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The NT-33A, USAF s/n 51-4120, was a variable stability in-flight simulator. It was owned by the Air Force Flight Dynamics Laboratory and, later, the Air Force Research Laboratory. The aircraft was maintained and operated by Calspan Corporation of Buffalo New York, under contract to the USAF. This T-33A was modified in the late 1950s for flight controls investigations and simulating the flight characteristics of other aircraft designs. Schedule permitting, the aircraft was sometimes made available for contractor or foreign government evaluations, usually to correct anomalies found in new aircraft designs. The aircraft was also used by both the USAF and US Navy test pilot schools as part of their flight controls evaluation curriculum. This is where I first encountered the jet. The F-94B nose houses computer units interfaced to the aircraft flight controls. The rear cockpit is modified with banks of controls to change the coefficients and variables of the flight control equations, thereby changing how the aircraft responds to control inputs. The Calspan safety pilot would occupy the rear seat while the research pilot or student would fly the aircraft from the front. The safety pilot could take control of the aircraft at any time using the basic T-33 flight controls. or if specified flight conditions were exceeded, usually yaw/pitch rates or Gs, the system would automatically kick off the variable stability control laws and revert to T-33 flight control operation. The aircraft has changed some over the years. During the 1960s, the aircraft tip tanks were modified to have the aft portion of the tanks act as clam shell speed brakes. This modification was later removed. In the late 60s/early 70s, the F-94 acquired rows of vents on each side to facilitate cooling as more computing power was added to the variable stability system. My TPS class team project was to investigate changing the roll axis of the aircraft through flight control changes and its effects on maneuverability. Most of the tests involved evaluating the ability to handle various target tracking scenarios. Lots of piccies… Ready for brake release... Returning to Eddie's Air Patch... A long pass down the Edwards Tower Fly-By Line... Nose-on view... Computers circa 1978... Some of the variable stability input controls in the rear cockpit Side-stick controller in the front cockpit. There's a center control stick as well. Nose detail in 1988 The stickers on the nose are from left to right, top to bottom: Swedish flight test center, IAI Kfir C2, NASA, USAF Test Pilot School, US Navy Test Pilot School, unidentified, SAAB JAS 39. The first and last are interesting in that the aircraft took part in flight controls development of the Gripen, yet in the following year, the Gripen would have the first of two mishaps attributed to Pilot Induced Oscillation (PIO) caused by flight control software issues. After the 1989 mishap, the NT-33A was again being used to investigate the cause and possible corrections to eliminate the PIO situation. The NT-33A was retired and put on display in the National Museum of the USAF in 1997 after many years of being the oldest aircraft in the USAF active inventory. When it went to the museum, it retained the dummy refueling probe used in one of its last research projects and remains there on display... Thanks for looking, Sven