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Now isnt it true that it was easier to land more critical hits on another aircraft with machine guns than it was cannons?
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Hi Suntracker,
>Now isnt it true that it was easier to land more critical hits on another aircraft with machine guns than it was cannons?
Definitely not.
Regards,
Henning (HoHun)
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No. It was easier to just land hits with machine guns than cannons.
When the adjective 'critical' comes into the picture, no machine gun round hit will ever be as 'critical' as a cannon round hit... (unless a shot goes through the pilot's head or something).
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I believe on average it took 20-30 rounds of fifty caliber to bring down an enemy fighter.
It took about 3 rounds of 20mm to bring down a fighter I believe.
I think it would be easier to land 20 to 30 hits of 50 cal.
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Hi Suntracker,
>I think it would be easier to land 20 to 30 hits of 50 cal.
Well, a numerical comparison is only meaningful if you define a basis for the comparison.
For example, you could say you'd allocate 1000 lbs to the armament of a fighter and see what kind of firepower that would give you. (That's about the weight of the P-47's battery.)
Here's what would result from formulating such a requirement to an aircraft designer if you'd also specify using an equally destructive ammunition load for each battery:
6x MK 108 - 14 rpg - 411 kg - 30,2 MW firepower - firepower per weight: 73,5 kW/kg - 60 shells/second
2x MK 103 - 37 rpg - 351 kg - 8,2 MW firepower - firepower per weight: 23,3 kW/kg - 14 shells/second
8x MG 151/20 (MX) - 47 rpg - 416 kg - 11,2 MW firepower - firepower per weight: 27 kW/kg - 96 shells/second
8x MG 151/20 - 52 rpg - 424 kg - 10,1 MW firepower - firepower per weight: 23,9 kW/kg - 96 shells/second
8x Hispano V - 53 rpg - 440 kg - 9,9 MW firepower - firepower per weight: 22,4 kW/kg - 96 shells/second
7x Hispano II - 59 rpg - 451 kg - 7,4 MW firepower - firepower per weight: 16,5 kW/kg - 70 shells/second
10x MG-FF - 45 rpg - 432 kg - 7,8 MW firepower - firepower per weight: 18,1 kW/kg - 80 shells/second
5x MG 151 - 239 rpg - 427 kg - 2,2 MW firepower - firepower per weight: 5,1 kW/kg - 60 shells/second
12x MG 131 - 259 rpg - 447 kg - 2,5 MW firepower - firepower per weight: 5,7 kW/kg - 180 shells/second
8x ,50 Browning M2 - 250 rpg - 452 kg - 2,3 MW firepower - firepower per weight: 5 kW/kg - 104 shells/second
15x Browning ,303 - 665 rpg - 449 kg - 1,3 MW firepower - firepower per weight: 2,9 kW/kg - 300 shells/second
(Edited to fix rpg figure)
For evaluating the results, just compare each battery suggestion to any other.
For example, you could compare the Browning M2 battery to the MG151/20 battery: Both use 8 barrels and put out about the same number of projectiles, but the MG151/20 is about 4.4 times more destructive.
Though in that example, each cannon is a bit heavier than each MG, the higher destructiveness of cannon shells means that the ammo load is a bit lighter, making up for the difference in weapon weight.
For an equal battery weight, the machine guns don't even have an advantage over the cannon in bare projectile count, so there's not much reason to assume you'd have any hit ratio advantage with MGs (at least not with the Browning M2).
If you think the Browning M2's trajectory gives it a hit rate advantage (usually, the literature tends to overestimate the effect since fighter combat was decided at rather short range in WW2), you can swap the MG151/20 for the Hispano II, which still has about 3 times the firepower of the Browning M2 with a similarly flat trajectory.
Projectile count for the Hispano II goes down slightly, but since each projectile is vastly more destructive with cannon, the Hispano in the end wins in this comparison just as easily as the MG151/20.
