Comments for Somewhat belatedly answering some questions

Somewhat belatedly answering some questions

2009-07-20T18:55:14Z

Reader Beach Bum Bill (not BillT and hereinafter B3) sent me a list of questions in response to this video I posted, showing a Canadian gun crew servicing their M777 in Afghanistan. B3 asks interesting questions – ones we take a few months to answer in detail in the various schools gunners attend to learn their trade. I decided if B3 is asking these questions, others of you might be wondering, too – so I decided to make it a weekend post.

I’ll intersperse the answers among B3’s

John,
I just looked at the Red Leg vid that you've posted and I've a bunch of questions as I know literally nothing about howitzers and big guns... * How do you designate targets? Crosshairs, map coordinates, GPS ??? Which generates another question: Are the trajectory calcs all done in a computer or do the crews have to do it manually?

The answer to this series depends on several factors and varies from country to country, and era to era. How Lieutenant Donovan did it in 1980 varies from how Lieutenant Donovan would do it today.
When firing direct, the gunner lays the reticle of the direct fire telescope on the target.

When firing indirect, i.e., at targets the gun crew cannot see, the crew gets a series of commands. First is what type of shell, what type of fuze, and what charge (also known as zone). That tells them what they’re going to shoot and how much propellant they will use. Then they get a fuze setting (if appropriate) to set on the fuze; a deflection, which is the direction to aim the tube; and a quadrant elevation, which is how high to point the tube. There are other commands they will receive, which includes how many rounds to shoot, whether or not they will be adjusting or firing for effect, and whether they will shoot when ready or on command. This gives the crew the data they need to send the projectile on it’s way. That data will either come to them displayed on the Gun Display Unit (GDU), or via telephone, or even shouted out across the battery position. The GDU is the preferred method. This data is also recorded on a form at the gun by the gun chief.

That data comes from the Fire Direction Center, where 99% of the time it has been calculated by computer, though we do have manual means for computing that data. Whether done by computer or manually, the data takes the target location and the gun location, and calculates basic trajectory data based upon what are termed “standard conditions” for the projectile type, weight, type of trajectory desired or required (low angle or high angle) and environmental conditions of altitude, temperature, humidity, and wind direction and standard muzzle velocity.

Then you apply factors that account for all the differences (which are legion). The projectile data is modified by a correction factor if the weight deviates from the standard. The muzzle velocity is modified by continual measurement of actual muzzle velocity for the gun in question, and a factor applied to account for the variation which accounts for wear of the tube. The same is true for altitude differences between the gun and the target, the effects of weather, the effect of temperature on the propellant (colder than standard propellant doesn’t burn as fast – so you lose muzzle velocity), and for long range shooting they’ll account for the spin of the earth, and even crossing the equator or shooting in the polar regions. It all sounds complicated, and it is, but we’ve got pretty refined methods for simplifying the data and the processes. That process generates the data that ends up at the gun.

* Does the gun crew turn dials or push buttons to aim? I ask because as a kid I got to sit in/on a gun on the USS New Jersey and that gun had handwheels to aim it.

Towed guns use handwheels to traverse and elevate. Towed guns require the crew to actually lift the trails (the legs behind the gun) to make large shifts in deflection if they're going to do so quickly. Self-propelled guns use hydraulics with a manual backup, and use a joystick-like handle to control the movement of the turret and gun. The Gunner sets the quadrant elevation on his sight and then cranks the tube until his bubble is level. When firing multiple rounds, he keeps an eye on his bubble to ensure the tube isn’t moving, and levels as needed. The Assistant Gunner sets the deflection on his panoramic telescope and then sights through the pantel and moves the gun left or right until his aiming reference point (another class in and of itself) aligns in his sight. The tube is then pointed where the FDC has determined. How and when all this happens depends on the elevation of the tube – if you are firing multiple rounds at high angles, you might have to bring the gun back down to “loading elevation” so the crew can load the piece. You might not.

Actually, that description above dates me and marks me as an old self-propelled artilleryman. In many, if not most, current towed gun systems, the elevation and deflection are set from a sight mount that combines both functions and are handled by one crewman. Only the direct fire telescope is separate. On guns like the Paladin, the gun is laid on target via computer, with the human crew there to spot-check and as a back-up.

