Certainly the most famous product of the Piper Company, the original version of the Piper PA-18 Super Cub, powered by a 67kW Continental C90-12F flat-four engine, first came on the market in late 1949 after gaining type certification on 18 November 1949. It continued in production with Piper until 1981, when the company disposed of all rights in this aircraft to WTA Inc. of Lubbock, Texas. In the intervening period the PA-18 had appeared in progressively improving form, and had been powered by a variety of engines rated between 67 to 112kW. In its final Piper production form, as the PA-18-150, its basic configuration was that of the earliest two-seat Cubs with braced high-set wings, wire-braced tail unit, and fixed tailwheel landing gear, but powered by a 112kW Avco Lycoming O-320 flat-four engine. This powerplant had been used also for a specialised agricultural duster/sprayer version designated PA-18A which had been introduced in 1952; it incorporated as standard a chemical hopper and spray/dusting gear, but was easily convertible for general-purpose use, and when production ended a total of 2,650 had been built. In addition to civil construction, Piper built 838 PA-18s with the 71kW Continental C90-8F engine for the US Army under the designation L-18C, 108 of this total being supplied to foreign nations under the Military Aid Program, and the army then ordered 150 examples of the generally similar L-21A which differed by having the 92kW Avco Lycoming O-290-II engine; at a later date a number of these aircraft were converted for use as trainers, then being redesignated TL-21A. Under the designation YL-21 the US Army evaluated two examples of a version of the PA-18 Cub powered by a 101kW Avco Lycoming O-290-D2 engine, later acquiring a total of 584 under the designation L-21B, a number of them being supplied to foreign nations under MAP. In 1962 in-service L-21Bs were redesignated U-7A.