Designed and initially produced by McDonnell Douglas, the Super Hornet first flew in 1995. It is used by the United States Navy and the Royal Australian Air Force. The Boeing F/A-18E and F/A-18F Super Hornet are twin-engine, carrier-capable variants based on the McDonnell Douglas F/A-18 Hornet. The F/A-18E single-seat variants are larger and more advanced derivatives of the F/A-18C and D Hornet. The Super Hornet is a new aircraft at about 20% larger and 3,200 kg heavier empty weight than the original Hornet. It carries 33% more internal fuel, increasing mission range by 41% and endurance by 50% over the "Legacy" Hornet. To aid safe flight operations and prevent confusion in radio calls, the Super Hornet is informally referred to as the "Rhino" to distinguish it from earlier Hornets. It is designed to be equipped with an aerial refueling system (ARS) or "buddy store" for the refueling of other aircraft.