Some early airships were fitted with wing planes, with the intention of providing additional dynamic lift. However, the added lift of planes can be less efficient than simply increasing the volume of the airship. At low air speeds, of or less, the increase in lift obtained by the use of planes on an airship would require a disproportionate increase in engine power and fuel consumption compared to increasing the size of the gas bags. Moreover, the attachment of flying surfaces to the airship's envelope would require significant structural strengthening, with attendant weight gain.