Lockheed L-188 Electra is an American Turboprop Airliner

The Lockheed L-188 Electra is an American turboprop airliner built by Lockheed. First flying in 1957, it was the first large turboprop airliner built in the United States. Initial sales were good, but after two fatal crashes led to expensive modifications to fix a design defect, no more were ordered. However, with its unique, high power to weight ratio, huge propellers and very short wings (resulting in the majority of the wingspan being enveloped in propwash), large Fowler flaps which significantly increased effective wing area when extended, and four engine design, the airplane had airfield performance capabilities unmatched by many jet transport aircraft today -- particularly on short runways and high field elevations. The type was soon replaced by turbojets and many were modified as freighters; the type is still used in various roles into the 21st century. The airframe was also used as the basis for the Lockheed P-3 Orion maritime patrol aircraft.

DEVELOPMENT
Lockheed had established a strong position in commercial airliner production with its piston-engined Constellation series and was approached by Capital Airlines to develop a turboprop airliner, but with no interest from other American carriers, the company did not proceed and Capital went on to order 60 British Vickers Viscounts.In 1954 the company offered a twin-engine CL-303, to meet an American Airlines requirement; it was a high-wing design for 60 to 70 passengers but again the design failed to interest other carriers.

American Airlines then revised its requirement to a four-engine design for 75 passengers with 2,000 miles (3,219 km) range. Lockheed proposed a new design, the CL-310 with a low wing and four Rolls-Royce Darts or Napier Elands. The CL-310 design met the American Airlines requirement but Eastern Airlines wanted more range and 85 to 90 seats. Lockheed enlarged the CL-310 design to use the Allison 501-D13, a civil version of the T56 developed for the Lockheed C-130 Hercules military transport

This design was launched as the Model 188 with an order for 35 by American Airlines on June 8, 1955, followed by an Eastern Airlines order for 40 on September 27, 1955.The first aircraft took 26 months to complete and by that time Lockheed had orders for 129. The prototype, a Model 188A, first flew on December 6, 1957 and was awarded a type certificate by the Federal Aviation Administration (FAA) on 22 August 1958. The first delivery was to Eastern Airlines on October 8, 1958 but it did not enter service until January 1959.
L188C Electra of KLM Royal Dutch Airlines operating a passenger service at Manchester Airport in 1963
An L-188CF of Atlantic Airlines
An Electra freighter of NWT Air at Vancouver Airport in August 1983
Lockheed L-188 Electra of TAN Airlines (Transportes Aéreos Nacionales S.A.) operating at Las Mercedes Airport, Managua, Nicaragua in 1970
Lockheed L-188 Electra of Bolivian airline Lloyd Aéreo Boliviano operated until 1975

In 1957 the United States Navy issued a requirement for an advanced maritime patrol aircraft. Lockheed proposed a development of the Electra that was later placed into production as the P-3 Orion, which saw much greater success. The Orion approaches nearly 50 years of front-line service.

DESIGN
The Model 188 Electra is a low-wing cantilever monoplane powered by four wing-mounted Allison 501-D13 turboprops. It has a retractable tricycle landing gear and a conventional tail. It has a cockpit crew of three and can carry 66 to 80 passengers in a mixed-class arrangement, although 98 could be carried in a high-density layout. The first variant was the Model 188A, followed by the longer-range 188C with room for 1000 gallons more fuel and maximum take-off weight 3000 lb higher.