Tanks 103: Rangefinding 

The shrubbery monologue had me laughing so much I had to rewind to catch up on what you said of import.

Drachnifel has a great video about naval rangefinding. They're a little deprecated nowadays because Radar, but the principles on optical rangefinders during the Battleship era are still the same.

1) When I was at the Basic Course in late 74-early 75 we were familiarized with the Stereoscopic Range Finder as some unfortunate, low priority Guard units were still operating M48A2's (The Coincidence Rangefinder came in with M48A2C - no prizes for figuring out what "C" stood for). I'm one of those unfortunates whose brain circuitry is incompatible with that device. Try as hard as I could, I couldn't do it. My instructor finally took mercy on me and told me to take a seat and relax, "It's OK, eltee, you'll never see one of these things" And I never did. 2) There is also non-precision or battlesight gunnery. You know the type of ammunition you are using and also know the average height of the target you expect to engage. You look up in the firing tables the range at which the maximum ordinate (height above ground) of a fired round equals the height of the target. You load one of these rounds and index the fire control computer to that range. If you see a target, the fire command is "Gunner, Battlesight, Tank". He lays the cross hairs of his sight on the base of the target and fires. This means the round never exceeds the height of the target nor will fall short. It must hit the target as long as it is at the indexed range or closer. IIRC, our battlesight for 105mm APDS was 1000 meters and our SOP was to always operate with the battlesight set as it was much quicker than using the rangefinder, allowing you to get that vital first round off first. You reverted to precision gunnery if the target was beyond 1000 meters and the second and subsequent rounds

Loved the Monty Python knights who say Ni reference :)

Oh lord I remember teaching the Direct support class on Laser theory to new M-1 tech at 7th ATC, Vilseck Germany when General Dynamic's/Chrysler was still fielding. The M-1 series uses a Neodymium Yttrium Aluminum Garnet type laser mounted to the gunner primary sight for ranging. The laser would take normal 24-volt power and through a series of step-up transformers produce an 8000 volt PFN (pulse forming network) charge and store it inside a capacitor. When the Gunner, or Commander pressed their ranging button. The laser would discharge the capacitor, and the energy would excite the garnet and produce a beam that would bounce back and forth between two retroflector mirrors until sufficient light energy was produced to cause a milky clouded exit lens to flash clear, releasing the beam. The beam would exit the gunners primary head mirror, (with eye-safe laser coating) passing by an optical sensor which tripped a timer to start. This timer was calibrated in nanoseconds. A nanosecond (ns) is an SI unit of time equal to one billionth of a second, that is, ​1⁄1 000 000 000 of a second, or 10−9 seconds. The M-1 series laser range finder, takes that formula and calculates the time it takes a beam of light to travel 1-meter. The M-1's ballistic computer uses this to determine super elevation angle to target. Gun lead angle is based on rate of slew (traverse) rate at that given range while tracking the target. The timer would continue to count until the First, or Last return beam (which ever was selected before hand) came back to the head mirror stopping the clock. The computer would then take number of nanoseconds counted and divide the total time in-half to achieve a distance to target. I've simplified this because as I remember the class on this subject was over 3-hours long and left many a new 45-Golf Fire-Control specialists head smoking. Edit: for Boo boo's. (sigh) what can I say, I'm old and my memory is utter rubbish sometimes. ^_^

The "SWAG" made me spit up my drink a little. I love it.

But Chieftan - Why do you need to find the Range when you can just Drive closer, in order to hit them with your Sword?

Worm formula is W=R/1000 and 1000 is represented by letter "M" in roman numerals by that way it becomes W=R/M aka "WorM"...

You could do a video on those "official" acronyms alone.

21:29 Have you and your tank crew ever played "Oh bugger, the tank is lava"?

My Dad was a M48 gunner and he often talks about the "flying the geese" sight. He talks about it proudly because I assume it takes a certain cunning individual to master it and apparently he did. "The second shot always hit the target." He turned 85 recently and I love talking to him about it.

