Jet planes are propelled by jet engines, the first of which was patented by Frank Whittle in 1930. The jet engine is a type of gas turbine engine that obtains forward thrust in reaction to a fast-moving "jet" of gases moving in the opposite direction, according to the World Encyclopedia. Modern turbojet engines propel planes at speeds of more than 500 miles per hour.
Military aviation tools, including jet plane technology, saw many advancements during World War II as military contractors such as the Boeing Company started producing high-speed turbojet planes for the war effort. More than 60 years later, the U.S. military continues to fly jet fighter planes such as the F-16 and F-22.
During the 1950s to early 1970s, passenger travel via commercial jets flourished, particularly with the introduction of 500-seater jumbo jets in the early '70s. The commercial jet aviation industry has faced several major economic setbacks since the mid-1970s, but, according to the International Encyclopedia of the Social Sciences, jet airline profitability will ultimately improve through greater market competition and cost-efficiency measures.
