P-51 gun spread

[Dirkan]

One thing I've noticed is that gun overheating is NOT modelled for the 109 or the 190. You won't have any increase in spread no matter how long you shoot, nor any decrease in bullet velocity.

 

I'd like to know if the code is correct though.

 

7.823 kJ - one shot energy. <---- Did anyone find anything about this? I've been unable to dig this up on the internet. I guess it's the amount of heat energy transferred to the barrel by one shot, but it's usually at around 30%, not around 50% like in this case.

 

[From the code] 7.823 kJ - one shot energy , 462 J (steel specific heat), 6 kg - barrels mass

 

Assuming all of this is correct, every shot will heat the barrel up by 2.82 degrees.

 

This also means that if you fire around 460 bullets in one go, your barrel has reached the melting point of steel. With 800 rounds per minute, this is after 35 seconds.

 

This feels way excessive.

Edited July 31, 2016 by Dirkan

[TwoLate]

This has been a very informative thread. I have gain a better understanding of gunnery. Thanks all.

[Yo-Yo]

Hi all.

 

Firstly this is not a critisism of dcs P51, ED Devs or any forum user, just a few observations of my own and questions about the topic of gunnery concerning the P51 and my own thoughts on this subject.

 

The actual Horizontal convergance setting in game for the P51 are:-

 

Inner guns 1007.814ft or 335.93 yards

Middle guns 1466.339ft or 488.77 yards

Outer guns 1337.86ft or 445.95 yards

 

The above was worked out using the info in the .lua files for gun muzzle positions and azimuths. I worked out the above, if i have made an error i apologise lol.

 

So the above will give a pattern to cover targets over a wide range of engagement distances and also give more chances of hits with a less than perfect aim, this will benefit average and good shooters a like, but at the cost of bullet density on target and less lethality of your bursts.

 

If the sim moddels bullet/gun despersion correctly, which are based on a 4 MIL Disperion cone in the original P51-D Harmonization charts, this will give a 4ft diameter cone of fire at 1000ft, so this gives some allowance in your aim, So to have 6 guns for example with a point convergance at 1000ft and fire a 1 second burst will place 80 projectiles within or very close to a 4ft diameter circle at this range and a good shot density. At shorter ranges the cones from individual guns will still be converging and dispersion will be smaller, so each cone will have a more density but the cones will be spread out. At longer ranges the cones from individual guns will be diverging but dispersion increasing so still giving good coverage but a lower shot density overall. So the point convergance delivers a very dense and destructive pattern from 6 guns only at or near to the point range. The "Optimised pattern will only really place 2 guns overlapping within this circle at this range with the other 4 guns overlapping slightly to the left and right.

The current pattern if i have understood other threads correctly is the "Optimised pattern for the K14" and is good overall setting for the guns but must fail to give really dense shot patterns at any range, but it is less sensitive to range. I find it works ok online and offline, but combat styles and shooting range varies from pilot to pilot, so i played with my files and tried different Horizontal convergance settings (offline) wont work online unless you have a mods on server. I set the vertical (elevation)convergance too so projectiles will cross the sight line at the convergance range. But lets just concentrate on the horizontal for now.

 

600ft Too short for me but did give excellent results at or near to convergange range and a good solid burst kills much more effectively than the current "Optimised pattern". Works well with K14.

 

1000ft This works best for me. A good short burst kills or cripples EA no problem, works well with K14. Good for ground attack as well. Less range sensitive than the 600ft convergance, works well + or - 150ft of the convergance point and its not that bad past these points either. More effective than the current "Optimised pattern"

 

1500ft Too long for me. Might be ok for bashing bombers or ground attack,

But not good as you get closer in. At this range gun dispersion is starting to work against you. Still worked ok with K14. Not quite as effective or flexible as current "Optimised pattern"

 

2000ft Way too long. Tried for comparison only. Not as effective as current "Optimised pattern"

 

I also copied a P51-D Harminization chart that uses a smaller pattern than the one currently in game and this was more effective too (than current), worked well with K14 and gave good results on target. I've added as an attachment at the bottom.

 

I also tried the 600ft and 1000ft point convergance using only 4 guns (inner and outer by altering lua file and removing the ammunition for the middle guns) and with only 4 guns it was more effective than the current "Optimised pattern" using 6 guns.

