Inside Look: Boeing Concludes EcoDemonstrator SAF Emission Test with NASA

Boeing has concluded a series of flight tests with NASA studying emissions from Sustainable Aviation Fuel (SAF) and its effect on the formation of contrails. The duo performed 10 test flights using the Boeing 737-10 EcoDemonstrator airplane and NASA’s Douglas DC-8 jetliner Airborne Science Laboratory. Each flight lasts from three to five hours, spanning from Montana to the Pacific coast. DLR, FAA, GE Aerospace, and other industry stakeholders also partake in the campaign.

Boeing and NASA conducted a series of flight tests studying emissions. (Photo: AirlineGeeks | Fangzhong Guo)

Boeing flew the EcoDemonstrator airplane with low-sulfur conventional aviation few in the wing tanks and SAF in the center tank. The flight crew alternated fuel supply during the cruise while the DC-8 flew behind the commercial jet and measured emissions produced by each type of fuel and contrail ice particles. The pair also gathered data to study the contrail formation visually. NASA collected satellite images of the contrail, and Boeing recorded the formation process from within the airframe using GoPro cameras.

Boeing Engineers mounted GoPros to study the formation of contrails. (Photo: AirlineGeeks | Fangzhong Guo)

The consortium hosted a debrief on Tuesday, sharing initial observations, and AirlineGeeks got a behind-the-scenes look at the test during the event.

A panel of scientists briefing the media. From the left Richard Moore, principal investigator, NASA-Boeing ecoDemonstrator Emissions Flight Test; Nicki Reid, operations engineer/DC-8 mission manager, NASA Airborne Science Program; Bill Griffin, ecoDemonstrator program technical lead, Boeing; Steve Baughcum, emissions technical fellow, Boeing; Cassi Miller, senior staff engineer, GE Aerospace; Christiane Voigt, research team lead, DLR. (Photo: AirlineGeeks | Fangzhong Guo)

Initial Observations

During the debrief, the group shared more details about the logistics efforts that went into conducting these flight tests. 

Since the primary focus for this test lies on non-carbon emissions from the SAF compared with the traditional jet fuel, the group delicately procured the same fuels with low sulfur content throughout the life of the EcoDemonstrator program to limit variability between the tests. 

Nicki Reid, operations engineer/DC-8 mission manager, also shared more details about the flight operation. Each test run lasts about 20 to 30 minutes on a fuel type. The aircraft would then turn around while maintaining the same altitude and power settings so the environmental factors are relatively constant.

NASA Douglas DC-8 following the EcoDemonstrator’s contrails. (Photo: Boeing)

While not many results have been shared and won’t be ready for several months, NASA’s principal investigator Richard Moore shared that the team has observed that contrails from the new 737 MAX 10 are much thinner and less sustained than those coming out of the DC-8.

Cassi Miller, the senior staff engineer from GE Aerospace, also thinks that these first tests with both CFM LEAP-1B engines running on 100% SAF could help the company push regulations forward to go beyond the current 50% SAF blend limit.

There is consensus that the amount of ice crystals forming in the contrails will have a warming and cooling effect on the environment. The group hopes that data collected from these tests can help scientists improve the accuracy of existing models.

An Inside Look

The DC-8 hosted 17 instrumentations onboard to measure emissions from the latest generation Boeing jet. For instance, it carried the Langley Aerosol Research Group Experiment (LARGE). The “classic” suite of instrumentation measures in-situ aerosol microphysical and optical properties of samples from an inlet on the top of the plane. The equipment groups small particles into droplets and measures the quantity in five groups ranging from 3nm to 32nm.

The NASA DC8 is filled with test equipment. (Photo: AirlineGeeks | Fangzhong Guo)

Cloud Aerosol and Precipitation Sensor mounted on the side of the NASA Douglas DC-8 jetliner. (Photo: AirlineGeeks | Fangzhong Guo)

The Right Amount of Dramamine Needed

Flight crew Andy Barry and Tracy Phelps also explained how they flew the DC-8 behind the MAX. 

” In the visible conditions, we know exactly where it is. They (NASA Scientists) liked us sweeping in and out since they want to clean out and get that ambient environment, then we get back in the wake and sample again. It’s really intense flying, very hands-on.”

NASA Crew Tracy Phelps talking about the flight test in the cockpit. (Photo: AirlineGeeks | Fangzhong Guo)

When the contrails are not visible, the flight crew had to predict the location of the contrail based on models established from previous DLR campaigns. However, that does not always produce the most accurate models, and the plane would respond rather radically when it went into the primary wake. As a NASA engineer says, “You dialed in the right amount of Dramamine after a few flights.”

Every seat is equipped with a five-point-harness due to the maneuvers of test flights. (Photo: AirlineGeeks | Fangzhong Guo)

A NASA engineer making equipment adjustments on the wing. (Photo: AirlineGeeks | Fangzhong Guo)

Lunch is Important in Flight Testing

While the DC-8 focused on measuring outputs from the EcoDemonstrator, the Boeing engineers onboard needed to ensure that it was producing consistent results. 

The aircraft is equipped with sensors to measure particle levels in the clean air so the parties can estimate the location of the contrails. The engineers are constantly monitoring that the engines are running as expected when it’s running on 100% SAF. All this could be valuable data points to pave the way for certifying running 100% SAF in commercial flights.

Cockpit of the Boeing 737 MAX 10. (Photo: AirlineGeeks | Fangzhong Guo)

Although the aircraft just came off the production line, it did not have a fully equipped galley. The flight test team has designated two overhead stowage bins for their lunches.

The EcoDemonstrator has a partially furnished cabin. (Photo: AirlineGeeks | Fangzhong Guo)

A preview of what’s to come on United Airlines Boeing 737 MAX 10. (Photo: AirlineGeeks | Fangzhong Guo)

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Fangzhong Guo

Fangzhong grew up near an OEM airport in northeastern China, where he developed his enthusiasm for aviation. Taking upon his passion, he's now working as an aircraft interior design engineer. Besides working in the aerospace industry, Fangzhong enjoys trying out different types of airplanes and seeing how airplane interiors have evolved. So far, he's flown on over 80 types of aircraft. He also planespots in his spare time. His rarest catches included the 747 Shuttle Carrier Aircraft and AN-225.

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