The date of its maiden flight has yet to be announced.
The machine is about 60ft (18m) longer than the biggest passenger jets.
British firm Hybrid Air Vehicles (HAV) has spent the past nine years developing the prototype in the Cardington hangar after the US Army ran out of money to develop it as a surveillance machine.
HAV has said the vessel could have many uses including surveillance, communications, transporting cargo, humanitarian missions and passenger travel.