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Super slow .50 caliber rounds


unltd

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Thanks NineLine. A tip for practicing... edit the Mig-15bis.lua as well and change the max g limit to about 4 to 6 g's and limit the max bank angle to 70-80.' This will curb their aerobatic ability and make it a bit more realistic for a non g suit aircraft with non flying tail and thick wings. They still climb like Sputnik but if you yo yo out or hammerhead in the vertical and keep your nose below his, you can follow them through the vertical and close in a dive. Let them go higher and keep your speed usable. Wait for them to come back down.

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[sIGPIC][/sIGPIC]

It's perfectly ordinary banter Squiffy, "Bally Jerry, pranged his kite, right in the 'how's your father.'" - Monty Python, RAF Banter Sketch.

Squiffy, a. slang. 1. Intoxicated; drunk. 2. Askew, skew-whiff. - OED

 

"Put that sucker in a 4G turn and keep it there!!" - Maj. Gen. "Boots" Blesse

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If you play single player, then for now you can change .lua files according to my post #163:

https://forums.eagle.ru/forum/englis...65#post6290565

 

Also you may reduce gun overheating dispersion to minimum or even 0 and increase round count to 300. It's described in some previous posts.

But better backup original files as you won't be able to join multiplayer. Also DSC World updates may overwrite your changes.

 

Thanks for this info. I'm not good enough for multiplayer yet (I am quite certain real players will thoroughly trounce me until I have a lot more practice flying), so I will probably do this so I can effectively play the single-player campaigns for it.

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On 10/27/2020 at 7:16 PM, NineLine said:

Sorry guys, I have been hammering the team on other things, I will get back to this soon.

Thank you Nineline for pushing on this topic. I hope it is still alive.

 

S!

 

No.54 Joker

 

from Repeating and Multi-Fire Weapons: By Gerald Prenderghast

SabreTopicM3GunAmmoReference.GIF

from TigerCheck: b ySteven A Fino

Sabre_Typical_M3_Loadout-TigerCheck_by_StevenAFino.GIF


Edited by JokerMan
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On 10/27/2020 at 6:16 PM, NineLine said:

Sorry guys, I have been hammering the team on other things, I will get back to this soon.

 

@NineLine

I don't know what your version of "soon" is, but it's been quite a while... I don't think we've seen ONE person say on this thread that this change is OP, or ahistorical, or incorrect, and given it's a simple lua change, can ED just pull their finger out and make it while I'm still alive so I can use the product I've paid good money for correctly? This complete lack of support and explanation is exactly the reason why I will not pay another penny to ED regardless of whatever modules they deign to make. I've spent over 200 quid on this module alone, purchasing several copies for squadron mates. Its frustrating to say the least.

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Really ED?   So disappointing that such an easy and important change has never been done.  WTF???  I'd guess most buyers like me of this module gave up flying it so long ago that they've all forgotten why they stopped flying the module.

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On 4/10/2021 at 10:24 AM, unltd said:

Really ED?   So disappointing that such an easy and important change has never been done.  WTF???  I'd guess most buyers like me of this module gave up flying it so long ago that they've all forgotten why they stopped flying the module.

Oof. You're honestly right, I'd imagine.

 

I have to say, ED, this is utterly unacceptable. A simple .LUA fix after this much evidence has been presented? It's incredibly frustrating to see goalposts constantly move and, even when met, to have them ignored. For half a decade.

 

I'll have to caution myself the next time I buy anything that's first party ED if this is going to be a result.


Edited by MiG21bisFishbedL
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Reformers hate him! This one weird trick found by a bush pilot will make gunfighter obsessed old farts angry at your multi-role carrier deck line up!

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On 4/15/2021 at 7:13 AM, Tucano_uy said:

There’s clearly, for whatever reason, no willingness to fix this issue. 

 

The module was* Belsimtek (now part of ED) and as ED are the platform as well, hopefully 'no willingness' is not the case (though it's a tough counter to make Tucano, I agree).  

 

NineLine has engaged with this topic above; it's just that the wheels are turning painfully slowly.

The whole topic is unnecessary and it's doing no one any good.

 

DCS2.7 has dropped (to acclaim, kudos ED) and once past the immediate bugs fix and patch cycle(s) that are inevitable, hopefully this will free up the short amount of time necessary to address this Sabre gun issue finally. 

 

As a community (on this thread in particular), we have put our best feet forward in the main, with research, testing our ideas and verifying a proposed solution. We have effectively communicated it in a mature and serious way.  

 

What boils down to little more than a tweak to an LUA line of code ........   

