He111 dorsal gun MG131

[III/JG2Gustav05]

Hello  all,

 

I have to say that this gun's ballistic trajectory is really really bad. maybe is the worst one in this game. it's muzzle velocity is 700-750m/s and VVS's UBT muzzle velocity is about 815m/s. So the difference is about 8%-14%.  but according my experience on dorsal turret of He111H16 and Pe2, I can feel huge difference between those 2 guns. I almost can not hit any target beyond 400m with MG131, but score lots hit even at 1000m with UBT. One question here, anyone knows MG131 cross hair range setting in this game?

[Boaty-McBoatface]

The rate of fire of the UBT would also make it much easier to put rounds on target though wouldn't it? Feels to me that the MG131 rate of fire was too slow for the job of shooting an airframe at fast closing speeds

Edited May 12, 2017 by B0SS

[6./ZG26_McKvack]

But if you hit it does serious damage tho

[ShamrockOneFive]

There are other factors beyond muzzle velocity.

 

The UBS is a 12.7x108 cartridge with a projectile weight of 52 grams.

The MG131 is a 13x64B cartridge with a projectile weight of 36.2 grams.

Source: http://users.telenet.be/Emmanuel.Gustin/fgun/fgun-pe.html 

 

Though I am not a physics major... I'm guessing that the heavier cartridge in the UB will maintain its energy for a longer period of time and make for a better trajectory.

[III/JG2Gustav05]

There are other factors beyond muzzle velocity.

 

The UBS is a 12.7x108 cartridge with a projectile weight of 52 grams.

The MG131 is a 13x64B cartridge with a projectile weight of 36.2 grams.

Source: http://users.telenet.be/Emmanuel.Gustin/fgun/fgun-pe.html 

 

Though I am not a physics major... I'm guessing that the heavier cartridge in the UB will maintain its energy for a longer period of time and make for a better trajectory.

Very interesting, thank you, ShamrockOneFive!

 

I hope someone can post UB trajectory chart here like the one for MG131 posted in update 146.

[71st_AH_Mastiff]

I dont think the game is that high of a detail; it only simulates.

[F/JG300_Gruber]

Other thing that is imho part of the explanation is the huge size of the metal ball of the sight.

It just covers the whole enemy fighter unless it's flying closer than 200m or so. 

 

You have absolutely no feeback with this system, neither on your bullet trajectory nor scored hits.

And as you don't see what your enemy is doing behind that big black dot, you can't accurately anticipate his movements either.

 

Compared to the UBS holographic sight, this is a very big drawback that could play even more than cartridge effectiveness.

[JtD]

Why does it have a big fat metal blob there in the first place? Both the weapon manual and the H-16 manual state Revi, has there ever been an explanation why we don't have it in game?

[LukeFF]

 

 

One question here, anyone knows MG131 cross hair range setting in this game?

 

400 meters 

Why does it have a big fat metal blob there in the first place? Both the weapon manual and the H-16 manual state Revi, has there ever been an explanation why we don't have it in game?

 

Insufficient references? Not sure either, so it's just a guess on my part. I've not seen any detailed photos of the MG 131 fitted with a Revi.

[JtD]

Well, solved that myself - Revi was possible with the WL131, but in case of the He111H16, it was used only for aligning the weapon during installation/maintenance and was taken off and replaced with mechanical ones for actual service/combat.

 

An error we have in game is that it is possible to shoot the aircraft itself, this was prevented with a mechanical limiter which basically was a flat metal strip (to protect the fuselage) with a vertical fin (to protect the vertical stab) in the immediate front of the gun/turret. The Mg131 simply couldn't be trained to shoot at the own aircraft.

Edited May 14, 2017 by JtD

[StG77_Kondor]

There are other factors beyond muzzle velocity.

 

The UBS is a 12.7x108 cartridge with a projectile weight of 52 grams.

The MG131 is a 13x64B cartridge with a projectile weight of 36.2 grams.

Source: http://users.telenet.be/Emmanuel.Gustin/fgun/fgun-pe.html 

 

Though I am not a physics major... I'm guessing that the heavier cartridge in the UB will maintain its energy for a longer period of time and make for a better trajectory.

Actually it's the opposite. The lighter round will have the flatter trajectory. With similar speed, the heavier bullet succumbs to gravity at a faster rate than the lighter bullet.

Edited May 15, 2017 by StG77_Kondor

[216th_Jordan]

Actually it's the opposite. The lighter round will have the flatter trajectory. With similar speed, the heavier bullet succumbs to gravity at a faster rate than the lighter bullet.

 

What? No really, back to physics class!

