"Tank warfare - target obscuration - from fire" Topic

Gents,

I ran across this passage in the excellent book – Spearhead, by Adam Makos (about exploits of a tank company/tank crew of the US 3rd Armored Division, ETO) -

"Bill steered Eleanor to a point farthest into the field before turning towards Grand-Sart and idling in the snow. Three more Shermans took their places to his side. Today, 2nd Platoon would be spearheading. Anchoring the left flank was Eagle, nearest the woods. Clarence sat back from his sights, concerned about the prospects of firing in snowdrifts that were as much as two feet deep. The top layers were powder and the 76's sizeable muzzle blast was bound to kick up quite a cloud. In a normal field, the dirt cloud would blind the gunner for up to thirty seconds."

…..up to thirty seconds. (!)

Does anyone have other excerpts/info on muzzle blast/target obscuration effects – WW2, multi-theaters, post-war modern data too?

Sounds too much like making the common seem impossible as a story.

Factors affecting observation and the consequences of fire have not really changed from what is currently taught in tank gunnery.

Thirty seconds of obscurration by blowing snow is quite the exaggeration. Don't forget the height of the barrel of a 76mm Sherman is nearly seven to eight feet off the ground level, so even a two foot snow bank should not be that much of anything against a trained gunners observation. Never mind the commander is another foot and a half above that observing too, if not being observed by the rest of the platoon in this case.

In a dry environment, dust kicked up when a large caliber gun was fired could be considerable. Vision could be blocked for even a minute(s) depending if there is a breeze blowing. I have read about ATG crew in the desert wetting down the area in fron of the gun to keep dust from being kicked up. The dust not only could obscure their view but it also would give the enemy an idea of where you were firing from.

So as the article above was written, "In a normal field the dust cloud could blind the gunner for up to 30 seconds." Key words "normal field" and "dust". I really never experienced snow causing vision issues when firing a tank, except if it was falling.

I've read many of the same accounts of the 76mm gun.

Sometimes Sherman 76's would have your wingman off to your side to spot or the commander is on the ground off to the side. Just observing unbuttoned could be painful and ineffective.

Around the end of 1944 a modified 76 mm gun M1A1C or M1A2 with muzzle-brake was later introduced. I think the main reason they did not put a muzzle brake on was that the gun was unbalanced and needed a balance weight. The original gun barrel was even longer. An unbalanced gun can more easily go out of boresight alignment, something you don't want to happen in the middle of combat.

If the blast obscured your view for just 2 seconds that meant that you could not track the shot inside of 1500m. If you missed inside that range it would be difficult to make elevation adjustments.

As Major Mike said, wetting the ground with water or oil or putting down a canvas sheet helped a lot, especially for dug-in anti-tank guns.

I came across this too:

WHY DIDN'T THEY JUST SLAP MUZZLE BRAKE ON THE M-4 SHERMAN'S 76-MM GUN TO TAME MUZZLE BLAST?We're talking about the US military in World War II and they did not seem to be thinking clearly at the time. The issue was that US tankers manning 75-mm gun armed Shermans were reluctant to accept the 76-mm M-1 wholesale (they wanted limited numbers only) for several reasons, one being excess muzzle blast obscuring the sight of the gunner and captain in dusty conditions, making it harder to note if a hit was made and if not then how high and wide the shot went.To a layman the obvious answer is

Just fit a muzzle brake on the danged gun!

Ironically, it isn't as easy as that: muzzle brakes are heavy. The elevation system and other parts of the gun has to be set up to handle a heavy weight on the very end of the barrel. For example, the first 600 of the 90-mm gun armed M-36 tank destroyers issued did not have one and as far as the military was concerned they never would. They weren't set up to accept one and there wasnt' time to convert them. (They were pressed for time and trying to get them into service; and the 90-mm had less of a muzzle-blast issue than its smaller kin). The issue with the 76-mm was that once the need became apparent, the actual devices were not produced fast enough. Thus, many tanks went to war with a cap covering the threads on the end of the barrel where one would be attached if it was ever provided. The initial tanks didn't even have threads on the end of the barrel to screw one onto. Of course, the powers that be could have developed the gun with a muzzle brake in the first place. Despite testing and plenty of time to work it out, the Ordnance Department didn't foresee a need for one. Perhaps they had lulled by the experiences of the M-10 tank destroyer units who mounted a 3-inch gun without a muzzle brake. It created excess blast and smoke, but the M-10 crews didn't complain.