* Is there a rule/reg that you have to have the target in sight? Meaning can you shoot over a hill where you cannot directly see the target?

The full answer to your question is really driven by the rules of engagement, the famous ROE. As far as the crew is concerned, for indirect fire, they never see the target. In fact, gun crews are pleased to never, ever, see the target in combat. Because that means the target can see you. The ROE usually requires that *someone* or *something* (a sensor of some type) or whoever is calling for the fires, have eyes on the target, for all the same reasons we do in direct fire engagements, so that you know what you are shooting at. In the “Big War” scenario, that may not be true, you may be shooting a series of pre-planned targets according to a schedule or plan, but in today’s environment, there are eyes of some sort on the target area. Just not the gun crew’s. There are always exceptions, but that’s the general rule.

* I imagine that you have to work with aircraft in the area so that they don't get hit by rounds going up or coming down and how does this impact joint ops? I'm thinking of a/c strafing afterwards.

We have a whole set of procedures set up to “deconflict” airspace – most often by not allowing indirect to be fired while aircraft are present and vice versa. We have a raft of graphical and time control measures designed to ensure that airplanes and projectiles don’t share the same space at the same time. It’s a little easier to do in today’s fighting vice the “big war” scenario, but everybody gets nervous and pays attention when airplanes are around, even unmanned ones. No point in shooting down your own UAVs. Pilots, for some reason, do not ascribe to the Redleg credo of "Big Sky, Little Bullet." Apparently, in the air, everything is magnified in size...

* In the vid, two of the crew carry a round up to the gun and turn away for a second pointing the nose of the round to another crew member before loading it. What are they doing?

The gun chief is personally responsible for every round that departs his position. The gun dogs are showing him the round and fuze so that he can personally verify that it is the correct round and correct fuze. Just as the powder monkey was holding up the zone charge so that the chief could verify that it was correct. He’s also going to verify the initial sight picture and that the bubbles are level on the sights – and keep an eye on them as a mission progresses.

* This last question is kind of stupid (please excuse) what is the proper term: Cannon, Gun or Howitzer? I know enough that my AR-15 is not a gun but a weapon.

A cannon is a generic term for anything bigger than a rifle, really. The tube of a mortar or the gun on a tank are properly referred to as cannons. In artillery parlance, a “gun” is a long-tubed, high velocity, flat trajectory weapon, whereas a “howitzer” is (generally) a shorter-tubed, lower velocity, arced-trajectory weapon. Guns were used to get long ranges, howitzers were used to get behind hills and walls and such – as well has they used to be cheaper. With the advent of the 50+ caliber tubes, we’re starting to blur the distinctions as we’re really building cannon that can do both jobs. Caliber is a term that can cause confusion, too. In small arms, caliber generally means bore diameter, as in .22 caliber or .50 caliber. In artillery, tube length is measured in calibers, meaning the length of the tube is expressed by dividing the length of the tube by it’s diameter. So the length of an artillery piece of 54 calibers is 54 times the bore diameter. In the case of a 155mm, that means a tube length of around 27 feet.

Comment from Justthisguy on 2009-07-23

2009-07-24T02:16:19Z

Wet finger in the breezes, the mind of the mortarman eases. No matter how much the hate, I am too impatient to calculate.

Comment from Da'Gunbunny on 2009-07-22

2009-07-22T21:05:35Z

Not ragging, just understand redundancy has been drilled into my head. Just as a gunbunny, you can't do the hop without something to put the crosshairs on.

Comment from John of Argghhh! on 2009-07-21

2009-07-22T02:04:24Z

Well, Gunbunny, I was answering the questions... not giving a class in service of the piece or gunnery!

Much less the elements of accurate predicted fires!

Comment from Da'Gunbunny on 2009-07-21

2009-07-22T01:38:45Z

I am reading this post and I'm noticing there is absolutly no mention of 5 critical things.
1. collimator
2. Aimming post's
3. DAP
4. Aimming circle
5. safety circle
Without those, you can't shot. The rest is semantics. The earth is round and it spins, math is math and you can't beat it. But if you take time to do the math to put a round on target, those numbers are useless if the gunner dosen't have something to aim at.
I've shot 'em all, from 8" (by far my favorite gun ever) to 75mm pack howitzers. We've always had those 5 things.

