Russian guns balistics...

[1PL-Husar-1Esk]

Easy empirical spread test can be setup in mission editor (stationary airplane plus wall 500m away with camera on it) mark holes and then compared side by side.

Edited September 14, 2017 by 307_Tomcat

[AndyJWest]

Easy empirical spread test can be setup in mission editor (stationary airplane plus wall 500m away with camera on it) mark holes and then compared side by side.

 

See my earlier post: https://forum.il2sturmovik.com/topic/31160-russian-guns-balistics/?p=510212

[1PL-Husar-1Esk]

This has been tried before, with rather unsatisfactory results. You need the engine running to fire most guns, and the combination of engine vibration and recoil while the aircraft sits on a flexible undercarriage results in a lot of spread that you wouldn't see in flight.

This test can be done with auto level and balloon. BTW I think that there is no engine vibration model and recoil (as separate parameters different from ground or in air ,rpms or else) - just set gun dispersion which agrees with data that Dev team have collected during research. Edited September 14, 2017 by 307_Tomcat

[IRRE_Centx]

and I don't see how your unquantified factors would negate this trend

 

Seriously? 

 

 

 

His estimation takes into account only two parameters for the projectile:

- the mass

- the velocity

 

So, same example as already used before (seriously it's an example for 5 years old kids...)

- 1 kg of lead

- 1 kg of feathers

 

Let's say you send both masses at 100 km/h

So with his approximation, since mass and velocity are equal, they should have exactly the same trajectory.

 

 

And YES it's right.

If you send them in complete vacuum... 

 

 

 

Even the rotation of the Earth have an influence on the trajectory of a bullet (ever heard about the Coriolis effect? Google it) and you're considering that his approximation is valid when he's neglecting the whole atmosphere   (among other things...)

Edited September 14, 2017 by -IRRE-Centx

[1PL-Husar-1Esk]

For sure you right, but the game do not take many real life parameters into account it's more to ideal (vacuum) environment. So simplicity must agree with real life results (taken from real life empirical test).

[IRRE_Centx]

For sure you right, but the game do not take many real life parameters into account it's more to ideal (vacuum) environment. So simplicity must agree with real life results (taken from real life empirical test).

 

Note that I never said that the game simulates everything, of course they don't!

There are things called semi-empirical models, which are basically models mixing some basic physic relationships with some curve fitting of experimental datas to enhance the approximations.

I have no idea how they simulate the bullets in game, but if I should bet on it I guess they use such types of models.

 

And by the way Han posted the ballistic of AP rounds for two incoming weapons in the last DD, and the curves fit pretty well the experimental datas:

https://forum.il2sturmovik.com/topic/168-developer-diary/?p=508214

 

 

But in this topic some people are assuming that you can obtain a somewhat realistic bullet trajectory by considering only the projectile mass and the muzzle velocity...

Moreover they compare different projectiles with only those two parameters, basically ignoring other parameters such as aerodynamic properties... 

Edited September 14, 2017 by -IRRE-Centx

[unreasonable]

Seriously? 

 

 

 

His estimation takes into account only two parameters for the projectile:

- the mass

- the velocity

 

So, same example as already used before (seriously it's an example for 5 years old kids...)

- 1 kg of lead

- 1 kg of feathers

 

Let's say you send both masses at 100 km/h

So with his approximation, since mass and velocity are equal, they should have exactly the same trajectory.

 

 

And YES it's right.

If you send them in complete vacuum... 

 

 

 

Even the rotation of the Earth have an influence on the trajectory of a bullet (ever heard about the Coriolis effect? Google it) and you're considering that his approximation is valid when he's neglecting the whole atmosphere   (among other things...)

 

If you had read the thread you would have noticed that I said at the beginning that ballistics was horribly complicated. I think anyone who has spent any time studying the subject knows that.  My own experience with the subject is with small arms.

 

The specific example SuperEtendard mentioned was comparing two 20mm cannon shells fired by different guns. Comparing this to a case involving feathers and bullets is ludicrous.   

 

AFAIK no-one is ignoring aerodynamic properties - simply stating that in the absence of detailed data on the difference in such properties between two different 20mm cannons, it is highly likely that the gun with  the heavier projectiles and higher muzzle velocity will have a flatter trajectory. If you do not know what the effect of the other properties are, and have no way to find out, your best starting point is that they are equal for the two cases.   If you were made to take a bet on which trajectory was flatter, and allowed two pieces of information on which to make the bet, I suspect that the initial muzzle velocity and the mass of the projectiles would be at the top of your list.

