Interstate L-6

The Interstate L‑6, introduced in 1947 by the Interstate Aircraft and Engineering Corporation, was a mid‑weight, twin‑engine transport that quickly became a workhorse for both civilian and military operators in the post‑war era. Designed to replace aging pre‑war models, the L‑6 featured an all‑metal stressed‑skin fuselage, low‑wing configuration, and two 1,200 hp Pratt & Whitney R‑985 radial engines mounted on streamlined nacelles. Its retractable tricycle landing gear and fully slatted wings gave it a cruising speed of 230 knots and a range of 1,800 nautical miles, allowing transcontinental payloads of up to 6,500 pounds. The cabin could be configured for cargo, passenger (up to 22 seats), or medical evacuation layouts, making it remarkably versatile. Notably, the L‑6 incorporated an early flight‑control hydraulic system and a pressurized cockpit, innovations that set new standards for safety and comfort. Over 350 units were produced before the line was phased out in the early 1960s, and the aircraft’s reliability contributed to the expansion of regional airlines and the logistical capabilities of the U.S. Air Force Reserve. The Interstate L‑6 remains a benchmark in post‑war utility aircraft design.

Interstate Aircraft and Engineering Corporation

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Design & Classification