Long Range Tank Gunnery -- Again

[DKTanker]

I think I began to digress from the intent of the original article I posted.  The author seems to have been trying to make the case for a new training round that can be utilized for long range gunnery practice.  The M865 is apparently a fairly descent training round out to typical gunnery training ranges – after which it’s odd cone stabilized shape and its rapid velocity decay make it rather erratic. 

Best Regards

Jeff

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M865 TCSDS-T was indeed about useless past 2400 meters. However, M865A1 succeeded M865 about 1994ish. M865A1 is fin stablilzed but uses a two piece sub-projectile that falls apart...at what range, I'm not sure but, it is a longer ranged training round. 1994ish because there were some initial problems getting the seperated portions of the round to fall to earth at the proscribed distance.

 

Distance X, the downrange distance required for the impact area is: The distance a round will travel when the weapon is elevated 5 degrees above the furthest target. So it isn't necessarily dependent on full elevation of the weapon, though if the firing tank is shooting up hill....

[nigelfe]

Not as the US Armor school defines it.  Calibration, by the US Armor school, is merely boresighting of the tank cannon.  After boresighting the tank fires a confirmation of calibration.

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The meaning of calibration was sorted out before the US Armor school was invented. Clearly they need to have some discussion with Ft Sill. Interestingly enough the Brit armoured corps clearly understood the differance in WW2, (but perhaps that was because the arty anti-tank gunners made sure they were properly educated) obviously they're slow learners at Ft Hood. Of course the coast gunners were direct fire and they used calibration not zeroing, but then the coast guys actually knew what long range direct fire was, none of the 5000m is long range fantasy.

[DKTanker]

Of course the coast gunners were direct fire and they used calibration not zeroing, but then the coast guys actually knew what long range direct fire was, none of the 5000m is long range fantasy.

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Hmm, back to that again, you equating hitting a battleship, after a few ranging salvos at 15000 yards, with hitting a 2x2 meter target at 5000 meters with only one shot. But then isn't 15,000 yards long range fantasy as well....compared to the likes of the Paris Gun striking Paris from some 120,000 meters.

[M1Buck]

If the two rounds result in a bad showing for an individual tank, than I think the tank is gone over with a fine toothed comb to look for maintenance and boresighting problems.  After which it is zeroed the old fashioned way and provided with its own unique set of CCFs.  This is what I was able to come up with.  However I would be interested to hear from DkTanker and M1Buck regarding if the above is really the current SOP.  Or does SOP vary from battalion to battalion?

 

Jeff

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That's about the size of it.

[DKTanker]

As I understand it individual tank calibration is supposed involve a screening process in which it shoots two rounds to see if the CCF inputs result in decent accuracy.  If the CCFs are adequate, than the tank is good-to-go for it’s tables.  I don’t know if the two check rounds are included in the 90-round yearly allotment or not.

Indeed the rounds used for confirmation are part of the annual allotment.

 

If the two rounds result in a bad showing for an individual tank, than I think the tank is gone over with a fine toothed comb to look for maintenance and boresighting problems.  After which it is zeroed the old fashioned way and provided with its own unique set of CCFs.  This is what I was able to come up with.  However I would be interested to hear from DkTanker and M1Buck regarding if the above is really the current SOP.  Or does SOP vary from battalion to battalion?

I don't know what is current policy but, we would evaluate each round. IOW, if the first round missed we stopped the exercise for that particular tank until a determination could be made of why it missed. If the first round is a good hit and the second round a miss, we would immediately confer with the tank crew as to what they did, what target they were actually aiming at, and what range they had to the target. Generally though, if a tank hit the first target near center it was a fair bet that it would do the same on the second round and target.

[jwduquette1]

Thanks M1Buck & DKTanker.

 

Just for posterity -- and to head off Willi calling B.S. on my last post – I did locate dispersion data for M865 & M865E3. It turns out to be reasonably uniform – conical rather than the trumpet shape I figured it to be. At least it is uniform between about 1000m and 2500m. Below are the summarized results from several sets of control tests done at Picatinny Arsenal back in 2002.