 

 

Friction only comes to play for a metal bullet after some time and then the length and diameter matter. A round object will also have quite little friction. Take a small caliber round and drop it - its quite heavy and I assure you that you will see rather little difference in the first 2 seconds after the drop if you take a bigger, heavier one (per area). I hope you know that in a vacuum everything accelerates with the same factor.

Additionally the round is subjected to other forces primarily (frontal) that will have a much more significant impact. A longer thinner and heavier round will of course experience a lot less friction compared to its weight. So if your bullet arrives after 1 second or after 2 seconds makes a big difference.

Edited May 15, 2017 by 216th_Jordan

[-TBC-AeroAce]

Actually it's the opposite. The lighter round will have the flatter trajectory. With similar speed, the heavier bullet succumbs to gravity at a faster rate than the lighter bullet.

Everything falls at the same rate regardless of mass due to gravity. Air resistance changes this hence a leaf will fall slower than a ball the same mass

 

Fun fact if u fired a gun horizontaly and dropped a bullet from ur other hand at the same height both will hit the ground at the same time

Edited May 15, 2017 by AeroAce

[Gunsmith86]

Actually it's the opposite. The lighter round will have the flatter trajectory. With similar speed, the heavier bullet succumbs to gravity at a faster rate than the lighter bullet.

 

If you want to proof yourself wrong than take a stone and throw it as far as you can.

After that take a pice of paper roll it into a ball that is about the size of your stone and throw it also as far as you can.

 

Which one flys further?

 

 

 

And you are not completly wrong about the flatter trajectory. The lighter bullet has a better one at the beginning but that changes very fast after the first 80-200m from that point it does lose so much more speed that the heavier bullet is over all much better.

Edited May 15, 2017 by Gunsmith86

[Yogiflight]

It is all about mass inertia. You need more power to accelerate something heavier, and you need more power to slow it down.

[Ypsan]

I think Breda 12.7 have the worst velocity and trajectory actually. On 90 degree deflection angle VVS fighter can pass through your bullet stream without taking a single hit.

[ShamrockOneFive]

I think Breda 12.7 have the worst velocity and trajectory actually. On 90 degree deflection angle VVS fighter can pass through your bullet stream without taking a single hit.

 

Oh it does. The Breda SAFAT 12.7mm is possibly the worst heavy machine gun carried by a fighter during World War II. At least in BoM its got some effectiveness... it was virtually useless in IL-2 1946.

Edited May 16, 2017 by ShamrockOneFive

[Inkophile]

Fun fact if u fired a gun horizontaly and dropped a bullet from ur other hand at the same height both will hit the ground at the same time

 

This is only true in "ideal" physics though, i.e. in complete vacuum. In actual real-world application the tumbling of the dropped bullet and the Magnus effect (the projectile's rotation relative to wind direction) on the fired bullet will make those times vary marginally respectively "significantly" (speaking of hundreds or tenths of a second), and under no likely circumstance will they ever hit the ground simultaneously. The projectile shape (center of mass and center of pressure) will determine the severity of the Magnus effect, as well as if it induces tumbling or not in the projectile. Thus even two different cartridges fired at the same muzzle velocity will hit the ground at different times.

 

Edit: So well... yeah. In broad principle what you say is absolutely true. Just depends on how detailed one wants to get.

Edited May 16, 2017 by Inkompetent

[JaffaCake]

This is only true in "ideal" physics though, i.e. in complete vacuum. In actual real-world application the tumbling of the dropped bullet and the Magnus effect (the projectile's rotation relative to wind direction) on the fired bullet will make those times vary marginally respectively "significantly" (speaking of hundreds or tenths of a second), and under no likely circumstance will they ever hit the ground simultaneously. The projectile shape (center of mass and center of pressure) will determine the severity of the Magnus effect, as well as if it induces tumbling or not in the projectile. Thus even two different cartridges fired at the same muzzle velocity will hit the ground at different times.

 

Edit: So well... yeah. In broad principle what you say is absolutely true. Just depends on how detailed one wants to get.

 

You forgot to include curvature  of the earth.

[Inkophile]

You forgot to include curvature  of the earth.

 

Omitted that intentionally, actually. But yeah, it factors in too. Even less than the Magnus effect unless you are shooting pretty darn far though, and in an air-to-air scenario it is irrelevant, but I suppose I should have included it since I at all bothered mentioning effects on the dropped projectile.

[Finkeren]

There are other factors beyond muzzle velocity.

 

The UBS is a 12.7x108 cartridge with a projectile weight of 52 grams.

The MG131 is a 13x64B cartridge with a projectile weight of 36.2 grams.

