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Background — Canadian Origins of the MOSV? —
the CL-70 RAT |
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The CL-61/CL-70 RAT – Remote Articulated Track
Bombardier may now personify Canadian snowmobiles but Canadair also tried its hand at snow machines. The prototype
CL-61 became a pattern for future articulated snowmobiles. The twin, tracked chassis were linked by an articulated
driveshaft/joint (a single engine – in this case, an industrial VW [1] flat-4 – in the forward cab driving
both chassis). Twin hydraulic rams between the two chassis provided steering power. [2]
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CADRE [3] trialled a half-scale Articulated Light Snow Tractor 'test rig' while Canadair produced the prototype
CL-61 RAT. The Canadian Army ordered 24 production RATs as 'Carrier, Cargo, Light Articulated'. [4] Two
CL-70 RATs went to the Swedish Army after Canadair demonstrated their new vehicle throughout Scandinavia
with conspicuous lack of success. [5] (Conceptually, at least, the RAT was an inspiration for later more
successful Swedish vehicles.)
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Canadair CL-70 RAT
Specifications
Size:
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Length: 3.98 m, Width:
1.22 m, Height:
1.55 m |
Powerplant:
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36 hp Volkswagen air-
cooled
flat 4-cylinder,
Trans: York Gears 4+1 |
| Suspen.: |
solid, pneum. tires [6] |
| Max speed: |
37 km/h, water 3.2 km/h |
| Weight: |
curb 682kg, load 454kg |
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The remaining RATs went to Canadian and US civilian agencies. But Canadair did demonstrate its RAT to the US Army in
1963 for a Remote Area Vehicle Evaluation. TACOM's 1963 RAVE II was to test 1/4-ton vehicles in preparation for
Vietnam. The test course featured trails (relatively dry, then marshy), simulated rice
paddy, and a lake. The CL-70 "broke the drive shaft between units and lost power to the trailer section"
climbing a dike in the paddy. Once over the dike, the RAT completed the test course with power to its front
section only. However, no US orders for RAT resulted. [7]
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For a continuation of
the Canadair snow machine story, see: the Canadair CL-91 Dynavert, (later used by the US Army as the XM-571).
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[1] Volkswagen marketed versions of its famous Beetle car's air-cooled 1.1L 'boxer' gasoline engine for
industrial and marine applications. This engine produced 27 kW (36 hp) at 3600 rpm (continuous brake horsepower was
21.5 kW or 29 hp at 3100-to-3600 rpm). In its maritime form, the Whirlwind Marine Four, a Paragon manual
gearbox or reduction gear was fitted (replacing the Beetle transaxle). The Whirlwind marine engine
weighed 84 kg (185 lb) complete except for its 6.36 kg (14 lb) electric starter. The Paragon gearbox weighed
32.27 kg (71 lb).
[2] Articulated steering was chosen to increase track life. The sole role of the near-full width cleated tracks
became traction on soft terrain.
[3] Related to the Defence Research Board, the Canadian Armament Research and Development Establishment, was
DRDC's predecessor.
[4] The CL-61/CL-70s were described variously in government publications as a Articulated Light Snow Tractor;
Carrier, Cargo, Light Arti- culated (Rat), . The US Army designated Canadair's RAVE II vehicle
as a Carrier, Cargo, Amphibious, Articulated, CL-70 (Canadian RAT). Why anyone in Canadair's marketing department
thought that the brand name RAT would be an aid to merchandising remains a mystery!
[5] Although only two CL-70s were ordered for the Swedish Army, the RAT demonstrations were said to impress.
However, as related in Ron Pickler's Canadair: The First 50 Years, a parking brake failure on a
ski ramp resulted in a spectacular crash. There were no injuries to the operator or serious damage to the RAT but,
Scandinavians may be forgiven for thinking they might be able to do it better themselves.
[6] Canadair relied on pneumatic tires to smooth out the ride. A 3.40/3.00x5 tractor tire was standard
but 4.00x6 aircraft tires were optional.
[7] According to Flight ( No 2535, Vol 72, 23 Aug 1957, p 260 ), Canadair was not alone among aircraft makers in
exploring side ventures to "increase their annual turnover" concluding that, once "fully developed, very large
contracts may be placed for the CL-61...a 'snowmobile' with extremely attractive characteristics which has been
developed in prototype form for the past eighteen months." But this wasn't to be. Today, there's little evidence
for Canadair's pioneering work other than a single CL-70 RAT displayed at Ottawa's Canadian War Museum.
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