Maybe they didn't know better, and certainly, they actually didn't get into a lot of fighting. The M-10 had been designed and the crews trained to counter the feared mass of panzers the Germans would throw at the USA. Which didn't happen until December 1944. While ground forces did encounter German tanks, they often were not that much an issue during 1943 and 1944. The tanks often took care of them first. There were long spans of time when US ground forces met very few German armored fighting vehicles. And thus the M-10 crews spent a lot of time in their intended secondary role as mobile artillery. And occasional jaunts supporting infantry. Front light fighting was not something they did a lot of, so why were they to complain about muzzle blast and HE shells? Whatever the case, the Ordnance Department dropped the ball and it took a little while before 76-mm guns with muzzle brakes arrived. They not only added a muzzle brake but also changed to a long primer ammunition (which no one has explained so far, but perhaps it results in better ignition of the propellent and less smoke).

Wolfhag

As suggested above, adding to the game some wind affects such as direction, and force from calm (no quick dissipation), to light (dissipation, e.g. after one turn), to strong (quick dissipation, no penalty to firing vehicle's next shot, would be reasonable.

Whether anyone wants to bother with the dust/other cloud affecting someone close to and downwind of the firing vehicle would be a somewhat fiddly option.

Then again, since the chance of hitting any target at any range under any other conditions would never be 100% (unless your muzzle is in contact with the target), perhaps the effects of obscuration should be subsumed into any "miss" that results.

Or not.

TVAG

Again, being seven to eight feet in the air above the snow bank, the resulting cloud of snow is little to none.
With wet or frozen snow being none and dry powdery stuff having small effect. I have spent enough time on tank ranges in Canada to confirm this.

Additionally such things as the gunner observing through his magnified gun sight, watching the trace of the round easily visible even in daylight, is more than enough to follow up immediately. From the 37mm and two pounder on forward trace element was always a part any tank ammunition.

Muzzle brakes are a nice story but only mitigated a bit of the flash. After the 17 pounder and the 90mm, they no longer are used.

Sounds like either a poorly trained crew or quite the exaggeration.

Going back to my old turret manuals and gunnery lessons, the factors affecting observation are;
the consequences of fire, (the flash, blast et cetera)
the nature of the ground,(especially dead ground before your target)
the weather, (temperature, humidity, conditions)
the ability to observe the tracer
the time of flight of the projectile and most importantly
the training and experience of the gunner.

Tank gunnery classes that one never forgets.

I think in the rush of wartime, as Wolfhag mentions with his passage above, in regards to the lack of a muzzle brakes available to initial Sherman 76s, the troops compensated for obscuration effects the best they could in the field.

In R.P Hunnicutt's book Pershing, A History of the Medium Tank T20 Series, there's the same obscuration effect detailed about the 90mm T7 (M3) gun w/o a muzzle brake, as planned for the series, and as fitted to the first two T26E1s -

"Firing test at Fort Knox showed a severe obscuration problem with the 90mm gun. So much dust was kicked up by the muzzle blast that the 90 was condemned as a one shot weapon, because of the long delay before it was possible to see well enough to fire again. The cure recommended was a muzzle brake which would deflect the blast sideways reducing the obscuration along the line of sight."

The brakes were designed to mitigate a lot of the pressure away from all of it being recoil. So brakes on certain vehicles were a must like the M18. The three inch gun of an M10, not sure if it had one, but by switching to a 90mm on the same weight of chassis sure bumped up the recoil to very border line levels of what the hull chassis could tolerate.

Mitigating some of the blast was a secondary effect but not to the extant that you may think.

The 17 pounder had a muzzle brake, mostly because it was originally designed as an anti tank gun and needed it to reduce the recoil force. I think all the barrels for that had a muzzle brake reardless of what they went into or on.

Surprisingly enough, the US M5 three inch anti tank gun did NOT have a muzzle brake! Especially with a barrel two to three foot off the ground the crews had no diffuculty observing the impact.

Even today it is easy for tank crews to follow the trajectory of a 105mm HEAT or a HESH round fairly easily because of its velocity. A APDS round is pretty hard for the untrained to even notice.

Back then perhaps a few of the rounds such as the rare APCR might have been difficult to follow. Few were trained to observe at the distances we now consider routine. Also the inherent innaccuarcy of the APCCR round as distance opened made it into a 'wild shot' past eight hundred yards or more.

In North Africa, the British Armoured Corp put a lot of the blame for not knocking out German tanks on poor gunnery, when in reality it was the inadequate gun and ammunition combination that was failing them. As a result, they went quite overboard on gunnery training in 1943 forward and have never backed down. It is going to pain people to hear this, but I suspect the quality of US tank crews was not at as equal a level.