Source: http://users.telenet.be/Emmanuel.Gustin/fgun/fgun-pe.html 

 

Though I am not a physics major... I'm guessing that the heavier cartridge in the UB will maintain its energy for a longer period of time and make for a better trajectory.

 

The size of the cartridge and amount of propellant has no influence on ballistics once the bullet leaves the barrel. The best way to show the effect of the amount on propellant actually is muzzle velocity. The weight of the projectile on the other hand is hugely important to ballistics. As a general rule, for projectiles of roughly similar shape and caliber, for the same muzzle velocity the heavier projectile will deccelerate slower and thus have a flatter trajectory. The UBS has both a higher muzzle velocity and fires a much heavier projectile, so it makes total sense, that the UBS will fire in a much, much flatter trajectory and do more damage at longer distances.

[ShamrockOneFive]

The size of the cartridge and amount of propellant has no influence on ballistics once the bullet leaves the barrel. The best way to show the effect of the amount on propellant actually is muzzle velocity. The weight of the projectile on the other hand is hugely important to ballistics. As a general rule, for projectiles of roughly similar shape and caliber, for the same muzzle velocity the heavier projectile will deccelerate slower and thus have a flatter trajectory. The UBS has both a higher muzzle velocity and fires a much heavier projectile, so it makes total sense, that the UBS will fire in a much, much flatter trajectory and do more damage at longer distances.

 

I wanted to explain the size to explain the added weight. I used to think, and many others probably still do, that the same calibre gun is apples to apples and in truth they are not when you look at the cartridge size. As you say... the UBS fires a heavier bullet at a higher velocity so its a slightly different kettle of fish than the MG131.

[Inkophile]

...so its a slightly different kettle of fish than the MG131.

 

It's a HUGELY different kettle of fish, actually. Okay that their damage potential up relatively close may be similar (okay, I know MG 131 uses a lot of explosive rounds, but hey have to hit too). It doesn't take all too much before the 12,7x108mm round has something like twice the velocity of the 13mm round because of different fall-off in speed, and that will make a humongous difference on the trajectory, and of course the damage potential of AP rounds.

 

The UB-series machine guns are plain and simple better weapons, vastly superior beyond a couple of hundred meters.

[JtD]

Not necessarily the "better" weapon, it simply was the bigger weapon. With all pro's and con's.

 

The MG131 was developed in order to have a harder hitting substitute for the light machine guns of 7.92mm, which were considered inadequate. Small size and light weight were design priorities, and the choice of the small 13x64B the result. It also came with electric firing. The qualities of the gun are most evident if you compare it to the one it replaced, the MG17.

 

The UB had to use the Russian standard 12.7x108 cartridge, and the rest was a result of that choice. It is both longer and heavier than the MG131, there's an as big as difference between the MG131 and the UB as there is between the MG131 and MG17. Naturally, the bigger gun with the bigger cartridge will also be harder hitting, no miracle to that.

[Inkophile]

That's a pretty good way of putting it. And although the UB isn't much heavier than a MG 131 (~5 kg heavier, which isn't that much on a turret ring or ball mount) it is also of much worse quality and basically designed as a disposable machine gun. The Germans would never do that, so to make a gun for that cartridge that'll actually last you can probably add a few kg more, and then you are starting to approach double the weight of the MG 131. At that point the MG 131's weight and cartridge size starts coming into its own right.

[Gunsmith86]

 

 

it is also of much worse quality and basically designed as a disposable machine gun.

 

 

so to make a gun for that cartridge that'll actually last you can probably add a few kg more

Your name fits thats absolutely wrong!

[III/JG2Gustav05]

I think Breda 12.7 have the worst velocity and trajectory actually. On 90 degree deflection angle VVS fighter can pass through your bullet stream without taking a single hit.inter

interesting to know, never tried this Italian fighter yet. Some resources suggest that the UBK is not very reliable, it is very often to get jam. 

Edited May 19, 2017 by III/JG2Gustav05

[Finkeren]

Some resources suggest that the UBK is not very reliable, it is very often to get jam.

Which sources are those?

 

What I've read seems to suggest, that the Berezin was actually quite reliable especially in very low temperatures and testing proved it to not jam when firing under G loads.

[III/JG2Gustav05]

just have a quick search, in Wikipedia Pe-2 "The Ammunition belt of the UBT machine-gun often jammed after the first burst of fire when shooting in extreme positions." seems not the gun itself but the belt.

[Finkeren]

just have a quick search, in Wikipedia Pe-2 "The Ammunition belt of the UBT machine-gun often jammed after the first burst of fire when shooting in extreme positions." seems not the gun itself but the belt.

