Gokcin Cinar

Purpose – The purpose of this paper was to create a generic and flexible framework for the exploration, evaluation and side-by-side comparison of novel propulsion architectures. The intent for these evaluations was to account for varying operation strategies and to support architectural design space decisions, at the conceptual design stages, rather than single-point design solutions. Design/methodology/approach – To this end, main propulsion subsystems were categorized into energy, power and… Show more

Purpose – The purpose of this paper was to create a generic and flexible framework for the exploration, evaluation and side-by-side comparison of novel propulsion architectures. The intent for these evaluations was to account for varying operation strategies and to support architectural design space decisions, at the conceptual design stages, rather than single-point design solutions. Design/methodology/approach – To this end, main propulsion subsystems were categorized into energy, power and thrust sources. Two types of matrices, namely, the property and interdependency matrices, were created to describe the relationships and power flows among these sources. These matrices were used to define various electrified propulsion architectures, including, but not limited to, turboelectric, series-parallel and distributed electric propulsion configurations. Findings – As a case study, the matrices were used to generate and operate the distributed electric propulsion architecture of NASA’s X-57 Mod IV aircraft concept. The mission performance results were acceptably close to the data obtained from the literature. Finally, the matrices were used to simulate the changes in the operation strategy under two motor failure scenarios to demonstrate the ease of use, rapidness and automation. Originality/value – It was seen that this new framework enables rapid and analysis-based comparisons among unconventional propulsion architectures where solutions are driven by requirements. Show less

The over-arching objective of this thesis is to develop a methodology to perform the sizing, integration and performance evaluation of electric power generation and distribution subsystems (EPGDS) and architectures within electric and hybrid electric aircraft concepts. To this end, this dissertation presents the creation of a novel methodological framework, called Electric Propulsion Sizing and Synthesis (E-PASS), which integrates EPGDS considerations into the aircraft sizing and synthesis… Show more

The over-arching objective of this thesis is to develop a methodology to perform the sizing, integration and performance evaluation of electric power generation and distribution subsystems (EPGDS) and architectures within electric and hybrid electric aircraft concepts. To this end, this dissertation presents the creation of a novel methodological framework, called Electric Propulsion Sizing and Synthesis (E-PASS), which integrates EPGDS considerations into the aircraft sizing and synthesis process to enable quantitative and adequate comparisons between different types of electric and hybrid electric propulsion architectures. E-PASS has three main capabilities to overcome the aforementioned limitations. First, the traditional sizing and synthesis approach is modified to incorporate a modular weight estimation technique along with an energy-based mission analysis approach which stems from the conservation laws. The new, generalized approach enables the design and performance evaluation of any vehicle configuration, including the electric and hybrid electric aircraft. Second, a power split schedule optimization algorithm is wrapped around the sizing and synthesis capability to ensure that the candidate architectures at their optimum performance. Third, the dynamic nature of the EPGDS is taken into account by developing bi-level, physics-based and parametric models in addition to the adaptive step sizing capability which enables performing transient analysis at the conceptual design stage without sacrificing valuable computational resources. As a result, the transient analysis are performed only when required so that the knowledge about the subsystem design is maximized while minimizing the computational burden. Consequently, E-PASS incorporates these elements and provides a capability to integrate subsystem performance and dynamics of novel architectures to the aircraft sizing process at early design phases, enabling adequate comparisons between competing architectures Show less

The drive for more efficient flying vehicles in all categories may necessitate a significant departure from the tube-and-wing or rotary-wing norms that have been the mainstay of aviation for many decades. This poses challenges for predicting the aerodynamic characteristics and the weight build-up of such unconventional vehicles in early design phases. Additionally, the design and assessment of advanced/unconventional all-electric or hybrid-electric propulsion system architectures require… Show more

The drive for more efficient flying vehicles in all categories may necessitate a significant departure from the tube-and-wing or rotary-wing norms that have been the mainstay of aviation for many decades. This poses challenges for predicting the aerodynamic characteristics and the weight build-up of such unconventional vehicles in early design phases. Additionally, the design and assessment of advanced/unconventional all-electric or hybrid-electric propulsion system architectures require consideration of degrees-of-freedom and trade-offs that do not arise for conventional purely fuel-powered architectures. Thus, there is a need for a flexible vehicle sizing, trade-off, and optimization capability that is not limited to a single vehicle configuration (e.g., fixed-wing, rotary-wing) or propulsion system architecture. To be suitable for the early design phases, such a framework must evaluate relatively quickly, not require extensive definition of the vehicle, and lend itself to customizable design optimization setups. This paper describes the initial creation of such a capability and demonstrates its application to design trade-offs for a General Aviation vehicle with an advanced propulsion system architecture. Show less