 

DCS 2.7 has one solitoary update for the Sabre and it is a tweak, (likely of similar magnitude to that needed to address this Sabre guns issue).

I read the changelog (linked) and ... heart sunk 😞 

https://www.digitalcombatsimulator.com/en/news/changelog/openbeta/2.7.0.4625/ 

 

Here's hoping that DCS2.7's release frees up the time needed on ED's side.

 

*EDIT: Update based on Buzzles correction below.

S!


Edited by JokerMan
*EDIT: Update based on Buzzles correction below.
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7 hours ago, JokerMan said:

The module is Belsimtek, ED are the platform and well, hopefully 'no willingness' is not the case (though it's a tough counter to make Tucano, I agree).  H

The module WAS Belsimtek, they were absorbed back into ED the other year. It's definitely now an ED module.


Edited by Buzzles
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On 10/28/2020 at 5:16 AM, NineLine said:

Sorry guys, I have been hammering the team on other things, I will get back to this soon.

Hi mate,

Any update on this?

All the modern stuff and WW2 has had so much love, we want our early jets to be next... please tell us some F-86 improvements soon?

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The drag on the bullets the Sabre uses are to high.

The F-86 uses the bullets as defined in the lua files as.

 

shells = {"M2_50_aero_AP","M20_50_aero_APIT"},

mixes = {{1,2,2,1,2,2}}, --

 

 

In the shell table the drag currently is  defined as

M20_50_aero_APIT.lua

cx = { 0.5, 0.61, 0.8, 0.27, 2 },

 

M2_50_aero_AP.lua

cx = { 0.5, 0.61, 0.8, 0.27, 2 }

 The variables are defined as. 

-- Drag (Сx) = {
0.5 , -- Cx_k0 Cd0 at low mach ( M << 1) 
0.61 , -- Cx_k1 Peak Cd0 value 
0.8 , -- Cx_k2 steepness of the drag curve before the transonic wave crisis 
0.27, -- Cx_k3 Cd0 at high mach (M>>1)
2 , -- Cx_k4 steepness of the drag curve after the transonic wave crisis  
}

 

Drag profiles for all the rounds are available from primary sources. Primarily, the US Ballistic Research Lab.

 

The first two drag profiles are from the Ballistic Research Lab's 1990 range test. "The Aerodynamic Characteristics of .50 Ball, M33, API, M8, and APIT, M20 Ammunition. By Robert McCoy.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a219106.pdf

Lets start with the API M8

oNfY1RyKPmEjAVTBpvsHbVfBc0r-iZFYWtsd0EfF7ypuG4glKHgsYBqQMZa8nv3tf1cUuDu3E8SsXg7JBN0KzSDwUsHdZ0NrBEojFurofQoeklc7LVWWBWUEkI_9HMJnNmtAPn3u

Then The M20.

LSFWZhH7xMOT-TORYx43uAk1JCAqCF9VEHWinQp2H2qP2dVEE11xVoz7XgNGnsCmOh0cPogqXv_jZvbLF5dbV1RuhMIitRn_jqyRTLYFA7m-C-90z-qGU6hpd2y5ntB6FCoi8jat

Finally We have a drag profile for the M2 AP round. This chart is in older format Kd. However this can be converted to the standard notation for the Drag Coefficient Cd / Cx.

 

The conversion is Cd = (8/Pi) * Kd

 

The method is given in McCoy's work. image.png

 

The drag profile is from Report 620,  Aerodynamic Data for Spinning Projectiles” H.P. Hitchcock Ballistic Research Laboratories, Aberdeen Maryland 1947.

https://apps.dtic.mil/sti/pdfs/AD0800469.pdf

knIjKeRrl5EwU_54TGA2l18fZa1HzkC5UbhywQ9c

From the chart, peak drag occurs at Mach 1.2 and the Kd is ~ .161

Converting using McCoy

Cd = (8/Pi) * .161

Cd = .4099

At mach 2 the Kd is = .14, therefore the Cd = .35

The slope of drag curve at Mach > 1 is  = .4 - .35 / .8 = .05

The drag at low Mach is  ~.078 Kd  = .1985 Cd

The slope of the drag profile before area transonic appears flat.

