View Full Version : Quad AA.
April 17th, 2007, 12:02 AM
I think I may have found something interesting relating to these two weapons from the USA and German OOBs. Here are the current in game statistics.
Weapon 215 "50cal Quad AAMG"________23________22________40
Weapon 007 "2cm FlakVierlng"________16________18________30
Interestingly the single 50 cal cal gets a Kill of 11 and a single 20 mm AA also gets a Kill of 11. However when the same guns appear in quad mode the 50cal Quad AAMG kil value is doubled to 22 but the 2cm FlakVierlng only gets 18?
For the vierling though cyclic ROF can be quoted as low as 1400, effective ROF is usualy 800
But heres the killer the 50 cal has an effective ROF 40! that translates into 160 RPM for the Quad!
Dont believe me? see
http://www.sscnet.ucla.edu/milsci/7-8/78appb.pdf tip(search for "M2 (.50 CAL)")
"11. What is the sustained rate of fire of the .50 Cal?
40 rounds or less per minute"
Note also that the barrel change for 50cal Quad AAMG occours after 6 mags ie 120 rounds.
Why such a low ROF for the Quad 50? Because the 50 cal doesnt have a quick change barrel! (20cm Vierling does)
from the latter sight,
"17. When should the head space on the .50 Cal machine gun be checked?
-After replacing the barrel
18. Head space adjustments on the .50 Cal machine gun is correct when what conditions are met?
-The recoiling groups are fully forward
-There is no independent rear ward movement between the bolt, barrel, and barrel extension
-The no-go gauge does not fit in the T-slot, and the firing gauge does fit
Timing must be checked and/or set each time head space is set
20. Timing on the .50 Cal machine gun is correct when what conditions are met?
-Firing takes place when the recoiling parts are in the correct position for firing (between .020 and .116 inch out of battery)
-When the gun fires on the Fire gage, and does not fire of the No Fire gage."
Certainly not quick change. So the gunners choice is to really lower his ROF to keep the barrel cool or fire fast and lose a lot of time changing the barrels.
So the Quad 50 gets 160 rpm compared with the 20 mm Vierlings 800 rpm.
If I do a little math on the Kill values. Assuming the 20 FlakVierlng should be 22 and using the diferent ROFS to get a ratio we calculate the Quad 50s kill value as 800/160 * 22 a kill value of 5!!!!!!!!!!!!!!!!
This is of course ignoring the fact that the 2cm FlakVierlng is firing HE and the 50 cal fires ball.
So even though the vierling has a Higher rate of fire and fires High explosive it gets a Kill factor of 18 compared to the Quads 22?
needless to say the quad outranges the vierling which is also incorrect.
Best Regards Chuck.
April 17th, 2007, 02:14 AM
"When should the head space on the .50 Cal machine gun be checked?"........... http://forum.shrapnelgames.com/images/smilies/rolleyes.gif
OK, how's this sound.
I have a large patch to produce for MBT and it will be released in the next 10 days. There is a small patch for WW2 that will follow at the end of the month and then both Andy and I are taking a bit of a break. It would appear on the surface that perhaps you may have a point but before I simply charge in and make changes I have to review ALL 20 mm guns in the game and ALL 12.7/50.cal type weapons and ensure that whatever I decide *MAY* need changing doesn't in fact cause another post like this to pop up later on from an equally disgruntled soul with a new axe to grind
However, The chance of that happening this April is somewhat similar to a snowballs chance in hell but rest assured I will keep this on file someplace and if/when we decide to carry on forward it will be looked into
I will refer you to the MOBHack help section that details how things are put together. Specifically the "Multiple Weapons" section
Single slots that are meant to represent more than one multiple of a weapon use the following multipliers:
2x is 1.5x HEK
3x is 1.75x HEK
4x is 1.875x HEK
So when a weapon has an HEK value of 10, and you want to convert it to a twin weapon (for example a single and a twin AA gun) you would multiply the HEK by 1.5 to have a total HEK of 15.
Now perhaps someone has tweaked either of these guns at some point but the single 50 cal AAMG is an HEK 11 and that times 1.87 = 20.57 so rounded up it should have 21 and not 22 but this is why just changing things becasue someone says it should be done is "problematic". The single german 20mm flak is rated 10 HEK and 10x1.87 =18.7 rounded up it should be 19 not 18 so at most by our own processes we are 1 too high for the 50 cal quad and one two low for the 20mm quad so at the very least I will someday look at correcting that in all the OOB's that use those weapons.