 

The data for the shells obviously depends on which ones - for example for HE ShVAK has a muzzle velocity of 790 m/s and a projectile weight of 91g.  The Hispano has 840 m/s and 130g.  They are both 20mm cannon shells - you would need a great deal of difference in shape,  spin, roughness etc to make the ShVAK trajectory flatter. 

 

I stand by my claim that I would be surprised if the ShVAKs trajectory was flatter than the Hispanos.  This is a completely different thing from claiming that anyone can obtain a somewhat realistic bullet trajectory  by only considering these variable. (ie mass and muzzle velocity).  From my earlier post "So my guess would be that in addition to the starting vector, the formula includes initial velocity, plus some value for the ballistic and drag characteristics of each round."  Drag characteristics!    

 

 Surprised - that means I think it likely - of course if you know differently perhaps you should tell us what the answer actually is.

Edited September 14, 2017 by unreasonable

[JtD]

- 1 kg of lead

- 1 kg of feathers

 

So which one is shooting the feathers - the ShVAK or the Hispano? Or is it possible that you're so keen on turning this into an academic discussion that you've completely lost sight of the issue at hand?

 

You do understand, even with your inclination towards the academic, that taking into effect the major factors while ignoring the minors will still give you a reliable approximation? And do you understand that the major factors in a comparison between feathers and lead are different from the major factors in a comparison between two projectiles of the same diameter?

Your example does not illustrate the inappropriateness of a simplified approach, it illustrates your personal unwillingness to simplify.

 

I'm with unreasonable, tell us what the answer is. What's having the flatter trajectory - a ShVAK round or a Hispano round of similar type?

[Holtzauge]

Maybe the problem is simply inexperience? Some younger engineers fresh out of school don't have the ability to make reasonable guesstimates like unreasonable just did. Just a theory mind you…..

[Brano]

Take T-34 or Pzkpfw III and fire the main gun against some elevated area/hill at 500-600m. You will notice that projectiles have side drift according to rifling (right twist) and will land not at crosshair,but rather a bit to the right. Wind has also impact on the projectile. It pushes the projectile in its direction.

[JtD]

If I truly did this, I'd be in real trouble with the police.

Edited September 14, 2017 by JtD

[Brano]

Hehe

No police in game. You can shoot at whatever you want :D

Shell drifting was first thing I checked when tanks were implemented in game and I was positively surprised that Devs paid attention to such details.

[[CPT]Crunch]

Nobody mentioned rate of fire, if guns are fixed at or near max rates in game, and many were actually regulated to fire through a prop, that can severely upset the oxcart.  That'll also splain the ability to take those long sniper shots, easy when you can pepper the target box quicker.

 

Don't have the game currently set up, new build in progress, but flight idle at min RPM's, time the ammo dump, than max RPM's.  If it's the same firing through a prop, something fishy.

[Venturi]

The ballistic coefficient and muzzle velocity of the projectile, not its weight, determine both wind drift and drop over sitance.

 

Heavier projectiles only gain inthese properties over lighter ones insofar as they typically have an intrinsically higher ballistic coefficient. (But require a lot more equipment - powder, barrel length, bolt mass - to enable them to reach equivalent speeds with lighter projectiles.)

 

My experience is with long distance rifle shooting to 600yds and beyond

[Finkeren]

Nobody mentioned rate of fire, if guns are fixed at or near max rates in game, and many were actually regulated to fire through a prop, that can severely upset the oxcart. That'll also splain the ability to take those long sniper shots, easy when you can pepper the target box quicker.

 

Don't have the game currently set up, new build in progress, but flight idle at min RPM's, time the ammo dump, than max RPM's. If it's the same firing through a prop, something fishy.

Synchronisation is absolutely modeled and very accurately so. It as been there since Rise Of Flight, where it is very noticable because you have far greater fluctuation in propeller rpm. In his sim we don't notice it as much, both because rpm is much more stable due to constant speed propellers but also because WW2 synchronisation gears give off far more firing impulses per propeller revolution than in WW1 (typically 3 or 6 per revolution for a three-bladed prop compared to 1 or 2 on most WW1 gears) - far more impulses than even the fastest firing gun needs at normal rpm - resulting in a lot more stable and generally higher rate of fire.

 

Still, it is definitely there. If you want to test it just fly the Fw 190 in QM, turn the engine off and start firing. You can hear the rate of fire start to fluctuate as rpm drops, then it becomes slower, then it stutters and finally the firing stops as the propeller comes to a halt.

