Birth of a Big Gun (1908)

remarkable


Birth of a Big Gun (198) - YouTube

Looks like the guys loading their pig iron were on a worker's exchange to England as well, those guys do get around . Big guns would have been the superweapon of the day lots of competition with other countries to have the best. I was thinking of borrowing that wire winding technique to reinforce a steel tube for use as a hydraulic press, the seamless tube is only good for 2000 PSI but I'd like 3000.

The breech block is very impressive, all pre cnc and computers. Anyone around that could do it the old way?

Probably John Oder...

Ditto on the breech mechanism, it was sort of a work of art...

Neat piece in American Machinist Grinding Book 1912 where Mr. Norton (the grinding machine maker) was grinding the wire wound tube AFTER winding on French 90mm jobs

I don't remember seeing this one before;
Building a Naval Gun - YouTube
Lot's of shaper and turret lathe work.

And the automation of the 8" naval guns of the 50's, it must have taken years to develop;
8 inch Guns - YouTube

The formation of armies of men and material is like a broad scattering of cash over a large area, but these weapons are concentrations of huge amounts of monies in small areas. But then there is the building of nuclear weapons and the delivery systems, the very expensive point of the spear.
Compound it by the number of nations so involved in such a massive waste of money, it's the labor of millions of human beings gathered together to defend them from other nations, by taxation.
One worlders think they will stop such waste by eliminating borders, but they institutionalize a far greater threat than opposing nations, that threat America's founders were so worried about, mega tyrants.

Anyway, my $.02

This is interesting footage. What is quite curious is that this same film, with English captions is posted as "Making an Armstrong Gun", at Armstrong, Whitworth & company, dated in the 1920's. Same people, doing the same things, no change in the plant, equipment or people, even down to the crew handling the gun on the proving range.

Tha Armstrong, Whitworth film has more footage, particularly of charging the Siemens steel furnace (looks like an open hearth furnace, if I am not mistaken). Both crews in the yard loading pig iron into the skip are one and the same, and the captions, translate from the German to English, one and the same.


I wonder whether the Germans got hold of Armstrong, Whitworth's film and re-captioned it for their own purposes ?

The stress analysis calculations for the large gun barrels were likely quite an involved mathematical analysis. How they arrived at the ideas of wrapping the gun barrels with tensioned wire, as well as shrinking on a jacket vs machining the barrels from heavier-wall forgings interests me as an engineer. I know that in the 1860's, in the USA, I believe Dahlgren (or maybe it was Ericcson ?) had come up with the idea of winding wire under tension around cannon or naval gun barrels.
This may have been done in an era when such gun barrels were castings with fairly low tensile strength metal in the walls of the barrels, or some doubts as to consistency of the castings (were there blowholes, sand inclusions, shrinkage defects, or problems with large pours from multiple ladles ?). Winding wire of a known tensile strength and putting a pre-tensioning on it would create a "hoop" around a gun barrel and enable it to withstand higher internal pressures. By the time this film was made, steel making and forging were a well-developed thing. The fact the barrel was made from a large ingot that was pierced and had the bore forged, follwoed by oil quenching and tempering leads me to think the barrel was a high grade steel. The German film does refer to shrinking on the "mantle" (German for "jacket" or "coat"), as does the Armstrong-Whitworth film. Same footage, different language captioning.

It just seems like making more work to shrink on a large jacket, rather than simply make the barrel as a one-piece forging.

The interesting thing is the progress of weapons has obsoleted the large bore guns, along with the battleships (or "Dreadnoughts") or gun emplacements. Various missiles have pretty much taken over. Instead of needing a massive gun emplacement, railway mounted gun, or a battleship as a platform for the guns, a relatively lightweight missile launcher and missiles do a much more effective job. The idea of a "smart" projectile with the kind of punch some of the missiles pack would have seemed unbelievable to the military and ordinance people in the era of this film. Missiles with conventional warheads, launched from mobile equipment like trucks, full tracked carriers, or from light surface vessels or aircraft have completely changed the way wars are waged, and have more than levelled the field in some regards. In the era of this film, only countries who could afford to build and arm capital ships with large guns, or build railway mounted guns (the German caption calls this a "travelling gun", if I recall correctly), could have the heavy armaments. We would later come to call such nations "super powers". When missiles got into common use, nations that would not have been taken seriously in the era of battleships and heavy guns suddenly were able to wage war against the superpowers. A case in point was the Falklands War. Leaving politics strictly out of this, consider the Argentinian Navy sinking a British frigate or destroyer (HMS Sheffield, I believe). No heavy cruiser or big guns, but an Exocet missile. The idea of the Royal Navy losing a ship to a country that had nowhere near the naval power would have been unthinkable, if not an impossibility (short of using a submarine and torpedo attack) in the big gun era.