Some comments re smoke and flash when firing US tank guns, taken from General Isaac White's report to Eisenhower – "A Report on United States versus German Armor":

Everette L Harris, Corporal, Gunner
Due to the type of powder a Jerry tank has, then can fire at your and are difficult to pick up because there is so little smoke or muzzle flash. When we fire our 76mm there is so much smoke and muzzle flash that you can hardly observe your burst, except for long ranges.

Henry W Johnson, Captain, Co F, 66th Armored Rgt
The German use of smokeless powder makes it very difficult for us to pick them up when they lie in ambush, whereas the flash of our own guns is easily discernible to an alert foe and may be easily observed from a great distance.

Michael Fritzman, Sergeant
I'm a gunner on a Sherman tank which mounts a 75mm gun. When the wind is blowing in the right direction while the round is being fired, we are unable to sense the round being fired. This is due to the muzzle blast and smoke which comes from the gun. This same muzzle blast makes us slow to fire at targets at extreme ranges because it immediately gives our position away. What we need …<snip>… is a muzzle brake.

Wendell Fife, Sergeant
The mount for a 76mm tank is too light to support the gun. The extra play causes inaccuracy in firing. After firing, it is almost impossible to observe the burst, because of smoke.

Philip C Calhoun, Major, 3rd Bn, 66th Armored Rgt
The 88 and 75 on the Mark V are superior to the 90mm, partly because of the higher velocity and flatter trajectory, …<snip>… and partly because of the muzzle brake which we have seen on both the Mark V and the Mark VI, thus allowing them to observe their fire better than our 90mm gunners or destroyer commanders can.

O A Lewis, 1st Lieutenant
The Germans' use of smokeless powder makes their gun positions very difficult yo pick up. Our guns give our positions away with their first round.

Paul A Bane, Major, 3rd Bn, 67th Armored Rgt
Our tank crews operating equipped with 76mm guns have experienced great difficulty observing the strike of a round due to excessive muzzle blast. It was necessary to use dismounted observers. Recently we have received a few M4A3E8 tanks equipped with muzzle brakes. Test firing an combat operations have proven the muzzle brake to be a great help. We consider muzzle brakes an essential part of the tank gun.

Some 76mm comments for Wolfhag ……………

Jess H Van Winkle, Corporal
"Consider the American 76mm gun improperly balanced. It is necessary to re-lay after every shot. At a range of 1,000 yards or more, it will vary 100 to 200 yards in range.

George C Miller, Corporal
Consider the 76mm gun improperly balanced. Re-laying is necessary after every round is fired. A variation of 100 to 200 yards results when fired at a range of 1,000 yards or more. (Same unit as Corporal Van Winkle?)

Edward W (unreadable), Corporal
Our 76mm is a little better than the 75mm, but the gun has a lot of lost motion, while the souped-up 75mm on the German tank is very steady.

B

There is a Youtube video of an 8.8cm Unit doing indirect fire in late 1944. After each gun fired there was a huge plume of white smoke from every gun. There are many clips of Tigers firing as well and I urge all those interested to check them out before believing German guns were smokeless/flashless/undetectable.
I like the way the booklet on German v US Equipment has a section on gunsights where it claims US sights are vastly inferior and cant hit anything. In the section on inferior US guns the crews bemoan the fact they come under long-range fire from(superior) German tanks. They return fire but have to watch as the inferior US ammunition 'bounces off' the German tanks. I guess no one noticed the contradictions………….

Blutarski, TY for taking your time to list all these contributing quotes.

"We consider muzzle brakes an essential part of the tank gun."

Mkenny, many videos do seem to present quite an obscuring blast, as you mention.

A gaming side-note here – in a post-game review of a scenario recently played, a comment was made to the effect, that in large, anti-tank effectiveness began and ended (during the later-war years) with the ability to achieve a 1st-round hit, which elevates the ambush position (combined with a 1st-round penetration probability), to being the preeminent tank-killing posture in tank warfare.

This has long been advanced, and/or contrasted/compared.

Perhaps what is of related interest in our discussion here, is whether target obscuration, and a lack of confidence in the gunner's ability to achieve a following, 2nd anti-tank round+ (within the combat environment), could and did largely affect, and dictate the tactical response?

I have never heard complaints of ammo powder being a problem outside of naval gunnery before. I have found no account from any Commonwealth, Polish or French source complaining about it. The German ammuntion powders were quite comparable.