On flexible mounts this will always be a concern. Just look at the massive guiding rails for the flexible .50 cals aboard a US bomber, and they still jammed quite often.

[Y29.Layin_Scunion]

With flexible mounts machine guns this will always be a concern simply happen.

FTFY

 

For someone to call a gun unreliable because the belt is being fed at an angle is like saying a car is a piece of junk because it doesn't run without oil.

 

A machine gun will jam if the ammunition is being fed awkwardly or at an angle.  I don't care who made it or where it's from or from what year.

[Field-Ops]

Your name fits thats absolutely wrong!

I think you missed the part where he was first talking about the russian gun, then switched to talking about the german gun.

[JtD]

Sorry to quote wiki with no further backup, but on the point Inkompentent was making:

 

the Beresin was deliberately expendable, that is, the Soviets' plan was to discard the entire gun after a short period of use during which one or another of the principal operating mechanisms became worn or broken.

The wiki article refers to a US study.

 

To me it makes sense, that the very competitive performance of the gun also in terms of weight would necessitate some compromises. The lack of a proper repair/maintenance capability would be such a compromise. Anyway, I've gotten curious. Does anyone have more info on that?

[Gunsmith86]

I think you missed the part where he was first talking about the russian gun, then switched to talking about the german gun.

no i didn´t miss that.

[Finkeren]

The wiki article refers to a US study.

 

To me it makes sense, that the very competitive performance of the gun also in terms of weight would necessitate some compromises. The lack of a proper repair/maintenance capability would be such a compromise. Anyway, I've gotten curious. Does anyone have more info on that?

I spent a bit of time a couple years back looking for info about the Soviet weapon systems in BoX. The Berezin was particularly frustrating, because despite its very widespread use (pretty much every major Soviet aircraft design made 1940-45 used it at some point) there seems to be very little reliable info in English. Much more appears to have been written about the more fancy ShKAS/ShVAK.

 

The idea, that the Berezin was deliberately made to be expendable always seems to come back to the same US Intelligence study from the 1950s. Soviet sources don't seem to mention it at all (from what i could find, Brano will probably show up and set me straight in a moment)

 

But the point is: Even if the Berezin was made deliberately weak and wore out faster than similar HMGs, that doesn't automatically translate into poor reliability. As long as it didn't break down from wear-and-tear it could be perfectly reliable, and at least Soviet tests during the war seems to indicate, that it was in fact quite reliable in operation (apart from the aforementioned belt-feed issue on flexible mounts)

 

We have to keep in mind, that aircraft machineguns generally speaking had very short service lives during WW2 (as did the planes) If a plane (and the guns inside it) survived 50 missions, that was considered extraordinary. Even if the Berezin fired all of its ammo on every single mission (which it wouldn't have) that would still be less than 10,000 shots total (or a little more than 10,000 if you go by the planes that carried the most ammo) over the gun's entire service life. That's not a whole lot for a machinegun.

 

I doubt many Brezins got worn out in service during WW2.

Edited May 20, 2017 by Finkeren

[Gunsmith86]

Christian Koll
SOVIET CANNON
A COMPREHENSIVE STUDY OF SOVIET GUNS AND
AMMUNITION IN CALIBRES 12.7MM TO 57MM

 

 

 

 

 

 

[ShamrockOneFive]

Thanks for sharing.

 

How does the estimated 10,000 rounds of reliable operation compare to similar weapons of the time such as the M2 and the MG131?

[Jaws2002]

The rate of fire of the UBT would also make it much easier to put rounds on target though wouldn't it? Feels to me that the MG131 rate of fire was too slow for the job of shooting an airframe at fast closing speeds

 

 

MG131 shoots 900 rounds per minute....That's very good for a  HMG.

 

 

Here's a nice video about the MG131.

 

 

 

 Switching from rifle caliber guns to to MG131's was a solid improvement in firepower in real world. 

Edited May 20, 2017 by Jaws2002

[Gunsmith86]

Thanks for sharing.

 

How does the estimated 10,000 rounds of reliable operation compare to similar weapons of the time such as the M2 and the MG131?

One dokument gives 11000 rounds without problems for two tested MG 131.

[Finkeren]

Usually, the thing you have to worry about first is not the cycling mechanism breaking down but the barrel getting worn out, which results in significantly reduced accuracy, but will generally not cause jamming. Barrel life for machineguns seem to range from approx. 5000 rounds on the low end to tens of thousands on the high end. Normally you should expect the cycling mechanism and breech lock to survive much longer than the barrel.