The era of the big guns and the various platforms to bring them to bear is long done with. I remember in 1972, when I first got out of engineering school. I was assigned by Bechtel to work on a jobsite at Potomac Electric's Morgantown (maryland) Generating Station. Across the Potomac River on a kind of diagonal from PEPCO's plant was the US Naval ordinance testing station at Dahlgren, VA. At various times during the days and into the evenings, the Navy seemed to have no end of ammunition to fire off. Everything from machine guns and anti aircraft guns to big naval guns. When they'd fire the big naval guns, the concussion would arrive at PEPCO's plant. If you were inside their powerplant (a coal fired plant), the dull concussion against the siding of the building would raise little puffs of flyash that had accumulated on the structural members, piping and odd places where no one cleaned. In the evenings, if the weather was nice, we'd go to the oil dock (where Stuart Petroleum oil barges unloaded fuel oil). PEPCO's plant was mainly coal fired, but they had a tank farm with a lot of oil storage for startup and for running gas turbine peaking units. We were extending the oil unloading dock, so I spent some time there. Evenings, if not much was doing, a couple of rods and spinning reels and lures were kept in the oil barge unloading dock operator's shed. We'd get the rods and sit on the oil dock and cast for rockfish (striped bass that come upriver in the brackish water), or perch. Mostly, it was catch and release. While we'd be fishing, the Navy over at Dahlgren often put on a show. Sometimes, they'd shoot up parachute flares, then lay on a barrage of anti aircraft fire with tracer rounds. We'd sit on the oil dock and fish and discuss what the Navy was up to. The consensus was they were shooting off "retrograde" ammunition to get rid of it. I'd often remark that high powered sporting rifle ammunition was expensive enough as it were, and that I would trade them my annual paycheck for the cost of the ammunition they were going through. Now, with missiles, I imagine there is little shooting going on a Dahlgren. Similarly, in the machine shop at PEPCO's plant, the senior machinist had come out of the US Navy "gun factory" in Washington, DC. PEPCO had a well equipped machine shop with a new American Pacemaker engine lathe. I was in there once to get a piece of steel turned down for a pin to go through sheaves on the block of a construction crane, and the senior machinist did the job "1-2-3" in the American Pacemaker lathe, telling me proudly that he'd come out the Naval Gun Factory. Other than photos and some film footage, I am sure the Washington Navy Yard and the gun factory within the yard are long gone. Missiles built on light-weight CNC machine tools and launched from very light means can do more damage more precisely than the big guns like this film depicts.

The reason for wire-winding or sleeving or auto-frettaging gun barrels is that the circumferential tensile stress from internal pressure is not evenly distributed through a solid, initially unstressed section.

Stress and strain are essentially proportional. Apply internal pressure, and the cylinder will expand. That lengthens the circumference, straining the metal, which sets up a proportional stress, which carries the load.

But as you move radially outward through the thickness of the wall, the circumference at that increased radius increases, while the radial expansion from the internal pressure is constant. Thus the circumferential percentage strain decreases, thus so does the stress, so successive outer "layers" of metal contribute less and less of their potential load capacity to the strength of the vessel.

There is a further effect which exacerbates this trouble, that is, as metal is stretched, it thins. Not as much as would be required to keep its volume constant, rather according to "Poisson's ratio" which for many materials is about 0.3. But this thinning operates to reduce the radial expansion of the outside of any imaginary inner "layer" of material which is available to transfer stress to the next "layer" out..

An equation can be written to account for these effects and accurately calculate the stress in a thick-walled cylinder, but still the increasing inefficiency with which successively added thickness of solid metal contributes to the bursting strength of the vessel not only makes it heavier and more expensive, but reaches a point of diminishing returns where you cannot increase the performance by increasing chamber pressure, regardless of how thick you make the wall..

The solution is pre-stressing the outer layers, either by wire-winding, shrinking on one or more sleeves, or "autofrettage" where the bore is plastically expanded either by forcing an oversize slug through or with hydraulic pressure which leaves residual compressive stress at the bore and residual tensile stress father out.

Done correctly, any of these tricks starts the vessel out with residual compressive stress near the I.D, slowly dropping to zero, and then increasing residual tensile stress as you move radially outward through the composite thickness.

When design internal pressure is applied, you get an approximately uniform level of appropriate tensile stress all through the thickness of the wall, so all the material is contributing efficiently to the strength of the whole assembly..

So here is my question which I have occasionally pondered without figuring out an answer of finding a reference which contains it: Do the outer layers of a composite barrel contribute nothing to resisting the axial load on the breech-block? The video appears to show the locking lugs engaging only that inner layer. Axial stress in a pressurized cylinder is only half the hoop (circumferential) stress, so perhaps this is sufficient.

One question - Is the wire covered somehow after winding ? And if the wire brokes in one place, all barrel is lost ?