AS far as unbalanced goes, well tank guns are heavy, adding another hundred pounds on the end for a brake was a desicion usually only taken into account in order to mitigate the recoil energy. The resultant effects on any blast or flash effect was minimal.

Having to relay the gun on to the target after each shot is standard practice. To think that you can pint a tank gun and it sits still like it is in a vice is ridiculous. Especially given that the 2 pounder and even 37mm guns quite often had shoulder stocks for the gunners. Only once up to the weight of the 75mm and forward did the allies use gearing mechanisms as standard for traverse and elevation.

Blutarski, I would be interested if you could delve a bit more into the nature of those complaints. A cursory read of them shows me that it is a comparison mostly by crews between their 75mm and new 76mm tank guns.

Going from the relatively benign recoil of the 75mm and its' pedestrian velocity of what 1,850 ft per second, where anyone can watch it sail liesurely through the air,,,
,,, to the M1 76mm travelling at a rate of hat 2,600 foot per second is a game changer and takes considerably better training and experience in observation for both the gunner and commander to follow.

I would love to have heard some follow up comments from the same people after a few months of ue of their new guns.

The M10 was in service some two and a half years before the tank gun. Were there no cries for muzzle brakes?

The 3 inch M7 gun had a muzzle velocity of 2,800 foot per second, faster than the M1 76mm even. Can I suggest that the artillery gunners did more training with them and had better experience in observing their fire.

The training and experience of the gunner and their determination to observe play a critical factor in tank gunnery.

I think quite a bit of those complaints are from crews being switched over to something new and being unhappy.

Reminds me of the rifle replacement in the field program of 1966-67. Even to this day I hear a lot of Americans bemoaning the loss of their M14, even though they never trained with one or carried one. Yet they forget that it was the shortest serving service rifle the US used for a reason.

They also forget how bad an idea it was to issue new rifles with no training and to mass produce it with the wrong powder. Yet now some 55 years later it is one of the most popular rifles in US history.

Why would we expect the change over from the 75mm to the 76mm Sherman to have been any better twenty years before that???

For parties interested in the smoke and flash topic -

Go to YouTube and search for "German War Files – Panzer IV Heavy Tank" on the "geesusdb" channel. First video, picked at random. Scroll to the 22:28 time mark and observe the discharge of an 88mm Flak gun firing in the ground role. Note the flash and smoke discharge signatures.

B

Hi FlyXwire,
Are you the same "FlyXwire" from the old Red Baron site on the Delphi Forum?

B

YouTube link

Go to 0:41 to see the 3.7 in AA guns firing and then let me know how the German flashless/smokeless powder is in any way different to what you see.

YouTube link

Note the 7.5 cm pak firing at 2:39 and the Flak guns firing at 3:51.

Hi troopwo,
It's a complicated topic IMO.

One aspect might be found here -

PDF link

CMH Publication 10-9
THE UNITED STATES ARMY IN WORLD WAR 2
The Technical Services
The Ordnance Deparmtent – Planning Munitions for War

p.352 -
"The Radford Ord-
nance Works carried on extensive experiments to improve manufacturing and testing techniques as well as to find better chemical compositions. Yet in the spring and summer of 1945 reports of the Combined Intelligence Objectives Subcommittee, established to locate data in Europe on Axis research and manufacturing procedures, indicated that Germany had developed several processes more effective than those of the United States. The most novel German method was one of casting propellent grains by adding a paste of moist nitrocellulose and diethyleneglycoldinitrate, DEGN, to molten TNT and pouring the mixture into steel molds to cool. Grains as large as 1,000-mm. were cast this way. After the war complete sets of the German equipment deemed most useful and novel went to Picatinny Arsenal for study.

- – – – -

We also know that the 76mm gun produced excessive smoke when fired until a longer ignition cartridge had been developed for use in the propellant case – again a late war development.

- – – – -

Another contributing factor IMO might have been the ubiquity of muzzle brakes fitted to German tank guns and the lack thereof on American tank guns until VERY late in the war. A proper muzzle brake would re-direct muzzle blast horizontally, which would reduce considerably the amount of dust, dirt and other ground debris blown into the air. By way of example we know that, in the case of 88mm Flak (no muzzle brake) emplaced for action in the ground role a great deal of effort would be expended in preparing the ground within the expected engagement arcs to reduce dust being blown into the air by the gun's discharge.

Note – The 88mm Flak firing video clip I referred to involved the gun firing at an elevation of 20 or perhaps even 30deg, which may have served to reduce ground dust being blown into the air. OTOH, it does show to advantage the flash and smoke characteristics of the gun itself.

