Lockheed 188 Electra

L-188 Electra
An L-188A Electra of Pacific Southwest Airlines.
Role	Turboprop airliner
National origin	United States
Manufacturer	Lockheed Corporation
First flight	December 6, 1957
Introduction	January 12, 1959 with Eastern Air Lines
Status	In limited use
Primary users	American Airlines Eastern Air Lines Braniff Airways National Airlines
Produced	1957–61
Number built	170
Variants	Lockheed P-3 Orion

The Lockheed L-188 Electra is an American turboprop airliner built by Lockheed. First flown in 1957, it was the first large turboprop airliner built in the United States. Initial sales were good, but after two fatal crashes that led to expensive modifications to fix a design defect, no more were ordered. 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-engined design, the airplane had airfield performance capabilities unmatched by many jet transport aircraft even today—particularly on short runways and high field elevations. Jet airliners soon supplanted turboprops for many purposes, and many Electras were modified as freighters. Some Electras are still being used in various roles into the 21st century. The air-frame was also used as the basis for the much more successful Lockheed P-3 Orion maritime patrol aircraft.

Lockheed had established a strong position in commercial airliner production with its piston-engine Constellation series. Further development brought turboprop engines to the Constellation airframe with the Lockheed L-1249 Super Constellation. In 1951, Lockheed was approached by Capital Airlines to develop a new turboprop airliner which was designated the YC-130, however there was no interest from any other carriers, so the design was dropped. Subsequently, Capital Airlines went on to order 60 British Vickers Viscounts. In 1954, as a result of American Airlines' interest in developing a twin engine aircraft, the idea resurfaced and the company offered a twin-engine design now designated the CL-303. This newer design was a high-wing type and would allow for 60 to 70 passengers. This design was also shelved for lack of interest from other carriers.

The following year, American Airlines revised its requirement to a four-engine design for 75 passengers with 2,000 miles (3,200 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 failed to meet another interested carrier; Eastern Air Lines. Its requirements were for a longer range; a minimum cruising speed of 350 miles per hour (560 km/h); and increased seating capacity to the 85-to-90-passenger level. Lockheed redesigned the CL-310 to use the Allison 501-D13, a civilian version of the T56 developed for the Lockheed C-130 Hercules military transport. The airframe was stretched to allow for more seats and handle the increased performance. This design was launched as the Model 188 with an order for 35 by American Airlines on June 8, 1955. This was followed by Eastern Air Lines with an 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, was completed and first flew on December 6, 1957, two months ahead of schedule. Lockheed was awarded a type certificate by the Civil Aeronautics Administration (CAA) on 22 August 1958. The first delivery – to Eastern Air Lines – was on October 8, 1958 but it did not enter service until January 12, 1959.

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