 

Therefore the drag for the rounds should look more like,

M2_50_aero_AP.lua

cx = { 0.198 0.4, 0.0, 0.4, .05 }

 

 

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  • The correct Muzzle Velocity for the M2 AP should be 2,840 FPS, 865 MPS.
  • The reduction in accuracy and velocity due to barrel heating should be reduced to reflect the qualities described in weapons manuals. Possibly replaced with either a cook off event or a jam. 

nIgD7CvtnBw0WTjz40tAHVDDZ-V7g_rB-xC68l31

 

With regards to the correct muzzle velocity for these rounds. The manual for the AN-M2 and AN-M3 both give the same muzzle velocity for the various rounds. From the 1947 version of the AN-M2 manual,  TM9-225  1947.

http://www.nj7p.org/Manuals/PDFs/Military/TM 9-225 28-Jan-47 Google.pdf

6lBHrHo3ftJGrW8xbHmGWk7AflBQFmXkF8ysIVoA

  The AN-M3’s ammo table and muzzle velocity from the 1955 version of the AN-M3 manual, TM 9-2190

JNEwnHoUAH1uowtKiVXJ-i9e0Z-upd9EWflli4B5

Both manuals also refer to the same document, which provides the ballistic profile of the ammunition. Ballistic Data Performance of Ammunition TM-9-1907

https://ia800909.us.archive.org/22/items/TM91907BalisticDataPreformaceOfAmmunition/TM%209-1907%20Balistic%20Data%20Preformace%20of%20Ammunition.pdf

mXg1hBh2xgvpbnb0ssTBFaNH5Twkqt7YNIrp3jcD

A cleaner version of this chart is available in 

https://cgsc.contentdm.oclc.org/digital/collection/p4013coll8/id/2374

TM 9-1907 also gives the muzzle velocity as 2,835 FPS.  So this appears to be the correct muzzle velocity for M2 AP round.   

However, in some of the literature, the muzzle velocity is quoted as 2700 fps. This lower velocity 2700 fps comes from 1940 version of the AN-M2 manual -TM 9-225 https://ia601208.us.archive.org/21/items/TM9-225/TM9-225.pdf

It gives the velocity of the M1 AP Round as 2700 fps at 78 feet. 

     RPZQKC6Kirh0N6sxc5VutBIMogNsuc57wOltlssz



 

CfSC05U0B1KquTqx6dDoIFSv7kLjjxijNFSD6jtS 

Then in 1942, the revised TM 9-225 manual states muzzle velocity for the M2 AP round is 2900 fps. 

AR1SL-ZxhmuZdqucyEObgSff_9NZDrisL5Eg6ZPM

 

https://digital.library.unt.edu/ark:/67531/metadc29988/m1/50/

It appears the correct muzzle velocity for the M2 AP rounds is 2840 FPS, As the most current sources list it.


 

On burst length.

The manuals for both guns, indicate barrel heat affects 4 aspects of the guns performance, velocity, accuracy, stoppage, and cook off.  

The 150 round limit cited before, a 11 second burst,  is the stoppage limit (the gun locks up) of the AN-M2, due to overheating.  

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There is also a burst limit due to the possibility of a ammunition cook off. That is, the rounds heating up to point where the powder charge ignites and causes inadvertent firing. 

F148iZnTzsoqJTJ8SXl0z4Q2hu6kByNzZz-JvABy

FeI1x5sWBJ1qWbqf-l9N7K1dE7utsrwBv21eBw3S

For the AN/M3 the 200 rounds burst limit is due to the possibility of a cook off, not a reduction in accuracy or velocity. XlTOWXRAY3OIzh0hM0KIwOR3_TBsZoRtLk6UlLhj

The reduction in accuracy or velocity due to barrel heat occurs at different temperatures. The accuracy reduction is referred to as Key-holing in the manual. The AN/M2 manual notes, the circumstance in which the accuracy is degraded separately from the conditions that result in a reduction of the bullet’s velocity. The conditions depend on the barrel type and the number of rounds fired.. 

u4ReCobHZZQltB_hwj1gbcZhR12GreK_zXPJw-3-

The 50 Cal AN/M3 has a plated and lined barrel and the ammo is more likely to cook off, before the velocity and  accuracy are reduced. As the cook off limit is 200 rounds and the accuracy degradation occurs at 300 rounds. 

nIgD7CvtnBw0WTjz40tAHVDDZ-V7g_rB-xC68l31

The maximum burst length before there is a reduction accuracy, is 300 rounds. This should happen without a reduction in velocity. 

 

Z12QfZ2hr3w0khXGrm38tMOPK8V5EkHsuPMZ0NGe

 

The AN/M3 manual also notes that the operating parameters described are for temperate conditions at low altitude. So perhaps the increase in barrel temp can be reduced to reflect operation at high altitude. VstKqUD1C5BtwIcBwS4vuDbY82y5F8_Byb1qV9Yp


Edited by Curly
clairty
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