- – – – -

Last comment – I myself did not read the commentary as tank crewmen making a distinctions between the 75mm gun and the newer 76mm gun. What did you read that gave you that impression?

B

This is for small arms, but may be of interest. From Yank magazine 1945:

General Marshall, page 31, first paragraph, first column under the picture:
link

Sergeant Joe McCarthy, page 4, last paragraph before the third column break:
link

Guys, thanks to you all for this deluge of pertinent links and documents.

Blutarski, hello, my fellow Great War sim pilot – salute to you, and to those good times past!

I like the 3.7 AA used against ground targets. Don't see much coverage like that. But, even in that clip the obscuration is only for a second or so. Not the thirty seconds of blindness assumed in the original post.

Also of note is that the flak guns weighed multiple tonnes to begin with with specially designed platforms to absorb the recoil however they were used. Additionally, a second or so of obscuration was accepted while waiting for your projectile to make it all the way to twenty thousand feet or more.

Later when those same cannon barrels, the 88 and 90mm, were used on tanks, they were fitted with muzzle brakes to help dissipate recoil energy. Even the 3.7 inch AA which was tried out as the 32 pounder on a 78 tonne thing called the Tortoise, but being a 78 tonne vehicle I am sure it could take the recoil. Canada did put a 3.7 AA gun on a thrity tonne Ram chassis for trials but didn't adopt it.

On muzzle brakes voiding blast away from the ground, that would be a good thing. Yet no one complains that the same blast is being voided sideways directly in front of the gunner and commanders optics and view???

Like I said the blast effect is only of a seconds duration. If the target is that close to be under one seconds flight time, the results should be obvious from what happens at the target end. Anything longer than one second flight duration will be easily viewable through the gunners and commanders optics or line of sight.

I submit that the new 76mm was more than the crews bargained for coming from the 75mm experience.

At 2:39 with the Pak firing it's hard to tell if it is smoke or dust thrown up from the muzzle blast.

Flashless Powder: Potassium Sulfate was added to the charge to reduce the flash:
link

link

They are called "flashless" and "smokeless" but in reality, there is still some flash and smoke, it is just reduced. Probably more effective at night than during the day. The problem with all of the videos is that we can't confirm if the rounds fired had the potassium sulfate to reduce the flash or not. It appears some rounds came with this addition and other times it was added in the field before firing. This could explain some of the discrepancies.

If the battery of 88s were performing indirect fire there may have been no need to add it to the charge or the unit may not have been supplied or run out of it too.

Some accounts said that flashless powder produced more smoke which could have been fine for naval battles at night.

This is combat footage of a Tiger I in combat with some good footage of the tank firing from the commander's position. I was surprised by how little smoke for flash there is at 0.58 and 1:18. The ground does seem to be wet.
YouTube link

I like the way the booklet on German v US Equipment has a section on gunsights where it claims US sights are vastly inferior and cant hit anything. In the section on inferior US guns, the crews bemoan the fact they come under long-range fire from(superior) German tanks.

It depends on the time frame. The "can't hit anything" is an overstatement I'm sure which I tend to ignore. There are accounts of Shermans getting hits at 3,000 yards.

The early Sherman periscope sight was terrible because loose linkage gave it a 4mil error. The Germans did not have roof panoramic periscopes for their gunners which gave the Shermans a big advantage in shooting first.

link
The M4 Periscope sight
The Periscope M4; it had an M38 telescope with ballistic reticle inside, but no magnification. The M4 was not well liked, and the mount it fit in was made from sheet metal and was a little flimsy. The linkage that attacked it to the gun wasn't very robust and could be knocked out of alignment annoyingly easily. On early Shermans, this was a big complaint, since they did not have a direct telescope yet. You couldn't really take advantage of the M3 75mm guns range with this sight setup either since it had no magnification. The later better periscopes like the M4, M4A1 and M8 series would all fit in the old mount though.

This is what the Sherman gunner was faced with in estimating the range and aiming:

What a pain!

I think the German TZF series had the advantage of range settings for different rounds and MG fire, two magnifications, and could be used as a stadiametric rangefinder if trained.
link

My opinion: The muzzle blast effects from the Sherman 76 depend on the weather and ground conditions and maybe your scenario write-up. At ranges of 500-800m, the gunner should have a 2/3 chance for a first-round hit which could be confirmed so in the end it may not be such a big deal. I think it would be difficult to include in most games.

Wolfhag

As you noted, only a fraction of a seconds worth of obscuration by blast and smoke.

Most allied tanks crews made a habit of sending as many rounds as fast as the loader could hustle into the gun at targets that were under 1,000 yards.

