Old Wombat: Following with great interest!
Canadair CF-104 Starfighter Developments - Orenda Turbojets
As the CL-90 was prepared for production as the CF-104, Canadair was approached by the producer of its J79 powerplant, Orenda Engines Ltd. Noting that the afterburning General Electric turbojet was not ideal for the RCAF's planned low-altitude strike role, Orenda suggested a remedy.
Orenda has studied the possibility of adapting the Starfighter airframe to the Rolls-Royce Spey turbofan. But the low-altitude role planned for RCAF CF-104s suggested a simpler alternative. Orenda's own Iroquois turbojet had roughly the same diameter as the Spey. But the Spey's full-reheat thrust could be matched by the Iroquois without recourse to afterburning.
Substituting an unreheated version of Orenda's Iroquois for the licensed J79 was a matter of slightly enlarging the Starfighter's removable rear fuselage section. Weight was not an issue since removing the Iroquois' large, Solar afterburner gave exactly the same dry weight as the afterburning J79-OEL-7 - 3,850 lb. The benefit would be the fuel savings made by using the PS-13U Iroquois' dry thrust of 19,250 lb.st in place of the J79's 17,835 lb.st in afterburner.
Canadair refined the Orenda concept slightly (removing the outer of three engine shrouds) and it was submitted to the RCAF as the Starfighter UOI (for Unreheated Orenda Iroquois). A second concept, more radical deviation from the original CF-104 was put forward at the same time. This 'Starfighter Strike' was to be powered by twin Orenda PS-18 Haida turbojets. [1] The engine pods were separated from the fuselage by a new stub wing section. The standard Starfighter wings were now outer panels attaching to hoop frames around the engines. By podding the engines, much of the fuselage could be dedicated to carrying fuel.
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[1] The PS-18 Haida was, in effect, a scaled-down PS-13 Iroquois. In this case, the afterburners were retained, producing 9,850 lb.st in full afterburner.
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