Aerospace scientific literature has exposed the reluctance and inability of aircraft designers to adopt detailed approaches to battery modeling that examine the internal electrochemical processes that govern electric discharge. For instance, lumped models are often used to represent the battery pack, oversimplifying the heat transfer between the coolant and individual battery cells. This prohibits accurate thermal analysis of the pack, making any attempt to optimize heat rejection futile. It also prevents understanding failure modes associated with distributed electric propulsion architectures. In L.E.A.D.S, we seek to leverage experimentation to validate and expand the community’s understanding of the impacts of repeated cycling of aircraft loads on batteries by quantifying dominant internal degradation mechanisms.  

Experimental Battery Cell Characterization Validation for Electric Aircraft Simulation

Hybrid pulse power characterization (HPPC) is a current pulse technique that is defined by its use of both charge and discharge pulses to assess the dynamic properties of a battery. HPPC serves as an effective method of characterizing batteries, providing valuable insights into battery behavior, which can subsequently inform simulations related to current load effects on battery degradation. However, despite its widespread use in general electric vehicle battery research, there remains a gap in the literature regarding HPPC’s applicability to electric aircraft. My research aims to be the first experimental study to directly investigate the effectiveness of HPPC for electric aircraft. To address this, my study aims to compare equivalent circuit models derived created from HPPC data both before and after applying an electric aircraft’s current profile to the battery. The primary questions I hope to answer are:

• How valid is HPPC for electric aircraft batteries?

• Can insights from HPPC be extrapolated to electric aircraft battery management systems?

• Is HPPC useful for initial performance prediction models in the context of electric aviation?

Optimizing Thermal Management Systems for Electric Aircraft

Thermal management of electric aircraft remains the Achilles' heel of electric aviation. To realize the true potential of electric aircraft, we need to fully understand the limitations and trade-offs of thermal management systems designed specifically for these vehicles. By determining the upper bounds of achievable range for 19-seater electric aircraft, which are among the largest vehicles falling under the Title 14 Code of Federal Regulations Part 23 jurisdiction, we can provide realistic estimates for regional air mobility within metropolitan areas. This study enables exploration into Battery Thermal Management System (BTMS) controller design to optimize its utilization, prolonging battery life during nominal flight operations while also demonstrating safe thermal management during emergency engine failure scenarios. It therefore marks a pivotal stride in the ongoing advancement of thermal management systems tailored for the unique challenges posed by electric aviation.

Renewable Energy Pathways and Novel Power Systems for Sustainable Aircraft Concepts 

Exploring alternative power and energy systems, as well as advanced aircraft concepts, is crucial for the environmental and commercial success of the future aviation industry. This project, in collaboration with Boeing and the Center for Sustainable Aviation (CSA) at UIUC, considers a range of energy systems, including electrical energy for battery charging, hydrogen, methane, ethane, propane, and synthetic kerosene. Dedicated power and propulsion system models are integrated into the RCAIDE framework (UIUC’s successor to the prior state-of-the-art SUAVE tool) for aircraft design and analysis, focusing on a fixed regional transport aircraft configuration. The environmental life cycle and techno-economic impacts of energy production, distribution, and usage for power generation on air vehicle platforms are also assessed. Based on the most promising energy carriers and power systems identified, new aircraft design concepts for future aviation markets are developed. 

Electric Aircraft Stability 

Stability for traditional, conventional aircraft has been extensively studied and modeled. However, the unique configurations and fundamentally different propulsion systems of electric and hybrid electric aircraft pose new challenges to designing stable aircraft. By their very nature, electric and hybrid electric aircraft have different weight distributions than their conventional counterparts. Heavy battery packs do not change mass in flight in contrast to fuel tanks. In addition, novel configurations such as tilt-rotors, distributed lift, blown wings, and more are seldom seen in traditional aircraft. Unfortunately, current aircraft stability principles rely heavily on historical aircraft data, which does not lend itself to the novel systems and configurations found on electric aircraft. L.E.A.D.S. seeks to address these issues by developing tools that combine physical and experimental vehicle data to provide a comprehensive look at aircraft stability regardless of its configuration. Using RCAIDE, these tools combine aircraft inertia data and vortex lattice perturbation methods for stability results. These tools can have a wide impact, from assisting in aircraft design to assessing aircraft stability under various failure scenarios, such as engine-out, airframe damage, and more. Together these tools can help optimize designs for safety, passenger comfort, and controllability.  

Noise pollution from future eV/STOL aircraft will not only govern the establishment of new air-traffic corridors but play an integral role in the placement of vertiports, potentially changing automotive traffic patterns in existing ground networks. This has driven designers back to the drawing board to conceptualize even quieter aircraft and devise clever noise-mitigating strategies that take advantage of the unique properties of sound, such as directivity, reflectivity, and phase attenuation. Given the nature of the aircraft design, this often means striking a balance between performance and low noise. At a time when new concepts are rapidly emerging, most of the computational tools for assessing aircraft noise, unfortunately, fall at the two extremes,  either being computationally expensive and unfit for iterative design or based on archaic data. L.E.A.D.S. thus intends to develop modern computational aeroacoustic predicting methods capable of estimating noise from distributed electric propulsion configurations. L.E.A.D.S. also seeks to go one step further by exploring more complex acoustics domains such as wall scattering, which is critical for modeling aircraft in urban canyons.  

 Multi-fidelity reduced-order models for rotor-craft noise predictions

Rotor-craft noise has been researched from an analytical perspective since the early 1950s. These models though, are suited for traditional rotor-craft systems such as single engine turboprops and helicopters. Noise prediction of EVTOLs requires more advanced mathematical models owing to the complex nature of the noise signature emanating from EVTOLS. At L.E.A.D.S we are working towards developing new multi-fidelity frequency domain mathematical models to analytically predict EVTOL noise as a function of propeller design variables. Alongside the novel noise prediction models, we are working towards advanced aerodynamic models based on the airfoil panel method to improve blade aerodynamics computations which would help improve noise predictions too. This would help us design quiet propellers while ensuring that the propeller design power requirements are met. 

Urban Noise Impact

remaining to be written