DALLAS —Today in Aviation, the Convair CV-240, the first pressurized, twin-engined airliner, took to the skies for the first time in 1947. The type was a revised design that had a longer but thinner fuselage than the Model 110, accommodating 40 passengers.

Convair produced the American airliner from 1947 to 1954 as a potential replacement for the widely used Douglas DC-3. The CV-240 series, which had a more modern design with cabin pressurization, made some inroads as a commercial airliner and had a long development cycle that produced various civil and military variants. 

Despite attrition, later variants of the "Convairliners" continued to fly well into the new millennium. Until recently, CV-580F still flew with Air Chathams (3C) from New Zealand.

Design and Development

American Airlines (AA) needed an airliner to replace its Douglas DC-3s, so the concept started there. Convair's first build, the unpressurized Model 110, was a twin-engine, low-wing monoplane with 30 seats made entirely of aluminum. Pratt & Whitney R-2800 Double Wasp radial engines propelled it. It had a tricycle landing gear and a passenger boarding airstair on the ventral side. 

The concept Model 110, NX90653, took to the air for the first time on July 8, 1946. By this time, AA had revised the specifications to include pressurization and the design was considered too limited. Convair used the first aircraft for development work on the 240 series before dismantling it in 1947.

Initial Operations

On February 29, 1948, Convair delivered the first Convairliner to AA. Seventy-five went to AA, as well as 50 each to Western Airlines (WA), Continental Airlines (CO), Pan American Airways, Lufthansa (LH), KLM (KL), Swissair (SR), Sabena (SN), and Trans Australia Airlines (TN).

Interestingly, the CV-240 was the first private aircraft to be used in a presidential campaign in the United States. During his presidential run 1960, John F. Kennedy used a CV-240 called Caroline (after his daughter). The National Air and Space Museum now houses the type.

Variants

The Model 340, which had a longer fuselage, longer-span wings, and more powerful engines, was introduced after the Model 240. The 340 took to the air for the first time on October 5, 1951. 

Later, in 1954, Convair designed the Model 440 Metropolitan to compete with turboprop-powered airliners like the Vickers Viscount. It featured more streamlined cowlings, new engine exhausts, and improved cabin soundproofing. 

The design reached the limit of piston-engine output as the "Super 240" developed into the CV-340 and CV-440, and future development focused on conversion to turboprop power with the CV-580.