Bristol Britannia, Canadair CL-28 Argus and Canadair CL-44
The Britannia was designed to fulfill the 1943 Brabazon Type III specification for a medium-range airliner to serve the Empire routes. By the time the Ministry of Supply formalised the requirement in 1947, British Overseas Airways Corporation (BOAC) had already taken delivery of a batch of ex-United States Army Air Force Constellations. Further Constellation deliveries were to follow to replace the uncompetitive Short Solent flying boats on the Kangaroo route to Australia, although BOAC eventually ordered 25 Britannias in 1949 to replace the Constellations from 1954. Development was slowed by a combination of factors: BOAC’s decision to change its choice of engine from piston to turboprop; the need for additional testing in the wake of the De Havilland Comet’s problems; and technical problems with the Proteus engine. The Britannia finally entered service on1 February 1957, by which time Boeing’s turbojet 367-80 had made its first flight and the aircraft was competing for commercial orders with the 707. A Royal Air Force (RAF) order for 23 helped swell sales, but overall the Britannia was a commercial failure. The type remained the mainstay of the RAF air transport fleet until phased out in the 1976 round of defence cuts.
In 1954, Canadair was awarded a licence to build a derivative of the Britannia as a maritime patrol and anti-submarine warfare aircraft to replace the Lancasters and Neptunes of the Royal Canadian Air Force (RCAF). Britannia wings, tail surfaces and landing gear were mated with a redesigned, unpressurised fuselage and, as speed was not required for the maritime role, Canadair replaced the Britannia’s turboprops with radials.
In 1957 Canadair was awarded a contract for eight aircraft to replace the RCAF North Stars then operating the air-bridge between Canada and its military bases in Europe. To fulfill the requirement, Canadair re-engineered the Argus to create an aircraft broadly comparable to the Britannia 300 series. The decision was taken at the outset to use turboprops, although the original choice, the Bristol Orion, had to be replaced by Rolls-Royce engines following the Orion’s cancellation by the British Ministry of Supply. A commercial version was also proposed, but airlines at the time were interested only in jets, and as a result the only significant orders came from cargo airlines, attracted by the CL-44’s lower purchase price. Eventually, the Icelandic airline Loftleiðir, acquired a batch of unsold airframes which it had stretched to carry passengers on its low-cost services between New York and Europe. A single CL-44 was converted to carry outsize cargo; this is stored at Bournemouth is occasionally the subject of some tinkering. Ambitious plans to bring back the last surviving Yukon to Canada in the mid-2000s fell through, although the aircraft remains on display in Ecuador.
First flight: 16 Aug 52 (c/n 12873, G-ALBO).
Production: 85 in the UK, comprising 55 at Filton and 30 by Short Brothers at Belfast. An additional 33 CL-28s were built by Canadair at Cartierville, QC.
First delivery: 30 Dec 55, to British Overseas Airways Corporation (c/ns 12904 and 12905, G-ANBC and G-ANBD respectively)
Last delivery: 31 Oct 60, to Royal Canadian Air Force (CL-28 c/n 33, RCAF 20742). (The last Filton-built Britannia to be delivered was c/n 13514, handed over the Royal Air Force as XM518 on 19 Mar 60.)
Variants: Britannia 101 - prototype, powered initially by 4 Bristol Proteus 625 turboprops but soon re-engined with Proteus 755s (2 built);
Britannia 102 - initial production version for BOAC, with seating for up to 74 passengers (15 built);
Britannia 252 - stretched version with mixed passenger and freight capability, strengthed cabin floor in forward area of fuselage and cargo door, initially ordered by Ministry of Supply for lease to charter airlines to operate trooping flights but delivered to the RAF as Britannia C.2 (3 built);
Britannia 253/C.1 - as Britannia 253 but built from the outset for the RAF with full-length strengthened floor and accommodation for up to 115 troops in rearward-facing seats (20 built);
Britannia 300 series - Britannia 200 series with further fuselage stretch, cargo capability deleted and accommodation for up to 129 passengers (8 built, first flight 31 Jul 56);
Britannia 310 series - long range version of Britannia 300 with additional fuel capacity and strengthened fuselage and landing gear (35 built, first flight 31 Dec 56);
CL-28 - heavily modified version optimised for maritime patrol developed by Canadair and powered by 4 Wright R-3350 turbo-compound radials (33 built in two versions for RCAF: 13 Argus I, equipped with APS-20 search radar and 20 Argus II, equipped with the APS-21; first flight 28 Mar 57).
First flight: 15 Nov 59 (c/n 1, RCAF 11501)
Production: 39, at Cartierville, QC
First delivery: 19 Jul 60, to RCAF (c/n 3, 11503)
Last delivery: 11 Mar 66, to Loftleiðir (c/n 39, TF-LLI)
Variants: CL-44-6 - initial production version for RCAF powered by 4 Rolls-Royce Tyne 11 twin-shaft turboprops, with cargo doors aft and rear and seating for up to 160 passengers (12 built, known as CC-106 Yukon in RCAF service); CL-44D-4 - commercial version, optimised for air cargo operations with “swingtail” rear-loading function (27 built).
Conversions: CL-44J - shorter range, stretched fuselage version for Loftleiðir, with accommodation for 189 passengers (4 converted); CL-44-O - modification for outsize cargo by Jack Conroy Aircraft, involving complete replacement of fuselage above the line of the cabin floor (1 converted).