HOWEVER what you perhaps have forgotten is that in the game a gun with.......lets say a 18HEK.... and a warhead of 2 does somewhat more damage to a target than a gun with a warhead of 1 and the an HEK of 22 so simply looking at HEK numbers and saying we are out of line is in itself, out of line. The bigger the warhead the more damage it causes. A very important point to remember.
April 17th, 2007, 07:03 AM
Ah you got me there, I was looking at flak 38 which has a kill of 11 but I see flak 30 does indeed have a kill of 10. And again yes I had looked at WH size but had forgotten it by the time I posted.
But still the very low ROF of 50 cal is an interesting turnup. I can't see that it can really put out the same sort of sustained fire that a water cooled or quick barrel change 7.62mm weapon can and so maybe should have lower rather than higher acurracy and kill factors? Help is a bit elusive about accuracy and kill values I'd be interested to know how these values are arrived at.
Make sure to enjoy your holiday.
April 17th, 2007, 06:21 PM
Post deleted by baggypants
April 18th, 2007, 10:20 AM
Thanks for replying.
Yes my apologies, when I say mags I mean cans. The site I sourced this from said that there was 120 rounds per can, close enough to your 110.
Ive been talking about "practical" ROF you mention cyclic ROF for 50 cal of 400-550, actually flak 38 has a cyclic ROF of 200-450 and vierling of 1400-1800 (sources vary). So you could safely say that for game purposes the two weapons have the same cyclic ROFs, However my point is that the practical ROF of 50 cal has to be lower than the vierlings as the 50 cals barrel isnt swapped out.
This site details the "on and off" firing you mention.
"Describe the Rapid method of fire on the M2 .50 Cal.
Rapid fire consists of more than 40 rounds per minute, fired in bursts of five to seven rounds, at 5- to 10-second intervals."
So "Rapid fire" still only gives you at best a practical ROF of 84 still well below the vierlings practical ROF of 200.
Also we should be aware that the barrel becomes soft and hence bent and innacurrate well before "shoot through". so using cyclic ROF means you will very shortly have a useless weapon.
I would suggest that the detailed Rates of fire arnt for officers but for soldiers that are so tired they cant think and can only rely on whats been drilled into them at training in order not to "burn out there barrels", ie five to seven rounds, at 5- to 10-second intervals.
If by volume fire you mean accuracy it would appear to me that accuracy should be higher for the vierling than the quad as even though both have a similar cyclic ROF the ability to swap out the barrels in the vierling must give it a much better Practical ROF.(as sources would seem to confirm) and hence much better "volume" fire.
The ROF for both weapons doesnt matter during aircraft engagements as the targets are fleeting anyway. But for the common in-game useage as a type of sustained fire heavy MG the practical ROF becomes much more important than the cyclic ROF.
Effective ceiling for the flak 38 is quoted at 2200m
but Im more interested in the comparison af a 50 cal with say a MG42. what do you think?
Point to note
being hit by a 12.7 or 7.92 round is going to put you out of action either way.
MG42 puts a lot more rounds on target, (250 vs 84 per min)
so does it follow that
MG42 should have a better accuracy rating than the 50 cal?
MG42 should have a better Kill value than 50 cal?
Also of interest in-game the British 20mm hispano cannon firing ball gets the same Kill value as the German 20mm MG 151 firing HE, 10. This seems wrong to me.
Best Regards Chuck
April 18th, 2007, 06:06 PM
Post deleted by baggypants
April 19th, 2007, 09:08 AM
Well hi again
Nice post, but I do have a couple of further comments.
For the quad/vierling comparison 15 seconds seems to be a long time to be firing at a fighter bomber, travelling at say 300 mph or so, it probabaly isnt in range for more than a few seconds? In any case as both weapons are no doubt firing a single long burst then they are both on their cyclic rate of fire and as these are similar then both weapons are putting the same number of rounds into the air? except of course -if- the engagement is long enough then the vierling will be slowed down by having to change mags but maybe this would only take a couple of seconds? one would certainly hope so anyway.
Yes Im sure you can change the 50 cal barrel and hope for the best. But do you know if spare barrels were actually carried for the quad? or for the 50 cal when mounted on the HMG tripod? or for a 50 cal mounted on a tank turret? I suspect the weapon doesnt come with spare barrels in any of its incarnations which is why we have the low ROF training as detailed for the ground target support fire. Obviously if no spare barrel is available then it might be best to adhere to the recommended practical ROF 84 rpm or 40 rpm?
Im not sure what you mean by advancing the ROF? do you mean you can increase the cyclic ROF or just fire longer bursts?
I doubt that the heavy barrel was equivelent to a water cooled or quickchange design or everyone would have opted for the heavy barrel design. once hot a barrel takes a lot of time to dissapate that kind of heat. The BAR has exactly the same problem.