If you decide to use real-life batteries for comparison, you'll find that the machine-gun armed aircraft usually carry a lot more weight in terms of armament and ammunition to achieve similar firepower as cannon-armed aircraft, so the superiority of cannon is somewhat hidden. Still, every MG-equipped WW2 fighter would have benefitted from a firepower increase if it would have been switching to cannon.
Regards,
Henning (HoHun)
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What's that last MG151 entry in your list? and why only 5?
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Begin Typing
New Sentence.This is kind of a silly question. Period.
New sentence. Cannons will have more critical hits than MG per round simply because cannons fire stronger rounds. Period.
Space
New Sentence. However, it would be easier to hit with MGs than cannons due to all sorts of factors such as recoil and bullet tragectory. Period.
End Typing :P
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For example, take a very destructive MG such as the .50 Cal firing API bullets. it took anywhere from 15-30 rounds to kill a plane (Not counting head shots, or freak engine/fuel tank 1 hit kills which were rare)
Then, look at the 262A-2(i think. it was one of em) with the Big Bertha tater cannon on the nose. 1 shot kills. provided you hit.
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Hi Gscholz,
>What's that last MG151 entry in your list?
That's the original 15 mm MG151.
>and why only 5?
Having allocated 1000 lbs to the battery, I first subtract the weight of the ammunition required for a certain muzzle energy from it. The remaining weight is used to fit as many weapons as possible into the battery.
Since 15 mm projectiles are heavier for the same energy than 20 mm shells and the 15 mm MG151 is as heavy as a 20 mm MG151/20, that leaves the 15 mm with fewer barrels.
Note that the MG151 15 mm battery has virtually the same firepower per weight ratio as the 12.7 mm Browning M2 battery, which might be the reason the US gave up their plan on copying the MG151 as 0.60" HMG. No significant advantage!
(I could have used 6x MG151, but then I'd have overrun the 1000 lbs limit. The 5x MG151 battery is a hair weaker than the M2 battery, but a hair lighter as well.)
Regards,
Henning (HoHun)
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No fighter mounted 8 cannons in World War II though. Highest I know of is 4 cannons.
A post war report showed the 50 cals could have been much more effective. There were three ways in which 50 caliber ammunition usually destroyed enemy aircraft. (1) Exploding the ammo stores (2) igniting fuel tanks (3) killing the pilot. It was found that the only truely effective 50 caliber ammunition was armor piercing incendiary.
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I've used the D9 mostly for the last two tours with some 300 odd kills - went back to the P51 for a couple of flights and suddenly realised how weak the P51 guns seemed in comparison - just couldn't get the snap shot kills that you get with the D9.
Is there any doc showing what the effectiveness of the guns of the various planes are in the game? I have seen a number showing effectiveness of the real life gun packs but is there any way of checking how this data carries over to AH?
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Hi Suntracker,
>No fighter mounted 8 cannons in World War II though. Highest I know of is 4 cannons.
That's because 4 cannons offered the best compromise between firepower and performance. To get halfway decent firepower, you had to use many more MGs than cannon, that's why you see 8 gun fighters.
I'm sure the P-47 could have mounted 4 x 20 mm cannon in each wing if it had been demanded by the USAAF. Supermarine made plans to mount 3 x 20 mm in each wing of the Spitfire, and the Jug is a lot bigger than the Spit.
>A post war report showed the 50 cals could have been much more effective.
Late-war cannon ammunition could have been much more effective as well. The Luftwaffe was developing special fuel-tank buster shells, for example, that were even more lethal against bombers than the highly effective shells they already had.
Post-war, it became that the best cannon developed in WW2 was the 30 mm MG213C revolver cannon. It was copied by the British and the French and continously developed as the Aden respectively DEFA cannon. The DEFA was selected for the Dassault Rafale, a latest-generation jet fighter, for example.
>It was found that the only truely effective 50 caliber ammunition was armor piercing incendiary.
My calculations are for a pure API loadout for the Browning M2.
Regards,
Henning (HoHun)
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Ah yes, the myth of the Browning .50 caliber machinegun's superiority rears it's head again.
