Proximity fuse

[pavlov]

I've read several accounts that describe US artillery using proximity fuses that result in air bursts even when there are no trees. I believe these were available in Tunisia and thereafter.

Does anyone know if this is modeled in CM at all. I don't think it is anyway.

[John D Salt]

I've read several accounts that describe US artillery using proximity fuses that result in air bursts even when there are no trees. I believe these were available in Tunisia and thereafter.

Does anyone know if this is modeled in CM at all. I don't think it is anyway.

The proximity fuze, developed in the US, was given the designation "VT". This was an arbitrary project code. The abbreviation "Variable Time" was later back-formed from these letters, a rather silly name, since it is not a time fuze of any kind.

VT fuzes were first used in action in 1944. They are modelled in the original CM:BO and in CM:AK for the appropriate time periods. They did not appear in Tunisia, although I believe that Rick Atkinson's otherwise admirable "An Army At Dawn" contains an erroneous reference to them.

Before the arrival of the VT fuze, airbursts could be achieved, less reliably, by powder-train or clockwork time fuzes. At shallow angles on appropriate ground, airbursts could also be achieved by ricochet fire with a delay fuze. None of these aspects of artillery fire is modelled in the CM series.

All the best,

John.

[stoat]

Does anyone know if this is modeled in CM at all. I don't think it is anyway.

As John so elequently explains, VT shells are present in the game. Airbursts can also be achieved by firing offboard artillery or mortars or onboard mortars at terrain tiles with trees. However, only the VT shells will airburst over open ground.

[John Kettler]

pavlov,

The proximity fuze, deliberately miscategorized as "Fuze, Variable Time" in order to hide its revolutionary nature by making it look like "Fuze, Mechanical Time," doesn't require anything other than a suitable radar reflective surface in order to generate airbursts. This is because the fuze IS a miniature radar set, and it triggers as soon as there's an adequately strong return signal from a nearby object, be it a plane, the ground, water, etc. The proximity fuze, because of its high secrecy and concern the enemy would develop countermeasures or copy it, saw no use in land warfare until the Battle of the Bulge, though it was used earlier over the English Channel

(near zero likelihood of dud recovery there) in the gun belts to defend against the V-1.

There, it roughly tripled the effectiveness of heavy AAA.

In CM, prox, as it's affectionately known, is expensive but deadly stuff, especially against troops in halftracks, trenches and other places normally providing cover vs. direct fire. The larger stuff (155 and up) is also quite capable of doing that plus clobbering troops inside heavy buildings. How? By sending big, heavy frags through the roofs! It's a waste to fire it into areas with trees, for normal fuzes will trigger then, creating the dreaded treebursts. What CM doesn't model, though, is the deadliness of prox in H&I (Harassment & Interdiction) fires. There, normally concealed night/heavy fog movement through crossroads, defiles, bridges and similar was now subject to zero warning airbursts with no adjustment fires.

Regards,

John Kettler

[Joachim]

What CM doesn't model, though, is the deadliness of prox in H&I (Harassment & Interdiction) fires. There, normally concealed night/heavy fog movement through crossroads, defiles, bridges and similar was now subject to zero warning airbursts with no adjustment fires.

Regards,

John Kettler

Add a TRP and CM does model it. Though CM scens with approach routes are rare.

Even in RL hitting something not in LOS needed preregistering - or resulted in inaccurate fire.

Gruß

Joachim

[Joachim]

As John so elequently explains, VT shells are present in the game. Airbursts can also be achieved by firing offboard artillery or mortars or onboard mortars at terrain tiles with trees. However, only the VT shells will airburst over open ground.

Any shell flying thru treetops is subject to airbursts in CM. The trouble is finding an aim point. IGs work as they are inaccurate and often overshoot their target on a forest edge.

A more common reason for DF airbursts in CM are houses - though you seldom see an effect as troops don't tend to be in the open outside a house.

Gruß

Joachim

[Bannon DC]

There seems to be some controversy surrounding the development of the proximity fuse as to who gets the credit for it... the Brits or the Americans.

The issue came up recently for me in a Charles Whiting book I was reading (Siegfried, the Nazi's Last Stand) where he mentioned "Now Houffalize was being pounded by Britain's latest secret weapon: the proximity fuse, a radar-directed shell with unprecedented accuracy and deadly effect." (Houffalize is about 20 miles north of Bastogne in the American operation sector).

First, was it more accurate than normal ammunition... or was it just the air-burst effect that made it so special?

