While the best airplane overall is difficult to define given the large variety of tasks aircraft perform and the consequently large number of different designs optimized for those tasks, jet-powered aircraft hold the majority of speed, size and payload records for aircraft as of 2015. However, a propeller-driven drone aircraft holds the record for longest duration in flight.
As of 2015, the fastest manned aircraft ever flown is the SR-71 Blackbird, a high-speed military surveillance aircraft that achieved an official top speed of 2,193.2 mph in 1976. Designed for surveying enemy territory at speeds too fast and altitudes too high for intercept by surface-to-air missiles or fighter aircraft, the SR-71 employed two ramjet engines rather than the more common turbojet engines to maximize its speed. Some pilots claim to have flown the SR-71 even faster than the record speed during missions, but these accounts are not officially verified. However, the SR-71 does hold several other official speed records for fastest travel between particular destinations.
The largest and heaviest plane in the world is the Antonov An-225 cargo aircraft. It is powered by six turbofan engines producing 51,600 pounds of thrust each and weighs approximately 640 tons. The 276-foot long plane was designed to transport the Buran space shuttle and also holds the record for aircraft cargo capacity at 250 tons.