Silly question: Tank HE shell fuzes?

[Ivan Sorensen]

I always assumed that tank high explosive shell fuzes were impact fuzes but is this actually the case? Are there any use of timed fuzes for HE shell? Any other interesting bits?

Thanks in advance

[Not Connard Sage]

I’ve always imagined they’re point detonation too. I’d have thought a tank crew would have other things to worry about than timing fuzes 🙂

Obvious contrarian and passive aggressive old prat, who is taken far too seriously by some and not seriously enough by others.

[John D Salt]

You swine do this deliberately, don’t you?

I have wasted most of the day flonking about the interwebs and looking through my electric copies of technical manuals to find the answer.

So far I have found only two time fuzes for tank main guns, but delay fuzes are popular. My flonking has been confined to American, British, German and Russian tank guns. I have also confined myself to “gun tanks”, so CS tanks, HMCs, StuHs or similar things carrying howitzers could no doubt offer a greater variety of fuze functions.

American fuzes:

BD M58: Impact fuze used in the M63 HE shell fired by the 37mm M3, M3A1, M5, M5A1 and M6.

PD M57: Impact fuze used in the M48 HE shell fired by the 75mm M2 and M3.

PD M48, M48A1 and M48A2: Impact and delay fuze used in the M48 HE shell fired by the 75mm M2 and M3, M42 HE fired by the 3-in M7, M42A1 HE fired by the 3-in M7, 76mm M1, M1A1 and M1A2, and M71 HE fired by the 90mm M3. Depending on version, this could be set for a delay of 0.05 or 0.15 seconds.

MT M43: Mechanical time fuze for the M71 HE fired by the 90mm M3, with a delay of up to 30 seconds. This is listed as compatible with the M3 gun, but I have never heard of either AFV delivering time fire, and doubt whether the fuze was ever issued to them.

British fuzes:

No. 255: DA percussion fuze for HE fired by 2-pdr.

No. 243: DA percussion fuze for HE Mk 10T fired by 2-pdr and HE Mk 2T in 6-pdr.

No. 244: DA percussion fuze for HE fired by 17-pdr.

No. 410: Graze and percussion fuze for HE fired by 17-pdr or 77mm.

German fuzes:

Kopf Z Zerl P: Impact, self-destroying fuze for Sprgr Patr 18 fired by 3.7cm PaK 36 and presumably 3.7cm KwK 36.

AZ 39: Impact fuze for Sprgr Patr 18 and Sprgr Patr 40 fired by 3.7cm PaK 36 and presumably 3.7cm KwK 36, Sprgr Patr 38 fired by 5cm PaK 38, KwK and KwK 39.

Fl AZ 23: Impact fuze for Sprgr Patr 34 fired by 7.5cm PaK 40, KwK 40 and StuK 40.

Kl AZ 23 0.15: Impact or delay fuze for Sprgr 42 fired by 7.5cm KwK 42 and StuK 42. Could be set for a delay of 0.15 seconds.

Kl AZ 23 umg 0.15: Impact or delay fuze for Sprgr 34 umg fired by 7.5cm PaK 40, KwK 40 and StuK 40. Could be set for a delay of 0.15 seconds.

AZ 23/28: Impact fuze for Sprgr L/4.5 fired by 8.8cm KwK 36.

Russian fuzes:

KTM-1: Impact and graze fuze for O 240 fired by 45mm guns, O-271 fired by 57mm guns, OF-350 fired by 76mm guns, and O-365 fired by 85mm guns.

KTMZ-1: Impact and graze fuze for F-412 fired by 100mm guns.

V-429: Impact fuze for OF-412 fired by 100mm guns and OF-472 fired by 122mm guns.

D-1: Impact or time fuze for OF-472 fired by 122mm guns. A drawing shows a scale on the fuze going up to 125, but I have no idea what units it is in.

It is noticeable that none of the German 8.8cm time fuzes listed for HAA guns in that calibre are listed for use in tank or anti-tank guns.

