Sky vessel
A spaceship with a complement of robot drones, observed by the Twelfth Doctor to have originated from the 29th century, crash landed on Earth in the past while on a destination to the Promised Land. The ship later surfaced as the castle of Nottingham in 1190 England. By this point, the robots, masquerading as medieval knights, served the Sheriff of Nottingham, who converted into a cyborg and aspired to take the English throne while the robots really planned to take off and fly to the Promised Land.
After the Sheriff was killed and most of the robots were destroyed, the remaining two took off, not knowing they didn't have enough gold content to fix their engines. As the ship would detonate and take out "half the country", the Doctor, Robin Hood and Clara Oswald shot a golden arrow into its engines, giving it the power boost it needed to reach orbit where it exploded. (TV: Robot of Sherwood)