It is a myth though. The VVS, Luftwaffe, RAF, IJN and IJA did not all stupidly decide that 20mm cannons were the optimum fighter gun at the time. Heck, the IJA liked the Browning .50 so much they copied it, lightened it for the Ho-103 12.7mm and upscaled the lightened version for Ho-5 20mm. You'll notice that is what the Ki-61-I-Tei, Ki-61-II, Ki-67, Ki-84 and Ki-100 are all armed with.
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Why would it be 10 times easier to land hits with a MG? Only if you have 10 times more of them. Want to mount 40 mgs on a fighter?
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Originally posted by SunTracker
No fighter mounted 8 cannons in World War II though. Highest I know of is 4 cannons.
What about the BF-110G2? 2 internal 20's, 2 external, and a pair of internal 30's... Now granted that isn't 8, but it's still nothing to sneeze at either.
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Pongo,
Even then it wouldn't increase your chances by a factor of ten. Forty guns will miss just as completely as two guns if your fighter isn't aimed correctly. Forty would increase your chances slightly due to the sheer quantity of bullets filling the dispersion zone, but I'd be surprised if it were even by a factor of 1.5.
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No one point harmonizes 40 guns karnak. 40 guns would increase the number of bullets that hit signifigantly. Have 4 harmonized in each 25 yard range from 150 to 400 hold down the trigger as you approach..even a loser will get lots of hits.
it would be a great gun package if it didnt weigh 3000 pounds and 200 square feet of gun bays to do it with 50 cals.
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Originally posted by Schaden
Is there any doc showing what the effectiveness of the guns of the various planes are in the game?
scJazz made a study for the effectiveness of the different gun rounds.
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=97083
Note: This was for AH1. Also this does not take into account the differences in the rate of fire.
Originally posted by scJazz
This update includes PT Boat's 37mm and 40mm guns as well as damage from Shore Batteries and Cruiser main guns.
Gun Type Dam in #
.303 Browning AC 0.296
.303 Browning GV 0.3125
7.6mm ShKAS 0.296
7.7mm Breda - SAFAT 0.28
7.7mm Type 97 0.296
7mm MG 17 0.3
.50 M2 AC 1.17
.50 M2 GV 1.25
12.7mm Breda - SAFAT 0.95
12.7mm Ho-103 0.998
12.7mm UBS 1.15
13mm MG 131 0.92
20mm B-20 3.47
20mm Hispano Mk II 4.03
20mm Hispano Mk V 3.94
20mm Ho-5 3.36
20mm M2 AC 4.03
20mm MG 151/20 3.55
20mm MG-FF 3.25
20mm ShVAK 3.47
20mm Type 99 Mk 1 3.42
20mm Type 99 Mk 2 3.85
23mm VYa 5.62
30mm Mk 108 11.63
37mm NS37 16.67
40mm Vickers S 13.89 *
37mm PT Boat 13.2
40mm PT Boat 15.6
37mm HE Ostwind 15.15 *
37mm AP 15.6 #1
37mm HE 31.2 #1
75mm AP 78.1 #1
75mm HE 156.2 #1
88mm AP 117.1 #1
88mm HE 234.3 #1
3.5" Rocket 140.0 #1
4.5" Rocket 93.0 #1
5" Rocket 156.0 #1
RS132 125.0 #1
RS82 93.0 #1
WGr21 200.0 #1
Shore Battery 250 - 500 #2
Cruiser Gun 250 - 500 #2
* The Vickers S and 37mm HE Ostwind are the only weapons I
am not 100% certain of the full series of tests had very
inequal results. The value shown is the maximum damage
inflicted per round. I suspect that the variance is caused
by a bug in the burst dispersion code.
#1 Testing for the GV main guns and rockets was different.
I fired 1 round into a hanger and constantly tweaked the
hanger's damage resistence until I found the maximum single
round damage.