Fun fact: 120mm APFSDS goes about a mile a second, so at battlesight distance of 1200m, the guy on the other end doesn't even have time to say "Oh ****"

First seven years as a crew commander were on the Cougar (Scorpian turret on a Canadian AVGP) - pretty much all estimated range unless we a hand-held laser range finder. Going to Laser with IFCS on Leopards was a dream after that!

I started on the M-60A3 and the laser was nice - fast, accurate and etc. Got back stateside and an M-60A1 RISE. Back to the coincident rangefinder. Range? Nope. Battlesight Sabot instead.

As a Gunner always start with 1200m for a snap shot . Battle sight . When looking though the sight after a time you can tell basically what the range is . 1200 sight picture shot at the top on the tank or a little above target close in shot low on the target -- no idea Laser 😎

Nice Monty Python reference, I see what you did there. As a career infantryman, I know all about range cards, and EIB still requires soldiers to figure out range finding with mils and math, in order to call for fire, which is probably my most hated method of doing so. Mostly because my math sucks, and I'm slow with it.

the 1mill = 1meter at 1000meters is pretty good, because of the small angle approximation, but it will break down once you get past about 200 mills, and quickly grow worse past 400, which I presume is a laughably large number for military uses anyway.

If you think "The floor is lava" is silly childstuff how else should one train for later "The tank is on fire"?

About range cards, a bit of trivia about the Maginot line. (Btw, the ouvrages (forts) of the Maginot line were treated as immobile battleships and their troops were referred to as crews). The guns were of course ranged up to the German border, but the machine guns went one step further: they had cams mounted on them so that when fully depressed they would just graze the glacis. No need to aim, just press the trigger: hard-coded range cards.

8:45 True. Accuracy, and precision are not the same thing. 1. Accuracy is defined as most/all of your shots landing inside the target. 2. Precision is defined as the grouping of your shots. So, if the grouping of your shots is very tight, then your a very precise shooter. If that isn't the case, then you obviously aren't precise. So...what's the difference between the two? For example, you can be the most precise shooter in the world, but it won't matter if all your shots don't land within the target (meaning that you have crap accuracy). On the other hand, you can be the most accurate shooter (all your shots land inside the target). But, the grouping of your shots is all over the place (meaning your precision is terrible) This has been your friendly PSA (public service announcement) for the week. Have a nice day :P

Thumbs up for the shrubbery reference! Ni. 👍

I had to stop the video because I was laughing so hard when you mentioned TLAR. For some old fart history, in the mid '70s I read a book called "God is my copilot" about a pilot in the AVG in China talking about using the rudimentary sights on the P40 to attack grounds targets. He called it TLAR, and I took that as my mantra for the rest of my life. As a soldier in the 1980's and 90's when I used it nobody knew what it meant, which told me that the army had lost one of its better acronyms. Mr Moran using it tells me that the army has reclaimed it from the ash heap of history, and in my opinion it ranks up there with SNAFU. Remember, no matter how many computers are involved, no matter how many graphs or mathematical problems are solved, there is still that man on the ground thinking, "Yeah, That Looks About Right"

So, is there a suitably army term for booting the littlest fellow out of the tank to go run up to the enemy with a tape measure? CREw DEployed Tape Cannister Analog Range and Distance, maybe? CREDETCARD? Wait, that might get confusing...

This is not just for tank rifles. Two things that the Army sniper is/was taught were most important being target discrimination and range estimation. The M24 shoots itself. As long as you know your holds and can estimate range, you are all ok jump master.

My father was an old WW2 tanker. His philosophy was over, under, and on target. He said all that electronics targeting system will fail on the battlefield after a short period of time.

Precision rifle shooter community commonly use mils with either meters or yards. A mil is simply 1/1000 of something. It can be 1 meter at 1000 meters. Or 1 yard at 1000yds. They function exactly the same. So if a mil is 1 yard at 1000yds. Its 36" at 1000yds. Move the decimal place over for both 36" and 1000 yards. That would tell you a mil is 3.6" at 100yds! So very easily you can see the angular unit of measure. 3.6 at 100 and 36 at 1000. It grows perportionally over distance. The issue most people have is they focus on that definition of what a mil is. And they do not focus more on its actual useage. The usage is simply....your 1 mil low. Dial or hold 1 mil higher and you hit. The angular unit of measures works across all ranges. It does not care that you call that target 200 meters or 219 yards away. It only cares that you need 0.5 mils to hit for the given trajectory.

the monty python reference had me laughing good.

