Presentation Title

Modeling for Stability and Control

Faculty Mentor

Dave Berger, Albion Bowers

Start Date

17-11-2018 8:00 AM

End Date

17-11-2018 8:15 AM

Location

C162

Session

Oral 1

Type of Presentation

Oral Talk

Subject Area

engineering_computer_science

Abstract

The goal of the Preliminary Research AerodyNamic Design to Land on Mars (PRANDTL-M) is to design and test a glider that can be used to collect atmospheric and ground mapping data on Mars. The aerodynamic design of this project focuses on correcting the lift distribution on the wing to match Ludwig Prandtl’s bell shaped curve lift distribution that was published in 1933. Prandtl’s theory veered away from the traditional elliptical lift distribution to correct for adverse yaw without a vertical tail. Previously, the majority of the aerodynamic calculations were conducted through Athena Vortex Lattice (AVL) which is a 2-dimensional aerodynamic analysis tool. Recently, there was a need to use a program called OpenVSP to create a three dimensional model of the glider so that the simulation of PRANDTL-M is more accurate. These two types of models are now used to verify their accuracy relative to the manufactured PRANDTL-M. A new feature to both computational models is the addition of the control surfaces. By adding the elevons to the models, trim can be calculated along a range of altitudes and dihedral angles which will facilitate a better understanding the control system and the optimization of the wing design of the PRANDTL-M.

Summary of research results to be presented

The AVL and OpenVSP models of PRANDTL-M 4.2 and 5.0 are being used to optimize the designs of the two wings. AVL was examined mainly and OpenVSP models were created to confirm the models were created correctly and to conduct future analysis. To begin analysis, the codes’ angle of attack definitions needed to be studied because the angle of attack varies along the wing due to the twist that is required for the glider to have a bell shaped span load. Therefore, the AVL and OpenVSP models were studied at various twist combinations and locations. The overwhelming result is that both models define angle of attack in the same way. However, OpenVSP defines where along the chord the twist is located, and AVL does not. In addition, since AVL is a two-dimensional code and OpenVSP is a three-dimensional code, both codes should return the same coefficient of lift, but the coefficient of drag should be higher in OpenVSP’s results by a fixed value, parasite drag. This was used to match the models. Based on PRANDTL-M 4.2 AVL results, a dihedral angle between 0 and approximately 2.5 would result in PRANDTL-M having proverse yaw, the ability to roll and yaw in the same direction without a vertical tail. In addition, PRANDTL-M 4.2 is stable in this range of dihedral angles because it has positive yaw and roll moment coupling with respect to beta. Therefore, based on initial analysis, the PRANDTL-M 4.2 should have a dihedral angle between 0 and 2.5 degrees.

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Nov 17th, 8:00 AM Nov 17th, 8:15 AM

Modeling for Stability and Control

C162

The goal of the Preliminary Research AerodyNamic Design to Land on Mars (PRANDTL-M) is to design and test a glider that can be used to collect atmospheric and ground mapping data on Mars. The aerodynamic design of this project focuses on correcting the lift distribution on the wing to match Ludwig Prandtl’s bell shaped curve lift distribution that was published in 1933. Prandtl’s theory veered away from the traditional elliptical lift distribution to correct for adverse yaw without a vertical tail. Previously, the majority of the aerodynamic calculations were conducted through Athena Vortex Lattice (AVL) which is a 2-dimensional aerodynamic analysis tool. Recently, there was a need to use a program called OpenVSP to create a three dimensional model of the glider so that the simulation of PRANDTL-M is more accurate. These two types of models are now used to verify their accuracy relative to the manufactured PRANDTL-M. A new feature to both computational models is the addition of the control surfaces. By adding the elevons to the models, trim can be calculated along a range of altitudes and dihedral angles which will facilitate a better understanding the control system and the optimization of the wing design of the PRANDTL-M.