In the history of aviation, there are few planes that can match the lethality and reputation of the F-15 Eagle. Several variants have been produced over the years, with no end in sight for the bird as a new generation of EX Eagles comes online.
But there’s one Eagle flying which is quite special compared to any other. It’s operated by NASA, and it’s the fastest and oldest F-15 still flying in the world.
NASA 836 is a highly modified F-15B used primarily for testing advanced propulsion concepts. It’s based at the agency’s Armstrong Flight Research Center at Edwards Air Force Base in Southern California.
But the supersonic flying wind tunnel also serves NASA and the greater aerospace industry and taxpayer in other ways. It’s used for crew training, pilot proficiency and safety chase support for other research aircraft. It also conducts a wide range of various flight research experiments. It can carry one of several flight test fixtures mounted underneath it to help conduct those experiments.
1,000 pounds lighter than any other F-15, but with modern engines
The jet first entered service in 1974 with the USAF. NASA acquired it in 1993 from the Hawaii Air National Guard. NASA then modified it to support their test programs. They made it 1,000 pounds lighter than any other F-15 flying in the world, and installed new modern engines.
The age of the jet, combined with its lighter weight and more powerful Pratt and Whitney F100-PW-220 turbofan engines, makes 836 the oldest and fastest flying F-15 in the world. The engines are equipped with more advanced technology and include digital electronic controls, as well as improved durability and reliability.
The engines can produce almost 24,000 pounds of thrust each in full afterburner. The crew regularly take the jet past Mach 2, at altitudes of 40,000 to 60,000 feet. Speeds are limited to Mach 2 when a flight test fixture is mounted beneath the fuselage.
Supersonic flight research
Some experiments and research the jet has conducted include investigating the suppression of sonic booms, improving airflow and fuel efficiency of jet engines at a wide variety of speeds, and even flying space shuttle insulating foam at Mach 2 to better understand how insulating foam loss behaves during launch.
Foam loss punched a hole through space shuttle Columbia’s thermal protection in 2003, which killed the crew when they hit reentry. NASA’s F-15 helped make a safe return to flight for the space shuttle program.
The jet operates with a unique data acquisition system onboard. It includes a research airdata system for the jet itself, a GPS navigation package, a nose boom that contains an airdata probe, a digital data recorder and telemetry antennas. An on-board video system also monitors from the rear seat and transmits high-speed video and photography to researchers on the ground.
More recently, 836 along with NASA’s other F-15 have been conducting Shock-Sensing Probe (SSP) research flights. NASA mounted a data probe on the nose of 836, to test its ability to measure the shock waves of another aircraft flying at supersonic speeds. The jet will fly with NASA’s X-59 soon, using the SSP to measure its unique shock waves in flight, helping validate the X-plane’s ability to reduce loud sonic booms to quiet sonic “thumps.”
NASA’s F-15s are an invaluable asset to America’s aerospace industry. The research trickles down to helping make flight safer and more efficient for everyone.
When I visited the crew last year at Edwards, they made sure to point out that their 836 could leave any other F-15 in their dust. If I had something that fast I’d brag about it too. Sure wish they had offered me a ride.