Excellent video. Would however suggest reading the late (CSM) Dick E.Morgan's books on this. He had some excellent insights to the challenges of training Tankers and some wayward scouts. ALLONS!

During the Polish campaign, Germans had some issues with rangefinding. They tried to estimate from the distance between Poles. Ehhehe. Interestingly, an old SLR camera I have seems to use a "coincidence"-like system for the manual focus. Which makes sense, focus is range to target. A smallish circle in the center of the eyepiece, where the image is split into two, and then one adjusts the focus, until they join up.

Like the video, looking forward to the Soviet doctrine video. Enjoyed the previous armored doctrine. Darn beer microbe is delaying the opening of the National Museum of Military Vehicles in Dubois, WY.

The TLAR method. The Army manages to make "im just taking a wild guess" sound all smart and tactical

Nicholas Moran has swag... And he's also a Knight who says *Ni* ! A wild guess on range is really difficult when there's a depression or valley between you and your target. If you're near the top of a hill, and your target is also near the top of a hill on the opposite side of say a pasture with a creek in the middle of it, it usually looks closer than it is because of an optical illusion.

Thank you sir that was very interesting and cleared up some misconceptions on my side

As soon as I saw that range card I had flashbacks to painstakingly drawing out these little bastards only for someone higher up the chain to decide they didn't want to set up there after all.

Gravity is a constant, but the speed an object falls at increases by the square, that is it doubles and doubles again, until terminal velocity is reached. That is at least as much the reason why a parabola is shaped the way it is as the object slowing down due to drag.

16:12. The image on the top left is an example of a stadiametric rangefinder, as the distance between the mast and the water line is used as the base of the triangle.

A very good example of range markers is in the last battle scene in the movie 'kingdom of heaven' . Great movie, very historically accurate pertaining to battle maneuvers and tactics and equipment and such. But in the last scene you see they painted large rocks with white paint on the side facing the defenders. As the invading forces march closer they fire their pre ranged trebuchet or catapults whatever they would be considered right as they're passing the different range markers.

1600 meter APDS battlesight used to be a US Army thing until about 1981. BOT tank gunnery was the primary method of adjusting gun fire until the M60A3 was introduced.

The biggest disadvantage of radar range finding must be that it actively radiates. And radiation can be detected and a bearing where it came from. So if the radar pulse comes from the tank it might give at least its bearing away.

Please do a series on all the different types of tank suspension systems and the benefits & detriments of each I.e. Christie, torsion bar, HVSS etc.

The British Centurion tank crews circumvented somewhat the problem by applying the Battle range technique, taught at the RAC Gunnery wing during the 1950-s. By the command ´Sabot action´, the gunner aimed at 800 yards, and fired. Without waiting for any corrections, gunner upped the sight to 1000 yards and fired again. If no hit, he went down to 600 yards and fired again. Ref. Vanguards ´the Centurion tank in battle´by Simon Dunstan pp 15-16.

Varmint hunters will be very familiar with most of the various schemes to either determine range or "make do". I have personally employed MPBR and TLAR, but didn't know the formal names.

great video

Re: Radar.... also many interesting problems involving radiation injury to crew, especially if the emitter is in a big metal box along with the crew!

So that's why those knights wanted a shrubbery....

One method of verifying which return of the laser rangefinder to use to hit the target that would work at night, if you do not mind emitting bright flashes of strobe light from the tank, is to borrow a method used to identify ships off of the coast, at night, by maritime vessel traffic monitoring services. Hypothetically, the ideal system could build up an image from reflected pulses of the ranging laser, but that is not possible when you want to image a ship with optical wavelengths and your ranging is accomplished with 20 cm wavelength radar. A low light camera with an electronically controlled high speed shutter is set to open its shutter, briefly, as light from the flash is predicted to return from the target. If the return used to set the range actually came from the target, the target will be imaged by the camera.

