Lockheed 3 Air Express

The very considerable success and proven reliability of the Vega made this aircraft of interest to many airlines, but Western Air Express required some of its own ideas incorporated, the association bringing the name Lockheed 3 Air Express. With a fuselage, landing gear and tail unit generally similar to the Vega, this aircraft differed primarily by having an increased-span parasol wing, a cabin seating four passengers or carrying 2.83m³ of mail, with the pilot's open cockpit moved to the rear of the cabin. Power was provided as standard by a 306kW Pratt & Whitney Wasp, but at least one was flown with a Wasp engine of 391kW, and some of these engines were enclosed by the NACA-developed low-drag cowling. A total of seven of these aircraft was built, plus one Air Express Special with which Laura Ingalls intended to make a non-stop transatlantic flight in 1931. Western Air Express, which had inspired this development of the Vega, acquired only a single example.

Variants

Lockheed 4 Explorer: derivative of the Air Express/Vega series with low-set monoplane wing, fixed landing gear and 336kW Pratt & Whitney Wasp; span was 14.78m and maximum take-off weight 4086kg; designed for a non-stop trans-Pacific flight to Japan; two aircraft only: first crashed during take- off for the record attempt in July 1929, and the replacement aircraft with jettisonable landing gear crashed during trials in September 1929; theoretical range was 8850km.

Lockheed 7 Explorer: improved version of Model 4 with 336kW Wasp C; first aircraft crashed during trials in May 1930, and second made some moderately successful flights before being written off