The Douglas DC-3 changed planes forever. It was the first aircraft to make passenger transport profitable without government mail subsidies because of its speed, range, and capacity. It transported 21 passengers, while a sleeper transport version carried 14-16 beds for transcontinental travel. By 1939, 90% of all globe flights were operated on a Douglas DC-3. Some DC-3s can still carry passengers today, after over 90 years of their first flight.
This plane established mail and passenger routes across the north Atlantic, south Atlantic, and Pacific. Every flight deck was luxurious at that time - made with a lounge, dining area, sleeping berths, and dressing rooms. It continued its reign until the Boeing 747 came out and it got dethroned.
The P-51 Mustang was flown just 102 days after its design was initiated. It was flown in WWII and the Korean War, with a top speed of 441mph. It also had great endurance, allowing it to escort bombers. It was developed with a powerful Rolls-Royce Merlin engine, allowing it to fly exceptionally well but still be a fighter. It was credited with destroying over 4,950 aircraft in Europe. It is still flown today as a coveted warbird.
This plane changed the course of the war. It was the most expensive project in WWII, costing over $3 Billion with a pressurized cabin, remote-controlled turrets, and its performance. Its max speed was 375 mph, with a range of 3700 to 5800 miles. It ended the war with the Atomic Bombs on Hiroshima and Nagasaki. It returned to combat in the Korean War to face jet fighters like the MiG-15. Of the 4,000 built, only 22 have survived today.