When lazing troops it Usually smart to laze the ground at there feat, because a single infantry man is vary compared to almost any type of vehicle and you will almost get a range from something else if you try to laze the torso.

Could you possibly do a inside the chieftains hatch video on the T-26 light tank. Me and the boys here in Canada just graduated from high school and we were in the middle of building a full scale T-26. But because of the pandemic we had to stop. But we are continuing the work from home with the tools we have and it would be awesome if you could do a video on the t-26 for further research and to get dimensions correct witch is a big thing for us. We don't want are build to look weird and out of place. Thank you if you even read this have a good day

The standard mode of operation of the optical rangefinder of the Leopard I was stereoscopic, coincidence was normally not used.

Addition why the height is less often used for ranging: the visible height changes with angle. ->When the target is uphill or downhill form your position the perceived height is less than the actual height, while width stays the same. (maybe less of an issue in tank warfare).

So it all works perfectly, except when it doesn't......

I was once a master of the coincidence rangefinder. Thank GOD for lasers.

Up vote for Holy Grail reference!

trigonometry really needs more coverage in all institutions. I'm working on a minor in math for an engineering degree and i was only required to take 1 pure trigonometry class. Granted, this class covered all known trigonometric principles I'm aware of but i wouldve appreciated more applied trigonometry for navigation and more amplitude/frequency coverage for electronic work. and alot less permutations of trigonometric definitions. those damned trigonometric definitions have only helped me prepare for more pure academic math classes. that's interesting and all but their applied purposes seem increasingly dubious to me as i start doing more applied engineering.

Good video, Allons!

8:00 Well actually, there are acoustic sensors that are tank-compatible (it's just that they haven't been commonly mounted on vehicles). There's the "Boomerang" (there's a man portable wearable version of it too, I think), and the "Individual Gunshot Detector" (from QinetiQ). They both use acoustic sensors to detect the enemy. They are fairly accurate enough in discerning the location of the target. However, the disadvantages with these types of acoustic detectors is that you have to get shot by the enemy in order for the sensor to detect them (at which point, it may be already too late. RIP). And secondly, they have relatively poor range. They typically only have a range of around 300-500 meters (maybe greater?). Or around few-couple of hundred meters. In contrast, the electroptics (namely thermal imagers) on tanks can comfortably detect targets from 1-2 km, and greater (generally within the range of many kilometers away).

I love the ol' frogface M48

Do you think that we will re-emphasize non laser range finding due to the increase use of laser detectors?

Apparently K2 from Korea use combination of some form of radar and laser.

M26 90mm is a slightly less powerful gun than the M48's 90mm. The 90mm round for the 48 won't fit the chamber of the M26, but the M26 round will fit the chamber of the M48, and push the shoulder a bit forward fireforming it to the chamber, if I'm not mistaken.

Great video! From which manual is the figure 10-1 at 10:40

Does todays Army still use maps. That's a good way to estimate range for a range card using terrain features and buildings. Better then driving out in a jeep.

Any chance that WoT introduce a better range finder?

FM 17-12. Oh yes. I both loved and hated that FM.

NOBODY EXPECTS A MONTY PYTHON REFERENCE.

Oh, when is Soviet tank doctrine is coming out?

Tlar. Awesome.

Why do some tanks have turret offset to one side? specifically Chi To and other Japanese tanks of the like

Very interesting video and excellently timed as I've been wondering about this concept recently! I have two questions that I was hoping would be addressed; 1) What was the planned rangefinding method for use in the German schmalturm? 2) Is the use of a stereoscopic or coincidence rangefinder part of the commander's job as hand-off of a target, or the gunner's job as laying on target? Does this change per vehicle (my immediate thought is the T29E3 and how far to the rear the rangefinder was mounted, presumably some way behind the gunner but immediately in front of the commander's cupola).

6:20 a path! a path!

They tried to teach us the Boer method of rangefinding, but I have my doubts about how well it worked.

Nice to see some SABOW shots used for the M60's rangefinder. What do you think about that game? I've always really enjoyed it as a holistic tank simulator- SBPro may do specific aspects better, but SABOW has stuff like crew morale and what I assume is an accurate portrayal of how fucking hard it is to see anything under armor.