With a delay fuze available to them, American, British and German tank gunners with 75mm weapons could presumably conduct ricochet fire. I have not heard of this being done, and will have to fish out my US tank gunnery pamphlet from wherever it’s hiding.

Corrections and additions welcome.

All the best,

John.

[John D Salt]

John D Salt wrote:

will have to fish out my US tank gunnery pamphlet from wherever it’s hiding.

The 1957 edition of FM 17-12, “Tank Gunnery”, states “Impact fuzes are most common to tank gun ammunition, although time fuzes are available”, and then never mentions them again. It does, however, recommend ricochet fire. The 1943 edition also recommends ricochet fire, but makes no mention of time fuzes at all.

All the best,

John.

[Ivan Sorensen]

Thank you so much. In return, whenever someone tells the story of what you did that one night at Gencon, I’ll say it was me 🙂

Do you have anything on the purpose of the delay fuze? I assume if you have a set delay, you can get it to go off at a fixed range, but was this something that was actually used?

[MartinR]

I’d don’t know what ‘ricochet fire’ is, that John mentions above, but I thought the main point of delay fuses was that they penetrate cover to a degree (earth, logs etc) before they explode.

"Mistakes in the initial deployment cannot be rectified" - Helmuth von Moltke

[John D Salt]

Ivan Sorensen wrote:

Thank you so much. In return, whenever someone tells the story of what you did that one night at Gencon, I’ll say it was me 🙂

I have no recollection of ever attending Gencon. I must have been incredibly drunk.

Ivan Sorensen wrote:

Do you have anything on the purpose of the delay fuze? I assume if you have a set delay, you can get it to go off at a fixed range, but was this something that was actually used?

Mr. Picky suspects that you are confusing delay fuzes with time fuzes. A time fuze goes off a certain time after the shell leaves the barrel; a delay fuze goes off a certain time after the shell strikes something.

To quote from the 1943 edition of FM 17-12:

“Delay action. The .05-second delay action results in the shell penetrating before bursting when it strikes light armor, gun shields, or buildings. If the shell strikes the ground, it ricochets, travels 20 to 25 yards beyond the point of impact, and then bursts about 10 feet in the air. Because of the downspray from the burst in the air, a ricochet burst has devastating effect on personnel without overhead cover. It is much more effective than the impact burst obtained from a superquick fuze setting.”

As a matter of detail, the M48 fuze had a delay of 0.05 sec, the M48A1 0.15 sec, and the M48A2 one or other of the two depending on what version you were issued.

Ricochet fire was I believe common practice with US field artillery, and apparently tank gunners. I have not heard of it being used with British guns, I suspect because most British tank and field arty fuzes lacked the necessary graze action, and also perhaps because British shell used weaker steel than US and so may have been less capable of withstanding the stresses involved. TM 30-430 “Handbook on USSR military forces” as I recall credits Soviet field artillery with the ability to perform ricochet fire, but I don’t recall seeing anything on the topic from Russian sources, I need to revisit my collection of Soviet artillerania (if that’s a word). Likewise I have never seen any German mention of ricochet fire, but I have never been able to find much on German artillery, it’s all panzers panzers panzers when it comes to the Germans.

I think I can safely say that I have never seen, heard of, or smelled a set of wargames rules that includes ricochet fire.

All the best,

John.

[Not Connard Sage]

MartinR wrote:

I’d don’t know what ‘ricochet fire’ is, that John mentions above, but I thought the main point of delay fuses was that they penetrate cover to a degree (earth, logs etc) before they explode.

A low trajectory shot that bounces at first impact and skips merrily on its way until the fuze triggers.

Used to be more of a thing in the age of solid shot, but it was used in WWII. Latest thinking is that it was such a shot that did for HMS Hood.

Obvious contrarian and passive aggressive old prat, who is taken far too seriously by some and not seriously enough by others.

[Thomaston]

This is some interesting stuff.

Tired is enough.

