March 2005-
If you’re lucky enough to visit NASA’s Dryden flight research center, located next to Edwards Air Force Base near Lancaster, CA; you can expect to see a lot of exotic airplanes. This, after all, was the home of the X-1, X-2, X-15, and Space Shuttle landings—among other things.
It’s a place where the sky is apt to be full of jet and rocket-powered airplanes in which Aerospace Research Pilots “push the envelope,” in the never-ending quest to make airplanes fly higher and faster than ever before… Well, that’s part of what’s done at Dryden.
It’s also the home of many less glamorous airplanes that don’t fly particularly high or fast, but nonetheless add vital information to what’s known about how airplanes fly. For almost 30 years, one of those airplanes was a Piper Twin Comanche. The Dryden Center bought a stock PA-30 Twin Comanche in 1967.
Over the years, ‘NASA 808’ was flown to test everything from General Aviation flight control systems and stall behavior to engine-only steering. It was a pioneering test-bed for remote piloting techniques used by the Air Force for its unmanned aerial vehicles (UAVs) today. It even acted as a “chase plane” in wake vortex experiments.
‘NASA 808’ was first used to investigate stall/spin behavior in flight. In the 60’s, it was common practice for multi-engine students to practice engine-out procedures at pattern altitudes, and more than a few were killed that way—particularly in the PA-30, which was used as a trainer, and had a Minimum Control Airspeed (Vmc) close to stall speed.
If a pilot got the airplane just a little slow, especially if the critical left engine failed, it was all too common for it to roll into an uncontrollable spin—and this at altitudes too low to have any chance to recover.
Dryden’s PA-30 was used to test this behavior (presumably at safer altitudes) and then sent to NASA’s Langley Research Center near Hampton, Va., where it spent time in a wind tunnel. There, in carefully controlled conditions, it was possible for engineers to observe the very complex aerodynamics that occur in the stall/spin environment.
I don’t know for certain, but suspect that input from this research may have influenced Piper’s later attempt to update the Twin Comanche with the PA-39 counter-rotating engine design, which eliminated the critical left engine problem.
But the service that ‘808’ could offer NASA didn’t end with stalls and spins. During the early 1970s, it was heavily modified, with a telemetry system that would transmit flight data from the aircraft to the ground—and later, with a television system and servos to allow the airplane to be controlled by a remote pilot.
This was used to familiarize pilots with the remote piloting system before using it with less forgiving test vehicles that included a wide range of drones and even a 3/8 scale model of the F-15 fighter.
Later in the 1970s, NASA got interested in wake turbulence from heavy jets—and the effects of the wake on smaller aircraft following below and behind them. A Boeing 727 jetliner was outfitted with smoke generators (similar to those used at airshows) to make the wake visible. One of several chase planes would follow below and behind to measure the effect of the wake.
Along with an F-104 Starfighter and a LearJet, NASA used the PA-30 for this job… It’s enough to make you wonder how much they were paying the pilots… Then again, this might be one time a pilot would prefer to fly an airplane by remote control!
In July 1989, a DC-10 crashed near Sioux City, Iowa after the center engine exploded and destroyed all three of the airliner’s supposedly redundant hydraulic control systems. Despite that, the flight crew managed the almost impossible task of landing an aircraft without conventional flight controls—they used differential thrust from the remaining two engines to steer, and got the crippled bird almost to the runway—saving themselves and about half the passengers aboard.
NASA engineers were intrigued by this feat, and decided to run a flight control program to find out just how hard it is to control a multi-engine airplane using only the throttles, and ‘808’ was one of the airplanes involved in these tests, along with a LearJet and an F-15.
Of the three, the PA-30 turned out to be the most difficult to fly with only the throttles, as a NASA report said: “Gross control of the PA-30 was possible but landing on a runway would have been difficult.” However much they were paying the pilots, I don’t think it was enough!
Who were the pilots? Aerospace research pilots who flew ‘NASA 808’ included ex-RAF exchange officer Einar Einvoldson, Steve Ishmael, Mike Swann, and Donald Mallick—but surely the most famous must have been Fred Haise, who went on to become an astronaut and served as lunar module pilot on the ill-fated Apollo 13 mission.
The last NASA pilot to fly ‘808’ was Tom McMurtry, who flew the airplane to Reedley California on May 12, 1995. It was turned over to Kings River Community College, and used in their aviation maintenance course.
Sources:
“The Smell of Kerosene, a Test Pilot’s Story” by Donald L. Mallick (NASA SP-4108) https://www1.nasa.gov/centers/dryden/pdf/88797main_kerosene.pdf
“In-Flight Simulation Studies at the NASA Dryden Flight Research Facility” by Mary F. Shafer (NASA TM-4396) https://www.nasa.gov/centers/dryden/pdf/88271main_H-1833.pdf
“Concept to Reality: Contributions of the NASA Langley Research Center to U.S. Civil Aircraft of the 1990s” by Joseph R. Chambers. (NASA SP-2003-4529) https://oea.larc.nasa.gov/PAIS/Concept2Reality/
John D. Ruley is an instrument-rated private pilot, and a freelance writer specializing in science and technology. He’s also a volunteer pilot for LIGA International (www.ligainternational.org), and past president of the Modesto Airport Pilot’s Association. You can write to John at jruley@ainet.com.
