Mechanical and Aerospace Engineering, 1924-2024

Feather-like control surfaces are shown to increase net lift at post-stall angles of attack, yielding benefits in efficiency and control for small aircraft and unmanned aerial vehicles (UAVs). Inspired by covert feathers on birds’ wings, ongoing wind tunnel experiments aim to optimize the design and configuration of passively-deployed aeroelastic flaps.

A single-degree-of-freedom model describes the aerodynamic forces on the flap due to the pressure differential over the wing surface, using a combination of analytical and numerical methods. The pressure distribution is integrated for the resulting forces; a user can determine the magnitude of the forces contributing to flap deployment for various locations (leading edge at 0.2 of the chord or trailing edge at 0.7 of the chord) and for distinct angles of attack and flow conditions.

Advancements in search and rescue (SAR) drone design have offered life-saving support to thousands of people around the world. Current drone technology typically favors flight time or maneuverability through the respective use of fixed-wing and quadrotor drones, however, in many instances, both features may be required. The goal of this project is to develop an unmanned aerial vehicle that is capable of achieving the benefits of both of these vehicle categories for enhanced versatility in SAR missions.

This thesis presents the design and analysis of WingSpan, a novel tailless UAV featuring a wing system that can expand to produce lift during long-distance aerial searches and retract to access confined spaces at low altitude. The design of the extended configuration proposes a tailless wing made from a symmetrical NACA 0016 airfoil profile, with a swept and tapered design to improve flight stability. Lifting-line theory simulations revealed that this design produces sufficient lift, indicating its effectiveness in improving flight time and increasing efficiency. In addition, FEA simulations indicated that the expanding mechanism could withstand standard operating loads without failure, while weighing less than 2 kg in total. Although theoretical in nature, this thesis aims to provide a foundation for further development and prototyping of morphing UAV platforms tailored to real-world SAR applications.

This study aimed to simulate and compare the thermal performance of a liquid cooling system and a phase change material (PCM) system for an electric vehicle battery pack. The liquid cooling system operates through the active dissipation of heat, where a fluid circulates around the thermal source, absorbing heat and transferring it away, thereby preventing excessive temperature rise. In contrast, the PCM system functions passively by storing thermal energy as it undergoes a phase change, typically from solid to liquid. This allows the PCM to regulate temperature by absorbing heat without immediately dissipating it, providing a buffering effect. However, a PCM has no way of effectively dissipating the heat it has absorbed through its phase change. This is where convective air cooling becomes essential, providing a continuous heat removal pathway that enables the PCM to maintain its thermal buffering capacity and prevent long-term temperature rise within the system. We constructed models of both systems in order to compare them in a direct context. However, the simulations failed to converge due to improper meshing techniques or inherent complexities with modeling the thermal behavior of PCMs around boundaries. Despite these difficulties, the proposed design remains viable, and with improved modeling techniques, future simulations could provide a direct comparison between the two systems and show the potential of an air-cooled PCM system.

A 6 Degree-of-Freedom (6DoF) Flight Simulator in Python was made, leveraging open source libraries to build a simulator capable of running in real-time and offline modes. This simulator, named Python Laptop Air Vehicles (PLAV) is capable of piloted control and has a Hardware-In-The-Loop (HITL) proof-of-concept mode implemented with an Arduino-compatible micro controller. The project is open-source and prioritizes simplicity, with the intent that amateur aircraft designers can use it to test their unique designs with their own flight dynamics model and simulate their flight control with HITL simulation.

The simulator has been validated using the NASA Engineering and Safety Center's Check-cases for Verification of Six-Degree-of-Freedom Flight Vehicle Simulations, ensuring that for a good Flight Dynamics Model (FDM) the simulation gives accurate results. The relevance of implementing the a rotating ellipsoidal Earth is also analyzed in amateur contexts such as high power rocketry. The code is published at https://github.com/adinkojic/PLAV