Also, about the big guns - in Vietnam the efficacy was something like 10 406mm shells for one dead soldier. Quite expensive.

But I've heard that one WWII battleship was used in Gulf War and the benefit was that missiles were almost useless against the old-school armor. And they used drone to pick artillery targets. And after a while, all they did was just use a drone without artillery because word spread in Iraq army and seeing the drone was enough motivation for iraqs to surrender.
I wonder how big the hole is after the ground meets 406mm shell

Artillery may be technically obsolete, but I doubt it is economically obsolete, and much of war is economics. If I run out of money to buy things to throw at you before you run out of ings to throw at me, I lose no mater how much braver or smarter I am.

A missile is a war-head, a propulsion system, and a guidance system. All are destroyed in each shot. Artillery makes only the warhead expendable, the guidance and much of the propulsion systems are re-used.

Of course heat-seeking and other guided, as opposed to ballistic, missiles are a whole new order of capability, but at the same time a whole new order of cost.

Then there's this...

M982 Excalibur - Wikipedia

A Viet Nam vet once told me that the worst thing he ever endured was an artillery barrage. Artillery drove countless men mad for life, there's no fighting back, you can dig a hole but not deep enough quickly enough to protect from a direct hit.

I heard the same thing said by another 'Nam vet about mortars.

Those smart shells, used by modern automatic loading guns, three rounds in the air simultaneously to arrive on target at the same moment, computer directed of course. Not much chance against that.

Thanks to every person who fought for our freedoms.

I wonder also with Madis what about local failure or bad spots in the wire, and particularly how the wire ends were secured . Winding would be much cheaper and faster than sleeve-fitting, and the pre-tension could be actually measured rather than calculated. A lot of military equipment need not be designed for long life, as it gets blown up or abandoned, but you don't want a gun blowing up in use from its own charge and killing the crew.

If the wire-wound section was ground after winding, it seems a sleeve was to be shrunk over it. Friction, then, might secure the wraps. But still seems a lot of chance for movement and unloading and fretting during propagation of shock waves through the material. Also, if the wire-wound gun needed grinding and a shrunk sleeve also, seems little is gained in simplicity by the winding. Speculating is fun but I wish we had an old-timer in this business on the board to straighten me out.

The sleeve should provide two functions.

First, it protects the winding,

Second, it gives structure to the gun, since the winding has no bending strength. Something has to be the "beam strength" against gravity, as well as "whip" when it is fired, and you have to be able to attach the gun to the mount. The sleeve gives that capability.

I would suppose that the tension of winding would need to vary with the layers. Otherwise the inner layers would be relieved of all stress as the outer layers were wound on.

Hasn't "autofrettage" made such methods obsolete? Or is that only for the smaller guns.

My own experience swaging and expanding tubes suggests that autofrettaging a gun tube by forcing a solid slug through it would risk buckling and galling. Hydraulic expansion (like slugging) would give you a stress distribution dependent on the yield properties of the material...as the inner surface yielded it would also work-harden, and if you went too far it would weaken again, maybe before you got enough tensile pre-load in the outer layers. With successive shrunk tubes, you can get more-or-less exactly what you want.

Yes to JST, a sleeve stiffens against whip, which might be good or bad depending on the dynamic response of the whole gun and its effect on the accuracy (where is the muzzle as the projectile leaves, and which way is it moving and how fast, AND how reproducibly). (Ruger Mini 14 barrel flex and muzzle blast, high speed camera - YouTube, AK47 Barrel Flex - high speed video, 6fps - YouTube, Romanian PSL 8 rounds 12 frames per second - YouTube

As far as transmitting recoil, if you put the sleeve on from the breech end against a shoulder on the inner tube, then it would transmit recoil, otherwise not so much. If you want it to resist pressure against the bolt or breech-block, you want the opposite, which leads to my question in my first post in this thread.

Obviously something does transmit the forces, and it must be outside the wires, or out of the way of them.

The guns have double inner tubes, anyway. One is support, the other carries the rifling. After X number of rounds, the rifling is worn, accuracy suffers, and the gun needs to be "re-tubed".

Hydraulic expansion (like slugging) would give you a stress distribution dependent on the yield properties of the material...as the inner surface yielded it would also work-harden, and if you went too far it would weaken again, maybe before you got enough tensile pre-load in the outer layers. With successive shrunk tubes, you can get more-or-less exactly what you want.

Click to expand...

I think all US made medium caliber guns are done this way, and have been since the 50's at least.

Done which way, autofret or sleeve? What is the method for replacing a looong interference-fitted inner sleeve? A trick I used once with great success to remove a heavy press-fit gear on hollow shaft was to plug the bottom of the hollow shaft with disc against which my puller bore, heat the whole ass'y to s few hundred deg F, then dump ice-water into the tube. came off with a bang!

Any recommendations of reference books on this stuff?