It will thus be seen that five engines are installed in the ship; these are all of the same type and horse-power, namely, 250 horse-power Sunbeam. R 33 was constructed by Messrs. Armstrong Whitworth Ltd., while her sister ship R 34 was built by Messrs. Beardmore on the Clyde. In the spring of 1918, R 33 and R 34 carried out several flight trials, and though various difficulties were encountered both with the engines and also with the elevator and rudder controls, it was evident that, with these defects remedied, each of these ships would prove to be singularly reliable. On one of these trials made by R 34, exceedingly bad weather was encountered, and the airship passed through several blinding snowstorms; nevertheless the proposed flight of some seventeen hours was completed, and though at times progress was practically nil owing to the extreme force of the wind, the station was reached in safety and the ship landed without any contretemps. This trial run having been accomplished in weather such as would never have been chosen in the earlier days of rigid trial flights, those connected with the airship felt that their confidence in the vessel's capabilities was by no means exaggerated. The lift of the ship warranted a greater supply of petrol being carried than there was accommodation for, and the engines by now had been "tuned up" to a high standard of efficiency. Accordingly it was considered that the ship possessed the necessary qualifications for a transatlantic flight. It was, moreover, the opinion of the leading officers of the airship service that such an enterprise would be of inestimable value to the airship itself, as demonstrating its utility in the future for commercial purposes. Efforts were made to obtain permission for the flight to be attempted, and although at first the naval authorities were disinclined to risk such a valuable ship on what appeared to be an adventure of doubtful outcome, eventually all opposition was overcome and it was agreed that for the purposes of this voyage the ship was to be taken over by the Air Ministry from the Admiralty.