#2 The Main Guns on the Cruisers fire 3 shells at a time
each shell does 250lbs to 500lbs of damage. If all 3 hit then the
target just took 750lbs to 1500lbs of damage. The damage is scaled by range 250lbs at maximum range, 500lbs at point blank, 390lbs at 6400 yards.
[/B]
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Which weapons are meant by '37mm PT boat' and '40mm PT boat'?
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion
forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by Pongo
No one point harmonizes 40 guns karnak. 40 guns would increase the number of bullets that hit signifigantly. Have 4 harmonized in each 25 yard range from 150 to 400 hold down the trigger as you approach..even a loser will get lots of hits.
it would be a great gun package if it didnt weigh 3000 pounds and 200 square feet of gun bays to do it with 50 cals.
There'd have to be a new saying: "I gave him the whole 90 yards" :)
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion
forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by SunTracker
A post war report showed the 50 cals could have been much more effective. There were three ways in which 50 caliber ammunition usually destroyed enemy aircraft. (1) Exploding the ammo stores (2) igniting fuel tanks (3) killing the pilot. It was found that the only truely effective 50 caliber ammunition was armor piercing incendiary.
The .50 M8 API (copied from a Russian design, incidentally) was introduced in Spring 1944 and was the standard US fighter ammo for the last year of the war. However, it only contained a tiny quantity of incendiary material - less than one-tenth that of the RAF's 20mm Hispano SAPI, which had similar penetration.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion
forum (http://forums.delphiforums.com/autogun/messages/)
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Mr.Williams, the PT boat is the US Elco 80' PTs. I'm not sure this if it is right, but I've found the armament details listed as:
20mm(fwd.): Oerlikon Mark-4 with shoulder rest
20mm(aft.): Oerlikon Mark-4 on tripod
37mm: Same gun as the P-39 Aircobra, on factory mount
40mm: Bofors Automatic, on standard mount
.50s: Dual Browning 50 caliburs, on turret mount
Rockets: 5" Rockets, on swivel mount
..
Hope this helps.
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In that case, I'm surprised by some of the figures. Without doing the calculations, I would expect the order of merit of the individual 37-40mm rounds to be as follows:
37x145R for US M4 (P-39 gun) - by far the weakest.
40x158R for Vickers S - significantly more destructive
37x263B for German Flak - possibly around the same (except M-Geschoss - but that was rare, and for aircraft only AFAIK)
37x195 for NS-37 - a bit more destructive
40x311R for Bofors - the most powerful (it developed almost three times the muzzle energy of the 37x145R).
The figures in the table don't seem to match up with this.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and discussion
forum (http://forums.delphiforums.com/autogun/messages/)
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Tony do the figures for the a/c mounted weapons look relaistic to you?
(Thnks for posting the thread...very interesting)
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Hi Schaden,
>Tony do the figures for the a/c mounted weapons look relaistic to you?
Here's a comparison of a selection of the above numbers to the energy of a single projectile (relative to the 12.7 mm Browning M2's API):
Gun Type Dam in # Energy
.303 Browning AC 0.296 0.20
.50 M2 AC 1.17 1.00
12.7mm Breda - SAFAT 0.95 0.55
12.7mm Ho-103 0.998 0.55
12.7mm UBS 1.15 1.28
13mm MG 131 0.92 0.64
20mm B-20 3.47 2.4
20mm Hispano Mk II 4.03 4.9
20mm Hispano Mk V 3.94 4.7
20mm Ho-5 3.36 2.3
20mm MG 151/20 3.55 4.8
20mm MG-FF 3.25 4.5
20mm Type 99 Mk 1 3.42 3.0
20mm Type 99 Mk 2 3.85 3.6
23mm VYa 5.62 6.1
30mm Mk 108 11.63 23.0
Note that the two columns are not directly comparable - increase the right hand column by 17% for that, using the 0.50" M2 as a calibration point.
Regards,
Henning (HoHun)
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Suntracker, the key to kills with the 50's is that you must land those 20 to 30 rounds in ONE spot. Not scattered all over the plane.
