I worked on flight test analysis the Sea Vixen D3 program at FR Aviation in the late 70s and early 80's at Tarrant Rushton, then Hurn. XP924 of the recent wheels-up landing was the back-up trials aircraft (XN657 being the lead D3 conversion). The drone conversion involved a Universal Drone Pack "UDP" being produced by FR and this slid down onto the ejector seat rails of the Observer position and contained the telemetry system and flight computer. The goal of the "Universal" Drone Pack was something that could largely be re-used for future drone conversions - I recall the MoD also had their eye on the Lightning and then Phantom in the future. Electronic servo valves were added to the flight control actuators around the aircraft - so a form of analogue FBW was added to the Sea Vixen.
During the trials at Hurn and Llanbedr a safety pilot was always on board. All of the flight commands that could be sent from the ground were duplicated on a series of push-buttons in front of the pilot so he could effectively "fly" the aircraft by push buttons to mimic what a ground controller would do. pitch up, pitch down, bank left, bank right etc could all occur by pushing a button dedicated to that command with the flight computer turning the button pushes into proportional analogue commands to the servo valves on the control surfaces and throttles.
During the trials on quite a few occasions the pilot flew the aircraft from lining up for take-off to landing entirely by pushing buttons, then we did it from the ground too. At any time the pilot could grab full manual flying control back by squeezing a button on the stick.
So with XP924 am intrigued as to whether this reverted back to proper FAW2 status with the D3 conversion wiring, electronic servo valves, push-button console etc fully removed? Or some form of hybrid with the D3 servo valves and push-button flying controls still there but now disabled?