It may be something that needs to be factored into scenarios, because WW2 gunnery tables don't address these battlefield conditions.

Makos's book, which inspired the conversation here, serves to relate what veteran gunner Clarence Smoyer, who is heavily featured in the book, relates's from his WW2 combat experience –

"WHAT DID FIRING THOSE BIG GUNS FEEL LIKE?
It shakes you up, inside and out. The recoil of the gun rattles you to your bones. You're vibrating from it. Fumes from the fired shells build up and sting the eyes. Dust and debris flies everywhere from the ferocious muzzle blast and it takes forever to settle, which makes you even more stressed. Everyone is just a bundle of nerves. It was a shoot-first-ask-questions-later situation. Survival is all it was."

link

Hard to imagine that back then, one drop of sweat might have changed everything trained, practiced, and hoped for when in the heat of battle.

My own experience of tank gunnery is a single round from a Challenger II's L30 120mm gun at Lulworth range. It was a training round, so possibly less propellant was used. The weather was calm and the tank static on a concrete apron so no wind dispersion or dust to kick up.

On firing my vision of the target – an old FV432 700m away – was completely obscured and this remained the case for about three seconds. Although the round apparently had a tracer element and flash tip I didn't see the impact. I can't comment on the commander spotting the fall of shot but from the gunner's position I would have had to wait for the crew to bale or the target to erupt in flames befofre I knew how effective my shot had been.

From outside and watching others engage the same target the fumes did hang about for about three seconds in front of the tank. Not directly useful for the discussion on WW2 tank gunnery but may be helpful as an anecdote. Obviously the tank moving, turret traversing or different weather conditions would change the situation drastically.

It improves a lot with training and experience.

All the turret training I did as a young man was based on timed engagements. You had to do all the drills exactly, safely and under the time limits, so every second mattered.
Knowing and being used to your equipment and what they did and what to expect was everything.

Typhoon2, appreciate you relating your experience with the Challenger II.

Clarence Smoyer and his tank crew were such veterans of the US 3rd Armored Division, that they were selected to crew one of the T26E3's given to the Division to test under combat conditions. Smoyer displayed his gunnery skills in the T26 before a demonstration arranged for the entire 32nd Armored Regiment, and witnessed by Spearhead's commander Maurice Rose himself – Clarence nailed every target proposed for the 90 – with his 1st shot, each time (this not on a range).

His tank duel in Cologne is iconic, and one of the few captured on film, by US Signal Corps photographer Jim Bates, who climbed to a third-story window of a building overlooking the Panther's position at the Cologne Cathedral in order to capture the event.

"The 90mm blast had stirred up so much dust that the Panther appeared to be just an outline, angular and threatening, with its gun still pointed at him." [this sighting difficulty at just a city block distance, certainly one layered in dust and debris from repeated Allied bombings]

YouTube link

I'll wager that Clarence Smoyer was a natural, almost instinctive gunner in fact. His words, and combat accounts do hold a certain weight.

only a fraction of a seconds worth of obscuration by blast and smoke.

US Army Ordnance did a study of flash and smoke effects in April 1945. Flash would last for only a fraction of a second. But the effect of smoke and dust was a far different matter; the US report suggested 2 to 4 seconds duration as typical under proving ground test conditions. ToF for a 76mm M93 HVAP-Tracer was -
0.47 seconds @ 500 yds
0.97 seconds @ 1000 yds
2.14 seconds @ 2000 yds

A close reading of the above US tanker accounts (IMO) illuminates how complicated the issue was under actual combat conditions. My personal opinion is that the presence or absence of a muzzle brake on the gun was an important factor.

Another point which jumped out at me was the direct mention of a notorious smoke problem connected with use of 76mm ammunition with the original short primer.

Random musings FWIW.

B

Hi FlyXwire,

BTW, Blutarski = Lord Byron (LE) on Delphi
You and Spindry are the only people I remember offhand.

B

Blutarski, I've just always been one of the noisiest. ;)

Good info above (again).

Correcting aim for successive shots likely did become impossible at times during WW2 combat. This can go towards explaining protracted tank battle results that don't square up with generous test-range probabilities.. Also, why the short stop, shoot, and scoot just became best practice.

Blutarski,
I think the muzzle brake edition and long primer were accomplished around Jan 1945.

I've been to Cologne and stayed in the hotel at the intersection where Smoyer fired at the Panther. I got up early in the morning before traffic and walked the areas of the engagement and took pictures.

