Low-Vibration Design of the Dragonfly Lander

Dragonfly is a rotary-wing lander, and its mission is to explore Titan. It will make multiple flights over several years to explore different sites on Titan. There is limited information on the chemical processes that led to life on earth. Among the other places in the solar system, Titan is the most like the early earth and therefore exploring its organic surface chemistry will help to better understand our own prebiotic history. During Titan flight the rotor induced unsteady aerodynamic loads, as well as the interactional aerodynamic loads due to the rotor to rotor and rotor to lander interferences drive the structural vibrations. Therefore, robust and accurate predictions of Dragonfly structural loads and vibrations are essential for designing a vehicle that can successfully perform its mission. This paper presents the structural loads and vibration predictions of the Dragonfly lander using Rotorcraft Comprehensive Analysis System (RCAS) coupled with the Viscous Vortex Particle Method (VVPM) inflow model as well as the high fidelity coupled Computational Fluid Dynamics/Computational Structural Dynamics (CFD/CSD) simulations. Elastic fuselage modal model, generated by the NASTRAN FEA, is also used to represent the dynamics of the flight lander in the simulations. Hub loads and the lander vibrations simulations are provided at multiple flight conditions. The paper also demonstrates how the comprehensive analysis can be used to provide insight on the design changes that can result in significant reduction of the structural loads and vibrations.