Comment from B3 - aka BeachBumBill on 2009-07-21

2009-07-21T22:27:51Z

I just returned from a visit to the left coast and lo and behold John had posted my questions! Thank you for the info, I had no idea it was so complicated.

Comment from Gunner Mk42 on 2009-07-21

2009-07-21T06:19:49Z

As a naval gunners mate, the system I worked on was a 5/54 Mk42, firing 72 lb projectiles at 30 rds per minute sustained.
One of the ship classes I served on were nicknamed gunslingers because of the three mounts and two directors. That is 90 rds per minute of a mix of rounds to include AAC, VT, PD and Illum on up to three targets simultainously. The marines liked that destroyer offshore of them. Also two 20 round loaders per mount.
As for Fire direction that was all handled in plot or the directors.
gunner

Comment from Grimmy on 2009-07-20

2009-07-21T04:13:51Z

I quit griefing gun bunnies after getting the opportunity to watch an 8" battery humping rounds from gun 6 to gun 1 at 3AM in the rain and mud.

Comment from fdcol63 on 2009-07-20

2009-07-21T02:01:26Z

Fortunately, we less educated and very junior 13B's weren't expected to do all that fuzzy math and just screwed fuzes and punched tubes. LOL

Comment from Brad on 2009-07-20

2009-07-21T01:11:04Z

I noticed the guy holding the "rammer" keeps putting the end of it on the ground. Doesn't that get grit, dirt and other unpleasant things in the breech?

Comment from Justthisguy on 2009-07-20

2009-07-21T01:03:19Z

Cap'n H, you are such a nerd, and I thought everybody already knew that.

As far as being an artilleryman goes, I don't think I have the patience for the calculations and would settle for holding up a wet finger to the wind as a mortarman and saying, "That seems about right! Rapid fire for a bit, and then we'll adjust, or leave!"

Comment from J.M. Heinrichs on 2009-07-20

2009-07-20T22:39:35Z

... and the photo tends to look more like a -198.

Cheers

Comment from J.M. Heinrichs on 2009-07-20

2009-07-20T22:30:13Z

"By double-base, do you mean a mix of granulated and stick propellant?"
Back in the early days, a number of chemical compounds were formulated and played with as possible replacements for black powder. The two most reliable were Nitrocellulose and Nitroglycerine, but there are other less popular Nitro-formulations. Initially, the new gunpowders used one of the two main Nitros as the active ingredient, with the addition of other chemicals to modify the explosive behavior. THeses were known as "single-based" powders.
Later, the chemistry guys experimented with mixes of both Nitros, for improved performance, and these became known as "double-based" powders.
And then there are "triple-based" powders, and powders which are not based on a Nitro.

Stick versus granulated is is decided on based on the desired burn within the chamber and the cartridge case configuration. Sometimes, experiments are used to decide.

Cheers

Comment from David M on 2009-07-20

2009-07-20T20:30:40Z

John - Thanks. Most likely I read that and didn't make the connection until you splained it to me.

Comment from BillT on 2009-07-20

2009-07-20T20:08:12Z

She only gets prickled after about six Cape Coddahs...

Comment from Boquisucio on 2009-07-20

2009-07-20T19:49:20Z

Somewhere near Boston, I can hear the not so quiet grumblings of a prickled dox.

Comment from BillT on 2009-07-20

2009-07-20T19:42:02Z

The swabbies were the ones who came up with this expression of tube length.

Right. As if it actually contributed to something other than Trivial Pursuit and in-house ads for the LCS or DDG (XX(21)).

Comment from Boquisucio on 2009-07-20

2009-07-20T19:15:33Z

If I may add... the current caliber usage for artillery was a naval invention. The swabbies were the ones who came up with this expression of tube length.

Comment from John of Argghhh! on 2009-07-20

2009-07-20T18:42:35Z

David - the answer to your question is in my post, at the end. Just not expressed obviously enough to make the connection.

In naval usage, the second number is barrel length expressed in calibers. That second tube in your example would be over *twice* the length of the first tube. 5"x23= 115 inches in length. Your second example would be 250 inches in length.

