Peter J. Gates
Drawing on its vast experience with the production of military aircraft, notably the B-24 Liberator, Consolidated Vultee Aircraft Corporation entered the commercial aviation arena with the Liberator derived RY-3 or Convair Model 101. This later led to a more efficient Model 39 (known as the Liberator Liner) which utilised the tall fin of the Model 101 married to a totally redesigned fuselage capable of carrying 48 passengers. The powerplant for this high wing and rather bulbous machine was the Pratt & Whitney R-1830-94 with each of the four engines capable of developing 1,350 hp. This aircraft never entered production, but the prototype registered NX30039 ‘City of Salinas’ was evaluated by the U.S. Navy and later appeared in the service of American Airlines for a brief period as a pure freighter on the coast to coast service.
Further development saw the emergence of the Model 110, an unpressurised aircraft which returned to a more conventional low-wing layout with accommodation for 30 passengers and powered by two 2,100 hp Pratt & Whitney R-2800-SC14G engines. The aircraft bore a striking resemblance to the later Model 240 with the exception of the position of the powerplants. The Pratt & Whitneys were positioned in a similar fashion to the Dart engines on the later HS-748 and Grumman Gulfstream aircraft. Once again this was an aircraft never to enter commercial production, but the aircraft did form a solid foundation for future designs. The Model 110, registered NX90653 first flew on July 8, 1946.
American Airlines Requirements
The initial demand for a twin-engined aircraft to replace the Douglas DC-3 on the general routes of approximately 1,609 km (1,000 miles) was tabled by American Airlines in 1945. This resulted in the previously mentioned aircraft, but before the Model 110 took to the air, American requested a larger and more powerful aircraft. From this was born the Convair 240 with a length of 22.75 m (74 ft 8 in), a maximum take-off weight of 18,956 kg (41,790 lb) and a range of 1,649 km (1,025 miles) with maximum fuel. The 240 was ordered ‘off the drawing board’ by American Airlines. The powerplant chosen was the Pratt & Whitney Double Wasp R-2800-CA18 (most successfully installed in the Curtis C-46, P-47 Thunderbolt, Grumman F6F and the Martin 202 aircraft) with a choice of several propeller models, thus giving operators the choice of equipment applicable to the routes each individual airline operated. The Hamilton Standard 43E60 was to become the most popular and later became standard issue on all future developments of the Convair 240.
The aircraft also featured a fully pressurised cabin, exhaust augmented cooling for the Twin Wasps, hydraulically actuated fowler flaps which extended from the aircraft wing root to the outboard end of the centre section. A choice of positions for the integral folding passenger airstairs was also offered, forward of the wing on the port or starboard side, and a rear ventral airstair which retracted into the fuselage under the tail area (as in the Caravelle, DC-9 and Boeing 727) was standard issue. The prototype NX90849 flew for the first time on March 16, 1947. American Airlines was the launch customer for the 240 series and operated the first service on June 1, 1948. An initial order for 100 aircraft was later reduced to 70 and the aircraft became a perfect operating companion to the American fleet of Douglas DC-3 and DC-4 airliners.
Western Airlines was next to introduce the Convair 240 on September 1, 1948 with NC8401H, followed by Pan American, TAA, United and Northeast Airlines. Convair went on to produce 176 commercial 240s and a substantial number of military versions such as 48 unpressurised T-29As along with 119 T-29C and 93 T-29Ds for the U.S.A.F. Another 49 Model C-131A (Samaritan Aeromedical Transports) and VC-131A were also manufactured. The Convair 240 did exceptionally well despite competition from the Martin 202 which first flew on November 22, 1946. This aircraft bore a striking resemblance to the Convair product and was built to specifications outlines by American Airlines. The Martin incidentally had the distinction of receiving the first CAA Type approval for a post-war twin-engined airliner. Northwest Airlines was the first Martin 202 operator and several carriers including Eastern ordered the unpressurised airliner in limited quantities, but it was the Convair machines that captured the lion’s share of the market despite the fact that the Martin first flew four months ahead of the Convair 240.
A structural deficiency was detected in the Martin 202 after a 1948 accident and a revised version the 202A was sold to TWA, but by and large the Martin 202 and the later 404 was to prove a disappointment with only 43 and 103 respectively being sold.
United Airlines was the sponsor for the 340 and placed an order for 30 aircraft on February 20, 1951. It was Braniff however who actually operated the first 340 commercially on November 1, 1952, with United following some 15 days later. The 340 Convairliner retained the effective ‘orange peel’ type engine cowls fitted to the earlier 240 series but dispensed with the rear ventral airstairs. An additional 2839 litres (750 US gallons) of fuel was carried thanks to the larger wing and Hamilton Standard 43E60 propellers became standard on all Model 340 aircraft. Another venture that was contemplated by Convair while the 340 was in production was the use of Turbo Compound engines.
