Improved Mars Helicopter Aerodynamic Rotor Model for Comprehensive Analyses

Abstract

The Mars Helicopter is part of the NASA Mars 2020 rover mission scheduled to launch in July of 2020. Its goal is to demonstrate the viability and potential of heavier-than-air vehicles in the Martian atmosphere. Ultimately, it aims to bridge the resolution gap between orbiters and the rover as well as allow access to otherwise inaccessible regions. The low density of the Martian atmosphere and the relatively small-scale rotor result in very low Reynolds number flows. The low density and low Reynolds numbers reduce the lifting force and lifting efficiency, respectively. This paper describes the generation of the improved Mars Helicopter aerodynamic rotor model. The goal is to generate a performance model for the Mars Helicopter rotor using a free wake analysis, since this has a low computational cost for design. The improvements in the analysis are two-fold and are expanded on from two prior publications. First, the fidelity of the simulations is increased by performing higher-order two-dimensional time-accurate OVERFLOW simulations allowing for higher accuracy aerodynamic coefficients and a better understanding of the boundary layer behavior as well as its transient features. Second, a version of the model is generated to duplicate the exact testing conditions in the 25-ft. diameter Space Simulator at the Jet Propulsion Laboratory, which allows for better correlation of rotor performance figures. Previous work correlated performance with that test, but did not consider the higher temperatures in the experiment compared to those of the Martian atmosphere. The higher temperatures in the experiment are expected to give conservative performance estimates, as they give rise to an increase in speed of sound and decrease in observed Reynolds numbers.

Mars Helicopter Technology Demonstrator

“…Calculations were performed using the codes FLUENT, OVERFLOW, and ARC2D/C81GEN. There was generally good agreement between the results of these methods, although differences were found post stall [7]. To support the development of the HeliCAT model, performance and hub loads were obtained from calculations using OVERFLOW.…”

Planetary Surface Mobility and Exploration: A Review

“…The Mars Helicopter Ingenuity [74][75][76][77][78][79] is a drone helicopter launched in 2020 to demonstrate the technology performance of flying robots in Mars atmosphere. Unlike the moon, which has no atmosphere to speak of, Mars possesses a very thin atmosphere (less than 1% of Earth pressure).…”

Mars Science Helicopter Conceptual Design

“…Airfoils for Low Reynolds Number Koning (Refs. 26,27,17) summarized the information available to support selection of airfoils for a future Mars helicopter. The low chord-based Reynolds number of the MH rotor results in relatively poor lift-to-drag ratios.…”