The Lockheed L188
Electra has the distinction of being the only large American turboprop
airliner. An excellent aircraft, the Electra was beset by unfortunate
and severe structural problems, and then was surpassed by rapid
improvements in pure jet aircraft. The Electra was first developed in
response to an American Airlines request for a medium-size short-haul
airliner for US inter-city routes. However, Eastern wanted a larger
plane, and negotiations led to the development of the final Electra
specs. American and Eastern placed the first orders (for 35 and 40
planes, respectively), and American received the first Electra on
December, 1958 (although it could not fly the first service due to a
strike, and Eastern was left with this honor). The orders came rapidly
then, from many US and Asian operators, as well as KLM in Europe.
However; two Electras were found to have broken up in flight (they
crashed in 1959 and 1960), and a structural fault was suspected. After
a speed limit was imposed, Lockheed began looking for the answer, which
it found in the phrase "whirl mode". If damaged, the engine mountings
developed a harmonic with the wing when a whirl mode oscillation was
generated, and this eventually tore the wing off the aircraft. The fix
was not cheap, but it was effective. However, by then the Electra's
reputation was tarnished, and many airlines shied away from the plane -
only 26 more were sold. The existing Electras continued to boast
excellent reliability and economics, and were not replaced until modern
short-range jets became available. The Electras were then sold to other
airlines or converted to freighters, and many are still flying today.
The virtues of the Electra were not ignored by the military, since it
was developed into the US Navy's highly successful P-3 Orion and other
L-188C - Four 2800kW (3750shp) Allison 501-D13 turboprops driving four
blade constant speed propellers.
L-188C - Max cruising speed 652km/h (352kt), economical cruising speed
602km/h (325kt). Service ceiling 27,000ft. Range with max payload
3450km (1910nm), with max fuel 4023km (2180nm).
L-188C - Operating empty 27,895kg (61,500lb), max takeoff 52,664kg
Wing span 30.18m (99ft 0in), length 31.81m (104ft 6in), height 10.01m
(32ft 10in). Wing area 120.8m2 (1300sq ft).
Flightcrew of three. Single class seating for up to 104 passengers.
Most aircraft now configured as freighters, max payload weight is
approximately 12 tonnes (26,000lb).
170 Electras built, including 55 L-188Cs. Approx 40 in commercial
service in late 2002, two used as corporate transports.