MOUNTAIN VIEW, Calif. --
It has been said that nothing worth doing is ever easy.
And things weren’t easy for the National Full-Scale Aerodynamics Facility test team assigned to the Aerodynamic and Acoustic Rotoprop Test, or AART. The group was tasked with completing the first-ever urban air mobility rotor acoustic test program at NFAC, which is managed and operated by Arnold Engineering Development Complex and located at the NASA Ames Research Center in Moffett Field, California.
Just as the team had gotten its bearings and the maiden test program got rolling, the global coronavirus outbreak escalated. At first, the pandemic prompted significant adjustments in the AART team’s approach. Later, it brought the test to a complete standstill.
However, the AART team members overcame the challenges they faced and managed to complete the testing in under a year. Their efforts did not go unnoticed and earned them high praise from one of the agencies they worked closely alongside during the program.
Earlier this year, AART team members learned the group was named a recipient of a NASA Group Achievement Award. This certificate is awarded to any combination of government or non-government individuals for an outstanding group accomplishment that has contributed substantially to NASA’s mission. Criteria to be considered for the award includes the quality of results and agency or multi-center level of impact on programs or operations, effective management of cost and schedule, customer satisfaction and success in responding to unforeseen crises.
William Bartow, test director for the AART entry in the AEDC NFAC 40- by 80-foot wind tunnel, said NFAC personnel who were members of the AART team, upon receiving word of the award, reacted with excitement and appreciation for both fellow team members and all who contributed to the test.
“It was a challenging experience during uncertain times,” Bartow said.
According to Dr. William Warmbrodt, NASA chief of the Aeromechanics Branch at NASA Ames who nominated the AART team for the award, the urban air mobility aircraft designs typically have aerodynamic configurations that result in complex aerodynamic and acoustic conditions, such as wing and propeller interaction. Multiple UAM aircraft designed and flown contain propellers or rotors that ingest aerodynamic turbulence from upstream bodies.
“In response, the Aerodynamic and Acoustic Rotoprop Test Program was implemented, a primary objective of which was to determine the aerodynamics and acoustics related to an auxiliary propulsor mounted behind an isolated wing in the National Full-Scale Aerodynamics Complex 40- by 80-foot wind tunnel,” Warmbrodt wrote in his nomination.
The AART in the 40- by 80-foot wind tunnel was a follow-up to a 2018 test program overseen by the Army in its 7- by 10-foot wind tunnel, also located at NASA Ames. The 7- by 10-foot wind tunnel was staffed with Army personnel to support the initial efforts of the program, and NFAC personnel took the reins once it migrated to the 40- by 80-foot tunnel.
The 7- by 10-foot tunnel entry served to collect all of the model performance, including any Particle Image Velocimetry, or PIV, measurements of interest, while the anechoic treatment in the 40- by 80-foot tunnel would make it possible to collect the corresponding acoustic measurements for the conditions collected in the smaller tunnel.
The data set in the 40- by 80-foot tunnel was compiled using model mounted balances and acoustic measurements from strut-mounted microphones and wall-mounted microphone arrays.
“Since our focus was the corresponding acoustic measurements of the 7- by 10-foot [tunnel] entry, we had to tailor our focus experiment from the perspective of obtaining quality acoustic measurements,” Bartow said. “This led to the design of three additional microphone struts that were fabricated for the entry along with an analysis for the customer on where the placement would be most effective.”
The AART would set a standard, as the combined data set from entries in both tunnels would provide researchers with a comprehensive dataset to build future analysis tools to aid in the development of rotorcraft systems.
“The team was looking to build a comprehensive data set on the performance of a tail-mounted propeller under the influence of upstream aerodynamic wake generated from empennage control surfaces,” Bartow said.
Working alongside the NFAC AART team onsite were test customer staff and civilian personnel from both the Army and NASA.
The test buildup process began in the fall of 2019 and continued through the early part of 2020. It was around that time the COVID-19 pandemic began to ramp up in the U.S., disrupting businesses and educational institutions nationwide. It was also when the challenges posed by the pandemic began for the AART team.
A rising number of COVID-19 cases across the country and fears of the spread of COVID-19 forced the test customer to depart NFAC and return to their base of operations on the East Coast. Although now on the other side of the country, the test customer was still able to provide valuable input to the AART team.
“While it’s typical to have customer representation onsite to oversee the various phases of the entry, the pandemic introduced some challenges to the team when it forced all of the customer personnel to return home,” Bartow said. “We were fortunate to have most of the installation effort completed but did have to perform some final model changes while relying on remote customer support.”
By mid-March of 2020, the remainder of the execution phase was performed with the customer supporting the NFAC team remotely.
It quickly became apparent COVID-19 wasn’t going away anytime soon. In the latter part of March 2020, California Gov. Gavin Newsome issued an order for residents to remain at home save only for essential travel, such as trips to the grocery store, convenience stores and banks. With this order implemented, NFAC personnel were forced to clear out, and the facility was vacant for several months. This officially put the AART program on hold.
When members of the AART team returned to the facility that summer, they didn’t miss a beat.
“COVID stay-at-home orders eventually put a pause in the progress we were making and prevented us from resuming test execution efforts until several months later in July when the center partially reopened to essential personnel,” Bartow said. “After about three months of being away from testing, our team was able to step back into operations efficiently and safely like no time had passed.”
More than 20 NFAC personnel were assigned to the test throughout the different phases of the entry in addition to the NASA and Army civil servants who worked closely with the team while the AART occurred onsite. Bartow added the collaboration with personnel from the Army and NASA rotorcraft groups made it possible to complete the test while ensuring the NFAC team met all data quality requirements.
“NASA provided the personnel, expertise and the equipment to acquire the acoustic data and perform the acoustic analysis and data reduction, while the Army provided personnel to help in the execution of the entry,” he said.
The test in the 40- by 80-foot wind tunnel, which originally began in October 2019, was completed in August 2020.
“Sometimes the excellence of our wind tunnel test organizations and test teams are challenged to prove their resilience and determination. The COVID-19 pandemic has done just that,” Warmbrodt wrote. “And the NFAC AART Test Team was up to the challenge.”
Members of the AART team were: Shawn Abadajos, Meliton Abenojar, Bartolome Aganon, Lex Alday, Geoffrey Ament, Russell Baker, William Bartow, Preston Bates, Kevin Boyce, Daniel Boyd, Nathan Burnside, Christopher Byron, Joseph Candaso, Louis Centolanza, Benny Cheung, Alvin Cruz, Steven Diamond, Michelle Dominguez, Scott Edwards, Michael Fleming, Brenda Fox, Todd Fuller, Nili Gold, Patrick Goulding, Paul Gracia, Effie Greene, Farid Haddad, Brian Hall, Christopher Hartley, Laquisha Highsmith, Kenneth Horn, William Horne, Levi Hubbard, Chakaria Hunter, Luisito Icari, Scott Jaffa, Jeffrey Johnson, Matthew Kwan, Jeffery Law, Mike Lonergan, William Lovvorn, Kyle Lukacovic, Kristen Mailhot, Matthew Nguyen, Thomas Norman, Christopher Nykamp, Austin Paige, Jose Rosario-Ferrer, Sandra Ruiz, Joseph Sacco, Cal Sargent, Emily Sayles, David Schatzman, Natasha Schatzman, Alex Sheikman, James Stephenson, Michael Strauss, Matthew Thomas, Brian Timmons, Calvin Tsurui, Johannes Van Aken, Thomas Wade, Brian Wallace, Adam Walsh, Scott Waltermire, Gina Willink, Jonathan Winegar and Nikolas Zawodny.