Edited September 15, 2017 by Finkeren

[unreasonable]

The ballistic coefficient and muzzle velocity of the projectile, not its weight, determine both wind drift and drop over sitance.

 

Heavier projectiles only gain inthese properties over lighter ones insofar as they typically have an intrinsically higher ballistic coefficient. (But require a lot more equipment - powder, barrel length, bolt mass - to enable them to reach equivalent speeds with lighter projectiles.)

 

My experience is with long distance rifle shooting to 600yds and beyond

 

A ballistic coefficient is just a short hand way of combining the mass, shape and other drag characteristics of a projectile to make calculation easier.  It is not a fundamental physical quantity.  It is entirely possible to calculate trajectories without using a ballistic coefficient at all -  just horribly time consuming. 

 

Heavier projectiles have a higher ballistic coefficient, other things being equal, because they are heavier - that is just the maths.

 

In the case we were discussing, where the other factors that affect the ballistic coefficient are not know, but can be assumed to be broadly similar (ie we are not discussing feathers and lead), then weight (or more properly mass) is indeed one of the determinants of trajectory.

[Gunsmith86]

7,92 mm Ammo:

 

15mm MG 151 Ammo:

 

 

20mm MG FFM Ammo:

 

 

20mm MG151/20 Ammo:

 

 

 

[BlitzPig_EL]

As I recall from my days shooting an M1 Garand in service rifle competition, we used heavier (175 grain) boat tail match bullets because they stayed supersonic longer than standard issue 147/150 grain ammo, and thus were more accurate at range (600 yards +) because when a projectile drops below supersonic it destabilizes and this greatly affects accuracy at range.

 

But as has been said, the weight is only part of the equation.  Because a heavier projectile will by necessity be longer than a lighter one of the same diameter, it will have better aerodynamic qualities, and greater sectional density.

 

An illustration of this is the 6.5x55 Swedish service round,  It is only around 140 grains in weight, but it has a very high ballistic coefficient and is known as one of the more accurate service calibers ever used.  I can personally verify that.   A bit off topic, but the Swedish M1896 rifle, in all it's variations is probably the best Mauser type rifle ever produced, and clearly the most accurate.

Edited September 15, 2017 by BlitzPig_EL

[unreasonable]

Agreed BlitzPig, weight is only one part of the equation. Although a heavier projectile will not necessarily be longer than a lighter one, if they use materials of different density.  Lead shot vs steel shot, for instance in shotgun pellets, or AP rounds with special cores.  

 

Although I doubt that applies to the Hispano vs ShVAK example. 

[Venturi]

An opposite illustration that weight does NOT matter - aerodynamic properties are the entirety - would be a round-nose 300gr bullet as used in 375 H&H versus a spire point 225gr bullet.

 

Go ahead and download a ballistics program, like I have, and run a drop over distance and wind drift for both bullets at the same muzzle velocity. You will find, just like the cartridge designers at the turn of the twentieth century, that the 300gr bullet does not do as well.

 

Weight is important only insofar as it gives greater ballistic coefficient and effect on target.

 

And it absolutely does play into 20mm cannon shells.

[unreasonable]

An opposite illustration that weight does NOT matter - aerodynamic properties are the entirety - would be a round-nose 300gr bullet as used in 375 H&H versus a spire point 225gr bullet.

 

Go ahead and download a ballistics program, like I have, and run a drop over distance and wind drift for both bullets at the same muzzle velocity. You will find, just like the cartridge designers at the turn of the twentieth century, that the 300gr bullet does not do as well.

 

Weight is important only insofar as it gives greater ballistic coefficient and effect on target.

 

And it absolutely does play into 20mm cannon shells.

 

This is just the lead vs feathers example, all dressed up.   Easier just to take a simple thought experiment.

 

1)  Take two identical cannons firing identical shells at the same initial muzzle velocity.

 

2)  Now make the shells so that one contains a slightly denser inner core - the weight is different but the size, external shape and finish are identical.

 

3)  Fire them again at the same muzzle velocity - which will take a larger charge (edit - or possibly longer barrel) for the heavier shell since a greater force is required to accelerate the greater mass from rest to the same velocity.  

 

4) The shells have the same drag - so the air resistance exerts the same force on each shell. It will decelerate the heavier shell less, so it will have a flatter trajectory, ie a greater range.

