The British Vickers corporation is primarily a manufacturer of military equipment. It produced one of the first aircraft designed from the beginning to carry a machine gun, the Vickers Gunbus. It also built the first aircraft to cross the Atlantic Ocean non-stop, a converted World War I RAF Vickers Vimy bomber. It was a pioneer in producing airliners, early examples being converted from Vimy bombers, and went on to manufacture the piston-engined Viking and Varsity, the Viscount and Vanguard turboprop airliners, and the stylish though noisy VC-10 jet airliner. The Valiant V bomber was another Vickers design. The corporation is currently focused on military vehicles and weapons. The VC-10 remains in RAF service as a troop transporter and aerial refueling tanker. The plane-building parts of Vickers were absorbed into the British Aircraft Corporation during the production of that type.