The Wright R-3350 was the chosen unit, but the plan failed to reach the development stage and although the engine was later employed on the Douglas DC-7 and Lockheed Super Constellation, many believe that it was a wise move considering the operating problems which the above-mentioned aircraft encountered. Carriers that ordered the 340 included K.L.M., JAT, Avensa, Delta, Hawaiian, National, Alitalia, Lufthansa, Garuda, Ansett, All Nippon and Finnair to name but a few.
The Convair 440 Metropolitan
In the mainline short-haul area, the Vickers Viscount was steadily and deservedly earning for itself a reputation among the European carriers and indeed the sleek dart-powered aircraft was viewed as a almost insurmountable obstacle by many, including Convair who had already tasted defeat when Trans Canada Airlines (now Air Canada) ordered a large fleet of Viscounts. Despite this, Convair chose to continue refining the basic design and hence the Model 440 or ‘Metropolitan’ as the European carriers dubbed it, was born. With almost identical dimensions of its predecessor, the 440 did however feature improved soundproofing, weather rada as an option (most carriers chose to have radar installed) and gone were the characteristic twin exhaust openings common to both 240 and 340 models being replaced with a cleaner, rectangular installation.
The 440 model made little impact on the American carriers, however it did surprisingly well in Europe and with stiff competition from the new generation airliners such as the aforementioned Viscount, it is clear indication of the success of the basic Convair airframe. The first 440 N842H flew its maiden flight on December 16, 1955. Continental Airlines was the first to operate the 440 on April 1, 1956 and others including Braniff, Delta eastern and National soon followed. The bulk of the 440 sales however were in Europe, in fact almost half of the Metropolitans built were destined for carriers such as Lufthansa, Swissair, Sabena SAS and Iberia.
Australian And The Convair
On December 22, 1946 the chairman of the Australian National Airways Corporation, Mr A. W. Coles accompanied by the TAA General Manager Mr A. J. Bain left Sydney for the United States to sign the contract for five Convair 240s. The trip was a culmination of many months of careful planning and the aircraft was destined to change the way Australian airlines operated and was a guaranteed ‘head turner’ from the moment it arrived in this country.
Trans Australia Airlines was most fortunate with their timing of this purchase, the price per aircraft at the time of signing was $US 295,000 each, but by the time the aircraft arrived in Australia the price had risen to $US 500,000 per aircraft. The first of TAA’s aircraft VH-TAQ ‘John Forrest’ arrived in Melbourne on September 7, 1948 under the command of Captain John Chapman. During the delivery flight the airliner was routed via Europe and the United Kingdom and departed the San Diego facility on August 26, 1948. On arrival in the UK the staff from Vickers were keenly interested in the Convair (this being the first such aircraft seen in the UK) and spent hours crawling over the aircraft, much to the joy and amusement of the TAA crew.
The publicity campaign waged upon the Australian public was well orchestrated and on September 16, 1848 TAA operated a demonstration flight from Melbourne to Sydney carrying 40 passengers. The aircraft completed the journey in the record time of 1 hour 45 minutes, and in doing so operated the first service of a pressurised airliner in this country. The first scheduled Convair service was operated by VH-TAQ from Melbourne to Sydney under the command of Captain Frank Fischer on October 18, 1948. The Convair 240 was an immediate success and had everything the passenger could wish, despite the fact that it was rather noisy in certain sections of the aircraft.
On April 2, 1950 VH-TAR ‘Thomas Mitchell’ had completed 4,000 flying hours and was the first Convair in the world to reach this figure. During this time, development was continuing at the Convair facility and Reginald Ansett had been keenly viewing the aircraft. Ansett Airways was granted approval on April 13, 1954 to import one Convair 340 aircraft, but after his return from the United States, Ansett announced that he had purchased an additional four aircraft. The first Ansett machine VH-BZD operated the inaugural Melbourne-Sydney-Brisbane service on October 4, 1954. The second ‘Super Convair’ as it was known, VH-BZE arrived in Melbourne on February 25, 1955.
Ansett also leased an aircraft from Hawaiian Airlines. Registered VH-BZG (s/n 33 ex N5507K) the airliner was leased from May 1956 to July 1957. Ansett operated a total of eight Convairs, two of the 340 series plus one leased aircraft and five Convair 440 Metropolitans.
The concept of re-engining airliners to create new orders for the original manufactured or simply breathe new life into tired airframes is certainly not new. In the majority of cases, the program is rarely a raging success, but that is certainly not the case with the Convairliner. As early as 1950, Convair was viewing a number of possibilities (obviously the emergence of the highly successful Vickers Viscount was a contributing factor) and as such the first production 240 was sold to General Motors and fitted with Allison 501-A4 turboprop engines. Registered NX24501 the aircraft known as the Turboliner, first flew on December 29, 1950. The type never entered production but was later fitted with the advanced Allison 501-D5C engines for use as a flying test bed for the Lockheed Electra. It must be remembered however that this was not the Prototype Convair 580.
