Convair 240 and 340/440
Convair, a shortened form of Consolidated-Vultee, was established in 1943 following the decision of Consolidated Aircraft’s founder, Ruben H. Fleet, to sell his shares in the company to Vultee Aircraft’s parent, AVCO. Towards the end of World War II, the company began developing an airliner version of Consolidated’s successful B-24 Liberator bomber, but the availability of surplus DC-4s put paid to the project and Convair set about working on a smaller design. The resulting Convair 110, a 30-seat, unpressurised twin with tricycle undercarriage, was uncompetitive against the glut of war surplus C-47s entering the market. However, with encouragement from American Airlines, Convair re-designed the 110 with a pressurised 40-seat cabin and the 240 (derived from 2 engines, 40 passengers) was born. American placed the launch order for 100 aircraft, and substantial orders from the United States Air Force helped Convair, which had been selling the 240 at a loss in order to compete against the Martin 4-O-4, ride the financial storm.
Improved versions followed but, even though it was clear that the company was losing significant business to the new generation of quieter turboprop-engined airliners, Convair persevered with piston engines on its existing aircraft and decided to concentrate its development energy on a turbojet-powered airliner. It was left to the Allison Engine Company, which had been using a Convair 240 as testbed for its T-38 turbine, to propose a turboprop re-engining programme, which PacAero took forward as the Convair 580. PacAero had also been involved in developing a Napier-engined version of the Convair 440, the 540, but only a handful of conversions was produced, and all were subsequently de-converted. As Convair prepared to put its 880 into production, tooling for the 440 was transferred to Canadair Ltd. (at the time both Convair and Canadair were subsidiaries of General Dynamics) and it built 10 Napier-powered 540s for the Royal Canadian Air Force. It was not until some five years later that Convair finally got round to offering its own turbine engine conversion programme, based on the Rolls-Royce Dart.
Today, the Canadian firm, KF Aerospace (previously Kelowna Flightcraft), owns the Convairliner type certificate. Survivor number have declined sharply in recent years, with Conquest Air now the sole operator of radial-powered Convairs.
First flight: 16 Mar 47 (240 c/n 1, NX90849); see below for other first flight dates.
Production: 1,076, at San Diego, CA and by Canadair at Cartierville, QC
First delivery: 29 Feb 48, to American Airlines (240 c/n 6, NC94023)
Last delivery: Nov 59, to General Motors (440 c/n 507, N5124 and 508, N5125)
Variants: 240 - initial production version powered by 2 Pratt & Whitney R-2800CA-18 Twin Wasp radials, with seating for 40 passengers (566 built, including: 48 unpressurised T-29A and 224 pressurised T-29B/T-29C navigation trainers; 92 T-29D bombardier trainers; and 26 C-131A air ambulances equipped with large cargo door, all for the US Air Force);
340 - stretched version for United Air Lines powered by 2 R-2800CB-16 Double Wasp radials, with seating for 44 passengers, (311 built, including: 36 C-131Bs and 33 C-131Ds with side cargo doors and accommodation for 48 and 44 passengers respectively; and 36 cargo door equipped R4Y-1s for the US Navy, redesignated C-131F in 1962; first flight 5 Oct 51);
440 Metropolitan - Model 340 with detail changes aimed at reducing cabin noise and seating for 52 passengers (209 built, including 15 as C-131E cargo transports for the US Air Force and 2 R4Y-2/C-131G passenger transports for the US Navy; first flight 16 Dec 55).
540/CL-66 - Model 440, powered by 2 Napier Eland turboprops (10 built, in Canada; plus 3 converted from 440 by Canadair as CL-66C; first flight 7 Jan 60).
Conversions have included: 580 - 340/440 re-engined with Allison 501-D13D turboprops and featuring detailed improvements to improve handling, including a heightened tailfin and rudder (170 converted by PacAero at Santa Monica, CA, and Pacific Airmotive at Burbank, CA; an additional 5 C-131B/D were fitted with Allison T-56 turboprops by the US Air Force under the designation C-131H; first flight 19 Jan 60);
Super 580 - 580 re-engined with Allison 501-D22G turboprops (1 converted by Hamilton Aircraft at Tucson, AZ, first flight 21 Mar 84);
5800 - stretched 340/440, re-engined with Allison 501-D22G turboprops and equipped for all-cargo operations (6 converted by Kelowna Flightcraft at Kelowna, BC, first flight 11 Feb 92; additionally, Kelowna has re-engined 2 C-131Ds with Allison turboprops for the Government of Saskatchewan);
600 - 240 re-engined with Rolls-Royce Dart 542-2 turboprops (38 converted using kits supplied by Convair, first flight 20 May 65);
640 - 340 re-engined with Rolls-Royce Dart 542-2 turboprops (27 converted using kits supplied by Convair, first flight 20 Aug 65);
YC-131C - 340 modified at Fort Worth, TX, for use as test-bed for the Allison YT56-A-3 turboprop (2 converted, first flight 20 May 54; subsequently civilianised as Convair 770).