Propliners
Generally, a propliner is a large passenger or cargo aircraft of primarily metal construction powered by two or four piston engines.
The propliner era began in the early 1930s and ended in the 1950s with the advent of jet and turboprop-powered airliners. It was a significant period in aviation that brought many changes to how people traveled and how many people had access to air travel.
During the propliner era, air travel became reachable to the masses. In the interwar period, air travel was primarily the domain of the wealthy. Post-WWII developments in aircraft and engine design reduced operational costs for large airliners. They led to airlines creating multiple passenger classes, thus bringing the price of air travel within reach of many more people.
During this period, land-based aircraft became capable of flying trans-oceanic distances, and the era of passenger service by flying boats ended. Large land-based propliners were faster, more efficient, less maintenance intensive, and much less limited in where they could operate; the flying boat never stood a chance against them.
A turboprop aircraft is similar to a jet aircraft in mechanical terms. Jets have turbine engines encased with fan blades, while turboprops have a propeller on the outside. These are much different from aircraft with piston engines, which also have propellers but are much different mechanically.
The first experimental turboprop aircraft, a modified Gloster Meteor fighter equipped with two Rolls-Royce Trent units, flew in 1945 in England. The first turboprop commercial airliner to enter scheduled service was the Vickers Type 701 Viscount, April 18, 1953.
Due to improvements in turbojet design, the turboprop - less efficient at high speeds - lost much of its importance in the 1960s, although aircraft manufacturers retained it for relatively short-range aircraft.