[John D Salt]

John D Salt wrote:

I have not heard of it being used with British guns

My memory has failed me, I *have* heard of it. NA piece number WO 291/113 “Lethal effect of artillery fire” reports the results of a trial conducted at the School of Artillery on 22 June 1943. The trial included several serials of ricochet fire, fired not only with US materiel (75mm and 105mm) but also with 25-pdr HE using fuze 231. The results seem to show good effectiveness of ricochet fire for the US guns, poor for the 25-pdr, which does better with superquick. The worst results for the 25-pdr are timed airbursts using fuze 222. Not what one would have expected. I have no idea how much influence this trial may have had on the unpopularity of ricochet fire with the RA.

NA piece number WO 291/496, “Anti-personnel effect of small HE shell”, suggests that HE under 75mm calibre can be effective against personnel in open-topped trenches using ricochet fire. As it is a theoretical paper, the fact that it mentions the lethal area of 6-pdr HE does not necessarily imply that a delay fuze was available for it, and the 2-pdr HE round it considers is for the 40mm Bofors.

John D Salt wrote:

I need to revisit my collection of Soviet artillerania

Lebedev’s “Field artillery officer’s handbook” mentions ricochet fire, but it’s all a bit modern, published in 1984. Much nearer the war is Tret’yakov’s “Artillery ammunition”, 1947, which mentions ricochet fire, and gives the best ricochet angles off land and water for guns and howitzers including 45mm anti-tank guns and 76mm regimental and divisional guns. In principle, then, I expect practically any WW2 Russian AFV would have been capable of ricochet fire. Whether they used it in practice remains an open question, they may have left such fancy shooting to the artillery.

Not Connard Sage wrote:

Latest thinking is that it was such a shot that did for HMS Hood.

Come on, give us a source, I can’t be chasing that as well, I’m up to my knees in terrestrial gunnery.

All the best,

John.

[Not Connard Sage]

John D Salt wrote:

Not Connard Sage wrote:

Latest thinking is that it was such a shot that did for HMS Hood.

Come on, give us a source, I can’t be chasing that as well, I’m up to my knees in terrestrial gunnery. All the best, John.

‘Latest thinking’ may have been a bit of a misnomer, insert ‘a current hare-brained theory’ instead.

As with all losses at sea, it’s rather tricky to settle on a single direct cause as all the evidence is rather wet. It’s held that the Bismarck’s fifth or sixth salvo penetrated the aft magazines through the decks, however a ‘current hare-brained theory’ suggests that a shell from the same salvo penetrated Hood forward, below her belt armour (her bow as well as her stern is detached), causing another explosion in a forward magazine. Obviously not a deliberate ricocheting shot, because that’s asking a bit much from 15,000 yards. Can’t find the source, but I know I read it just recently.

The HMS Hood Association website has a wealth of details, including excerpts from the Admiralty inquiry into Hood’s sinking, but it probably wasn’t there I saw the claim.

http://www.hmshood.org.uk/

 

 

Obvious contrarian and passive aggressive old prat, who is taken far too seriously by some and not seriously enough by others.

[John D Salt]

Not Connard Sage wrote:

a ‘current hare-brained theory’ suggests that a shell from the same salvo penetrated Hood forward, below her belt armour (her bow as well as her stern is detached), causing another explosion in a forward magazine.

I thought that was supposed to be a shot that fell short and continued underwater to strike below the waterline, and below the belt armour.

Leaving aside the fact that the angle of fall at the relevant range is probably too high for ricochets off water (if Tret’yakov’s guide for smaller calibres is anything to go by), it seems to me that the only advantage a ricochet would offer is meeting Hood’s belt armour at a more favourable angle.

All the best,

John.

[Not Connard Sage]

John D Salt wrote:

Not Connard Sage wrote:

a ‘current hare-brained theory’ suggests that a shell from the same salvo penetrated Hood forward, below her belt armour (her bow as well as her stern is detached), causing another explosion in a forward magazine.

I thought that was supposed to be a shot that fell short and continued underwater to strike below the waterline, and below the belt armour. Leaving aside the fact that the angle of fall at the relevant range is probably too high for ricochets off water (if Tret’yakov’s guide for smaller calibres is anything to go by), it seems to me that the only advantage a ricochet would offer is meeting Hood’s belt armour at a more favourable angle. All the best, John.

