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Xoon

Rheinmetall's New Tank Gun

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As a rough approximation, using sigma equals flexural force over width times depth (for a rectilinear cross section), I get that the increase in maximum axial load will be proportional to the increase in cross sectional area afforded by the thread vs just using ribs.  Using that model the increase is, needless to say, not worth getting excited about.  The thread ID doesn't look to be more than 10% smaller than the OD, 110% squared is 121%, so the cross sectional area difference will be less than that, exact amount depending on thread form and pitch.

When calculating the critical load under which the rod will fail with the use of Euler's critical load, you need the area moment of inertia. Which, for a circle, has the radius as quadrupled.

 

So calculating the area moment of inertia of the rod using your 110% we get:

0.25*pi*(10.4*1.1)= 13452.22 = Irib

 

And for one without the rib:

0.25*pi*(10.4)= 9188.05 = Ismooth

 

Throwing this in Euler's formula (Pcr = (pi2*E*I)/(KL2)): (Values for DM63 rod)

Prib = (pi2*530000*13452.22)/(1*6462) = 168618 N

Psmooth = (pi2*530000*9188.05)/(1*6462) = 115168 N

 

So a ribbed rod will buckle at ~168 kN, while a smooth one will buckle at ~115 kN.

 

Which is a 46,4% improvement.

 

 

...now that I'm done I notice I used the maximum diameter of a DM63 rod, instead of its minimum diameter. Values change, percentage should stay the same.

 

 

Disclaimer: This is a napkin calculation, do not use as scientific basis yadieyadieya, etc.

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German designs have a helical rib on the penetrator which prevents it from buckling or snapping too easily

 

Not entirely sure whether this is a German design (seeing the Asian text), but it does show the helical rib:

EUTzoUh.jpg

 

DM53 is segmented: short-short-long

DM56 is segmented in short-short-short-short-shoer

Of course it's not segmented during fly, but "semi segmented" - heavy tungsten alloys slugs (something like 30mm APDS ammo) are "melti" in diffrent material and coverd by diffrent mettal jacekd.

DM-53 can overcome K5 without it's initiation and overcome double-reactive (IMHO Relikt) armour.

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iQUE3CX.jpg

 

Mock-up of the 140mm round (not sure which one) next to the propellant case for the 120mm L1/M58, the rifled 120mm gun on the conqueror and M103.  As you can see, the ammo for this gun was quite a bit bigger than the ammo for the later NATO 120mm smoothbore, and a hell of a lot bigger than the ammo used in the 120mm L11/L30 rifled guns.

 

L9ILm83.jpg

 

I think the version of the T123 in the experimental T57 heavy tank was to use one-piece ammunition:

T57-1.jpg

 

The 140mm ammunition was also two-piece, which would have limited the length of the long-rod penetrators it could fling.

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lol. Photos were posted on otvaga. Terlikov and Demchenko (Armata designers) spying on Euroweaklings new gun  :D

I love how confident Demochenko looks. Makes you think...

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When calculating the critical load under which the rod will fail with the use of Euler's critical load, you need the area moment of inertia. Which, for a circle, has the radius as quadrupled.

 

So calculating the area moment of inertia of the rod using your 110% we get:

0.25*pi*(10.4*1.1)= 13452.22 = Irib

 

And for one without the rib:

0.25*pi*(10.4)= 9188.05 = Ismooth

 

Throwing this in Euler's formula (Pcr = (pi2*E*I)/(KL2)): (Values for DM63 rod)

Prib = (pi2*530000*13452.22)/(1*6462) = 168618 N

Psmooth = (pi2*530000*9188.05)/(1*6462) = 115168 N

 

So a ribbed rod will buckle at ~168 kN, while a smooth one will buckle at ~115 kN.

 

Which is a 46,4% improvement.

 

 

...now that I'm done I notice I used the maximum diameter of a DM63 rod, instead of its minimum diameter. Values change, percentage should stay the same.

 

 

Disclaimer: This is a napkin calculation, do not use as scientific basis yadieyadieya, etc.

 

What kind of engineer are you? You failed at the basic engineering

 

In order to increase the load, the increased diameter must run parallel continuously to the axis of the rod, e.g. a full rod, not discrete thread like that which is useless because the chain is as strong as its weakest link.

 

Your theory fails, imagine a steel rod with 1m diameter, but has a section with 1mm diameter. From your calculation, that rod is very strong and can not be broken, but actually it can be broken by human easily.

 

The thread is similar to a 1mm rod with many 1m disks attached discretely along its length, the disks are useless in increasing bending load of the rod, even the diameter is huge.