Comment from David M on 2009-07-20

2009-07-20T18:35:51Z

Okay, now that we have been discussing artillery and its intricacies. I have a question that will most likely only highlight my ignorance of the finer arts of the craft.

I’ve never seen it written like this for ground based weapons, but can anyone explain why naval guns have two designators, such as: 5 inch/23 caliber or 5 inch/50 caliber, etc?

Comment from John of Argghhh! on 2009-07-20

2009-07-20T18:21:23Z

Stupid Lieutenant Trick #98,785,401

Spend a day shooting Charge 5 White Bag. As in, over 100 rounds from that position. That leaves a *lot* of unused powder increments.

Shooting done, get the "Prepare to March Order" warno.

Gun Dogs gather their unused increment bags and bring them to a central location, dumping them in a pile in the next firing point over.

Night approaches and a chill wind blows. The order to march order given, the battery departs under the watchful eye of the BC and 1SG. The XO and FDO are doing the powder burn.

There's a *lot* of powder. Grab about 30 bags and lay them out in a double line from the pile. Grab three more bags, and extend the powder trail. Light the powder, move back a smidge more.

Nice flare from the trail, and very entertaining activity from the double line of bags.

Then the fire hits the big pile. And it starts to get uncomfortably warm from many feet away. And the fire roars up, a living, breathing column of phlogiston that streaks into a rapidly darkening night as if we were standing on a hill watching Sodom and Gomorrah burn.

The flames climb higher and the heat is really kinda disturbing. The noise is a bit much, too.

The flames, in a last paroxysm of of Lucifer's-Realm-on-Earth, arch overhead, and lick the ground behind the XO and FDO.

Oxygen is becoming a rare commodity as the fire gives up the last of its energy, leaving some burning embers here and there.

After a quick look to ensure the forest wasn't burning, the Lieutenants beat a hasty retreat in the jeep, lest someone from Range Control show up asking who set off the nuke simulator...

Comment from Oldloadr on 2009-07-20

2009-07-20T17:32:11Z

Response to BillT's TINS: Did you all see in the news on 5 July about the fireworks accident in NC where 4 pyrotechnicians were killed? They were with the same company I shoot for. The one photo on the net and in the papers showed a destroyed tractor-trailer and another smaller truck. They were probaly distributing their shows from the big truck. It appeared (can't tell for sure) that the 18-wheeler had a metal bed, violation of rule #1 in explosive transport. The point is: over the years, I've seen lots of people who should have known better do dumb things with explosives (in my younger days, I probably did too). However, it only takes one time when the sun, moon and stars are aligned against you and the next thing you know, your discussing your future career plans with St. Peter... That was probably the best thing that ever happened to that boy, 'cause A. nobody got hurt and no equipment was destroyed and B. after that a$$-chewing he surely received from his gun chief up to the BC, I would bet he was the safest redleg in his unit from then on...

Comment from BillT on 2009-07-20

2009-07-20T17:23:11Z

I *was* going to say that I was perched in the cargo compartment passenger seat of my parked Loach, but decided there were entirely too many allerative aspirated plosives for comfortable reading.

Comment from BillT on 2009-07-20

2009-07-20T17:09:58Z

- when you burn the unused increments, you open one to pour a powder trail...

I was perched in the weeds to the side of an 8-inch battery at Ft. Drum one summer afternoon and watched the battery dimbulb cut open bag after bag after bag after bag etc. and lay a powder trail a good 75 meters long.

The bad news is, he lit the end he ended up at -- and he had been walking *away* from the battery.

The good news is, he'd used *all* the bags to make the trail.

Which "good news" failed to ameliorate the BC's mood after he crawled out from behind a convenient rockpile, where he had joined me and half the gun bunnies the instant we all saw the smoke trail heading for the tubes...

Comment from John of Argghhh! on 2009-07-20

2009-07-20T17:07:55Z

That was a long 'un, to be sure.

Comment from Oldloadr on 2009-07-20

2009-07-20T16:52:13Z

Now that was the longest echo chamber delay I have ever fallen for (LOL).

Comment from John of Argghhh! on 2009-07-20

2009-07-20T16:51:00Z

Double-base refers to components, not shape or mixture.

