 Early fixed-wing aeroplanes were mostly single-engined.When the Russian Igor Sikorsky designed and flew his Ilya Muromets in 1913 it became not only the first four-engined aircraft but, with a wing span of and laden weight of , by far the largest and heaviest to date.By comparison the LZ 18 airship, which flew the same year, was long (the envelope had a capacity of ) and a empty weight of 20 tonnes.