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On 6/13/2016 at 9:08 AM, Xoon said:

It is entirely possible that it is a ordinary gun. It just seems weird to develop a new tank gun, with a new caliber a and with ETC technology around the corner.  It could have been a quick way to up gun Leopard 2s in service in reaction to the T-14, but having a 50% performance increase from the L55 seems hard with a shorter gun. Even if the case it longer,and it is not wider from the looks of it.

there is no more modular part of a tank than the gun.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA476392

even so, low-end ETC is most likely, which only improves accuracy, barring some immense improvement in capacitor density.

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On 7/29/2016 at 11:18 AM, Bronezhilet said:

I'm a better engineer than you apparently, since I do know what a thread is. "Thread similar to a series of disks attached.". ...what.

Also, are you familiar with the term "napkin calculation"?

But hey, welcome to SH I guess.

Better my ass, I am an inventor, enterpreneur, what did you do your whole life on my caliber?

I don't know napkin calculation, english is not my first language so my expression is not that good.

Being an inventor alone is far greater than anything an engineer like you can be, in both technology and financial achievement. Being a great inventor, who can influence the world, change how battlefield is fought, is not even in your dream, loser

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2 hours ago, lemd said:

Better my ass, I am an inventor, enterpreneur, what did you do your whole life on my caliber?

I don't know napkin calculation, english is not my first language so my expression is not that good.

Being an inventor alone is far greater than anything an engineer like you can be, in both technology and financial achievement. Being a great inventor, who can influence the world, change how battlefield is fought, is not even in your dream, loser

Firstly, what part of 'behave yourself' do you not understand?

 

Secondly, I work with inventors every day. Some (usually those who are also scientists or engineers) produce amazing improvements to cutting-edge technology. Others are fuckwits with overblown opinions of themselves who waste a lot of time and money trying to protect their insipid creations.

 

Saying that you're an inventor and entrepreneur means nothing. What you invent and make/sell is the important part. So put up or shut up.

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6 hours ago, lemd said:

Better my ass, I am an inventor, enterpreneur, what did you do your whole life on my caliber?

I don't know napkin calculation, english is not my first language so my expression is not that good.

Being an inventor alone is far greater than anything an engineer like you can be, in both technology and financial achievement. Being a great inventor, who can influence the world, change how battlefield is fought, is not even in your dream, loser

Well somebody needs to take a big dose of "shut the fuck up!". 

Inventor and Enterpreneur my ass! If you lack even the manners of a 5 year old child, you need to get your priorities straight. 

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For shiggles I threw together a few rods in solidworks and used the SimulationXpress default settings to judge stiffness. 3 rods: one smooth (10mm r 800mm l); one ribbed (11.5mm r with a 1.5x1.5mm revolved cut every 3mm, so just like the original rod with a series of 1.5mm square rings with 1.5mm between each, 800mm l); and one with a thread (11.5mm total diameter, with a 3mm pitch square thread cut 1.5mm deep - so like the second rod only with threads instead of a series of grooves).

All were fixed at one face and had 20N applied parallel to the other face, material assumed to be tool steel. Results were:

1) Solidworks hates threads. It took 1s for the smooth rod, 22s for the ribbed rod and half and hour for the threaded rod

2) Unsurprisingly, ribs or threads do improve stiffness. Max displacement was 2.139mm for the smooth rod, 2.001mm for the ribbed rod and 1.994 for the threaded rod. This is an improvement, but I'm not sure if it corresponds to a 46% improvement in second moment of area

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On 2/5/2017 at 7:43 AM, lemd said:

Better my ass, I am an inventor, enterpreneur, what did you do your whole life on my caliber?

I don't know napkin calculation, english is not my first language so my expression is not that good.

Being an inventor alone is far greater than anything an engineer like you can be, in both technology and financial achievement. Being a great inventor, who can influence the world, change how battlefield is fought, is not even in your dream, loser

I design tank ammunition.

 

Now get the fuck out.

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On 2/4/2017 at 11:43 PM, lemd said:

Better my ass, I am an inventor, enterpreneur, what did you do your whole life on my caliber?

I don't know napkin calculation, english is not my first language so my expression is not that good.

Being an inventor alone is far greater than anything an engineer like you can be, in both technology and financial achievement. Being a great inventor, who can influence the world, change how battlefield is fought, is not even in your dream, loser

 

Ok, you've won the exceptional prize of drawing my attention for being a particularly noteworthy bag of flaming shit, let me honor you on this occasion by shitfucking you back to the stone age real fast. (Which is where I imagine your level of actual technical prowess sits.)

You come here with 2 of the most mind agonizingly retarded posts I've ever seen, spaced out months apart no less, the first showing you can't read, the second showing that, rather the cutting your losses and quitting while you're behind, you just came to prove that you really are an exceptionally dumb motherfucker making grandoise claims of shit you've never been and never will be to try and save face, not realizing this actually just made you look like a fucking scumbag piece of shit.

