The Piper L-4 Grasshopper evolved from the successful Piper Cub series that took to the air as early as 1930. By 1941, the US Army was in the market for such a light observation and liaison aircraft with rugged reliability, procured four such examples and evaluated the type as the YO-59, later ordering no fewer than 40 more as the O-59. The series saw a dedicated US Army model emerge as the O-59A (soon to be redesignated as the L-4, to which the "L" identified the aircraft series as "liaison"), a type which offered up improvements to many of the components to make the system "battlefield" ready.
At its core, the L-4 Grasshopper was of a high-wing monoplane design, braced at the fuselage, with seating accommodations for two that could include a pilot and passenger/instructor. The lightweight and rugged reliability of the system endeared it to her crews and the Grasshopper went on to provide decades of service in war and peacetime with several nations. Having been designated as the L-4 by 1942, the system was ordered for evaluation as training gliders and accepted by the USAAF (United States Army Air Forces) as the TG-8. The US Navy took on their own versions of this Grasshopper as the NE-1 and the NE-2. An ambulance version of the Grasshopper existed in later forms as the HE-1, though the "H" in the designation was soon reserved for helicopters alone, leaving the HE-1 now as the AE-1.
The L-4 Grasshopper served armed forces well over the years, concluding production in 1981, though the popularity of the system triggered the reopening of the production lines in 1988. These new line Grasshoppers, appearing with modifications and upgrades, failed to light the fires that were burning in the early years however. Some 5,500 aircraft of this series were said to be produced, though some sources put the number as high as 5,700. In any respect, the Grasshopper series proved vital for the US military in the Second World War and the Korean War.