Abstract This paper presents a geometric adaptive control strategy for an underactuated quadrotor-slung load system that enables accurate trajectory tracking of the load. This work is motivated by the increasing demand for slung-load transportation in low-altitude logistics, leveraging the demonstrated capabilities of quadrotors in diverse applications. A comprehensive mathematical model is derived to account for dynamic coupling effects and external disturbances. The load position is regulated by exploiting the system’s differential flatness, whereas the quadrotor attitude and cable direction are governed by the controller dynamics. The proposed geometric adaptive control strategy comprises a feedback control law for load position tracking and a radial basis function neural network for compensating external disturbance. The tracking performance and robustness of the proposed control strategy are validated via numerical simulations.
Abstract This study successfully develops lunar and Martian regolith-based strain-hardening cementitious composites (SHCC). Mixtures incorporated four different regolith simulants, lunar highlands (LH) and lunar mare (LM) for the Moon and Martian global (MG) and Martian polyhydrated-sulfate (MS) for Mars, with five formulations per celestial body at 65% by weight simulant replacement and 1% by volume polyethylene (PE) fibers. Characterization included calorimetry/thermogravimetric analysis (TGA), compressive and direct-tensile testing, crack-pattern analysis under both loading and unloading conditions, and particle-packing evaluation. Ductile Mooncrete achieved compressive strengths of 44–68 MPa and tensile ductility of 2.3%–5.7% with an ultimate strain of 4.9–7.2 MPa at peak stress, consistently coupling strength with ductility. Ductile Marscrete reached 31–50 MPa in compression and 4.4%–9.2% tensile strain at 3.2–5.9 MPa peak stress, showing composition-dependent tradeoffs between strength (MG-rich) and ductility (MS-rich). Crack mapping confirmed a multiple-cracking pattern without localization. Mooncrete exhibited fewer, tighter cracks while Marscrete showed higher crack multiplicity with wider openings, and both systems displayed measurable crack-width recovery upon unloading. These results demonstrate the feasibility of fabricating simulant based, strain-hardening composites from lunar and Martian regolith simulants and highlight composition as a lever to tune stiffness, strength, and ductility for resilient space infrastructure.
Abstract This study examines the impact of uncertainty propagation and design exploration techniques on robust airfoil optimization processes. The RAE2822 airfoil geometry is selected as the case study and parameterized using the class/shape transformation (CST) method. The functional relationship between design inputs and outputs is modeled using a computational fluid dynamics (CFD)-driven surrogate model based on Gaussian process (GP) regression. Uncertainty calculations are performed using Monte Carlo sampling (MCS) and polynomial chaos expansion (PCE). In addition, the effects of different design exploration methods are analyzed using deductive design exploration (DDEM) and inductive design exploration (IDEM). The results indicated that the DDEM method is sensitive to the choice of uncertainty propagation technique, leading to variations in the optimization results. In contrast, solutions obtained using the IDEM method are found to be independent of the uncertainty propagation approach and more robust than those from the DDEM method. Furthermore, the robustness metric provided by IDEM makes it a practical and efficient method for robust airfoil optimization processes.
Abstract With the growing demand for faster, higher, and more advanced aircraft, breakthroughs in aerospace propulsion technology remain an ongoing pursuit. In recent research and applications, pintle injectors have demonstrated outstanding performance due to their adjustable flow rate and stable combustion characteristics, making them the injector of choice for many new rocket engines. However, few studies have explored their feasibility in broader application scenarios. This study designed a sector combustion chamber equipped with three adjustable pintle injectors, using liquid oxygen/kerosene as propellants and an oxygen/kerosene torch igniter as the ignition device. A series of hot-fire tests were conducted. The experiments focused on the ignition process and combustion performance under idle-start conditions. Results showed that even at a low flow of 10% nominal rate, the sector combustion chamber maintained a combustion efficiency of 86.7%. The spray combustion characteristics of the pintle injectors governed the heat-release distribution, leading to high-temperature zones primarily located between two adjacent injectors. Consequently, thermal protection design must account for this circumferential variation in temperature distribution. This research verifies the feasibility of pintle injectors in sector combustion chambers, providing a basis for application in full-scale annular combustion chambers and offering a new explorable direction for the development of aerospace propulsion technology.
Abstract This study investigates the influence of five design parameters on the combustion characteristics of a three-strut combustion chamber through single-factor analysis, clarifying their relationship with combustion efficiency and resistance. A Halton sequence with mean squared error–based infill sampling was employed to generate a sample set, and an accurate surrogate model was developed using Gaussian process regression. The Nondominated Sorting Genetic Algorithm II (NSGA-II) was then applied to optimize the chamber geometry with the objectives of improving combustion efficiency and reducing resistance. Through clustering analysis, two distinct high-efficiency combustion modes were identified: a multizone violent combustion mode and a blended mild combustion mode. In the former, the rapid combustion of pilot fuel creates favorable conditions for subsequent fuel combustion, increasing the combustion efficiency from 73% to 93% compared with the baseline case; however, due to excessively abrupt flow field changes, the reduction in resistance is not significant. In the latter, the flame fronts merge and develop smoothly, and although it only improves combustion efficiency to 85% compared with the baseline case, it substantially reduces resistance from − 7,762 newtons (N) to − 8303 N . This work provides enhanced design flexibility for high-performance scramjet combustors.
