40 - 3682


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This aircraft was originally delivered to the RCAF on 27th May 1954 as the 21st of 66 aircraft ordered. Originally designated as a CSR-123 it was recovered to DHC to fulfill a demanding role as an experimental development aircraft until its last flight - by then converted to an experimental twin otter (1963) - on 15th July 1965.

The History of this aircraft is detailed in Sean Rossiter's
Book "Otter & Twin Otter".

Otter 40 was delivered to the RCAF on 27th May 1954 with serial 3682. It was originally posted to Air Material Command at Rockcliffe, but almost immediately continued on across the country to the Sea Island base at Vancouver, where it joined 121 Communications & Rescue Flight, with whom it was to serve for three years. It adopted the unit's QT code and during this period flew alongside the Flight's other Otter 3680. During August 1955, it was engaged in the search for Pacific Western Airlines Grumman Mallard CF-IOA, already referred to in relation to 3680. It joined the search on 12th August, flying to Price Island via the Douglas Channel. It also searched along the Kittimat-Terrace-Lakelse route, and the Skeena River en route to Smithers. Whilst based at Sea Island with the Flight, it was also involved in many marine rescues and medevacs.

3682 suffered a “C” category accident on 10th May 1957 in the course of a cross-country training flight from its base at Sea Island. To quote from the report: “A glassy water approach was begun from about 150 feet above the water, at 55 knots, and with between 18 and 20 inches of manifold pressure. This was maintained until nearing the water. The starboard wing dropped and the aircraft settled rapidly. Power and left rudder partially corrected the attitude but the aircraft stalled heavily onto the starboard float. Rippling of the skin of the tail section resulted. The pilot initiated his approach from an altitude which did not give him sufficient opportunity to have settled into the proper landing attitude before the aircraft touched down”.

In June 1957 the Otter went to DHC at Downsview for repairs as a result of this incident and for incorporation of the All Up Weight modification and in January 1958 it went to No.6 Repair Depot at Trenton for storage. In March 1958 however it went back to Downsview, having been loaned to DHC for experimental purposes. It was to become an experimental STOL Otter. The first modifications made to the aircraft were to install oversize flaps and drooped outer-wing leading edges. Known as the “Batwing Otter”, 3682 was flown in this configuration during summer 1959. “In order to study the flap's behaviour in the regime known as 'ground effect', 3682 was mounted on a twenty foot high steel tube frame, and rigged at an in-flight attitude, with calibrated balance pick-ups at each of the three landing gear axle sockets. This contraption, mounted on wheels, was towed at up to 40 mph up and down the runways at Downsview, behind a one-ton truck, to quantify the lift and drag induced by the huge flaps”. The test data was used, amongst other purposes, to design a new vertical tail, which was installed on 3682. It was flown in an all-silver scheme, with 'DRB-DHC Stol Research Aircraft' titles on the rear fuselage, the 'DRB' being the Defence Research Board. These tests with the “Batwing Otter” concluded in 1960.

The next modification to 3682 was to install a General Electric J-85 jet engine in the cabin, with a nozzle protruding out through the fuselage sides. The nozzle could be varied, to provide thrust on take-off and drag to slow the speed for landing. Testing in this configuration continued during 1961/62, with 3682 making its last flight with its P&W R-1340 piston engine installed on 10th October 1962. The Otter's next modification was to have two P&W Canada PT-6 turbine engines installed, still retaining the J-85 jet engine in the cabin, this conversion taking place during the winter of 1962/63. It made its first flight as such on 7th March 1963 and flight testing continued until 15th July 1965. It had to be grounded at that stage, as it was found that the very extensive modifications made to the aircraft over the years and the rigorous flight testing which the Otter had undergone, had caused serious structural cracking. The Otter was pushed off to the airfield perimeter at Downsview and the
engines, instruments and all useful parts removed. It languished there until “reduced to spares and scrap in March 1967”. The full story of 3682's modifications and test flying and the personnel involved is very well told in Sean Rossiter's book “Otter and Twin Otter”, to which the reader is recommended.

History courtesy of Karl E Hayes from DHC-3 Otter: A History (2005)