From Ohio State to Mars

Posted: December 19, 2022
Isaac Bensignor holding a rotorblade he fabricated
Bensignor with a rotor blade he fabricated.

Since he was an undergraduate aerospace engineering major, Isaac Bensignor has been contemplating how to fly a rotorcraft on Mars. Those dreams have taken flight — Bensignor is now a research technician at The Ohio State University Aerospace Research Center where he’s building prototype rotor blades intended for flight on the Red Planet. His work aims to propose a new correction to a well-known rotorcraft performance estimation model used across the aerospace field.

Trajectory to Mars

Soon after Bensignor began investigating Martian flight as an undergraduate, he shared his ideas with Professor Jim Gregory and then Research Scientist Matt McCrink, who guided him through an undergraduate honors thesis and ensuing master’s fellowship with the NASA/Ohio Space Grant Consortium on the topic.

Bensignor discovered that computational fluid dynamics (CFD) modeling commonly used to estimate flight performance of airfoils, rotors and full scale vehicles was cumbersome. Typical 3D CFD methods can take days to calculate a single analysis case and are too inefficient for analyzing hundreds of cases. He surmised that there could be a better way.

Bensignor’s solution to the time-consuming 3D computational modeling is to employ the much faster blade element momentum theory (BEMT), coupled with a 2D CFD model processed through the Ohio Supercomputer Center, to generate performance metrics for flight in the Martian atmosphere. Calculation time was reduced from days to hours. BEMT had never been documented as being used to calculate Mars rotorcraft flight performance.

Isaac Bensignor in a lab fabricating rotorblades
Bensignor fabricates rotor blades using custom molds he refined by hand sanding them for over 60 hours.

“I coded a simple BEMT computer model for this specific project to allow for rapid rotor performance feedback,” shared Bensignor. “The model has been verified against results digitized from a textbook assessing the same conditions and with physical experiments of a simple rotor for a set of operational conditions.”

Those physical experiments were developed during his graduate work. He learned precision tooling techniques in the Aerospace Research Center’s machine shop in order to build a rotor test stand for comparison experiments to validate the model. Rotor blades were also made in-house using custom molds created by reverse-engineering data published by NASA.

McCrink, now an assistant professor and director of the Aerodynamic Flow Control and Advanced Diagnostics Research Group, is enthusiastic about the research. “This is a very unique project and complements our lab’s investigations into the entire autonomous aerial vehicle ecosystem,” he said. “Isaac’s degree covered engineering aspects from modeling to design, exposing him to many parts of the field.”

After graduating in August 2022, Bensignor began working full time at the center where he is conducting the final experiments to validate his computational and numerical modeling work.

The Aerospace Research Center’s Gas Turbine Lab, which houses a 14-by-14-foot vacuum chamber, provides a location to test the rotors in a Mars-like atmosphere. There, Bensignor will trial the model of the Mars-optimized rotor blades. The resulting data will inform the new proposed empirical correction to the BEMT model for conditions related to Mars flight.

Rotorblades and molds.
Physical experiments using custom molds (center top) and blades (center bottom) will help verify Bensignor's model.

Transferable technology

According to Bensignor, the modeling technology helpful for Mars research has relevance on Earth. He anticipates that the correction to BEMT will accelerate investigations into high-altitude Earth flights.

“Flying a rotorcraft on Mars is basically like flying a helicopter near 100,000 feet on Earth,” he said. “The atmosphere is very thin and cold.”

Bensignor is also focused on documenting and validating his work to allow the model to be utilized by others. His findings were presented at the 2022 American Institute of Aeronautics and Astronautics (AIAA) Aviation Forum and future publications aim to share more details about the approach.

“This project puts Ohio State on the radar for developing these capabilities,” he commented. “There are only a handful of Mars research facilities in the world.”

With his sights set above, step by step Bensignor is making his dream of flying helicopters on Mars a reality.

by Holly Henley, communications specialist