Martian Helicopter Takes Flight in Moorpark

Engineers at AeroVironment Inc. showed off this month a terrestrial version of the helicopter the company developed to fly on Mars.

Nicknamed Terry, the terrestrial aircraft was flown for members of the media on May 13 by Matt Keennon, the technical lead for the rotor system development on the Mars Ingenuity helicopter program at the Moorpark facility of the Simi Valley unmanned aircraft manufacturer.Ben Pipenberg, engineering lead on the helicopter program, explained before the flight that Terry has an airframe identical to Ingenuity and that structure composites and mechanism were built from the same molds as the Mars version.

“Terry is designed to fly here on Earth, so the motors were redesigned and are more powerful and have a higher torque to handle the denser atmosphere and the higher gravity,” Pipenberg said.

Ingenuity has flown five times on the surface of the red planet since its initial flight on April 19 when it became the first aircraft to fly on another world. The company made the helicopter for the NASA Jet Propulsion Laboratory, or JPL, in La Cañada-Flintridge, which oversees the space agency’s missions on Mars.Before flying Terry, Keennon explained how engineers at AeroVironment developed the rotor motor. The original motor was about a half-inch thick.“That was a really excellent motor, but we couldn’t fit it in with all the other systems that had to absolutely fit in there,” Keennon said.

So the size of the motor was shrunk down to a quarter-inch thick. However, the challenge that presented was that a smaller motor requires a larger diameter than the original design and can be less efficient, he added.

The efficiency of the motor was dealt with through the copper wiring used in it, Keennon said.

“The more copper you get in there, the less air and the more efficient the motor is,” he said. “I needed to develop little wedges and hand tools and a motorized system to wind these pretty much perfectly.”The first motor delivered to JPL was fabricated in about 100 hours, with 80 of those hours dedicated to winding the copper wire.  “Then we did six additional motors, and the last two were the ones that went on Ingenuity and on to Mars,” Keennon said.

In the end, he added, the motors hit their design specifications and the assembly and fabrication methods he developed for them worked great, Keenon continued.

“They are obviously working very well on Ingenuity on Mars and we are extremely happy about that,” Keennon added.

Other AeroVironment staffers discussed their roles in developing the carbon composites and the landing gear used on Ingenuity.

For the landing gear, Jeremy Tyler, a senior aeromechanical engineer, said that it was developed to absorb the hardest landings on the red planet.

At the top of the gear is an aluminum damper that “buckles and fatigues” with each landing, acting like the crumple zone in a car, Tyler said.

“It absorbs that impact and prevents the helicopter from bouncing after each landing,” Tyler added. “The spring folds back into shape after each landing and prepares for the next one.” Applicable technologyAeroVironment Chief Executive Wahid Nawabi said there are many applications that come from Ingenuity that apply to other aircraft being developed by the company.As an example he gave the Sunglider, the solar-powered drone that last October reached an altitude of more than 60,000 feet and successfully demonstrated mobile broadband communications. The aircraft’s development and testing is funded by HAPSMobile Inc. a joint venture between AeroVironment and SoftBank Corp., a Japanese telecom and internet company.The Sunglider must be lightweight, just like the Mars helicopter. The large drone, with a wingspan longer than 260 feet, is propelled by 10 electric motors powered by solar panels and is designed for continuous flights of months without landing.“Every single gram of weight that goes into this airplane we have to be able to justify and rationalize,” Nawabi said.

Additionally, there are environmental conditions that are similar between the Sunglider and Ingenuity as well as the communications on both aircraft.

“These are autonomous systems. Nobody really flies (the Mars helicopter). It has to fly by itself,” Nawabi said. “The same thing with the Sunglider.  The computers really fly the airplane. So what we learn here or there is cross-applicable to all of our products and businesses.”