 

M865 Dispersion @ 1000m

Vertical: 0.23-mils

Horizontal: 0.31-mils

 

M865 Dispersion @ 2500m

Vertical: 0.27-mils

Horizontal: 0.27-mils

 

The round apparently doesn’t do as well in cold temperatures. @ -32-deg C

M865 Dispersion @ 1000m

Vertical: 0.3-mils

Horizontal: 0.42-mils

 

M865 Dispersion @ 2500m

Vertical: 0.33-mils

Horizontal: 0.42-mils

[nigelfe]

Hmm, back to that again, you equating hitting a battleship, after a few ranging salvos at 15000 yards, with hitting a 2x2 meter target at 5000 meters with only one shot.  But then isn't 15,000 yards long range fantasy as well....compared to the likes of the Paris Gun striking Paris from some 120,000 meters.

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Don't know where 15000 yds comes from. The longest range coast btys could reach 55 km, just a teeny bit further. Interestingly the Norwegians kept at least one of these btys in service throughout the Cold War. It's still there and open to visitors, so if anyone wants to know what real long range direct fire gunnery is about then it's the place to go.

 

And the Paris gun was not direct fire, is there no end to these remarkable displays of ignorance about direct fire gunnery?

 

I'm still puzzled why these whatevers at Ft Hood use the term calibration to mean something else (assuming they do of course). The US is usually quite good at sorting out consistant terminology, and the authors of FM 6-40 definitely know what calibration is, and this presumably means that TRADOC knows. So what's the problem here?

[jwduquette1]

Fire control system “calibration” for the Abrams includes:

 

Prepare to fire checks.

Muzzle boresight procedures.

Armament accuracy checks.

Special gunnery checks.

 

So there is no "problem" here that I can see. The context is long range accuracy issues associated with the US Army’s M865 training ammunition.

 

If you are still confused about US Army nomenclature there are a number of tank gunnery manuals written on the subject. You may wish to consult with this material.

 

Regards

JD

[DKTanker]

Don't know where 15000 yds comes from.  The longest range coast btys could reach 55 km, just a teeny bit further.  Interestingly the Norwegians kept at least one of these btys in service throughout the Cold War.  It's still there and open to visitors, so if anyone wants to know what real long range direct fire gunnery is about then it's the place to go.

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55,000 meter direct fire hitting first rounds? From what, a mountain top to another mountain?

[nigelfe]

Fire control system “calibration” for the Abrams includes:

 

Prepare to fire checks.

Muzzle boresight procedures.

Armament accuracy checks.

Special gunnery checks.

 

So there is no "problem" here that I can see.  The context is long range accuracy issues associated with the US Army’s M865 training ammunition.

 

If you are still confused about US Army nomenclature there are a number of tank gunnery manuals written on the subject.  You may wish to consult with this material.

 

Regards

JD

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There seems to be a problem to me because the armored branch are using a different definition to the field artillery branch. When you get two parts of an army using the same term to mean very different things then you most certainly have problem.

 

It's always been usual to site coast batteries on cliff tops, first it helps local defence, historically it probably made it more difficult for ships to shoot back, and from the late 19th C it enabled depression rangefinders. Of course coast guns don't need to see the ship's hull either, if then can detect and recognise the upperworks then they could probably get a range to the ship, but that might not be good for fall of shot observation!

[jwduquette1]

55,000 meter direct fire hitting first rounds?  From what, a mountain top to another mountain?

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Hey Dave:

 

I had to get some help with this one from Antonio Bonomi. A Naval historian guy who has done a lot of writing about the Battle of Denmark Straights. He indicated the longest naval gunfire shoot (using bullets and not missiles or the like), a shoot that actually hit something, was between the Battleships HMS Warspite and Italian BB Cesare. Range was 26400meters. The destroyers HMS Hareward and HMS Decoy were damaged in the exchange.

 

Course the other famous long range shoot was Scharnhorst hitting HMS Glorious at about 24175m.

 

Dogger Bank -- WWI -- the HMS Lion opened fire at an initial range of about 21000-yards on SMS Blucher (ass end of the German line). After a stern chase lasting several hours the grand total hit rate by the RN was less than 2% on all of the German BCs involved with the battle. Much of this hit rate was a function of the RN BCs close range snapping at the heels of the Blucher after she was crippled and dropped out of the main battle line. The infamous "engage the enemy rear more closely" signal by Beatty.

 

Dunno about a 55Km shoot -- at least not one done in anger that ended up hitting anything. Maybe it was David Niven in the "Guns of Naverone".

 

Regards

JD

[jwduquette1]

There seems to be a problem to me because the armored branch are using a different definition to the field artillery branch.  When you get two parts of an army using the same term to mean very different things then you most certainly have problem. 