You speak of "financial achievement", see, unlike you, this forum knows of my finances because I've shown them pieces of it, and I would bet millions it's higher then yours, you're fucking nothing, you're a goddamn pretender who wants to feel important but won't ever amount to shit, but at least you can project that on others.

Being and inventor that "can change the world and how the battlefield is fought", ok, humor us, show us your amazing inventions you sloth brained inbred shit, actually, don't, no one here believes you and we all know you're full of shit pretending to be someone you're not, you're goddamn dumpster trash, you'd have less chance of influencing battles or technological advancements then fucking Mike Sparks and Blacktail, infact, they're sadly smarter then you are, your brain cavity is filled with nothing but rotted pulp that's been fucked into nothing by the dick of your ego and delusions of grandeur.

Now then, seeing as how you made all of 2 posts and proved you're completely, utterly useless, kindly get the fuck out of here, I am fucking Lion of Judah, I carry in me blood of fucking kings, I am the doombringer and thrower in the fucking dumpster of shitstain failed abortions like you and the bringer of light the the darkness of the semen coated walls of the places your type thrive, the greatest honor in life would be you getting hit by a bus and me fucking your corpse and using the blood to paint my face and using it to purge other inbred shit eaters like you in a witch hunting ritual to better the world.

In short, fuck you you pretender projecting piece of shit, Bronez has proven himself here, you've proven to be a likely sub 10 IQ dumpster tier goatfucker who will never actually amount to anything.

Now get the fuck off this forum and never return, you anime body pillow fucking cum stained spastic retard.

 

 

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3 hours ago, sevich said:

wouldn't it increase stiffness width-wise, but not length-wise?

I'm not sure, what do you mean?

If we consider a generic cylindrical rod:

=============================    <ascii rod

There are 3 axes that we can consider bending in: along the x axis (left to right); the y axis (up and down); and the z axis (into and out of the screen). Whichever axis we consider the bending in, the forces involved must be oriented in one of the other axes - so for the x axis, any bending forces must be applied in the y or z axes. As the rod is rotationally symmetric, many of these cases look identical:

  • for bending in the x axis, it doesn't matter whether the force is applied in the z or y axis - the result is the same
  • bending in the z axis with force applied in the x axis looks identical to bending in the y axis with force in the x axis (for a shorter rod, think of this case as breaking a cylindrical tablet in half - without the scored line, the case is the same when you rotate the tablet about the x axis)
  • bending in the y axis with force in the z axis is identical to bending in the z axis with force in the y axis, but this is a weird case anyway so ignore it

In the simulation, the rod was bent in the x axis, which corresponds to fixing the left hand end of the generic rod above while applying a load downwards to the right hand end.

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8 hours ago, Xlucine said:

 

In the simulation, the rod was bent in the x axis, which corresponds to fixing the left hand end of the generic rod above while applying a load downwards to the right hand end.

Just to make sure, is this the same principle behind why bird cages are so strong?

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15 hours ago, sevich said:

Just to make sure, is this the same principle behind why bird cages are so strong?

It's related. There's a mathematical measure of how well a cross-section will resist bending, which I was taught as second moment of area (although bronez calls it area moment of inertia earlier, same difference). Using the same axes as my earlier post, when bending in the x axis with a force in the y axis you double integrate y^2 over the y axis and the z axis. This, combined with the stiffness of the material and the bending moment at that particular point, gives the curvature; and integrating the curvature twice along the x axis dives you the displacement (the first integral gives the angle the beam is at, the second the displacement). So for a rod without a constant cross section, the thicker bits have less curvature and the thinner bits have more curvature. The second moment of area scales with the width (in the axis of the bending force) cubed multiplied by the other width, so a wide structure (like a birdcage) is much much stiffer for the same weight as a thin structure (like the wire the cage is made from).

 

In practice, the maths for beams with constant cross-section is fiddly and a pain, and non-constant cross-sections even worse, so everyone hides the maths in a computer FEA model

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On 2/5/2017 at 1:43 AM, lemd said:

Being an inventor alone is far greater than anything an engineer like you can be

Ahahahah you idiot. I'm an engineer, and if I had a nickel for every "inventor" who failed out of high school calculus and thought he just made a fantastic breakthrough, I could retire. Whenever one of you geniuses has an idea you claim is revolutionary, there's a 99% chance it was either tried before or defies the laws of physics and could never work. The remaining 1% is inventions that are actually decent but so hilariously inefficient that you would need an engineer to hammer it into shape to not get laughed out of any investor meeting.

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