Darling, which had previously conducted tests at Namao Air Base, Alberta, were part of the climatic detachment of Central Experimental and Proving Establishment; testing commenced during the following month. In March 1956, a batch of four CF-100 Canucks were dispatched to Eglin AFB to conduct comparative armament trials, where the type was flown by several United States Air Force (USAF) crews. The operational suitability tests, dubbed Project Banana Belt, were carried out by the 3241st Test Group (Interceptor) of the APGC's Air Force Operational Test Center, in conjunction with a project team belonging to the RCAF. Production During September 1950, the RCAF placed an initial production order for 124 Mk 3 aircraft, the first of which entering service in 1953. This model was armed with eight .50 caliber machine guns. The definitive rocket-armed Mk 4A was based on the prototype Mk 4 (a modified Mk 3), which first flew on 11 October 1952. The nose housed the much larger APG-40 radar, while the wings were equipped with wingtip pods, each containing up to 29 Mk 4/Mk 40 "Mighty Mouse" folding-fin aerial rocket, to be used in addition to the guns. During 1954, the last 54 of an order for the Mk 3 were swapped for the more advanced Mk 4, the total orders for the Mk 4 rose to 510. The Mk 4B version was furnished with more powerful Orenda 11s. Five versions, or marks, were produced. The high-altitude Mk 5 was the final variant, production of which commenced during 1955. This model featured a -longer wingtip and enlarged tailplane, along with removal of the machine guns. The proposed Mk 6 was to have mounted Sparrow II missiles and been powered by afterburning Orenda 11IR engines; this was intended to be adopted as an "interim" fighter prior to the introduction of the more advanced Avro Canada CF-105 Arrow, which was then under development. An advanced derivative of the CF-100 was the CF-103, which was equipped with a swept wing and projected to be capable of transonic speeds; this was built in mock-up form during 1951, but was considered obsolete even before the CF-100's demonstrated ability to exceed the speed of sound in a dive. On 18 December 1952, Squadron Leader Janusz Żurakowski, the Avro company chief development test pilot, took the CF-100 Mk 4 prototype to Mach 1.0 in a dive from , becoming the first straight-winged jet aircraft to