 

It would be good to have some presets for convergance in game (i know not totally historic but neither is turn fighting on deck with 10% fuel but people do it) say 5 presets for example 750ft, 1000ft, 1500ft, small pattern and current "Optimised pattern". I understand the devs time is in short supply, but it would be a good feature to some.

 

Whilst looking in the lua files i noticed some figures in there that seemed strange to me, and if anyone can explain them i would be greatful.

 

Gun weights. barrel 6 (i presume KG), body 32 (again i presume KG)

this gives a total individual gun weight of 38 (KG?) This is the weight of an M2HB an AN/M2 aircraft gun weighs around 27KG so each gun is 11KG Heavier in game? +66KG Overall for 6 guns?

 

Ammunition quantity. On pg 50-51 of the manual it says 400 rds for the 2 inner guns and 270 for the 4 outer guns. But in the lua file for the guns the inner guns carry 500 rds per gun, 100rds too many per gun, 200rds overall too much ammunition thats approx +27KG of ammunition and links? too much?

 

Shot heat. 7.823Kj. I have no idea how accurate this is, but the guns even when used very carefully seem to heat up but not cool down, and as i've seen in other threads others have noticed this too.

I tried changing it to 5.825Kj just for comparison and the gun over heat is managable, but i have no idea what the real figure should be.

 

There are probably reasons for the above points, if anyone can help please get in touch.

 

And lastly i would love it if i could choose whether i carry tracers in my guns or not, and not too un historical as i've seen pilot quotes that talk about not using them, theres a very good quote from a US p51? ( i cant remember the Gentlemans name) pilot talking about removing the tracers from their belts, its in Shaws book. I'll look for it and add it. I can remove tracers by altering the lua files but again only for offline practice, would be nice to loose them online too.

 

The above are just my thoughts on the subject and i understand Dev time is short. Thanks for reading.

 

S! Hub.

 

I think that get the numbers from lua directly as they are written is not a good idea... :) because sometimes it's not a pure physical constants but rather results of preceding calculations, sometimes - estimations and experimental adjustment. By the way, you do not see, for example, cooling of the barrels that is behind the scene, so finding the melting point is not a good idea... :)

 

Anyway. M2 as well as several Russian .50 machine guns do have restrictions to the fire rate and number of rounds fired.

 

Regarding German's weapon. I tried to find official direction regarding overheat and jam preventing without success. Then I asked Erich Brunotte about it and he told that no restriction were for 190 and 109 he flew as well as he never experienced jams and other fails due to overheat. He told that they shoot as long as it was necessary.

[BSS_Sniper]

Pure speculation, but I think the gun barrels warp because of the heat.

 

I've seen .50's so hot during a night fire that they were glowing red/white and you could see the rounds traveling through the barrel. The same for the 60 and 240, never see a barrel warp. I take that back, I've seen one barrel warp/bent, but it was on an M16A2 and I don't think it was from firing.

[BSS_Sniper]

I think that get the numbers from lua directly as they are written is not a good idea... :) because sometimes it's not a pure physical constants but rather results of preceding calculations, sometimes - estimations and experimental adjustment. By the way, you do not see, for example, cooling of the barrels that is behind the scene, so finding the melting point is not a good idea... :)

 

Anyway. M2 as well as several Russian .50 machine guns do have restrictions to the fire rate and number of rounds fired.

 

Regarding German's weapon. I tried to find official direction regarding overheat and jam preventing without success. Then I asked Erich Brunotte about it and he told that no restriction were for 190 and 109 he flew as well as he never experienced jams and other fails due to overheat. He told that they shoot as long as it was necessary.

 

US .50's do have restrictions on rates of fire as well as total rounds fired. It's in every TM that comes with the weapon. Having said that, the aircraft .50's may very well be different in employment, but they do have limitations.

[Merlin-27]

also "cook-offs" were a result of the hot barrels...

 

[Dirkan]

So then, is it possible to implement the barrels being repairable when you request it from the ground crew? Or if it's done at the same time you rearm and refuel like in the MiG-21 with the radar coolant and radar time.

 

Because right now, they are not repairable.