The N1 used kerosene-based rocket fuel in all three of its main stages, while the Saturn V used liquid hydrogen to fuel its second and third stages, which yielded an overall performance advantage due to the higher specific impulse. The N1 also wasted available propellant volume by using spherical propellant tanks under a roughly conical external skin, while the Saturn V used most of its available cylindrical skin volume to house capsule-shaped hydrogen and oxygen tanks, with common bulkheads between the tanks in the second and third stages.