Motivated by the need for very inexpensive, easily updated, first-order-accurate estimates of airport capacity required in system-wide analyses, we propose a novel approach to generate a predictive categorical model. The underlying hypothesis tested in this work is that for the same weather conditions airports with a similar runway configuration and fleet mix will have similar capacities. Accordingly, if airport categories with known capacity are defined a-priori on the basis of similarity in… Show more

Motivated by the need for very inexpensive, easily updated, first-order-accurate estimates of airport capacity required in system-wide analyses, we propose a novel approach to generate a predictive categorical model. The underlying hypothesis tested in this work is that for the same weather conditions airports with a similar runway configuration and fleet mix will have similar capacities. Accordingly, if airport categories with known capacity are defined a-priori on the basis of similarity in fleet mix and runway configuration, then a membership function to the set of categories essentially constitutes a predictive model. We test this hypothesis by formulating and implementing such a model in order to examine its feasibility and discuss key practical considerations. Verification demonstrates model fit error within 4% with a categorical training set of 35 major United States airports. Validation against European airports for model representation error is limited by data availability but shown to be in the order of 7%. Results suggest that elemental runway configurations are the primary driver for categorical definition, and variations within each category can be associated to fleet mix variations. The implementation of the proposed method to generate other such models with different data sets is encouraged. Show less

The ongoing efforts to reduce aviation related greenhouse gas emissions and fuel burn have led to advancements in power generation and distribution (PG&D) subsystem technology. Due to the absence of historical data, PG&D subsystem models must be created from first-order analysis without compromising crucial information on their characteristics.This paper demonstrates the development of parametric, physics-based subsystem models such as battery, electric motor, power distribution and management… Show more

The ongoing efforts to reduce aviation related greenhouse gas emissions and fuel burn have led to advancements in power generation and distribution (PG&D) subsystem technology. Due to the absence of historical data, PG&D subsystem models must be created from first-order analysis without compromising crucial information on their characteristics.This paper demonstrates the development of parametric, physics-based subsystem models such as battery, electric motor, power distribution and management system, and propeller speed reduction unit for rapid and low-cost sizing, simulation and analysis at early design stages. A special focus was put on rechargeable battery technology and implementing a dynamic (rather than steady-state) discharge behavior into the propulsion architecture. A methodology to integrate the developed subsystem models was presented. A sample application was also provided to demonstrate the combined capabilities of the models. To this end, the models were applied within a sample parallel hybrid electric architecture using Dornier 328 as a test bed. The subsystem behaviors under varying power requirements were then analyzed. Finally, the importance of having more dimensionality at the subsystem level at early design stages was highlighted by comparing the results of two different architectural choices. Show less

This paper presents a methodology for the sizing and synthesis of power generation and distribution (PG&D) subsystems. The PG&D subsystem models developed in a previous work done by the authors were applied within a parallel hybrid electric propulsion architecture using the Dornier 328 as the baseline aircraft. The hybridization took place only during the cruise segment. Analyses were performed in Pacelab SysArc, a system architecture design tool, to assess the impact of different hybrid… Show more

This paper presents a methodology for the sizing and synthesis of power generation and distribution (PG&D) subsystems. The PG&D subsystem models developed in a previous work done by the authors were applied within a parallel hybrid electric propulsion architecture using the Dornier 328 as the baseline aircraft. The hybridization took place only during the cruise segment. Analyses were performed in Pacelab SysArc, a system architecture design tool, to assess the impact of different hybrid electric propulsion architectures and changing PG&D subsystem characteristics at aircraft and mission levels. To this end, sensitivity analysis was conducted to reveal the sensitivity to the subsystem level characteristics. Moreover, six different architectures were compared in terms of their mission level performance. These architectures included the PG&D subsystems with current state of the art technology, NASA 15-year technology goals and a more advanced battery technology. Although neither the current state of the art PG&D subsystems nor NASA 15-year technology goals were advanced enough to match the design range requirement of the baseline aircraft, some of the competing architectures met the practical range target while enjoying substantial amount of fuel reductions. Finally, it was observed that in order to reach a break-even point in terms of the design mission range, a battery specific energy of 5 kWh/kg was necessary for a 50% level of hybridization during cruise. In this work the Dornier 328 was used as a testbed, however the methodology can be generalized for all parallel hybrid electric propulsion applications. Show less

Traditionally, interactions between aircraft and their subsystems are estimated by empirical relationships based on historical data. However, in the case of unconventional designs or implementation of recent technologies, these estimations cannot fully capture the interactions between system and subsystem levels. This paper lays out a methodology for evaluating subsystem level effects of electric propulsion technology on system level design metrics of an unmanned aerial vehicle (UAV). The… Show more