This study develops a probabilistic modeling framework—PWDRIV (Probabilistic Wind-hazard Damage and Resilience Investment Valuation)—to assess the economic viability of climate resilience investments in the coastal transmission sector. Focusing on the Tampa Bay region, the model incorporates climate change-induced trends in extreme wind hazards through stationary and non-stationary Gumbel distributions. Using Monte Carlo simulations and a calibrated cubic excess-over-threshold (CEOT) damage function, the framework translates future wind hazards into annual damage cost projections. These are then evaluated using both Net Present Value (NPV) and Decoupled Net Present Value (DNPV) methodologies to quantify maximum justifiable investments under varying climate and financial scenarios. Results show that non-stationary climate assumptions significantly increase estimated damages and justifiable resilience investments. The DNPV method more accurately reflects the long-term benefits of resilience by separating risk and time-value effects, supporting its adoption in policy and planning. This work offers a replicable tool for guiding infrastructure adaptation decisions under deep climate uncertainty.

In the wake of widespread decarbonization efforts due to climate change, hydrogen and ammonia have emerged as promising clean alternatives to hydrocarbon fuels. As such, H2 and NH3 have been explored in a number of industry applications ranging from manufacturing to power generation. In many such applications, the surface reactions between these fuels and common industrial materials are not well understood. In this study, the surface mechanisms of reduction and nitridation via H2 and NH3 were examined. An apparatus was designed to stagnate H2 and H2/NH3 flames on the surfaces of iron and nickel test plates mounted above a burner. Experimental investigation was supplemented by 1-D flame simulations using Cantera to develop an understanding of how temperature and radical formation led to the observed surface phenomena. X-ray photoelectron spectroscopy was used to quantify the extent to which surface processes occurred. Conditions for considerable nickel nitride formation at temperatures beyond those previously studied for this surface phenomenon were discovered. Once these conditions were established, the height of the test sample above the burner and the time of flame exposure were varied to observe the effect of changing kinetics on surface reactions. Iron was found to nitride considerably less under the same conditions. Reduction of both metals under H2 flames was minimal, though the degree of reduction of the nitrided nickel samples was much higher. The present work lays the groundwork for future study of these surface processes and their mechanisms.

As Urban Air Mobility (UAM) vehicles become a key area of interest for sustainable and efficient short-range transportation, there is a growing need to optimize propulsion systems for performance. Counter-rotating stacked propellers present a promising alternative to traditional single-rotor systems, offering potential benefits in thrust generation, efficiency, and swirl minimization. This thesis explores the aerodynamic performance of these stacked systems, with a focus on how aft rotor parameters—axial spacing, radius, RPM, and blade count— influence overall system performance. Using CROTOR, a range of configurations were analyzed and compared to baseline single-rotor setup. The results demonstrate that tailoring the aft rotor radius and RPM in response to the axial velocity distribution can improve normalized thrust by up to ≈3.5%. Furthermore, lower aft blade counts were found to achieve higher efficiency. These findings contribute empirical insight into stacked rotor dynamics and provide a foundation for deriving sizing heuristics that can streamline design of optimal eVTOL propulsion systems.

The International Moth is a small racing sailboat that can reach top speeds of 35 knots (18 m/s), due to its use of hydrofoils, which lift the entire hull clear of the free surface. The hydrofoils replace the hull as the primary generators of hydrodynamic forces within the vessel system, and in turn, heavily drive the overall performance of the vessel. Optimizing the shape and planform of the foils is a key to achieving race-winning designs. However, hydrofoiling sailboats are highly coupled systems that operate in two simultaneous fluid media, and a change in foil configuration can have cascading effects on the overall vessel state. Thus, a design framework is formulated that allows foil designs to be evaluated within a 6 degree of freedom velocity prediction program (VPP). The framework integrates gradient-based shape optimization tools in 2 and 3 dimensions. Evaluation of the framework demonstrates functionality for design optimization independent of the VPP, but the presented approach to modeling hydrodynamic forces within the VPP requires improvement in order to produce meaningful results that can inform design decisions.