Most of us who've manned the guns have seen the powder - when you burn the unused increments, you open one to pour a powder trail so that you aren't leaning over with your face hovering over 5 pounds of propellant trying to start it burning...

Think old movies, with guys trailing black powder from the hut full of barrels of powder.

Same concept.

Comment from Oldloadr on 2009-07-20

2009-07-20T16:44:03Z

By double-base, do you mean a mix of granulated and stick propellant? I think non redlegs would be interested in knowing that some of your all's propellant looks like licorice sticks...

Comment from Oldloadr on 2009-07-20

2009-07-20T16:39:36Z

By double based, do you mean granulated and stick mix? I know this is probably more detail than a civilian passer-by at the castle can stay awake for, but this is an area where your old job and mine intersect, so I'm professionally curious...

Comment from John of Argghhh! on 2009-07-20

2009-07-20T16:34:37Z

Oldloadr - I'll have to break out a TFT to refresh myself on the correction factors for prop temp. We shoot artillery in the arctic, so I'm guessing *pretty cold.* Greater worry is with the hyrdaulics of the recuperators, seals, hoses, etc.

As for heat - there's lots of factors there. As in what the powder is made of, whether it's single- base or double-base, how old it is, and how long it's been exposed to excessive heat or other environmental degraders. There's enough involved in figuring that out, I'd leave those determinations to your local friendly EOD guys.

Comment from Oldloadr on 2009-07-20

2009-07-20T16:22:51Z

John, how cold is too cold for the propellant to work properly?

Also, how hot is too hot for a serviceable CC A prop charge to be unsafe to handle. We found with the left-over junk we worked with in Iraq that over 110F was very bad, so we tried to get rid of as much old propellant in the Fall - Spring months...

Comment from John of Argghhh! on 2009-07-20

2009-07-20T16:14:14Z

Pogue - nothing wrong with your definitions, they fall within mine - and mine hearken back to the older days in terms of the distinctions.

I think it was more the demonstrated lack of professional courtesy than being at 2,000 feet and seeing smoking chunks of WP flying past the windscreen that annoyed me...

Hey, *you* (or someone else) said, "Mark Center of Sector." Not our fault no one told us you were flying through it.

Comment from Pogue on 2009-07-20

2009-07-20T16:06:33Z

Up to a couple years ago at least (when AZ shut down the 153rd FA Bde) they still trained manual computing occassionally for back up. I can't speak to how often they actually shot with manual data - as risk adverse as they were they didn't even want us shooting off aiming poles. I'll demonstrate my ignorance here, but I always though it was low angle = gun, high angle = mortar, both = howitzer.

Comment from BillT on 2009-07-20

2009-07-20T15:39:41Z

I -- *hem* -- wore crossed fire-hydrants in Vietnam...and they *still* tried to blow me up.

I think it was more the demonstrated lack of professional courtesy than being at 2,000 feet and seeing smoking chunks of WP flying past the windscreen that annoyed me...

Comment from John of Argghhh! on 2009-07-20

2009-07-20T15:14:11Z

Yanno, MM, I dunno if they do or not. I've got a set of 155mm HE, SMK, and Illum sticks and 203mm HE. Plus a 155mm site stick, too. I've got a 4.2 inch fire direction set, complete. Someday I'll figure out a way to do a display of an OF chart without it having to take up a lot of space.

Someday.

I love Bill's snarkage. Tells us again what your company-grade MOS was, Bill?

Comment from MAJ Mike on 2009-07-20

2009-07-20T14:30:02Z

I have a set of "sticks" from e-Bay. When I, a mech infantryman, went to FAOAC in 1991, they were traing on the BCS, but still taught the older methods. Now with GPS, etc, I'm wondering if they still teach "charts and darts" and the old sticks/slide rule method of computing gun data?

Please enlighten this over-paid 11B10.

Comment from Casey on 2009-07-20

2009-07-20T14:26:11Z

Apparently, in the air, everything is magnified in size...

Not gonna say it. Nope. Not touching it. Not with Bill standing right there.

Comment from BillT on 2009-07-20

2009-07-20T13:59:37Z

That process generates the data that ends up at the gun.

And sometimes, it's even accurate.

The remaining times, great consternation occurs among innocent helicopter pilots, infantry types, and armored units with their turrets in al fresco-mode...