Path: utzoo!utgpu!watserv1!watmath!att!cbnews!military
From: emery@linus.mitre.org (David Emery)
Newsgroups: sci.military
Subject: re: VT rounds
Message-ID: <15601@cbnews.ATT.COM>
Date: 14 Apr 90 04:12:14 GMT
Sender: military@cbnews.ATT.COM
Organization: The Mitre Corporation, Bedford, MA
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From: emery@linus.mitre.org (David Emery)
>From: nelson_p@apollo.com
>   What is it exactly and what does VT stand for?
VT  stands for "variable time".  The VT fuse is a radio-proximity fuze,
and was one of the U.S. high-tech, secret weapons that contributed
materially to WWII.  

The basic idea (these days) is simple:  the fuze puts out radio waves
and measures (via doppler??) how far it is above the ground.  At a
pre-set height, it detonates.  The "Variable Time" comes in via a
setting that establishes the minimum time for the fuze to start
working.  The idea is you set min time a couple of seconds before actual
impact, reducing the transmission time (because the fuze has a
limited battery), and more importantly, adding to safety (the round is
well past friendly troops when the fuze starts working).

Basically, this removes the requirement for adjusting height-of-burst
using mechanical time fuzes, to get an air burst.  Air bursts are most
effective, because the entire shrapnel pattern falls to the ground, as
opposed to a ground burst, where a lot of the shrapnel just digs into
the earth.  VT (and time) fuze is particularly useful against troops
in trenches.  VT fuzes don't work well against swampland or snow, but
are great otherwise.  Firing VT fuze, you could mass a whole lot of
artillery and fire-for-effect, without having to adjust each battery's
time fuze.  (Remember, after the first round the smart soldier ducks,
and subsequent rounds are much less effective.)

				dave emery
				emery@aries.mitre.org