 

This is just simple physics. But if you want to do it in ballistic coefficient terms: Here we are from Wiki:

 

" The formula for calculating the ballistic coefficient for small and large arms projectiles only is as follows:

BC = m/ (d^2 . i) 

Where:

• BC_Projectile = ballistic coefficient as used in point mass trajectory from the Siacci method (less than 20 degrees).
• m = mass of bullet
• d = measured cross section (diameter) of projectile
• i = Coefficient of form"

 

Note that the formula for ballistic coefficent contains mass as the numerator!  In other words, as in my thought experience, if the terms d and i are the same for two shells, the difference in BC is down to mass. 

 

I really do not know why this is causing so much confusion.  I have said that I would be surprised if the ShVAK's trajectory was flatter than that of the  Hispano's since the latter has a heavier shell with the faster muzzle velocity, not that it was impossible.

For the ShVAK to be flatter, either I have got my facts about velocity and shell mass wrong, or there is a large difference in some other factor. We know that d^2 is the same, don't we?   SuperEtendard mentioned the shape of the shells - as does Venturi above in a small arms context.

But in this case the ShVAK shells seem to be blunter - ie other things being equal they would have more drag.

 

If someone has specific facts about the two shells - or cannons - in question that would explain how the ShVAK's trajectory can be flatter, please post them.  

Edited September 16, 2017 by unreasonable

[Holtzauge]

I absolutely agree unreasonable: The ShVAK has a number of muzzle velocities listed, the highest I have found being 860 m/s with a 96 g round. The Hispano is listed at 860 m/s with a 130 g round. They both are 20 mm calibre and consequently have the same cross section. Aerodynamically they look rather similar. So how on earth could the ShVAK shoot a flatter trajectory with a lower cross section loading and same muzzle velocity?

[Lusekofte]

Yes, ..it's very funny. You can see in a combat at distance, Russian planes firing laser beams straight to his target, ..and you can see the Germans airplanes spreading tracer bullets like a grandpa with parkinson watering a garden.    

I´m sure that something is wrong in the ballistic model.

 

 

Funny I flown the sturmovik from the beginning, there is no lazerbeam shooting. You have to take ballistic travel into consideration when aiming. For your information Russian cannons and mg surprised Axis and allied by their efficiency 

[E69_geramos109]

I also flown BOS for quite a long and everyone knows that I use to fly a lot more German side. So is quite surprising how i make sniper shots with a quite short practice with a red plane like 700-800m far

[Guest deleted@83466]

I also flown BOS for quite a long and everyone knows that I use to fly a lot more German side. So is quite surprising how i make sniper shots with a quite short practice with a red plane like 700-800m far

 

Well, maybe you can teach me how to do it, because for the last 6 months at least I've flown almost exclusively VVS, every night, and while "long distance" shots at a fleeing 109, flying straight and level and complacent, are not uncommon, the distance is probably more like 400 meters at best, and lots of ammo is wasted in doing so.  I am simply not making these supposedly easy 800 meter sniper shots that Luftwaffe-only pilots talk about as a given.  A couple of months ago in an attempt to improve my gunnery I started to pay a lot more attention to the apparent width of aircraft in mils (and with the rangefinding sight in the Spitfire), and I realized that aircraft out past a certain distance were actually a lot closer than I would have estimated.

[3./JG15_Kampf]

I have seen many video of red planes hitting the 700-800 meters. Does anyone have a German plane video hitting a red plane at this distance? Please share

[1PL-Husar-1Esk]

I have seen many video of red planes hitting the 700-800 meters. Does anyone have a German plane video hitting a red plane at this distance? Please share

 

1:43 & 2:28

[3./JG15_Kampf]

THX Tomcat.

Any with MG 151/20?

[BraveSirRobin]

Why would a 109 or 190 driver shoot from 800 meters when he'll only be 80 meters away in a minute or two?

[Lusekofte]

I also flown BOS for quite a long and everyone knows that I use to fly a lot more German side. So is quite surprising how i make sniper shots with a quite short practice with a red plane like 700-800m far

 

You know that many russian fighters are much more stable weapon platform than the 109, you know there are way more reasons for accuracy than ballistic travel? I think it is redicioulus that Luftwaffe always the ones that insist to set the standard on how planes should perform , it has become pathetic 

[Guest deleted@83466]

Wasn't it just the other day, BSR, that we in 1b's and were chasing Kampf in his 190 down there on the deck?  He was a lot closer than 800 meters, and I was blasting away at him with no visible effect, until I was very worried about my ammo supply.  You were too.  So we turned away to get back to our side, but he came back after us, apparently still in fighting condition, after so much ammo was expended on him, at ranges I'm guessing were no more than 500 meters.  The stats show that I didn't make a single logable hit on him during our original chase with my long range firing.  There was certainly no impression on my end of "laser cannons".  I only hit him later on, when he was dogfighting with us.  This situation is typical of my experience flying Russian aircraft.

