Kristof Risse

Aircraft Cost Model for Preliminary Design Synthesis

in preliminary aircraft design is presented. The proposed model allows for estimating aircraft list price, unit costs, as well as non-recurring and recurring costs for development and production. Further, the targeted aircraft units during life cycle and for break-even are estimated. Focus is put on civil jet transport aircraft and on applicability of the proposed model in early preliminary design. Although the proposed model is tailored for early design, it shows the required sensitivities to important design parameters, so that design trade-os can be assessed in terms of costs. The dierent cost items are derived from a combined top-down and bottom-up approach. The model is based on list price data of current transport aircraft in combination with semiempirical analyses that are published in literature. The proposed methodology is directly integrated into the ILR Preliminary Aircraft Design Suite for fast assessment of new aircraft concepts and was veried against current aircraft cost data. In the scope of this paper, sensitivity studies are presented to show the inuences of dierent design parameters on costs. In a case study, the proposed model is applied to an existing aircraft program. In another case study, the proposed model is fully integrated into preliminary design synthesis and the resulting inuence of costs on multi-disciplinary design optimization are discussed.

Framework for Sustainability-Driven Aircraft Design

For sustainable development of air transport future aircraft designs play a crucial role. New technologies as well as new design strategies could lead to aircraft designs with higher economic efficiency without impact negatively environment and society. Therefore, sustainability aspects have to be addressed well-balanced already in the design process. Currently the main objectives in aircraft design are economic and environmental aspects with focus on block fuel, operating costs, noise, and emissions. This paper deals with the question, how overall sustainability can be measured and an indicator set for aircraft design purposes is defined. For sustainability assessment of aircraft designs at conceptual design stage quantification models for each indicator are presented. All models are integrated into the Multidisciplinary Integrated Conceptual Aircraft Design and Optimization (MICADO) environment of the Institute of Aerospace Systems (ILR) of RWTH Aachen University. Furthermore, for the use of multiple sustainability criteria two multi criteria decision analysis (MCDA) methods have been selected and integrated. This design and assessment framework enables sustainability-driven aircraft design already at conceptual design stage. Two case studies are presented to show the applicability of the framework. For a designed aircraft a parameter study varying Mach number and flight level is performed and the pareto optimal operating points for the optimization criteria climate change and operating costs are determined. The results show possibilities how to operate existing aircraft designs for lower climate impact without economic disadvantages. To show the impact on overall aircraft level, the same parameter study is performed for the design mission within the design loop. The aircraft designs optimal for single sustainability indicators and, using MCDA methods, for overall sustainability are presented and discussed.

Conceptual Wing Design Methodology for Aircraft with Hybrid Laminar Flow Control

This paper presents a wing design methodology for civil aircraft with hybrid laminar flow control (HLFC), conceived for application in conceptual and preliminary aircraft design. It is based on a quasi-three-dimensional approach that comprises sophisticated methods for estimation of transonic aerodynamic characteristics and transition prediction. It allows to design and multi-point optimize HLFC airfoils as well as predict large arrays of drag polars in a short time. The methodology has been implemented into an automated and robust process and integrates itself into the ILR overall aircraft design platform MICADO. The paper focuses on the elements of the aerodynamic process flow and shows its integration and applicability to overall aircraft design.

Assessment of Potential Benefit of Formation Flight at Preliminary Aircraft Design Level

In order to close the gap between formation induced drag calculation and the estimation of formation flight benefit at preliminary aircraft design level, a framework for fast assessment of formation aircraft performance has been developed at the Institute of Aerospace Systems (ILR) of RWTH Aachen University. By integrating the aerodynamic methodology into the in-house preliminary aircraft design platform, the framework can estimate the potential induced drag reduction for arbitrary aircraft configurations in formation. For specific flight missions, the block fuel reduction can be determined. As a result, formation flight impact on fuel consumption related emissions and direct operating costs (DOC) can be quantified. The presented results show that a block fuel reduction up to 16% can be expected with two short range commercial aircraft in formation, which corresponds to a cruise flight CO2 reduction around 20% and a DOC savings of more than 6%. For the case of two long range aircraft in formation, the results show slightly more benefit when compared with the short range aircraft. At the very end, this paper briefly investigates the operational considerations of formation flight.

Economic assessment of morphing leading edge systems in conceptual aircraft design

This paper presents an economic assessment of an aircraft design incorporating a morphing leading edge (MLE) device and electrical anti icing (EAI) as necessary technology for its operation. For a representative comparison to other designs direct operating costs (DOC) are chosen as a parameter to capture the multiple impacts of the change from a conventional turbulent design to a natural laminar ow (NLF) and further to the incorporation of the MLE technology. The process of integration of the technologies neccessary to operate a MLE device are described. For a better understanding of the propagation of changes, technical parameters i.e. block fuel (BF) are analyzed as well and compared between the di erent design steps. The designs compared are derived from the mission of a regional aircraft with a maximum capacity of 185 passengers. The software tool applied incorporates empirical and analytical methods that have been validated for the conceptual design phase. The results of the presented process give an indication for decision making towards the potential of innovative technologies.

Assessment of an Innovative Morphing Leading Edge Considering Uncertainties in Conceptual Design

ow technology is its incompatibility with conventional leading edge high-lift systems. Current research that is funded within the EC 7th Framework Program Collaborative project SADE concentrates on the development of an innovative morphing leading edge system. The project recently concluded in conceptual design, feasibility studies as well as in hardware and wind tunnel testing of the technology. For integration and technology assessment on overall aircraft-level, the concept lacks the required maturity in important design parameters such as estimated system mass or high-lift performance. In the scope of this paper, a framework is presented that allows for integrating and assessing innovative technology already in the conceptual design phase on overall aircraft-level by considering the most important design uncertainties with a probabilistic approach. Further, the proposed framework concludes in denition of minimum performance margins for the innovative technology, which are directly fed back into the systems development process as direct performance requirements. In a case study, the proposed framework is applied to technology assessment of an innovative morphing leading edge for a commercial transport aircraft with natural laminar ow technology. The assessment is based on technical parameters such as fuel eciency and specic hourly productivity.