On the issue of who developed it, I think it depends on which side of the Atlantic you live on. The US Navy was quite emphatic that it was an American development. The wording of the statement makes me think the controversy must have been hotly debated.

"British scientists were working on proximity fuze devices for rockets and bombs at least as early as 1939. Captured documents indicate that German work on proximity fuze development had begun in the early 1930's, and was still in process when hostilities ended in the European Theatre.

In brief, there is nothing unique about the "idea" of a proximity fuze. The possibility that proximity fuzes of various types might be feasible has been recognized for a long time. The American achievement, accomplished by no other country, was the actual development of a proximity fuze that would function and that could be manufactured by mass-production techniques."

http://www.history.navy.mil/faqs/faq96-1.htm#anchor1190487

I had some trouble with this site in terms of load time. Also, the article was cut off for me. Here is a longer excerpt:

Development of Proximity Fuzes (VT) for Projectiles-VT Fuzes Mks 32 to 60

Introduction

During the summer of 1940 shortly after the formation of the NDRC [National Defense Research Committee], work was started on the development of a proximity fuze. The initial development was undertaken by Section T of Division A of the NDRC. The initial project was very broad in objective; namely, to develop a proximity fuze of any type (radio, acoustic, photo-electric, electro-static, infra-red, etc.) for rockets, bombs, and projectiles. Such a project was assigned to Section T by the Navy.

At the time this project was started, the primary objective was to provide better defense against aircraft. Methods of using proximity fuzes for this purpose then being considered included use in bombs for air-to-air bombing, use in rockets, and use in projectiles. At about the time this project was started, it was learned that the British had been developing proximity fuzes and had some considered to be fairly promising for use in bombs and rockets. The British had considered fuzes for projectiles, but felt that the technical difficulties in making such fuzes rugged enough to withstand firing from a gun were insurmountable, at least during World War II.

While the original project covered all types of proximity fuzes, for rockets, bombs, and projectiles, a primary interest to the Navy was a proximity fuze for the Navy 5"/38 projectile, as this weapon was the Navy's principal antiaircraft weapon. Section T at the outset considered the development of the projectile fuze as a primary objective, and undertook investigations leading toward achievement of sufficient ruggedness of electronic parts and the like to permit firing from a gun. By the spring of 1941 work on the radio type of projectile fuze had progressed to the point where it appeared to he the most promising type of fuze, and at that time Section T dropped its work on investigation of other types of proximity fuzes and concentrated entirely on the radio-type of projectile proximity fuze. This development ultimately led to the present type of radio proximity fuze for projectiles and is the development with which this report is concerned.

In addition to the U. S. Navy interest in the projectile proximity fuze, the British and the U. S. Army were also interested. Agreements were made that all projectile proximity fuze work would be carried out by the Navy and Section T. The Army had also entered the proximity fuze program, but in line with these agreements, the Army concentrated on proximity fuzes for rockets and bombs. The British had also started some work in Canada on the proximity fuze for British projectiles, and this development was carried out cooperatively with the Section T program. At that time the priorities for projectile proximity fuze development were set up as follows:

(1) U. S. Navy, (2) British Navy, (3) U. S. Army, (4) British Army.

The first development was a fuze, known as the VT fuze Mk 32, for the Navy 5"/38. This development was followed by modifications in design to permit adaptation of the projectile fuze to British Navy guns, U. S. Army guns and British Army guns. At that time the primary objective was to provide better defense against aircraft; and hence, the fuzes being developed were all antiaircraft fuzes.

[JasonC]

The US developed the proximity fuze.

It also solved the servo control problem of radar fire direction at a moving target, founding control theory in the process. Naval AA was the biggest beneficiary of both, and Japanese airmen the leading victims. (It was also effective against V-1s).

Use against ground targets was an afterthought and unintended byproduct. The serious gain was that AA actually had a chance of hitting a plane in flight.

[JonS]

deliberately miscategorized as "Fuze, Variable Time" in order to hide its revolutionary nature by making it look like "Fuze, Mechanical Time,"

Yes and no. A Prox fuse is variable in the amount of time it runs, unlike MT fuses, which will only ruin for the time set before loading.

Incidentally, prox fuses - at least modern ones - also include a mechanical time fuse in order to prevent flight-prems.

Development of the first prox fuses was a joint effoprt, with Canada, the UK, and the US each contributing critical components (sort-of like the Manhatten Project writ small). Any of them probably could have done it on their own, in the end they did it together.