Traditionally, interactions between aircraft and their subsystems are estimated by empirical relationships based on historical data. However, in the case of unconventional designs or implementation of recent technologies, these estimations cannot fully capture the interactions between system and subsystem levels. This paper lays out a methodology for evaluating subsystem level effects of electric propulsion technology on system level design metrics of an unmanned aerial vehicle (UAV). The proposed approach relies on parametric subsystem models to estimate vehicle and mission level measures of performance and integrates the electric propulsion subsystem sizing with vehicle sizing at the conceptual design stage. The methodology is applied to a baseline UAV in the Pacelab SysArc design environment. Then, the electric propulsion architecture is compared to a turboprop engine through the estimated vehicle and mission level performance characteristics. Show less

This paper lays out a methodology for evaluating system-level requirements feasibility during System-of-Systems (SoS) conceptual design, especially in the absence of historical data, and simultaneously documents the methodology’s application to the design of small aerial vehicles. Developed as part of a larger effort to set requirements for autonomous robots operating to support combat troops in urban environments or otherwise complex terrain, the methodology manifests itself in a parametric… Show more

This paper lays out a methodology for evaluating system-level requirements feasibility during System-of-Systems (SoS) conceptual design, especially in the absence of historical data, and simultaneously documents the methodology’s application to the design of small aerial vehicles. Developed as part of a larger effort to set requirements for autonomous robots operating to support combat troops in urban environments or otherwise complex terrain, the methodology manifests itself in a parametric, interactive, and virtual design environment. The proposed approach relies on a comprehensive set of parametric models to estimate subsystem performance characteristics from user-supplied subsystem design parameters. These models are then integrated such that, through optimization and the use of response surface methodology, the system-level performance characteristics can be rapidly computed. This allows the environment’s user to visualize design tradeoffs across the entire design space, quantify the sensitivity of system-level performance measures to subsystem design parameters, and evaluate the feasibility of system-level requirements. It will be shown that, in the current application, this methodology allows the designer to identify the feasible portion of the system-level design space and thereby dramatically narrow the scope of future SoS design efforts. IMADE (Integrated MAST Analysis and Design Environment) is a GUI–based implementation of the methodology as it was applied to the design of small aerial vehicles. Example analyses from IMADE demonstrate that a quadrotor designed for a hypothetical 10-minute reconnaissance mission will need to be approximately a third of a meter wide but could shrink to a quarter of a meter wide if only the lidar were excluded. These analyses also show that the quadrotor is capable of transmitting video for hours if perched in position and will be visible from hundreds of meters away. Show less

When Cassini passes through Saturn's inner magnetosphere, the Radio and Plasma Wave Science (RPWS) instrument occasionally observes a series of whistler mode emissions that each rise in frequency over a period of five to ten minutes and repeat every five to ten minutes. These waves are present in the RPWS data set from 2005 through the present date and are observed over a large range of planocentric distances and latitudes. These waves are strongly correlated with the rotating density asymmetry… Show more

When Cassini passes through Saturn's inner magnetosphere, the Radio and Plasma Wave Science (RPWS) instrument occasionally observes a series of whistler mode emissions that each rise in frequency over a period of five to ten minutes and repeat every five to ten minutes. These waves are present in the RPWS data set from 2005 through the present date and are observed over a large range of planocentric distances and latitudes. These waves are strongly correlated with the rotating density asymmetry inside of ~5 RS, but do not appear to be correlated with the spacecraft's position relative to Enceladus. We estimate that the source electrons would have energies greater than about 1 keV, much higher than the eV thermal electron temperature. Lastly, RPWS observes these waves between 5 and 10% of the time spent inside of ~5 RS. We discuss possible sources of these azimuthally-asymmetric and time-variable electrons and consider consequences of their presence in inner-magnetospheric dynamics. Show less

In Saturn's magnetosphere, the electron density inside of 5-6 RS has been shown to vary with longitude. When Cassini passes through this space, the Radio and Plasma Wave Science (RPWS) instrument occasionally observes a series of whistler mode emissions that each rise in frequency over a period of five to ten minutes and repeat every five to ten minutes. These waves are present in the RPWS data set starting in 2005 and continuing through to the present date, and are seen over a large range of L… Show more

In Saturn's magnetosphere, the electron density inside of 5-6 RS has been shown to vary with longitude. When Cassini passes through this space, the Radio and Plasma Wave Science (RPWS) instrument occasionally observes a series of whistler mode emissions that each rise in frequency over a period of five to ten minutes and repeat every five to ten minutes. These waves are present in the RPWS data set starting in 2005 and continuing through to the present date, and are seen over a large range of L shells and latitudes. In this study, we perform a first analysis of these waves in which we study their occurrence and propagation characteristics. We focus on source mechanisms and correlations with known aspects of the Saturnian system, such as position relative to the moon Enceladus and position within the magnetosphere. Lastly, we examine possible implications that the generation of these waves has for longitudinal asymmetries in the electron population beyond the known density structure. Show less