testbed aircraft
aeroplane, helicopter or other kind of aircraft (specially designed or modified from serial production aircraft) intended for flight research or testing the aircraft concepts or on-board equipment
en-GB/ˈtɛstbɛd ˈɛəkɹɑːft/
aeroplane, helicopter or other kind of aircraft (specially designed or modified from serial production aircraft) intended for flight research or testing the aircraft concepts or on-board equipment