 

It's always been usual to site coast batteries on cliff tops, first it helps local defence, historically it probably made it more difficult for ships to shoot back, and from the late 19th C it enabled depression rangefinders.  Of course coast guns don't need to see the ship's hull either, if then can detect and recognise the upperworks then they could probably get a range to the ship, but that might not be good for fall of shot observation!

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Calibrate is a pretty generic term. Websters gives the following:

 

1: to determine, rectify, or mark the graduations of (as a thermometer tube)

 

2: to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors

 

3: to adjust precisely for a particular function

 

To that end I personally calibrate my boxer shorts on a regular basis to keep blood flowing to critical areas.

 

I understand where you want to go with this, and sort of see your point about language and the possibility of confusion in using the same term to mean something different between differing branches of a service. But while I see your point -- it is pretty far removed from the intent of the thread. The language in FM17-12 is the language in FM17-12, and I don't see that “calibrate or calibration” is somehow being miss-used in the manual or by the author of the article I originally posted. The author of the article is therefore not "confused" about the terminology he is employing. He wrote the article for Armor Magazine with the intent that US Army Abrams tankers might read it. The target audience would therefore be "confused" if the author decided to employ language appropriate to FM6-40 "Artillery Gunnery" rather than "FM17-12 Tank Gunnery". Whether you like or dislike the way the manual employs “calibrate or calibration” is sort of beside the point. It is what it is.

 

Regards

JD

Edited June 28, 2006 by jwduquette1

[nigelfe]

Calibrate is a pretty generic term. Websters gives the following:

 

1: to determine, rectify, or mark the graduations of (as a thermometer tube)

 

2: to standardize (as a measuring instrument) by determining the deviation from a standard so as to ascertain the proper correction factors

 

3:  to adjust precisely for a particular function

 

To that end I personally calibrate my boxer shorts on a regular basis to keep blood flowing to critical areas.

 

I understand where you want to go with this, and sort of see your point about language and the possibility of confusion in using the same term to mean something different between differing branches of a service.  But while I see your point -- it is pretty far removed from the intent of the thread.  The language in FM17-12 is the language in FM17-12, and I don't see that “calibrate or calibration” is somehow being miss-used in the manual or by the author of the article I originally posted.  The author of the article is therefore not "confused" about the terminology he is employing.  He wrote the article for Armor Magazine with the intent that US Army Abrams tankers might read it.  The target audience would therefore be "confused" if the author decided to employ language appropriate to FM6-40 "Artillery Gunnery" rather than "FM17-12 Tank Gunnery".  Whether you like or dislike the way the manual employs “calibrate or calibration” is sort of beside the point.  It is what it is.         

 

Regards

JD

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Personally, I 'adjust' mine.

 

I'd love to be a fly on the wall if armor and artillery ever get around to discussing calibration. The confusion would be wonderous to behold.

[DKTanker]

Personally, I 'adjust' mine.

 

I'd love to be a fly on the wall if armor and artillery ever get around to discussing calibration.  The confusion would be wonderous to behold.

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But why would they? By the same token I reckon...and this is in the same branch of artillery. Calibration means something entirely different to the gun chief as is it does with the guy operating the counter-battery radar. It would be like a tanker discussing zeroing of the maingun with a grunt who's only experience is with zeroing his M16. What's a boresight knob, what's a CCF? You put what in the muzzle of your gun....what's the matter with your gun, got the clap?

 

Speaking of which, how often do cannon cockers boresight.....hmmm? That's right, they don't. .

Edited June 29, 2006 by DKTanker

[jwduquette1]

Personally, I 'adjust' mine.

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You adjust rather than calibrate? Now I'm really confused

[jwduquette1]

Dave:

 

I figure you are probably tired of answering these sorts of questions – but if you’ll indulge me once more about your description of sight zeroing right before the start of Desert Storm. You indicated your battalion had been allotted three or four rounds per tank of M829 to zero. Did you zero both your GPS and GAS using this same shot pattern?

 

Thanks again.

Regards

JD

[DKTanker]

Dave:

 

I figure you are probably tired of answering these sorts of questions – but if you’ll indulge me once more about your description of sight zeroing right before the start of Desert Storm.  You indicated your battalion had been allotted three or four rounds per tank of M829 to zero.  Did you zero both your GPS and GAS using this same shot pattern?

 

Thanks again.