Mars exploration is governed by a ruthless mass-ledger: every kilogram of ascent propellant ferried from Earth displaces payload or science return. Laser-ablation propulsion (LAP) addresses this constraint by transferring energy remotely. A laser mounted on a lander or orbiter delivers nanosecond pulses to a small pad on the vehicle; the pad ejects a high-velocity plasma plume, and the recoil produces thrust while the power plant stays off-board. This thesis quantifies LAP performance for the first time under Martian ambient (600 Pa, 210 K CO₂). A coupled thermal–mechanical model implemented in ANSYS Mechanical APDL tracks crater evolution, phase explosion, and impulse generation for polytetrafluoroethylene (PTFE), carbon-fiber composite, and basaltic/regolith ablators. Parametric sweeps over 1–10 J pulse energy and 50–200 µm spot diameter predict momentum-coupling coefficients up to (4.2 ± 0.3) × 10⁻⁵ N·s·J⁻¹ and specific impulse 900–3200 s. These figures exceed chemical engines in propellant efficiency and encroach on Hall-thruster territory while retaining orders-of-magnitude higher thrust-to-mass because the laser mass is external.

Mission-level scaling indicates a 500 kW orbital fibre-laser can loft a 50 kg sample-return canister to 1.2 km with <15% pad mass, cutting Earth-launch mass by ~30% relative to methane/LOX ascent. Pulses shorter than 20 ns favor plasma-dominated ablation and maximum specific impulse (I_sp); pulses around 50 ns maximize the momentum-coupling coefficient (C_m) for hopper-scale thrust. A hybrid composite–regolith pad is proposed to reconcile coupling efficiency with in-situ manufacturability.

In the future, laboratory validation can be done using a torsional thrust stand and gated schlieren plume imaging, after which computational fluid dynamics can be embedded to capture dusty-gas entrainment. By mapping the material–pulse design space and demonstrating a credible mass advantage, this work positions externally powered LAP as the missing middle ground between high-thrust chemical rockets and high-I_sp electric thrusters—enabling agile surface mobility and lightweight ascent for the next generation of Mars missions.

Pressure-gain combustion presents an exciting potential to increase engine efficiency over conventional engine cycles. The rotating detonation engine (RDE) is an engine concept which utilizes detonation to generate a pressure-gain combustion cycle. RDEs have a cylindrical geometry where a detonation wave continuously rotates around an annulus to produce thrust in the axial direction. However, since detonation is an extremely fast and volatile combustion mode, nonidealities in the cycle cause the control and stability of the engine to be difficult. These nonidealities include parasitic deflagration, mixture inhomogeneities, and multiple competing detonation waves. This study focuses on a stoichiometric, variable hydrogen and methane composition fuel RDE with air as the oxidizer. Specifically, an analysis was done of the effect of inlet number and increasing methane composition in combination with hydrogen fuel on the stability and performance parameters of an RDE. As the composition of methane increased, the performance values such as specific impulse and detonation wave velocity decreased up to 1000 seconds and 60 meters per second, respectively. The addition of methane in the fuel also decreased the range of inlet number in which the detonation wave was able to sustain itself. Two different scenarios produced the destabilization of the detonation wave: the coupling of parasitic deflagration and a slower detonation wave and the coupling of the Kevin-Helmholtz effect and the Rayleigh-Taylor phenomenon. However, the inclusion of methane in the fuel caused weaker reverse compression waves to be created and produced more uniform thrust. Therefore, for methane mixed with hydrogen fuel up to 15% of the mole fraction, performance and efficiency will decrease, but the detonation wave is more stable and has more uniform performance values over the cycle for certain inlet configurations. Once the methane mole fraction is greater than 15% of the fuel, the detonation wave can no longer sustain itself.

Flexible, polymer-based wearable sensors have been extensively studied over the past 30 years. Conventional sensors usually consist of a conductive material deposited into or onto a polymer substrate. Laser direct writing (LDW), a more recent innovation, allows conductive graphitic carbon to be directly patterned onto the surface of a polymer sheet, eliminating the need for the addition of a separate conductor. However, there are still ways to further streamline the fabrication process, including the use of LDW to induce formation of the substrate and conductive material simultaneously. This thesis presents a route towards the functionalization of this technique through the laser irradiation of uncured, liquid-phase polydimethylsiloxane (PDMS), a thermosetting elastomer. Scanning a near-infrared, continuous wave laser in a grid pattern across the surface of PDMS produces a mesh of conductive, graphitic carbon lines within a matrix of cured, solid polymer. The resulting structure shows potential as a wearable sensor, with a resistance at rest of about 26.9 k$\Omega$. Resistance increases with the application of external forces, and the sensor is able to detect changes in pressure and strain. As a possible avenue toward higher conductivity or graphene content, small concentrations of carbon black were added to uncured PDMS. No conductivity was observed for the resulting grid structures, possibly due to changes in material absorption.