Can you make a short video about setting fuzes and their history?

Does this present a problem - or at least a disadvantage - for UK tanks firing slower HESH ammo, should the laser range finder go down?

Width OveR Mils WORM maybe?

Can you link a source on the "flicker range finders" (or just name one of the models) - the 3rd type you mentioned? I'm having little luck googling for it and while the mechanics of the other types are all fairly self-explanatory the flicker type sounds like it'd have a much more novel mechanism driving it that I'd be interested in learning about. Thanks.

If your looking for subjects how about side arms for tankers? Maybe get with Ivan over at forgotten weapons.

800 meters was battlesight for M551.

You'll be sitting you your house for another yr. I hope you have a lot of models to build

you must be using a colllomating lens or the divergence due range and atmospheric conditions would make the laser inefficient thanks for making the vid

Just a thought: has there been any research, that you're aware of, into stereoscopic or coincidence laser range finders? Seems to me, if you have lasers of different frequencies, you might be able to get more accurate range and not have bleed over into the detector of the laser. Then again, the base line might not be wide enough.

Width over Range (in Thousands) equals meters.

I have a question for you that has its origins in what i remember from school back in the late 1970's. They stated that the Sherman started to get bad press from the large casualties suffered in the hedgerows of France. My question is who'd any other thank produced prior to 1950 have been significantly better or is it that the terrain so favored the defenders that the casualties were inevitable ?? I hope that this question is interesting enough for you to consider.

Would be nice to have Drachinifel talking about pre-radar naval range finders. So, with some of these earlier systems, you could have a half scale recon version of a standard tank and really confuse the people trying to shoot at you. I think I've suggested this before, but since you are now forced to cover non-vehicular topics, I would like to ask again for a thorough discussion of WW2 Anti Tank Guns. Compare and contrast all the different 76mm guns, the Soviet 85mm, the German 75 and 88mm, and the USA 90mm. How do these weapons and munitions compare? Or looked at another way, When did the German's need something better than their long 75mm? If German heavy tanks were coming your way, would you want a USA 76mm or a British 16 pounder? Or would the Soviet 85mm have been even better. And finally, was it the gun or the ammunition? Based on Tik's coverage of the Battle of Stalingrad, Soviet Armored Doctrine (at that time) was identical to USN torpedo bomber doctrine at the time of Midway.

Laze and blaze

The Chieftain must have a pair of tillers in his pants if Soviet tank doctrine is driving his nuts.

Did anybody try using the focal distance of the optic for range finding? Edit corrected punctuation.

Nothing about Ranging Machine Guns, or British Battle Range techniques? Both were the basic reason for widespread adaptation of L7 105 gun.

When are you coming to latrun it has tanks from every genartion

As a gunner on an M60A2, we had the computer set to 1000 meters, and HEAT as the battlesight ammo. If (when ) the laser RF worked, we would use that. And in one instance my main sight failed, so I used the choke sight in the telescope. If a target was obviously distant, we could switch to the missile. BTW, is that a shillelagh missile to your left?

I'd no idea lasers scattered that much at range. I knew there was dispersion but not enough for a tank and a building to compete with each other.

Well after the various Range finding tutorials for naval vessels how hard would a tank be, distances are much shorter the earth doesn't move you in various directions like the sea would,

Once Rail Guns for tanks are developed, range finding will be at mute point. Put dot on target and fire.

We could give them a shrubbery?

Width Over Range = Mils

Eh, just use a small dart round from, say, a 75mm gun, at a massive velocity. Such as, say, 10,000 to 15000 FPS. Flat trajectory, and a devastating hit. And for anti infantry, you can have a HEAT Missiles fired off the roof, combined with a Remote Weapons System, and problem solved. A Mk 19 Grenade launcher in the RAS could also be valuable in clearing shallow mine fields.

NOW a discussion of Point blank range. from Jeep to Tank to ships. Then Maybe, Why there is/should be a MIN range.. lets consider WOT and WOWS, and why the armour on ships seems abit THIN., and warheads abit WEAK.

Does laser rangefinder basically real life auto aim

The best way to range find is to use your standard issue E4-and-Below. 😂

Monty Python reference?