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From: davecb@nexus.yorku.ca (David Collier-Brown)
Newsgroups: sci.military
Subject: Re: Bull 155mm Howitzer
Message-ID: <1991Feb15.064642.8068@cbnews.att.com>
Date: 15 Feb 91 06:46:42 GMT
References: <1991Feb13.220740.4885@cbnews.att.com>
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From: davecb@nexus.yorku.ca (David Collier-Brown)

ron@mlfarm.com (Ronald Florence) writes:
[...]  How much better are these bull-designed artillery pieces, and
| what accounts for their superiority?

  The improvement is between 10km and 10mi (:-)), based on public
quotes in a country which changed to the metric system right around
that time.
  The means of improving the range is called ``base bleed''.  A conventional
shell has a flat or boat-shaped base (tail), which produces drag and
turbulence through air flowing chaotically into the vacuum behind the shell.
  A base-bleed shell has a quite small, slow-burning rocket motor in its
base, which fills the vacuum with exhaust gases.  This substantially
smoothes out the flow in the immediate vicinity of the shell's base, and
prevents turbulence from trying to steer the shell.  It obviously reduces
the drag, too, making it practical to try for targets out at or past the
maximum range of a conventional shell.

  Please note that this is quite different from a rocket-assisted shell: they
have a significant amount of the volume taken up with a motor, and the
accuracy of the shell is approximately that of the equivalent unguided
rocket: **not** very good.

--dave
sources: Toronto Globe and Mail (via a leaky memory) and a CBC special
  last night.
-- 
David Collier-Brown,  | davecb@Nexus.YorkU.CA | lethe!dave
72 Abitibi Ave.,      | 
Willowdale, Ontario,  | Even cannibals don't usually eat their
CANADA. 416-223-8968  | friends.