Subsonic Wing Optimization for Handling Qualities Using ACSYNT

The capability to accurately and rapidly predict aircraft stability derivatives using one comprehensive analysis tool has been created. The PREDAVOR tool has the following capabilities: rapid estimation of stability derivatives using a vortex lattice method, calculation of a longitudinal handling qualities metric, and inherent methodology to optimize a given aircraft configuration for longitudinal handling qualities, including an intuitive graphical interface. The PREDAVOR tool may be applied to both subsonic and supersonic designs, as well as conventional and unconventional, symmetric and asymmetric configurations. The workstation-based tool uses as its model a three-dimensional model of the configuration generated using a computer aided design (CAD) package. The PREDAVOR tool was applied to a Lear Jet Model 23 and the North American XB-70 Valkyrie

HTS Motors in Aircraft Propulsion: Design Considerations

©2005 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.Current high temperature superconducting (HTS) wires exhibit high current densities enabling their use in electrical rotating machinery. The possibility of designing high power density superconducting motors operating at reasonable temperatures allows for new applications in mobile systems in which size and weight represent key design parameters. Thus, all-electric aircrafts represent a promising application for HTS motors. The design of such a complex system as an aircraft consists of a multi-variable optimization that requires computer models and advanced design procedures. This paper presents a specific sizing model of superconducting propulsion motors to be used in aircraft design. The model also takes into account the cooling system. The requirements for this application are presented in terms of power and dynamics as well as a load profile corresponding to a typical mission. We discuss the design implications of using a superconducting motor on an aircraft as well as the integration of the electrical propulsion in the aircraft, and the scaling laws derived from physics-based modeling of HTS motors

A methodology for the probabalistic assessment of system effectiveness as applied to aircraft survivability and susceptibiliy

Ph.D.Dimitri Mavri

Formulation of a Methodology for the Probabilistic Assessment of System Effectiveness

Presented at the AIAA 2000 Missile Sciences Conference, Monterey, CA, November 7-9, 2000.There exists a need for an integrated and efficient framework that can rapidly assess system effectiveness for today? complex systems. The analysis of air superiority in the theater environment is considered here, and the steps taken in the formulation of a cohesive methodology are presented

Methodology for Assessing Survivability Tradeoffs in the Preliminary Design Process

Presented at the 5th World Aviation Congress and Exposition, San Diego, CA, October 10-12, 2000.Aircraft survivability is a key metric that contributes to the overall system effectiveness of military aircraft as well as to a lower life cycle cost. The aircraft designer, thus, must have a complete and thorough understanding of the interrelationships between the components of survivability and the other traditional disciplines as well as how they affect the overall life cycle cost of the aircraft. If this understanding occurs, the designer can then evaluate which components and technologies will create the most robust aircraft system with the best system effectiveness at the lowest cost. A synthesis and modeling environment is formulated and presented that will allow trade-off studies and analysis of survivability concepts to be conducted. This environment then becomes the testbed used to develop a comprehensive and structured probabilistic methodology, called the Probabilistic System of System Effectiveness Methodology (POSSEM), that will allow these trades to be conducted. Initially, consideration of the survivability discipline will be restricted to components of aircraft susceptibility. The methodology is presented here in its formative state, with primary issues being identified and tentative solutions presented. A theater level test case of susceptibility trades is presented

The Need for a Military System Effectiveness Framework: The System of Systems Approach

Presented at the 1st AIAA, Aircraft, Technology Integration, and Operations Forum, Los Angeles, CA, October 6-18, 2001The need for a comprehensive framework for the analysis of military system effectiveness is presented. Changes in the world’s economy and its effect on decision making is discussed, as well as the three primary ways decision makers use information: resource allocation, requirements definition, and trade studies between system components. “System” and “system effectiveness” are clearly defined. The idea of a system of systems formulation for military system effectiveness analysis is presented, discussing the need to expand the consideration of the system from the vehicle (engineering) level to the theater or campaign level. The use of probability theory as part of the methodology is defended. Finally, an intuitive overview of the proposed methodology is presented, in a step by step manner. The methodology is called POSSEM (PrObabilistic System of Systems Effectiveness Methodology)

Power Based Sizing Method for Aircraft Consuming Unconventional Energy

Presented at the 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, Nevada, Jan. 10-13, 2005.Traditionally, most fixed wing and rotary wing aircraft have been powered by internal combustion engines that consume hydrocarbon fuels. Only in a few exceptional designs, such as solar powered air-vehicles, are attempts made to apply alternate energy sources. In the past decade, however, the aerospace community has shown a renewed interest in alternate energy sources for revolutionary propulsion systems. In particular, fuel cells are increasingly being considered as an alternate power source for their potential outstanding advantages over the traditional power system. Nevertheless, traditional aircraft sizing methods are not immediately applicable for such unconventional-energy consuming air-vehicle designs. This paper proposes a generalized aircraft sizing formulation that is also applicable to revolutionary aircraft concepts powered by unconventional energy sources and/or have revolutionary propulsion systems. A power based formulation, which allows easy tracking of energy transformation process from the first power generation to the last propulsive power production, is introduced. Lastly, a generalized aircraft weight estimation formulation that is also valid for unconventional-energy consuming propulsion systems is developed

Probabilistic Assessment of Handling Qualities Constraints in Aircraft Preliminary Design

Presented at the 36th Aerospace Sciences Meeting and Exhibit, Reno, NV, January 12-15, 1998.A method is introduced and demonstrated which uses parametric stability derivative data (in the form of regression equations) and probabilistic analysis techniques to evaluate the impact of uncertainty on the handling qualities characteristics of a family of aircraft alternatives. While the method is based on the use of elementary design parameters familiar to the configuration designer, it enables the computation of responses more familiar to the stability and control engineer. This connection is intended to bring about a more complete accounting of stability and handling quality characteristics in aircraft design, based on engineering analysis instead of historical data. Another key advantage of the method is that it allows for the quantification of analysis imprecision and information quantity/quality trades through fidelity uncertainty models. The metrics for these quantifications are the cumulative distribution function and probability sensitivity derivatives. The method is exemplified through the investigation of the longitudinal handling qualities trends for a defined High Speed Civil Transport design space, in the presence of fidelity uncertainty in the stability derivatives

An Application of a Technology Impact Forecasting (TIF) Method to an Uninhabited Combat Aerial Vehicle

Presented at the 4th World Aviation Congress and Exposition, San Francisco, CA, October 19-21, 1999.In today's atmosphere of lower U.S. defense spending and reduced research budgets, determining how to allocate resources for research and design has become a critical and challenging task. In the area of aircraft design there are many promising technologies to be explored, yet limited funds with which to explore them. In addition, issues concerning uncertainty in technology readiness as well as the quantification of the impact of a technology (or combinations of technologies), are of key importance during the design process. The methodology presented in this paper details a comprehensive and structured process in which to explore the effects of technology for a given baseline aircraft. This process, called Technology Impact Forecasting (TIF), involves the creation of a forecasting environment for use in conjunction with defined technology scenarios. The advantages and limitations of the method will be discussed, as well its place in an overall methodology used for technology infusion. In addition, the example TIF application used in this paper, that of an Uninhabited Combat Aerial Vehicle, serves to illustrate the applicability of this methodology to a military system