That is why its easier to do it with cannons.
Your odds of getting enough significant damage in any one area is always going to be greater with cannons which had exploding shells. Your not dealing with pure kinitic energy, as you are with the .50's.
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It is my opinion, that with the thousands of pilots the U.S. had to train per year,that the 50 caliber gun was the best choice. I believe due to wing resonance, that bullets were lucky to hit in a 12ftx12ft box at 300 yards.
So 30-50 seconds of firing time, compared to as little as 8 seconds for some cannon armed planes, was a big benefit. Almost all the gun camera footage I have seen of U.S. aircraft attacking German or Japanese planes show the ammo bays or fuel tanks exploding.
What was the other choice for the U.S. besides the 50 cal? The M9 37mm? The M2 Hispano? Both of these weapons were subpar.
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Hi Schaden,
>Tony do the figures for the a/c mounted weapons look relaistic to you?
Here's the table again with the right-hand column made directly comparable:
,303 Browning AC 0,3 0,23
,50 M2 AC 1,17 1,17
12,7mm Breda - SAFAT 0,95 0,64
12,7mm Ho-103 1 0,64
12,7mm UBS 1,15 1,5
13mm MG 131 0,92 0,75
20mm B-20 3,47 2,81
20mm Hispano Mk II 4,03 5,73
20mm Hispano Mk V 3,94 5,5
20mm Ho-5 3,36 2,69
20mm MG 151/20 3,55 5,62
20mm MG-FF 3,25 5,27
20mm Type 99 Mk 1 3,42 3,51
20mm Type 99 Mk 2 3,85 4,21
23mm VYa 5,62 7,14
30mm Mk 108 11,63 26,91
Regards,
Henning (HoHun)
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So 30-50 seconds of firing time, compared to as little as 8 seconds for some cannon armed planes, was a big benefit. Almost all the gun camera footage I have seen of U.S. aircraft attacking German or Japanese planes show the ammo bays or fuel tanks exploding.
You'll also notice that most of the guncam footages are shot from very very close distances. At that distance, there's nothing the .50 could offer which the 20mm cannot outdo.
What was the other choice for the U.S. besides the 50 cal? The M9 37mm? The M2 Hispano? Both of these weapons were subpar.
The Hispano Mk.II 'subpar'?
You've gotta be kidding.
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Certainly you have not read the articles on the M2 Hispano. Controlled by the same agency that regulated artillery, the m2 was overweight, had a relatively low cyclic rate, and was prone to jamming.
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Hi Suntracker,
>I believe due to wing resonance, that bullets were lucky to hit in a 12ftx12ft box at 300 yards.
Sure. But the Browning M2 had about the largest dispersion among all WW2 guns for which I've seen data, and cannon like the Hispano II and the MG151/20 were more accurate.
>So 30-50 seconds of firing time, compared to as little as 8 seconds for some cannon armed planes, was a big benefit.
This is a list of batteries selected to give approximately 2.3 MW firepower (equivalent to 8 x Browning M2) at 30 s firing duration:
1x MK 108 - 300 rpg - 236 kg - 5 MW firepower - firepower per weight: 21,4 kW/kg
1x MK 103 - 210 rpg - 334 kg - 4,1 MW firepower - firepower per weight: 12,2 kW/kg
2x MG 151/20 (MX) - 360 rpg - 238 kg - 2,8 MW firepower - firepower per weight: 11,8 kW/kg
2x MG 151/20 - 360 rpg - 238 kg - 2,5 MW firepower - firepower per weight: 10,7 kW/kg
2x Hispano V - 360 rpg - 261 kg - 2,5 MW firepower - firepower per weight: 9,5 kW/kg
2x Hispano II - 300 rpg - 248 kg - 2,1 MW firepower - firepower per weight: 8,6 kW/kg
3x MG-FF - 240 rpg - 328 kg - 2,3 MW firepower - firepower per weight: 7,1 kW/kg
5x MG 151 - 360 rpg - 538 kg - 2,2 MW firepower - firepower per weight: 4,1 kW/kg
11x MG 131 - 450 rpg - 573 kg - 2,3 MW firepower - firepower per weight: 4 kW/kg
8x ,50 Browning M2 - 390 rpg - 575 kg - 2,3 MW firepower - firepower per weight: 3,9 kW/kg
26x Browning ,303 - 600 rpg - 728 kg - 2,3 MW firepower - firepower per weight: 3,1 kW/kg
As you can see, the Browning battery weighs 575 kg, compared to the MG151/20 battery with just 238 kg.