In our games, you must fire again at the tank or crew if you don't see a fire or brew-up result. I've started using a point system for the level of destruction of the tank (immobile, fire, brew up) and additional points for the crew killed. Lost of mg fire against crews bailing out in the game.

I'm making some changes to the Sherman 76 "reload & aim" action timing.

Wolfhag

I'm making some changes to the Sherman 76 "reload & aim" action timing.

Hi Wolfhag,
Am I correct in recollecting that the same ammunition was used in the 3-inch guns of the TDs? Or was the projectile the same, but the cartridge case differed?

B

It appears so, at least the HVAP:

The success against enemy armor of the hyper-velocity, armor-piercing round developed for the 76 mm and 3 inch guns has resulted in standardization of the T4El7 and T4E20 shots as Shot, HVAP-T, 76 mm or 3 inch. M93.

They both use the same aim points in the gunsight too.

Wolfhag

Am I correct in recollecting that the same ammunition was used in the 3-inch guns of the TDs? Or was the projectile the same, but the cartridge case differed?

The projectiles were the same. The cartridges were different. This is why they were referred to as different caliber guns -- the ammunition for the 3-inch gun and the 76mm gun was not interchangeable.

The 3-inch gun was of an older design. It was derived from a naval gun of the pre-WW1 era. It was bulky and heavy.

The 76mm gun was of the most modern design (for 1942). It was specifically designed to provide the same ballistics as the 3-inch gun, using the same projectiles, but in a substantially lighter gun that would fit into the turret of the "new" M4 medium tank. The cartridge was also shorter, for easier handling in the confined space of a turret.

The 90mm gun M3 was based on an Army AA gun (same ammunition), but was designed to be of the same size and weight as the 3-inch gun, so that it would fit into the same turrets as the 3-inch gun (the M10 TD and the M6 heavy tank). In fact the first test-firings of the 90mm gun M3 took place in an otherwise un-modified M10.

None of this is to say that the ballistics were exact matches or the fits of the guns were perfect -- just that they were designed to be the same. Also the Armor Board rejected the first M4 Sherman with the 76mm gun mounted in the same old turret, even though it did fit, leading Ordnance to re-design the 76mm Shermans with a new turret explicitly designed for the 76mm gun (the turret from the T23 program). And Ordnance decided to re-design the turret of the M10 before mounting the 90mm gun just because they wanted to make a better turret (not because it didn't fit), thus producing the M36.

-Mark
(aka: Mk 1)

from Blutarski,
US Army Ordnance did a study of flash and smoke effects in April 1945. Flash would last for only a fraction of a second. But the effect of smoke and dust was a far different matter; the US report suggested 2 to 4 seconds duration as typical under proving ground test conditions. ToF for a 76mm M93 HVAP-Tracer was -
0.47 seconds @ 500 yds
0.97 seconds @ 1000 yds
2.14 seconds @ 2000 yds

Without a wingman spotter or the TC standing outside away from the blast observing with binoculars, the gunner would not know the results of the shot unless it ricocheted, started a fire, or fired HE. The blast could last up to 30 seconds, which may decrease the rate of fire too. Of course, much depends on the condition of the ground.

Halfway down the page, you can see the 88 observer standing off to the side. link

and here too: link

Here is a good one of a 17pdr blast and the observer standing to the side: link

Anti-guns would put water, oil, or canvas on the ground to decrease the muzzle blast. That, combined with smokeless and flashless powder, made it hard to spot them.

My game system uses timing to execute orders and actions. Guns that may be affected by muzzle blast are defined in the scenario notes. Their reload time would be increased by rolling a D6, D10 or D20 with a + modifier to determine how many additional seconds it will take to get off the next shot.

Anti-tank guns reload time is doubled when under MG or HE suppressive fire, the gun cannot pivot or use a rangefinder.

From troopwo,
All the turret training I did as a young man was based on timed engagements. You had to do all the drills exactly, safely and under the time limits, so every second mattered.
Knowing and being used to your equipment and what they did and what to expect was everything.

Exactly and why I use OODA Loop Timing for actions and orders. Better crews are a little quicker and poor crews are slower. Once you "Act" go back to Observe the results and roll a D6 to determine how long it will take to shoot, reload, engage a new target, etc. There is no order phase and units are always active to react and issue/cancel an order.

To quote Otto Carius, "Everything depends on prompt identification of a dangerous target, usually seconds decide".

Once I get the videos done I will put some of the work online.

