Canadair CL-91 Dynatrac

The Canadair CL-91 Dynatrac was a high-mobility tracked vehicle made up of two or three units joined by articulation joints, which let each unit move up to 30 degrees from the centreline in any plane. It developed the ideas of Canadair's earlier RAT snow vehicle. The engine was moved forward into the front cab to free space for passengers, and the drivetrain was redesigned to cure the RAT's fragile transfer joint and the overheating of its Volkswagen engine.

Design and performance

A single 65 hp General Motors Corvair air-cooled flat-six drove all units through a Dana four-speed gearbox. The vehicle could reach about 50 km/h over snow, mud and muskeg. Thanks to its light construction and 20 cm of freeboard, it could swim at about 3 km/h carrying a 900 kg payload. In deep snow and fully loaded, it could tow 12 ski troops or a 1,100 kg toboggan, climb a 60 per cent grade and cross a 40 per cent side slope. It was 6.09 m long and 1.58 m wide, had a gross weight of about 3,300 kg and carried up to ten people.

Service

Canadair built 63 Dynatracs. The US Army bought 57 for trials as the XM-571, the Canadian and British armies took two each, and two were kept as test vehicles. In Vietnam, XM-571s served with some success as utility carriers, but never in their intended role of carrying ammunition for frontline artillery. The aircraft-quality materials Canadair used made the vehicle too expensive. A request from the Australian Army for 384 vehicles was turned down by the Canadian government, and a Dynatrac II was started but went no further. Canadair closed its vehicle division in 1976.