This thesis explores the design and simulation of a control system that would enable omnicopter drones to simulate close proximity spacecraft rendezvous maneuvers. Close proximity rendezvous simulations typically exist either as simplified online models that lack real-world dynamics or as prohibitively expensive physical testbeds. By leveraging the six degrees of freedom (6-DOF) capability of omnicopters—drones with non-planar rotor configurations allowing complete spatial movement developed by Dario Brescianini and Raffaello D’Andrea—this research provides a cost-effective middle ground between purely digital and full-scale physical simulations. The study implements relative orbital motion using the Clohessy-Wiltshire equations to model the dynamics between a ”chief” and ”deputy” omnicopter, simulating target and approaching spacecraft respectively in close proximity operations. A cascaded control architecture that separately handles attitude and position control enables the simulated deputy omnicopter to approach and maintain specific poses relative to the chief within small distances, mirroring the final critical phase of spacecraft rendezvous. Using MATLAB, the research validates this control strategy through simulation, demonstrating its effectiveness for precise close proximity maneuvers. This work’s contributions lie in: (1) implementing close proximity orbital rendezvous control for omnicopters in simulation, (2) providing improved documentation of omnicopter capabilities to address gaps in publicly available resources, and (3) establishing a foundation for future physical implementation and testing. While physical deployment remains outside the scope of this thesis, the comprehensive modeling and simulation work presented here creates a viable pathway between theoretical spacecraft dynamics and accessible hardware implementation for future research in close proximity operations.

The Princeton Field-Reversed Configuration (PFRC) Micro-reactor presents unique neutron shielding and fusion energy capture requirements due to its compact nature. Efficient thermal energy capture and extraction is critical to the implementation of the PFRC. The goal of this project is to design and implement an experimental setup to measure the temperature profile under heating and cooling conditions within a packed pellet bed. This was done by constructing a test set up scaled by pellet diameter with wall heating on one side. Carbon steel pellets of two varying sizes were selected, 3 mm and 7 mm. Each system was heated to steady state and then cooled with a working fluid of compressed air. The energy absorption of the pellet bed during heating developed a deeper understanding for the relationship between bed size and energy capacity. Energy extraction due to air showed the importance a hot outlet flow temperature will play in creating an efficient heat exchanger. The conductivity of the pellet bed will need to be high enough such that a temperature gradient along the direction of wall heating can facilitate heating of the entire incoming flow. This was seen to relate heavily to the void fraction of the respective beds such that as the voidage increases so does conduction within the bed.

For spacecraft hardware, performing environmental qualification testing is of paramount importance as such tests ensure that they can survive harzardous vibration and shock loads experienced in their lifetime due to launch and deployment stresses. TigerSats, an ongoing Princeton University undergraduate CubeSat program, has a vested interest in developing the lab's vibration and shock testing capabilities across a wide range of budgets and test article sizes. This report details such development of in-house dynamic test qualification capabilities for various test articles as well as the establishment of partnerships with third party stakeholders. In this project, a novel TigerSats solar panel is subject to random vibration testing to check the functionality of a LabWorks electrodynamic shaker and develop operational procedures for future use. The Princeton Rocketry Club's orbital payload was also subject to vibration testing on the same equipment. Lastly, a mission-critical component of the Rutgers University SPICEsat was vibration tested in collaboration with Nu Laboratories. All of these tests were conducted according to NASA- or industry-established vibration environment specifications, and the test articles' survivals were predicted by theory. Adapters were designed and manufactured to perform testing. The verification of inherited design, modification of said design, and physical assembly of the TigerSats shock hammer fixture's primary structure were successful. Holistically, these results demonstrated the ability for TigerSats to develop in-house vibration and shock tests for various test scopes while satisfying interests of external stakeholders.