The first successful Convair turboprop conversion was G-ANVP converted from Model 340-42C s/n 153 which was fitted with two Napier Eland turboprops and first flew on February 4, 1956. This aircraft became known as the Eland Convair or Convair 540. A second aircraft, G-AOFC was acquired by Napier Eland and PacAero began conversion to an aircraft known as the Napier Eland Convair 340/440 Mk11. The prototype was leased to Allegheny Airlines for evaluation purposes, and it entered service on July 1, 1959. Allegheny eventually operated six 540s in a 52 passenger configuration. The closure of the 440 Metropolitan production line saw Convair transfer the manufacturing jigs to Canadair at Montreal who, along with PacAero, were involved with the Model 540. Canadair converted ten aircraft to 540 standard for the Royal Canadian Air Force but development and production of the 540 was terminated in 1962. An interesting point is that the Allegheny machines were converted back to piston engines in later years and the RCAF aircraft were re-engined again to become Convair 580s with the Allison engines.
The Convair 580.
As mentioned earlier, the Allison division of General Motors was no stranger to the Convair airframe. In the ensuing years since the development of the Turboliner, engine development continued and the powerplant chosen for the 580 was the 501-D13, which was in fact the civil version of the military T-56 engine. Again it was the smaller regional carriers who showed the most interest, although initial sales were limited to the executive market, where Convair ventured into the domain of aircraft in the Grumman Gulfstream category. The Convair 580 made its maiden flight on January 19, 1960 and Frontier Airlines, the first carrier to operate the 580, commenced services with it on June 1, 1964. Frontier went on to operate a substantial fleet of Convair 580s numbering 32 in later years. Other airlines who operated the 580 included Braniff, North Central, Aspen, Avensa and SAHSA to name a few. The aircraft is still in regular service with several carriers and large numbers are employed as pure freighters.
The Convair 600 - 640.
The constant development of the Rolls Royce Dart engine to the higher rated R.Da 10/1 standard (developed for use in the Japanese NAMC YS-11) saw the eventual mating with the Convair fuselage. Developing 3,025 ESHP, the conversion was carried out by the Convair division of General Dynamics or supplied to clients in kit conversion form. The initial Convair 600, a model 240, was obtained from Garuda. This aircraft, s/n 178, was incidentally the last 240 production model for the civil market. The aircraft was registered N94294 and flew for the first time on May 20, 1965. This aircraft was sold to Central Airlines as N74859 on December 20, 1969.
Convair based the type number on the original aircraft type, for example the converted Convair 240s became the 600 series, and the 340-440s were renamed the 640 series. The first Convair 640 went into service with Caribair on December 22, 1965 and Convair went on to convert 38 model 240s and 27 440s in later years. Airlines who operated the type included Trans Texas, Frontier (after the merger with Central Airlines) who later replaced them with a fleet of 580s and Hawaiian Airlines. A plan to convert military T-29s for the U.S.A.F. to 600 series configuration unfortunately failed to materialise. In the long run however, it was the Convair 580 with those huge and powerful Allison turboprops that proved the most reliable and indeed the most popular conversion.
Eventually 1,086 Convairliners were sold and the sound and thoroughly proven airframe is certainly a credit to the original design. The airliner in its original piston engined form notched up a healthy order book and managed to outstrip its nearest competitors. The Convair 340-440 series in particular, faced stiff competition from the new generation turboprops, yet still managed to sell successfully. The operational life of this exceptional airliner has been further increased with the various conversion programs. Indeed the Convair has proven that it has been totally successful in the re-engining program, a field that as mentioned earlier, rarely produces any large sales or airline acceptance. The type has been well accepted by passengers and crew alike and apart from the annoying and excessive noise levels caused by the exhaust augmentors on the earlier piston models, the aircraft is well respected for its standards of comfort and reliability.
Conversion In The ‘90s.
Just when it seemed that the Convair airframe had been
used to its fullest, the announcement was made in August 1991 that Kelowna
Flightcraft, a British Columbia-based firm was preparing to market the
Convair 340 with a 4.25 metre fuselage stretch under the name Convair
5800. Aimed squarely at the freight market, the 5800 will be completely
rewired, feature Honeywell FZ-450 electronic cockpit instrumentation
and major structural strengthening. The aircraft has a planned range
of more than 1,600 km with a payload of up to 10,000 kg. A top speed
of 520 km/h (courtesy of the Allison D22 engines) should make this a
most attractive proposition. The first aircraft was rolled out on November
5, 1991 and it will be interesting to see how the airfreight industry
reacts to this aircraft that looks very much like a huge Swearingen
Convairs Registered In Australia
This article has been reproduced with the author's permission.
It was originally featured in 'Flightpath' magazine