In other words, your aircraft becomes 743 lbs lighter just by stepping up to 20 mm cannon! =8-O
If you want 50 s firing duration, the cannom advantage increases to more than 1000 lbs.
Regards,
Henning (HoHun)
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But that brings me back to my original point. A pilot firing cannons would not have the same amount of shells in the air, nor the dispersion if firing with 1 or 2 cannons.
So basically it all comes down to this. At the average engagement distance, would it be easier to land 20-30 hits with 6 50 cals (the average U.S. Armament), or would it be easier to land 2-5 cannon hits with two cannons (the standard cannon armament)?
6X800rpm=4800rpm. 4800rpm/60=80 rounds per second. It would take a 1/4th second burst to down an enemy aircraft. Though indiviudal machine guns could be ramped up to 950 rounds per minute by armorers.
Hispano MkII= 600rpm. 600rpmx2=1200rpm/60=20 rounds per second. Figuring 2 rounds to down an enemy aircraft, it would take 1/10th of a second. Figuring 5 rounds, it would take 1/4th of a second.
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Hi again,
Here are the same batteries, but this time with so much ammunition to bring them all up to the weight of the 8 x Browning M2, 30 s firing duration battery:
1x MK 108 - 881 rpg, 88 s duration - 575 kg - 5 MW firepower - firepower per weight: 8,7 kW/kg
1x MK 103 - 472 rpg, 67 s duration - 575 kg - 4,1 MW firepower - firepower per weight: 7,1 kW/kg
2x MG 151/20 (MX) - 1149 rpg, 96 s duration - 575 kg - 2,8 MW firepower - firepower per weight: 4,9 kW/kg
2x MG 151/20 - 1149 rpg, 96 s duration - 575 kg - 2,5 MW firepower - firepower per weight: 4,4 kW/kg
2x Hispano V - 998 rpg, 83 s duration - 575 kg - 2,5 MW firepower - firepower per weight: 4,3 kW/kg
2x Hispano II - 966 rpg, 97 s duration - 575 kg - 2,1 MW firepower - firepower per weight: 3,7 kW/kg
3x MG-FF - 484 rpg, 61 s duration - 575 kg - 2,3 MW firepower - firepower per weight: 4,1 kW/kg
5x MG 151 - 401 rpg, 33 s duration - 575 kg - 2,2 MW firepower - firepower per weight: 3,8 kW/kg
11x MG 131 - 452 rpg, 30 s duration - 575 kg - 2,3 MW firepower - firepower per weight: 4 kW/kg
8x ,50 Browning M2 - 390 rpg, 30 s duration - 575 kg - 2,3 MW firepower - firepower per weight: 3,9 kW/kg
26x Browning ,303 - 404 rpg, 20 s duration - 575 kg - 2,3 MW firepower - firepower per weight: 4 kW/kg
Again, the 0.50" Browning M2 battery compares quite poorly, the Hispano and MG151/20 batteries getting about three times the firing duration from the same total weight at the same firepower.
Regards,
Henning (HoHun)
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If the 20mm was superior (especially the Hispano) to the .50, why didn't the British and Americans use them for bomber defense? I see that they might be tough for hand-held positions but they would work in a turret mount, right? Wouldn't a 20mm be a better defensive weapon too?
63tb
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Hi Suntracker,
>But that brings me back to my original point. A pilot firing cannons would not have the same amount of shells in the air, nor the dispersion if firing with 1 or 2 cannons.