Regards

JD

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In my battalion the consensus was to use the established fleet boresight correction factor, that's what I passed along to the tank crews and what I myself did. The reason is that there are too many variables involved with using the GPS that cannot be transfered to the GAS with consistent confidence. It's one thing to quickly put digital information, such as ammo temp and air temp, into the computer control panel, its quite another to constantly change the GAS boresight knobs. Moreover, if the crew consistently puts in the book correction factor, if and when required to change to HEAT, they merely need to turn their knobs to the HEAT correction.

[Ken Estes]

Don't know where 15000 yds comes from.  The longest range coast btys could reach 55 km, just a teeny bit further.  Interestingly the Norwegians kept at least one of these btys in service throughout the Cold War.  It's still there and open to visitors, so if anyone wants to know what real long range direct fire gunnery is about then it's the place to go.

 

....

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A CD gun [presumably German WWII?] in Norw service shooting 55,000m?? I cannot see what it would be, even the Kriegsmarine 380mm would not have that range. Moreover, it is no news for the US Army, operating their six magnificent M1919 Mk I 16"/50 in service since 1923 [Pearl H, NY, Boston], with a range of 60,000 yds.

 

In any case, these guns are only effective beyond 20K with radar control. What you are saying is 'direct fire' is in fact 'director control' fire, using observation, rangtaking and direction stations remote from and higher than the gun positions. Direct fire would be using gunsights on the weapons themselves, provided only for emergency use and not effective very much beyond 12K.

 

[edit to add]Calculating the height one would have to have one's director to fire observed shots to a horizon 55K distant...I get 200m above sea level??

Edited June 29, 2006 by Ken Estes

[jwduquette1]

A CD gun [presumably German WWII?] in Norw service shooting 55,000m?? I cannot see what it would be, even the Kriegsmarine 380mm would not have that range. Moreover, it is no news for the US Army, operating their six magnificent M1919 Mk I  16"/50 in service since 1923 [Pearl H, NY, Boston], with a range of 60,000 yds.

 

In any case, these guns are only effective beyond 20K with radar control. What you are saying is 'direct fire' is in fact 'director control' fire, using observation, rangtaking and direction stations remote from and higher than the gun positions. Direct fire would be using gunsights on the weapons themselves, provided only for emergency use and not effective very much beyond 12K.

 

[edit to add]Calculating the height one would have to have one's director to fire observed shots to a horizon 55K distant...I get 200m above sea level??

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The long range naval shoots I posted earlier would also have been director controlled shoots rather than local control -- i.e. dudes up on the top of tripod masts or the like, well above the turrets were directing the fires. Not technically direct fire I suppose – perhaps semi-indirect would be a more applicable term. Except in the last case when I think HMS Lion was employing both director controlled shoots and local controlled shoots at Dogger Bank. I think Beatty's thoughts were that the highest rates of fire were only possible with local control -- rapid independent. However, he also recognized that the initial ranging salvos up to the point where straddling occurred would have to be director controlled. But than Beatty and his BCs are rarely complimented on their gunnery skills. Perhaps his thoughts on this subject are flawed.

 

I understand the New Jersey blasted away at a Japanese Destroyer at the unheard of range of about 40,000-yards. A Radar directed shoot. However they didn’t hit anything.

[jwduquette1]

In my battalion the consensus was to use the established fleet boresight correction factor, that's what I passed along to the tank crews and what I myself did.  The reason is that there are too many variables involved with using the GPS that cannot be transfered to the GAS with consistent confidence.  It's one thing to quickly put digital information, such as ammo temp and air temp,  into the computer control panel, its quite another to constantly change the GAS boresight knobs.  Moreover, if the crew consistently puts in the book correction factor, if and when required to change to HEAT, they merely need to turn their knobs to the HEAT correction.

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Thanks Dave.

[Ken Estes]

Love to go OT on naval and CD gunnery, my early interests, Jeff. The fighting tops [tripod, cage mast mounted] contained spotting stations, but the director was too large and cumbersome [later became almost a turret in its own right] to be up there, usually placed uppermost on the forward superstructure [crowning the conning tower armored structure in modern ships], and later a secondary one [still for main armament] placed in the after structure. Secondary & AA batteries could have their own directors, placed at less advantageous heights and positions as designs permitted.

 

Naval gunnery, even direct fire [battery local control], remained shot, spot, shot, spot in order to gain straddles. I had my tankers man a twin 3"/50 mount to fire local surface competition with the other 5 mounts of USS Hermitage (LSD), using a goldplated gun crew with 2 of my TCs as gunner, a-gunner, my GySgt as mount captain. We used BOT [with their iron-ring AA sights] and knocked the navy dicks in the dirt, so to speak, at 2-3000 yds. Ken

 

[edit to add: NJ [and others?] did sink an IJN DD at very long range with radar as they finally arrived at San Bernadino Strait in TF34, too late for the Sama Battle at Leyte Gulf '44. I think they sank Nowake?]