Reactivity-controlled compression ignition (RCCI) presents a promising avenue for improvements in internal combustion engine efficiency and emissions. As combustion phenomena are critical to optimizing RCCI engine performance independently of flow characteristics, a turbulent combustion model is developed within the PDRs manifold framework. The aim is to contribute to ongoing research on simplified computational models for multimodal combustion and developing a fundamental RCCI combustion model that can be applied across a wide range of fuels. A linked one-dimensional manifold model is proposed to simulate RCCI combustion by decoupling auto-ignition and homogeneous burning. High-reactivity fuel auto-ignition is modeled as an asymptotically non-premixed case, and low-reactivity fuel combustion as an asymptotically premixed case. The ignition delay time (IDT) hypothesis is presented, suggesting that true combustion behavior can be extracted by minimizing characteristic burn times. Preliminary investigations suggest that the IDT hypothesis does not hold for the particular parameters chosen here. However, the analyses conducted in this thesis provide a starting point and some generalized algorithms for future work in simplified multimodal combustion modeling

Soft mobile robots offer distinct advantages for navigating complex terrains because of their inherent flexibility, which enables exceptional adaptability and versatility. However, their compliant bodies introduce significant challenges, such as motion uncertainties and unpredictable interactions with their environment, that are difficult to control. Furthermore, the complex dynamics of soft mobile robots complicate the realisation of full autonomy, a challenge that is further exacerbated by the limited sensing and proprioception capabilities employed in the field.

This thesis aims to advance the field of autonomous origami-enabled mobile robots, a subclass of soft mobile robots, by enhancing their capability to traverse complex terrains and improving their viability for real-world applications. Previous work from the Bio-inspired Adaptive Morphology Laboratory (BAM Lab) developed an Origami-Enabled Soft Crawling Autonomous Robot (OSCAR) in pursuit of this goal. OSCAR is a novel soft mobile robot that leverages origami-inspired mechanisms to mimic the crawling motion of caterpillars. Hence, building upon that foundation, this work enhances OSCAR’s capabilities by enabling traversal of complex three-dimensional spaces without relying on external sensors, paving the way for implementation of truly autonomous navigation.

OSCAR’s mechanical stability is first enhanced with a double-celled design, and vertical actuation is introduced by employing four origami towers per cell. These upgrades improve stability, maneuverability, and locomotion range, enabling complex three-dimensional terrain traversal in the updated version called the Slinky Origami-Enabled Soft Crawling Autonomous Robot (SOSCAR). Afterwards, control systems are developed to realise the new mechanical design and demonstrate vertical obstacle avoidance. Finally, internal sensing mechanisms, using Time-of-Flight distance sensors and Inertial Measurement Units, are integrated to provide proprioception, or self-awareness, that enable closed-loop positional feedback control. Whereas previous versions of OSCAR relied on external sensors for control, all sensing in SOSCAR is fully integrated onboard the robot.

Ultimately, this thesis presents a soft mobile robot that integrates the necessary elements for future implementation of autonomous navigation in complex three-dimensional terrains. As a result, it advances the real-world readiness of origami-enabled robots and highlights their potential for operating in challenging environments.

Fusion has the potential to be a paradigm-shifting energy generation source with the capability to accelerate both the transition to renewable energy and meet growing global demand. Recent advances in the computational optimization of one fusion reactor design, the stellarator, have produced the need for various physical experiments to study their plasmas. However, building a new stellarator is a complex, expensive, and time-consuming process, largely due to the manufacturing challenges of their nonplanar magnetic field coils. As a result, it is cost prohibitive to build multiple stellarator experiments. By reevaluating the coil design, a single experimental machine could be built with the ability to generate the magnetic field of many unique stellarator designs, lowering the investment required to study a range of optimized plasmas. This thesis presents a method of manufacturing a continuous 2D "surface coil" for a stellarator to replace the typical set of discrete coils. To this end, a twelfth torus stellarator coil was built out of Galinstan using a plastic mold. The magnetic flux density at coil currents of 300 and 900 A was measured at 128 distinct points by a set of Hall effect sensors on a custom printed circuit board. Compared with simulation in COMSOL Multiphysics, the measurements in the axial direction of the coil had maximum, median, and mean errors in the Y direction of 47.72%, 12.79%, and 9.51% for 300 A and 18.84%, 3.61% and 4.76% for 900 A. For the other directions, these errors were one to two orders of magnitude higher, likely attributable to the influence of unshielded wires external to the coil. Although the error in the magnetic flux density for a real-world fusion device should be less than one percent, this thesis made a significant step towards demonstrating the feasibility of a 2D "surface coil."

