nelson_p@apollo.com (04/12/90)
From: nelson_p@apollo.com
[ for submission to sci.military ]
Forgive me if this is a stupid question: I was reading
a book on the battles in the area of Pork Chop Hill in
the Korean War and I saw frequent references to an artillery
round called a VT round. From context it appeared to
be some kind of antipersonnel, proximity-fused round.
What is it exactly and what does VT stand for?
Thanks in advance.
---Peterjeff@aplcomm.jhuapl.edu (JEFF NANIS ) (04/14/90)
From: jeff@aplcomm.jhuapl.edu (JEFF NANIS ) In article <15516@cbnews.ATT.COM> nelson_p@apollo.com writes: > Forgive me if this is a stupid question: I was reading > a book on the battles in the area of Pork Chop Hill in > the Korean War and I saw frequent references to an artillery > round called a VT round. From context it appeared to > be some kind of antipersonnel, proximity-fused round. > What is it exactly and what does VT stand for? The proximity fuze was developed (as opposed to being invented - the Brits though of it and told us) in 1942 by the place where I work, the Johns Hopkins Applied Physics Laboratory. It basically involved mini- aturizing a radar and putting it in the nose of an artillery shell, enabling the shell to explode when it reached a pre-set distance from ground or target. It was called VT for Variable Time - a decptive ruse for security, to make it sound as if there was just a fancy timer inside, instead of a whole CW radar. The Battle of the Bulge was the first use of VT in ground combat. It had been used earlier, with great effect, at sea, in 5" shells, decimating Japanese air raids and kamikaze attacks. Its use was delayed over land by concern of dud rounds being captured and exploited by the Germans. -- Jeff Nanis "You can't send me out there, jeff@aplcomm.jhuapl.edu I'm an analyst, not a field agent!" Not an official opinion which might get me put in jail.
chamber@ee.udel.edu (04/14/90)
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 Chamberlainbxr307@csc.anu.oz (04/14/90)
From: bxr307@csc.anu.oz In article <15516@cbnews.ATT.COM>, nelson_p@apollo.com writes: > > > From: nelson_p@apollo.com > > > [ for submission to sci.military ] > > > Forgive me if this is a stupid question: I was reading > a book on the battles in the area of Pork Chop Hill in > the Korean War and I saw frequent references to an artillery > round called a VT round. From context it appeared to > be some kind of antipersonnel, proximity-fused round. > What is it exactly and what does VT stand for? > > Thanks in advance. > ---Peter VT stands for Variable Time. It is basically a proximity-fused round. The idea behind the term Variable Time is that the fuse does not have to be set to explode after a certain time, to hopefully explode above the ground to get an optimal dispersion of its fragments or splinters. Rather it is simply armed after leaving the barrel and then when it approaches the ground at a set height explodes, hence the name Variable Time. Brian Ross P.S. While we are on the subject on of artillery. Have you people in the land of the free heard yet about the giant artillery barrel confiscated in England Yesterday (12 Apr'90)? It apparently belonged to Iraq and was 1,000mm in calibre and 45 metres long. That makes it the largest artillery barrel ever constructed (The previous record, Gustav by the Germans was an 800mm monster. It was basically found to be tactically quite useless).
emery@linus.mitre.org (David Emery) (04/14/90)
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