This modification meant that there was no longer room for the fuel tank under the observer's seat, which had to be replaced by a centre section gravity tank; in order to give the "d" a superior endurance this tank was unusually large, adding extra weight and drag that reduced the type's performance, particularly in the climb. Most B.E.2ds were used as trainers, and the few used on operations by the RFC seem to have been flown from the normal (rear) pilots' seat.