The only problem (I know bugger all about ballistics, although there are some ballistics tables on the aforementioned site) is that a shell entering the water will be slowed by the incompressibility of H2O and the angle might be somewhat less than favourable. Besides, skip bombing was a thing, so…

I’m just throwing it out there, I won’t state it as fact.

Obvious contrarian and passive aggressive old prat, who is taken far too seriously by some and not seriously enough by others.

[John D Salt]

Dragging the discussion back to dry land, I have found a couple more snippets that make it plain that both German and British field artillery had occasion to use ricochet fire. There’s also a bit about the relative effectiveness of ricochet and groundburst shell.

From Field Artillery Journal, Sep 1943:

GERMAN RICOCHET DOCTRINE
Considerable progress has been made by German artillery in the use of ricochet fire. It is recognized as being useful, effective, and not mysterious. Although it can not be used in every case, the possibility should always be examined. Our own investigations have borne great fruit, and as our doctrine develops it is interesting to see what the Germans have to say.
“Investigate the possibility of using ricochets. The decisive factor is the angle of impact on the terrain, not the angle of fall. Angles of impact up to 270. (15º) can be expected to result in ricochets; and even beyond that (up to 360 or 20º) ricochets are possible. In many instances it will be necessary to resort to practical trial.” We have found ricochets entirely practicable at angles of impact of 520 mils and greater.
“Irregular lateral position of ricochet bursting points with respect to one another, is not sufficient evidence that the shots were not fired from parallel barrels. The lateral position of such points of burst is to some extent determined by the nature of the terrain at the point of ricochet.” In other words, a projectile may be deflected from its plane of fire when it ricochets.
“Adjust with non-delay fuze, obtaining a bracket conforming to the depth of the target. After a shot has been placed within the target, change to fire for effect with delay-action fuze at the range diminished by 50 meters.” Reducing the limits of the zone for fire for effect compensates for the projectile’s additional travel, between its point of impact and point of burst. If ricochet fire for effect were conducted through the bracket established by a super-quick-fuzed projectile, part of the effect would be “over” and the near edge of the target would remain unscathed.
“When firing ricochets, a change in charge calls for renewed bracketing.”

RICOCHET AND TIME SHELL FIRE IN NORTH AFRICA
Practically no ricochet fire was sought or used by our artillery at the front, although artillery units in rear areas and British units armed with 105-mm Motor Carriage M7 used ricochet as well as time shell. Several reasons were given for non-employment of ricochet fire:
(1) Time fire has functioned satisfactorily. If the testimony of numerous prisoners is to be believed, Germans dread time shell. One of our divisions is reported to have based its plan of maneuver, to a great extent, upon the limiting range of time shell.
(2) No delay fuzes (other than the .05) have been available.
(3) The terrain was believed to be too broken for ricochet fire.
(4) Capabilities of ricochet fire were not fully appreciated. Since their entry into action, FA units have been engaged continuously with the enemy and have had little or no opportunity to train. Commanders were impressed with results recently obtained using ricochet fire in the United States, and stated that at the first opportunity its capabilities would be explored.
Most of our time shell concentrations appear to have been adjusted for a height of burst of about 50-60 yards. Results of tests in this country indicate that a burst center 15 yards high gives best effect.
Some German air bursts approximately 60-80 yards in the air were observed over one OP. These were fired approximately every half hour, apparently for harassing effect. The only other enemy artillery fire observed were impact bursts.

From FM 6-40, “Field Artillery Cannon Gunnery”, 1960:

Ricochet fire should be used only against personnel dug in or under light cover when VT or time fuzes are not available. Ricochet fire is not as effective as VT or time fuzes against targets requiring air bursts. Ricochet fire is not used against troops in the
open. Against troops prone in the open, it would require ricochet action from approximately 80 percent of the rounds fired to be as effective as the same number of rounds fired with fuze quick. Factors which determine whether a projectile will ricochet cannot be evaluated for a particular point of impact until the bursts are sensed. Ricochet fire must be observed. Another fuze must be used if ricochet action cannot be expected from at least 50 percent of the rounds fired in fire for effect.

