Path: utzoo!utgpu!watserv1!watmath!att!cbnews!military
From: chamber@ee.udel.edu
Newsgroups: sci.military
Subject: Re: VT rounds
Message-ID: <15599@cbnews.ATT.COM>
Date: 14 Apr 90 04:12:10 GMT
Sender: military@cbnews.ATT.COM
Organization: University of Delaware
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Approved: military@att.att.com



From: chamber@ee.udel.edu
VT stands for variable time/proximity.  A radio transceiver in the fuze emits
a signal and the strength of any return is measured; when a certain threshold
is surpassed the fuze detonates its projectile (warhead). These fuzes were
originally designed for aerial (surface to air) use.

In most cases it is much more effective to detonate high explosive (HE)
artillery rounds above ground. This effect was traditional accomplished (and
is still an option) using a "mechanical time" fuze, but VT is more consistent
for height of burst (HOB) applications of high explosive projectiles.
(Mechanical, and now electronic, time fuzes are used for cargo carrying
projectiles.)

A VT fuze activated just prior to impact by a timer set with a brief back-off
time. There were problems with the earlier VT fuzes, like sensitivity to rain,
but these have been corrected.

A partial list of VT Fuzes used with US artillery/mortar projectiles
(based on memory):

M513    Deep Cavity 105mm  Arty Rds    20m HOB    replaced by M728
M514    Deep Cavity 155mm+ Arty Rds    20m HOB    replaced by M728
M728    Deep Cavity   Arty Rds         20m HOB    replaced by M732
M732    Normal Cavity Arty Rds          3m HOB    current VT fuze

M727    Used with M454 155mm Nuclear Round

M517    81mm mortar projectiles
M532    81mm mortar projectiles, 1-6 m HOB
M734    new digital, all-purpose fuze for 60mm, 81mm, 107mm, 120mm mortars.
        Point Detonating (PD), VT (2 HOBs), Delay (DL) Operation.

Obviously, the trend is toward "digital, one fuze does all".


Sam Chamberlain