Human space exploration represents the culmination of the best of what our world has to offer—scientific and technological capability walking hand-in-hand with the human drive to explore and understand. Mars, the closest and most similar neighboring planet to Earth, has long been a source of inspiration for both science fiction and scientific advancement. It is the first logical target for investigating the presence of life on other planets and launching an era of interplanetary human existence. Designs for crewed Mars missions have long been tied to development of technology and operational capabilities on and around the Moon, but some of the aerospace community has historically been divided on the role the Moon should play in the development of crewed Mars mission architecture. This thesis explores the viability of executing a crewed mission to Mars without significant prior development of technology and operational capabilities on and around the Moon. Current prominent Mars mission architectures are compared and contrasted, technological and knowledge gaps are identified, and the necessity of the lunar prerequisites is evaluated. This paper compares the mission architectures of Mars Direct, NASA’s Design Reference Architecture 5.0, NASA's System Analysis Cycle 2021, SpaceX’s Starship architecture, and the preliminary architecture discussions of NASA’s Moon to Mars program. Commonalities of the prominent architectures are identified. Sub-architectures are then reviewed, including: entry, descent, and landing systems; ascent systems and in situ resource utilization; life support systems; communication considerations; surface power systems; and crew health and performance. The extent to which the Moon serves as a beneficial "proving ground" for the development of these areas is evaluated and discussed, ultimately determining the extent to which creating a robust, feasible, and safe crewed Mars mission architecture depends on prior development in the lunar domain.

Germany’s goal of achieving net-zero emissions by 2045 has accelerated its transition to renewable energy after the previous decade’s push towards a nuclear phase-out, but simultaneously contributed to rising electricity prices and economic strain. The Russian-Ukrainian conflict further exposed vulnerabilities in Germany’s energy system, driving up energy costs and impacting both citizens and the industrial sector. As a result, debate over the role of nuclear power has reignited in political and public discourse. This thesis evaluates the economic feasibility of reactivating decommissioned nuclear power plants using the PyPSADE energy system model. Through the simulation of investment and dispatch scenarios through 2050 across Germany and neighboring countries, this study compares the impacts of nuclear reactivation with continued renewable expansion in terms of cost-effectiveness and CO2 emissions. Results from the model indicate that the reintroduction of nuclear power is too time-consuming and therefore not economically feasible due to the rise of solar and wind power, suggesting the need for additional infrastructure to support the growing renewable energy sector.

Technology is ever-evolving, and its usefulness in sports training applications has increased with each evolution. Coaches and teams turn to technology to analyze player movements, break down game footage, and improve athletic performance. The sport of ice hockey has seen rapid player development over its history, with the game becoming faster, player equipment constantly improving, and the sport more popular and accessible than ever [4]. However, despite the abundance of training technology available for ice hockey players, one position still lags behind in development: the goalie. Ice hockey goalies often develop at a slower pace than their skater teammates due to a lack of expert coaching and resources at the lower levels, as well as the specialized equipment required, which makes the position more expensive and creates barriers to entry [19]. Additionally, goalies see the most growth in their playing ability when they get meaningful ice and game time. This thesis explores various designs of automated ball pitching and launching machines, as well as previous attempts to develop hockey puck shooting machines for goalie training. It also investigates why these earlier designs failed to gain widespread adoption within the goalie training community. Drawing on these insights and market research conducted for this project, the goal of this senior thesis is to design and build a functional puck launcher that is portable, versatile in capability, and can operate both on and off the ice, while being easily transported between different training locations.