An Application of Response Surface Methodology to the Design of Tipjet Driven Stopped Rotor/Wing Concepts

Abstract

The possibility of a new aircraft that is capable of solving the increasing demand of inter-city transportation has attracted the attention of the aerospace industry for quite some time. Under the High Speed Rotorcraft Concept (HSRC) program, both NASA and the U.S. helicopter industry have studied a series of candidate rotorcraft configurations capable of cruising at high speeds and capable of taking off and landing vertically at vertiports located at downtown. Among these candidates, the stopped rotor/wing configuration has been the least studied due to lack of appropriate analytical tools to assist in its design and due to a general lack of understanding of the physics behind this unconventional concept. Even though the HSRC program has since been canceled, Georgia Tech's Aerospace Systems Design Laboratory (ASDL) recognized the need for a design methodology capable of handling the synthesis and sizing of such vehicles and has continued its pursuit. Therefore, such a computer simulation code has been developed to size reaction driven stopped rotor/wing vehicles which may or may not enable Circulation Control. The difficulty in sizing such a concept is primarily due to the unique coupling of rotor and engine which need to be sized concurrently since they are directly linked to each other and cannot be studied in isolation. This coupling, in fact, is not seen in any other concept. The methodology and computer simulation tool presented in this paper show how this coupling is accomplished. Furthermore, the results from this rotor/engine coupling are presented in the form of Response Surface Equations that is derived through the application of Response Surface Methodology. These RSE's also provide the designer with a unique ability to predict what the response will be, based on the settings of the design variables that he/she chooses. The robustness advantages of using these RSE's are also presented in the vehicle sizing portion of the overall design methodology for the stopped rotor/wing configurations.