If the Low ROF is put in place to stay on target you wouldnt need to wait 10-15 seconds between bursts one second would be sufficient. How much ammo you expend is determined by the situation and controlled by the NCO in change of the gun, not by the manual. Also if the barrel is prone to overheating then long pauses between bursts is exactly, and the only, way to keep the 50 cal barrel cool. which seems to be a bit to big of a coincidence to me.
For the purposes of the game it doesnt matter that James survived, (apologies James we are all glad you survived) what matters was that he was incapacitated, Many people point out the extra punch but it is overkill, only a very very few people can collect a 7.62 bullet and jump up and continue fighting. For incapacitation 7.62 is every bit as good as 12.7 both will put the man down. For this reason I think 7.62 and 12.7 should have the same kill value vis a ve infntry targets. On TV recently a veteran of Omaha beach recalled a burst from a mg42 cutting a man clean in half.
Both MG 151 and hispano have a ROf of 750.
two quotes from
"The added mass and surface area of the new (heavy) barrel compensated, -somewhat-, for the loss of water-cooling, while reducing bulk and weight (the M2 weighed 121 lbs, with water, whereas the M2 HB weighs 84 lbs). This new variant was the designated the M2 HB (HB for Heavy Barrel). Due to the long procedure for changing the barrel, an improved system was developed called QCB"
(QCB is post WWII)
"The M2 machine gun's -sustained- rate of fire is considered to be anything less than 40 rounds per minute"
Best Regards Chuck.
April 19th, 2007, 07:37 PM
Post deleted by baggypants
April 20th, 2007, 10:38 AM
Actually I dont think its touchy I just think that as it doesnt have quick change barrel or water cooling then there is a very real possibility that the barrel can become overheated making the gun useless. To avoid this the gun comes with the recomended ROF of 40 rpm
Now ignoring the AA stuff for a moment and lets look at the tripod ground mount. lets compare it to the .30 cal both have the same cyclic ROF 550. The 30 cal has accurracy of 20 kill of 5 while the 50 cal has 23 11.
Now the 30 cal has a sustained or practical ROF of 150 rpm and the 50 cal has a sustained or practical ROF of 40
So after a few turns when the honeymoon is over the 50 cal barrel has warmed up and now has to run at the recomended 40 rpm. The .30 cal however can continue to fire at 150 rpm for the entire game so its firing nearly 4 times as many bullets as the 50 cal. Now if accurracy and kill values incorporate ROF then I think the 50 cals values are two high. Untill someone tell us how accurracy and kill values are worked out though I cant be sure.
Now my argument depends on 50 cal barrels not being swapped out. And that is true because no spare barrels are issued.
I doubt very much if much heat from the barrel gets into the receiver(gun) only a very small proportion of the barrel in in contact with the gun maybe 1 percent? and the barrel is going to lose heat to the air quicker than to a lump of metal anyway.
pouring water on the barrel would seem to be a good way to warp the barrel and again I dont think this would be particularily effective as the steam is going to block your sight give away your position and all the water on the deck might annoy the loaders.
You have a point regarding cover I hadnt thought of that. might be worth 1 point of Kill I guess.
if your infantry carriers are bradleys then we are in the wrong game, I would put good money on no spare barrels being carried during ww2 they may be by now as the current version of the gun does now have a quick change barrel.
I see the higher RPM is just the higher end of the cyclic ROF, fair enough. We have already established that for a burst of 20 or less rounds both AA quads put up the same number of rounds.
For the hispano vs mg-151 750 ROF is for the individual weapons.
I think the gunner will track the target and keep the trigger pressed irrespective of what the loaders are doing. so I think AA weapons are comparable in this. If the BAR gunner has to change the mag himself he has a problem.
Best Regards Chuck
April 20th, 2007, 07:50 PM
Post deleted by baggypants
April 21st, 2007, 02:47 AM
I know they didnt have spare barrels because if they did then they would have been used and this would have given the 50 cal the same practical ROF as the 30 cal which it hasnt(40 vs 150 rpm). (not forgetting both have the same cyclic ROF) the 50 cals low practical ROF is proof they didnt swap out the barrel.
But the Low ROF didnt matter, because on the ground tripod mount it wasnt used as the coy sustained fire MG this was the 30 cals job. It used as a heavy punching automatic cannon.
On a tank turret it was simply decoration, there were no planes to shoot at and the british ditched them as impractical. It makes a passable AA quad mount as the engagement time is low but when the 50 quad is shooting at ground targets, the 20 mm outclasses it because of its higher practical ROF.
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