Wolfhag

Wolfhag, this fits well a recent passage I've read in the book Panzerjager, that relates the wartime experiences of Bernhard Averbeck, compiled in English by William B. Folkestad -

"Our squad leader explained that the gun had been too low and we needed to relocate it onto higher ground. He then turned and ordered me to go to the embankment and give fire coordinates. With an antitank gun you always need to have someone observing out front because with each round fired, the barrel blast sent dust and everything flying up. In such instances you are unable to see if you hit the target, or the ground in front, to the side or in the back of a tank. My job was to correct the fire and give new coordinates using arm and from hand signals. I ran over to the berm, clambered up to the edge and from there began directing fire towards the T-34s…….."

That link above showing the 17pdr blast with the observer standing well away from the piece, supports Averbeck's related passage very well (excepting Averbeck oddly stating he would locate out front, instead off to the side).

So there can be initial AT gunner error (and/or with gun-leader range estimation error), then there can be observer correction of range or direction error, and then there could be follow-on gunner error in response to the observer's corrections – being relayed in the din of battle by hand signals (a potential Loop-ful for things gone wrong). After a short while, I imagine there could be screaming involved too (and impolitely).

I can't find the details right now but the Germans used an established method of bracketing.

If the Gunner sensed the tracer, he'd make his own adjustments. If not, TC gave corrections.

IIRC if the target was estimated to be at <= 1200m the correction would be up or down 200m. If over 1200m it was up or down 400m. This corresponds to about a 20% range estimation error. If the second round missed the correction was 1/2 of the second shot. With that in mind, all the TC would need to do is use a hand signal up or down. KISS. Maybe someone can find a historical source or a real tanker that could fill us in?

This is from the US M60 tank manual:

Illustration of the Battlesight & Burst on Target Method:

Battlesight: Getting the first shot off in an initial engagement was the most important. The gunner would go into combat with his elevation set for the expected range of an encounter. This method was reliable out to about one second Time of Flight. At ranges longer than that you need to perform range estimation.

My system uses the same method as in the diagram. If it takes 8 seconds to estimate the range, aim, and fire the player (unknown to his opponent) can deduct from 1 to 8 seconds to shoot sooner (Battlesight or Snap Shot) but with an increasing accuracy error for each second he is shooting sooner. This means you can miss even at point blank range if you hurry your shot. I call it a Risk-Reward Tactical Decision.

Using a rangefinder takes longer. Veteran crews are a few seconds quicker without a penalty, and poor crews take longer to do the same thing.

The future Act Time to shoot is hidden from your opponent so you never know the exact second your opponent will shoot. This creates an interesting Fog of War as the game clock ticks off each second/turn.

Wolfhag

Outstanding discussion. I really enjoyed it.
I will make a few minor remarks. These are not an attempt at arguing but just some facts.
In the 1977 Tank Gunnery book, the introduction has a statement that it would take 13 shots at a target 500 meters away to reach a 50% chance to hit. This was using the V system gunners sight.

Now I fired gunnery in the 1970s but our Sheridans, M551, used the V sighting system and not the ghost system of the M60A1. The ghost system reduced the affects of kick up and mussel flash was worse at night.
Now the Sheridan had a short barrel 152mm gun. So the kick up and mussel flash were significant, especially at night. While those factors may have made it hard to stay on target, it was not the main reason. When the main gun fired, it would raise the track to the second road wheel when stationary. On the move the recoil could even turn it over if not firing at the correct angle.
I saw several drivers and even a TC hauled off with busted ear drums. Once the ACAV armor even broke off during the recoil.

In my opinion, the V sights affected chance to hit more than anything.

Guys, the German techniques for range estimation and adjustment had a few permutations also, and were put into the vernacular in the Tigerfibel and Pantherfibel manuals, and the manual just assumed the crews' hearts would be into the advice – so on fire for Elvira -

PDF link

Here's some scans from the Tigerfibel English translation (there's 19 pages in the manual on gunnery tips and techniques alone)!

If another page(s) seen in the original PDF linked seem interesting, I can scan those also (would be later today).

Pages 63-76 of the PDF go into detail on how the gunner used his sight as a stadiametric range finder. Here is a more detailed English version:

German reticle design
Range estimation

German reticles were designed to aid gunners estimate the width of their target in mils. Most reticles had a number of triangles that had specific mil sizes, which could be used to estimate the width and height of the target.

link

The way I handle the details is that crews using this type of gunsight take a little longer to estimate the range, aim, and fire but with a slightly better chance of scoring a first-round hit.

More Time = better accuracy but slower shooting
Less Time = worse accuracy but quicker shooting
The player makes the decision based on the engagement situation.

Wolfhag