Still nothing more specifically tank gunnery related.

All the best,

John.

[John D Salt]

John D Salt wrote:

Still nothing more specifically tank gunnery related.

OK, so I have finally got some evidence of panzer gunners being expected to use ricochet fire.

Thanks to Stephen Taylor, who has shared a vast number of WW2 manuals on his site:

WW2 Manuals – Over 130 Downloadable Manuals!

The two sources I have chosen are the Merkblatter (pamphlets) for a couple of AFV-only weapons, so we know this is information aimed at tank gunners, not artillerists.

The transcription and translation are my own, leaning heavily on Google Translate. Please shout out if you spot any errors; the 8.8cm document was printed in Fraktur, which I find very hard to read.

H. Dv. 481/55, Merkblatt für die Munition der 7,5cm Kampfwagenkanone 42 und 7,5cm Sturmkanone 42, 28 Jan 1943.

Abpraller: sie entstehen auf festen Gelände bei flachen Aufschlagwinkeln. Sie eignen sich zum Bekämpfen der ungedeckte sowie hinter Deckung in Gräben und Häusern befindlichen lebenden Ziele.

Ricochets: these occur on firm ground at shallow angles of impact. They are suitable for attacking live targets in the open or behind cover in trenches and houses.

H. Dv. 481/60, Merkblatt für die Munition der 8,8cm Kampfwagenkanone 36, 08 Jan 1943.

Abpraller (Luftsprengpunkte)
Besonders geeignet gegen alle ungedeckten sowie hinter Deckungen und in Schutzgräben befindlichen lebenden Ziele. Voraussetzung sind ein festes Auftreffgelände und Fallwinkel nicht über 360-. Grenze der ausreichenden Splitterwirkung gegen lebende Ziele bei 4 bis 8 m Sprenghöhe, 20m seitwärts und 10m vorwärts des Geschoßsprengpunktes.

Ricochet (airburst)
Particularly useful against all living targets in the open, behind cover and in fire trenches. Prerequisites are a firm impact area and an angle of fall no more than 360 mils. Limit of sufficient fragmentation effect against living targets at 4 to 8 m burst height, 20 m to the side and 10 m to the front of the projectile burst point.

So far, then, there seems to be good evidence for the use, in doctrine if not in the field, of ricochet fire by American, British, German and Russian gunners, and American and German tankies. Now where can I find British and Russian tank gunnery manuals?

All the best,

John.

[Whirlwind]

John D Salt wrote:

Thanks to Stephen Taylor, who has shared a vast number of WW2 manuals on his site: WW2 Manuals – Over 130 Downloadable Manuals!

That is a great link – many thanks!

[shelldrake]

As a gunner by trade, having crewed M2A2s, M198s, M777s and 81mm mortars I can explain the different type of artillery fuses, but not a reason for delayed fuses by tanks.

[John D Salt]

Not Connard Sage wrote:

‘Latest thinking’ may have been a bit of a misnomer, insert ‘a current hare-brained theory’ instead.
[snips]
The HMS Hood Association website has a wealth of details, including excerpts from the Admiralty inquiry into Hood’s sinking, but it probably wasn’t there I saw the claim.

I’m going to hazard a guess that you read the discussion of ricochet in the detailed and expert discussion in http://www.navweaps.com/index_inro/INRO_Hood.php

One possibility I have never seen discussed, but which seems a simple and adequate explanation, is that the Hood was struck in an spot where she had defectively-manufactured armour plate. I am sure that naval armour quality testing was as good as better as it was for tank armour, but armour plate manufacture is a very demanding task, more so for thick plate, and quality control is (at least until six sigma came along) never 100%. I am reminded of the British test shoot against an early captive Tiger in North Africa when shots were going through the 80mm plate on one side at large multiples of the ranges found on the other side, thanks to a defective plate having crept into the tanks construction.

All the best,

John.

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