It’s more an engineer’s dream than nightmare – to rapidly prototype and redesign aircraft using 3-D printed parts. That’s just what a team of student interns and engineers at NASA’s Ames Research Center in Moffett Field, California, got to do: custom-build aircraft by repurposing surplus Unmanned Aerial Vehicles (UAVs). Grafting fuselages side-by-side adds more motors, propellers and batteries to improve power and performance capacity. By lengthening the wings, the team was able to improve aerodynamic efficiency and help extend the flight time of small, lightweight electric aircraft.
The prototype aircraft are constructed using components from Aerovironment RQ-14 Dragon Eye UAVs that NASA acquired from the United States Marine Corps via the General Services Administration’s San Francisco office. Unmodified, these small electric aircraft weigh 5.9 pounds, have a 3.75-foot wingspan and twin electric motors, and can carry a one-pound instrument payload for up to an hour. NASA can use these Dragon Eyes to penetrate the dangerous airspace within the plume of the volcanoes because their electric motors do not ingest and are not affected by the contaminated air. The Dragon Eyes are proving to be an effective way to gather crucial data about volcanic ash and gas emissions.
The team – comprised of full-time students and summer interns from Stanford University, University of California (UC) Los Angeles, UC Santa Cruz, UC Davis, Virginia Polytechnic Institute and Northeastern University, as well as Ames engineers – modified Dragon Eyes by harvesting spare parts from other Dragon Eyes and reassembling them along with specially designed 3-D manufactured parts to create new aircraft the team dubbed “FrankenEye.”
The NASA team created the name FrankenEye to reference “Frankenstein.” The student teams participating in summer activities harvested parts from surplus aircraft and reanimated them using new 3-D printed parts with the goal of increasing payload capacity and endurance for use in Earth Science missions.
“We essentially created two entirely new machines,” said Kevin Reynolds, principal investigator of the FrankenEye project at Ames. “We worked alongside a group of students to rapidly prototype, manufacture, test and demonstrate key capabilities in preparation for next year’s volcano plume-sampling field work.”
The FrankenEye project team used 3-D printers at Ames and Stanford to create prototypes and make conceptual models. The donated stock UAVs did not come with any blueprints so 3-D scanning technology was essential to design the interface to existing hardware, and create mechanical drawings. After finalizing designs that featured longer and more slender wings and dual fuselages, the teams printed new parts including wing sections, nose cones, winglets, control surfaces, wing ribs and even propellers using the NASA Ames SpaceShop. The 3-D printed wing sections were reinforced using carbon fiber tubing or aluminum rods to give them extra strength without adding significant weight.
“The more weight we carry in material is less weight we can carry in sensors or batteries,” said Reynolds. “Dragon Eyes can fly approximately one hour using the existing lithium-ion battery. But with two fuselages – meaning two batteries – and a more efficient wing design that allows it to fly slower and conserve energy, our variants can fly up to three times as long using electric power.”
Within two months, the student interns also customized open source flight and navigation software to conduct nine test flights of two variants of modified aircraft named “Chimera” and “Alicanto” at Stanislaus County’s Crows Landing Facility in California. The teams demonstrated the ability of their aircraft to take off autonomously, navigate through a series of waypoints, enter into a glide and land at a predetermined location without pilot intervention.
“This project is very exciting for us because it has demonstrated a new capability for quickly and inexpensively modifying existing aircraft to tailor them to specific mission goals,” said Matt Fladeland, Ames co-investigator on the FrankenEye and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) validation projects. “In this case the modified aircraft will be able to stay up longer while carrying more science payload over the volcano.”
The Costa Rican Airborne Research and Technology Application 2015 mission will be the latest in a series of deployments of small unmanned aircraft (UAVs), led by David Pieri, volcanologist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and is supported by the NASA Earth Surface and Interior Focus Area, the ASTER Mission and a consortium of NASA centers, including Ames, NASA’s Goddard Space Flight Center in Greenbelt, Maryland and NASA’s Wallops Flight Facility in Wallops Island, Virginia and the agency’s Glenn Research Center in Cleveland, as well as the University of Costa Rica (CICANUM) GasLab.
Flying as high as 12,500 feet above sea level, multiple small converted Dragon Eye UAVs, including the specialized and highly modified “FrankenEye” platform, will study the chemistry of the eruption plume emissions from Turrialba volcano, near San Jose, Costa Rica.
The goal of the activity is to improve satellite data research products, such as computer models of the concentration and distribution of volcanic gases, and transport-pathway models of volcanic plumes. Some volcanic plumes can reach miles above a summit vent, and drift hundreds to thousands of miles from an eruption site and can pose a severe public heath risk, as well as a potent threat to aircraft.
“The use of UAVs to carry out potentially hazardous sampling of volcanic gas emissions sharply reduces risk to volcano researchers,” said Pieri. “Such data also will be used to help mitigate risk for people living on or near active volcanoes and for passengers and crews flying over them.”
The project directly supports the current Terra and ASTER missions and NASA’s planned Hyperspectral Infrared Imager (HyspIRI) mission by improving satellite data-based observations of gases and aerosols associated with volcanic activity as well as volcanic emission transport models.
Turrialba was chosen because the continuously-erupting volcano has a relatively minimal updraft and wind shear with minimal ash content. In addition, commercial and private air traffic is very infrequent in the airspace around and over Turrialba volcano.
During the research flights in 2013, the team coordinated its data gathering with the ASTER instrument on NASA’s Terra spacecraft, allowing scientists to compare sulfur dioxide concentration measurements from the satellite with measurements taken from within the plume.
Through the fall, the FrankenEye project will continue to develop the aircrafts’ capabilities by focusing on sensor integration and a larger triple-fuselage design. This research effort seeks to show that FrankenEye is more than the sum of its parts and can be optimized to be more capable than its individual units.
Next spring, members of the FrankenEye team will witness their creations take flight over Turrialba volcano. Working alongside NASA Earth science researchers, they will fly the aircraft over and into the volcano’s sulfur dioxide plume. Scientists believe computer models derived from this study will help safeguard the National and International Airspace System, improve global climate predictions, and mitigate environmental hazards (e.g., sulfur dioxide containing volcanic smog or “vog”) for people who live around volcanoes.