OrnithopterAn ornithopter (from Greek ornis, ornith- 'bird' and pteron 'wing') is an aircraft that flies by flapping its wings. Designers sought to imitate the flapping-wing flight of birds, bats, and insects. Though machines may differ in form, they are usually built on the same scale as flying animals. Larger, crewed ornithopters have also been built and some have been successful. Crewed ornithopters are generally either powered by engines or by the pilot.
Flying wingA flying wing is a tailless fixed-wing aircraft that has no definite fuselage, with its crew, payload, fuel, and equipment housed inside the main wing structure. A flying wing may have various small protuberances such as pods, nacelles, blisters, booms, or vertical stabilizers. Similar aircraft designs, that are not technically flying wings, are sometimes casually referred to as such. These types include blended wing body aircraft and lifting body aircraft, which have a fuselage and no definite wings.
ButterflyButterflies (Rhopalocera) are insects that have large, often brightly coloured wings, and a conspicuous, fluttering flight. The group comprises the superfamilies Hedyloidea (moth-butterflies in the Americas) and Papilionoidea (all others). The oldest butterfly fossils have been dated to the Paleocene, about 56 million years ago, though they may have originated earlier. Butterflies have a four-stage life cycle, as like other holometabolan insects they undergo complete metamorphosis.
Fuel economy in aircraftThe fuel economy in aircraft is the measure of the transport energy efficiency of aircraft. Efficiency is increased with better aerodynamics and by reducing weight, and with improved engine BSFC and propulsive efficiency or TSFC. Endurance and range can be maximized with the optimum airspeed, and economy is better at optimum altitudes, usually higher. An airline efficiency depends on its fleet fuel burn, seating density, air cargo and passenger load factor, while operational procedures like maintenance and routing can save fuel.