Edited September 16, 2017 by Iceworm

[3./JG15_Kampf]

Why would a 109 or 190 driver shoot from 800 meters when he'll only be 80 meters away in a minute or two?

Perhaps to test the range and accuracy of the weapon

[3./JG15_Kampf]

Wasn't it just the other day, BSR, that we in 1b's and were chasing Kampf in his 190 down there on the deck? He was a lot closer than 800 meters, and I was blasting away at him with no visible effect, until I was very worried about my ammo supply. You were too. So we turned away to get back to our side, but he came back after us, apparently still in fighting condition, after so much ammo was expended on him, at ranges I'm guessing were no more than 500 meters. The stats show that I didn't make a single logable hit on him during our original chase with my long range firing. There was certainly no impression on my end of "laser cannons". I only hit him later on, when he was dogfighting with us. This situation is typical of my experience flying Russian aircraft.

This is true. I heard at least 2 blasts in my fuselage (FW190), but I did not see any damage. It is also true that I already had the fuel tank drained (FW190, on another server) at 760 meters, by an yak

Edited September 17, 2017 by 3./JG15_Kampf

[BraveSirRobin]

This is true. I heard at least 2 blasts in the fuselage, but I saw no damage. It is also true that I already had the fuel tank drained (on another server) at 760 meters for a yak

 

How many kills do you have shooting from 500+ meters in the Yak?

[Finkeren]

To put it bluntly: The reason we don't see German pilots open fire at +500m has nothing to with accuracy of their guns. They don't do it because they don't have to, since they generally have no trouble quickly getting close to an opposing plane and get a better shooting solution.

 

VVS pilots on the other hand will sometimes resort to long range shots, because they know that it might be the only chance they'll get. Sometimes it works, mostly it doesn't - but even when it does work, it is a huge waste of ammo that the VVS pilot would avoid, if he had other options.

[BraveSirRobin]

Perhaps to test the range and accuracy of the weapon

 

lol  And yet you never seem to want to test the range and accuracy of the Yak's weapons...

[3./JG15_Kampf]

How many kills do you have shooting from 500+ meters in the Yak?

 No, I do not have yak.

  Is this one?

https://forum.il2sturmovik.com/topic/30187-can-someone-define-distance/?do=findComment&comment=490933

Share your kill + 500 meter flying bf109 or fw190

Edited September 17, 2017 by 3./JG15_Kampf

[BraveSirRobin]

 

 No, I do not have yak

 

 

Yes, you do have Yak.  But you never fly it in MP.  Right?  

 

BTW, I'm not sure what you think that video proves.  Anyone can spray and pray.  Even 190/109 drivers.  Of course, they have no reason to take long range shots.  All they have to do is wait until they can get a short range shot.  It's actually funny watching them try to ignore that rather obvious fact.

[JtD]

They don't do it because they don't have to, since they generally have no trouble quickly getting close to an opposing plane and get a better shooting solution.

I agree with as far a fighter combat goes, but picking away at bombers from several hundred meters away is useful for everyone, because you can stay outside the bombers defensive guns range. It probably is more useful for LW fighters here, given the larger defensive guns on VVS bombers.

[Wraithzlt]

To put it bluntly: The reason we don't see German pilots open fire at +500m has nothing to with accuracy of their guns. They don't do it because they don't have to, since they generally have no trouble quickly getting close to an opposing plane and get a better shooting solution.

 

VVS pilots on the other hand will sometimes resort to long range shots, because they know that it might be the only chance they'll get. Sometimes it works, mostly it doesn't - but even when it does work, it is a huge waste of ammo that the VVS pilot would avoid, if he had other options.

^^^This all the way.

109s and 190s are "almost" untouchable when flown well holding the alt advantage. This is the reason there are alot of VVS snipers. VVS are forced to take these shots all the time, so it is no wonder some of them become excellent at it. Also in these situations (stalling VVS shooting at 109 at zoom climb apex/near stall) the german planes are usually very slow themselves, so alot easier to hit.

I personally have been hit (and downed) at what i thought was extreme range by by german fighters while holding a large alt advantage (in rare cases) over them in the mig and yak. 

Though i would be interested to see some proper testing carried out by some dedicated people on this forum about the ballistics in question. The closer to real life the better!