military-sociology literatures for the Western Balkan operating environment.

This article develops an engineering-grounded framework for determining the optimal depth of entrenched infantry positions intended to defeat top-attack strikes delivered by firstperson view (FPV) quadcopter drones carrying approximately 200 g of RDX-based high explosive — a charge mass now canonical on the Russo-Ukrainian frontline. The analytical problem is framed around three coupled physics regimes that jointly determine survivability: the peak incident and reflected airblast overpressure field generated by a near-vertical detonation above an open trench, the fragmentation flux produced by the drone's steel or cast-iron casing and embedded preformed fragments, and the attenuation of ground shock in soils of different grain-size and moisture-content classes. Using the Kingery–Bulmash polynomial representation as validated in recent SCOPUS blast-engineering literature, and benchmarking against Kinney–Graham scaleddistance predictions, the study computes peak overpressure, positive-phase impulse and fragment impact kinetic energy as functions of entrenchment depth, parapet height and soil type. The analysis integrates empirical data from the Russo-Ukrainian war, where FPV fragmentation warheads now cause over 70 % of frontline infantry casualties, with computational fluid dynamics findings reported in the 2024 Defence Technology study of trench blast injury. The principal original contribution is the formulation and quantitative calibration of an Entrenched Position Survival Index (EPSI) — a five-dimensional composite metric aggregating airblast attenuation, fragmentation shielding, ground-shock dissipation, thermal-flash mitigation and structural-collapse resistance — specifically tuned to the 200 g RDX-class top-attack threat. Results indicate that legacy field-manual depths of 1.5–1.8 m, which were calibrated for indirect artillery fire, offer EPSI scores below 0.55 against FPV top-attack, whereas a 2.0–2.2 m trench with a 0.3–0.5 m sandbagequivalent overhead cover and a 0.5 m parapet raises the composite to 0.88–0.93, yielding predicted >95 % survival probability for a soldier at the trench floor. Soil grain-size modulation is non-trivial: sandy loams require an additional 20 cm of depth relative to cohesive clay loams to achieve equivalent EPSI, a consequence of higher blast coupling and reduced fragment-arrest capacity documented in the 2018 Lu and Fall review. The findings argue for doctrinal revision of entrenchment standards in FPV-saturated battle-spaces and provide a transparent engineering template for small-unit engineer officers.

High-hardness armor (HHA) steels such as Armox 500T are qualified against singleshot threats, yet multi-hit studies show that repeated impacts within a limited footprint can degrade residual protective capacity in ways the single-shot paradigm does not capture. This paper develops a theoretical framework for the cumulative thermomechanical degradation of Armox 500T under repeated 7.62 × 51 mm NATO impacts and introduces the Cumulative Thermal Degradation Index (CTDI), a dimensionless predictor constructed from independently measurable or published inputs. The CTDI couples the Johnson–Cook constitutive response of Armox 500T (Iqbal et al., 2016; Saleh et al., 2018) with the Taylor–Quinney plastic-work-to-heat conversion framework revisited by Rittel et al. (2017) and with a one-dimensional thermal-relaxation model parameterized by published diffusivity data for martensitic steels. Hardness, fracture toughness and microstructural state appear only as validation outputs — never as inputs — removing the circularity that has complicated earlier cumulative-damage indices. The CTDI is validated against published datasets of Demir (2023) for Armox 600T and Saleh et al. (2018) for Armox 500T. Against Demir (2023) the CTDI shows Pearson r = 0.993 (p < 0.001, RMSE = 0.34 %); against Saleh et al. (2018) r = 0.997 (p = 0.003, RMSE = 0.11 %). Under hypothesis H1, localized heating can exceed the 720 °C recrystallization threshold for dense impact patterns with inter-shot intervals below approximately six seconds. The framework identifies inter-shot interval, overlap geometry and local plastic strain as dominant controls, and suggests that STANAG 4569 protocols may under-report residual-capacity loss for realistic short-burst engagements. All code, tables, figures and raw CTDI outputs are released as open supplementary material.