2014/02/20

A blast from the past, mimicked by the present (I): Cobra AFV

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The public discussions about future armoured vehicles tend to assume that many if not most of the near-future designs will be equipped with a diesel-electric drive. Band tracks as high ride comfort, low noise alternative to steel tracks enjoy favourable opinions en masse as well, at least for vehicles well below 30 tons.

What would you think if I claim that one such vehicle was trialled at the facilities of the US Army's Tank Automotive Command in Detroit, Michigan. (...) the test drivers (...) evaluated the Cobra for both performance and manoeuvrability and found this to be equal or superior to other recently fielded vehicles."?
All this in a concept which "provides advantages in size, weight and configuration flexibility".

These quotes are indeed about the ACEC SDT Cobra, a family of vehicles based on an armoured personnel carrier with diesel-electric drive and steel-reinforced rubber band tracks and a full squad of 10 dismounts in the rear. It was amphibious without prior preparations (10 km/h in water), 75 km/h fast, max. road range 600 km, 12.7 and 7.62 mm machineguns in unmanned turret ("remote-controlled weapon station", RWS). Its weight was half of what we consider normal APC weight nowadays, about third of a GTK boxer (remember the air deployability fashion).
Granted, there wasn't much battery capacity installed.

ACEC Cobra, 1985
The catch: Said evaluations happened in 1987, and the vehicle was developed from 1977 after earlier feasibility studies. In Belgium.

It was astonishingly light, had a confusing 7.62 mm bow machinegun in at least one of its prototypes and the battery capacity was not meant to drive the engine. other than this, it's basically what many people expect of future light tracked armoured vehicles, similar to the Swedish Hagglunds SEP project in its tracked version.

 
There was also a light tank version with 90 mm low pressure gun:
(click to enlarge)

And it was an utter commercial failure.
No production took place.

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I consider it a warning if a hyped technology or hyped set of technologies has failed in the past already. It's even more of a warning if this happened repeatedly, or if the seemingly novel technologies are in fact quite ancient.
 
Talking of ancient; I present you continuous rubber bandtracks:
K├ęgresse track, installed in 1911
 And a hybrid drive:
Lohner-Porsche racing car, 1900

Diesel-electric drives including much battery capacity? The sole in-service propulsion of submarines for half a century, and still a big deal another half century later.

First tank experiment with a hybrid drive: In the thing that's responsible for why people say "tank". Another failure a generation later.
 
Hybrid vehicles are still sexy in military applications and generally in all-wheel drive applications (AWD is very elegant with in-wheel electric motors). Technical history justifies reservations about this fashion, though*.
 
S O

*: There are more issues with the technology, but this text is all about the technical history and precedent.
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4 comments:

  1. What were the problems with manufacturing this vehicle?

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    1. Well, the book mentions no production orders, and the company went bankrupt shortly after it was published.

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  2. 'other than this, it's basically what many people expect of future light tracked armoured vehicles, similar to the Swedish Hagglunds SEP project in its tracked version.' God, that just goes to show how low our expectations have dropped.

    'And it was an utter commercial failure. No production took place.' Because these morons wouldn't know a good design if it came and bit them on the ass!

    'I consider it a warning if a hyped technology or hyped set of technologies has failed in the past already.' Well, its a nice thought, but doesn't really apply to this vehicle in particular. Military sales boil down as much to the companys marketing proficiency as to their products utility.

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    1. The hybrid fashion waned a bit because the Americans fucked up their FCS and MRAPs got much attention for a while (but I'm sure it will return in force).

      There was on the height of the 'hybrid tank' fashion back in 2004 an article in the German journal "Soldat und Technik", January 2014 issue. Written by the German equivalent of Ogorkiewicz, Rolf Hilmes.
      He mentioned several issues with hybrid drives:

      * Almost everything propagated for hybrid drives is feasible without (and has been built into other vehicles already)
      * no safety, reliability and long-time testing of a hybrid drive for army purposes so far (2004)
      * coolant temperature at most 70°C, not 110°C, thus bigger cooling system
      * hybrid requires a mix of oil and water coolant cycles, conventional can have one
      * hybrid drive is heavier
      * hybrid drive is more voluminous
      * hybrid drive costs more (approx. multiplier 1.6...2)
      * impractical to store enough energy for silent driving offroad over useful distances
      * hybrid drive disadvantages are more troublesome with tracked than with wheeled drive

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