Edited June 30, 2006 by Ken Estes

[nigelfe]

But why would they?  By the same token I reckon...and this is in the same branch of artillery.  Calibration means something entirely different to the gun chief as is it does with the guy operating the counter-battery radar.  It would be like a tanker discussing zeroing of the maingun with a grunt who's only experience is with zeroing his M16.  What's a boresight knob, what's a CCF?  You put what in the muzzle of your gun....what's the matter with your gun, got the clap?

 

Speaking of which, how often do cannon cockers boresight.....hmmm?  That's right, they don't.  .

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Without exploring US terminology I can safely say that radars don't do 'calibration', they do 'tests and adjustments', usually called 'Ts & As'.

 

Indirect fire artillery doesn't 'boresight' either (again without exploring US terminology), I'd guess the equivalent is a 'quick sight test', which is done at least daily and before firing a fireplan. Full sight test is done about weekly or if the quick sight test reveals a problem. Of course in the days when field branch artillery operated anit-tank guns they 'zeroed'.

 

These days calibration is a continous process, at least in those armies that have the sense to fit a MV radar to every gun. This has several advantages, most notably it solves some of the problem of the unattributable variables, ie occassion to occassion (or day to day if that's your terminology). Also picks up attributuable variables such as the change in barrel temperature and any others that aren't a round to round variable.

[nigelfe]

A CD gun [presumably German WWII?] in Norw service shooting 55,000m?? I cannot see what it would be, even the Kriegsmarine 380mm would not have that range. Moreover, it is no news for the US Army, operating their six magnificent M1919 Mk I  16"/50 in service since 1923 [Pearl H, NY, Boston], with a range of 60,000 yds.

 

In any case, these guns are only effective beyond 20K with radar control. What you are saying is 'direct fire' is in fact 'director control' fire, using observation, rangtaking and direction stations remote from and higher than the gun positions. Direct fire would be using gunsights on the weapons themselves, provided only for emergency use and not effective very much beyond 12K.

 

[edit to add]Calculating the height one would have to have one's director to fire observed shots to a horizon 55K distant...I get 200m above sea level??

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The Trondenes battery (4 guns) is on a small island near the small port of Harstad north of the arctic circle. The guns are 40.6 cm, there was at least one other battery (3 guns) of these guns in Norway at Engelsoy near Narvik.

 

Basic data for these guns is: std shell 2300 lbs, MV 2657 f/s, max rg 47600 yds, Adolf shell 1322 lbs, MV 3449 f/s, max rg 61000 yds.

 

Hogg states that these guns were designed for the H class bttleships, which were never built. He also states max rg as 56000m/61241 yds.

 

Hogg also states 6that the 38 cm gun developped for Bismarck and Tirpitz and also used in cast batteruies had a max range of 55700m/60914 yds with the long range shell and 42000m/45931 yds with the standard shell.

 

However, it can be argued that these guns weren't true direct fire becasue these were given firing data electrically from a command post. However, their associated optical range finder was good for 100 km!

[Guest bojan]

One note - don't know if actualy usefull but here it is:

In Yugoslav service modernised 88mm M18/36/37 coastal guns (Yes, that is WW2 German 88mm flak) in the mid-80s (included SNAR-10 radar and LRF with balistic computer) would regulary acheave 1st round hit with salvo fire (eg 6 guns from same battery would fire) at 7-8km. Target was 2 x 10m panel towed behind a boat at 15-20km/h.

Note that in salvo fire "first round hit" is considered on the battery level - so if only one gun out of six hit it would still be considered "first round hit".

 

For the individual guns firing to "pass" your crew had to do at least 50% with 10 rounds. Most crews did about 6-7 with some getting to 9-10.

 

Unfortunetly I don;t have a data for the gns w/o balistic computers/LRFs/radars to compare.

Edited June 30, 2006 by bojan

[Ken Estes]

The Trondenes battery (4 guns) is on a small island near the small port of Harstad north of the arctic circle.  The guns are 40.6 cm, there was at least one other battery (3 guns) of these guns in Norway at Engelsoy near Narvik.

 

....

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Great note! I had forgotten about those guns, many thanks! Ken