Number of rounds or dispersion don't increase your probability of a kill.
A higher number of less destructive projectiles with larger dispersion just ensures that you get a lot of subcritically damaged targets.
That was the actual German combat experience, and the reason they went to projectiles capable of destroying the aircraft structure immediately.
>So basically it all comes down to this. At the average engagement distance, would it be easier to land 20-30 hits with 6 50 cals (the average U.S. Armament), or would it be easier to land 2-5 cannon hits with two cannons (the standard cannon armament)?
The most important factor is firepower. Here's a comparison of real batteries:
Me 262: 20,1 MW
Fw 190A-8/R2: 13 MW
Fw 190A-8: 5,5 MW
Me 109K-4: 5,5 MW
Tempest: 4,9 MW
Fw 190A-4: 4,3 MW
Typhoon: 4,2 MW
Spitfire IXE: 2,7 MW
Spitfire VC: 2,5 MW
P-47D: 2,3 MW
P-38: 2,2 MW
Me 109G-6: 1,8 MW
Me 109E-4: 1,7 MW
P-51D: 1,7 MW
Me 109G-2: 1,6 MW
P-51C: 1,1 MW
Hurricane IIA: 1,1 MW
Spitfire II: 0,7 MW
Me 109F-2: 0,6 MW
Me 109E-1: 0,3 MW
Regards,
Henning (HoHun)
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Hi 63tb,
>If the 20mm was superior (especially the Hispano) to the .50, why didn't the British and Americans use them for bomber defense? I see that they might be tough for hand-held positions but they would work in a turret mount, right? Wouldn't a 20mm be a better defensive weapon too?
It would! Note that even the USAAF, otherwise dedicated to the Browning M2, added a 20 mm cannon to the B-29 tail, recognizing its superior power.
(It got pulled out when Le May did away with most of the defensive armament of his B-29s and went for night raids, and Korean War B-29s had a 12.7 mm MG in its place. They were facing jets with 23 mm and 37 mm cannon then ...)
Fitting 20 mm cannon in turrets can be difficult, though, and even the countries that did use them confined them to the positions most likely to see action (or the front position, which would have only very limited firing time in a head-on pass).
Regards,
Henning (HoHun)
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HoHun, I don't believe your table takes into account the different factors of aerial gunnery. Muzzle velocity, shell trajectory, recoil vibrations.
According to your table, wouldnt a B-25H reign supreme, with its 75mm cannon?
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Suntracker, you have to take note that 'more shells in the air with faster firing time' is still only about effective as a single cannon fire. As Karnak points the US Navy has determined a single 20mm Hispano cannon is worth three M2 50cals.
In reverse logic, it means to achieve the overall effectiveness a single 20mm cannon would wield, you needed more guns, more shells, and more hits to the same spot on the surface, plus the negative effect of the sheer weight of the weaponery as oppsed to a single 20mm cannon.
Why attach three M2 50cals which needed more space and added more weight, when a single 20mm cannon could do the same thing?
Theoretically a gun with a flatter trajectory and faster rate of fire would greatly benefit in the ability to hit at far distances.
However, this is only taking ballistics and figures into the equation. There are more factors to aerial gunnery than just ballistics and RPM and velocities, and these very factors prevented practically ALL form of weaponery to be more or less useless when over 400m distances.
According to Mr.Williams the absolute limit of successful gunfire against fighters would be around 200m, for bombers around 400m. Anything further out than that, and it made no difference whether or not a plane was armed with 20mms or 50cals - the distance was simply too far, and you couldn't hit it.
Better trajectory and rate of fire brings proportionate increase in hitting chances only upto a certain distance. Further out than that, other factors intervene and drop the effectiveness drastically for all guns.
Thus, the only real effective firing range would be inside 200m, where there wasn't any large difference between the 20mm cannons and .50 guns.
Imagine you're in a P-51. You see a Fw190 in front of you and fire 6x 50 cals.
You'd achieve more hits than 20mms, yes. But all of those hits still mount up to the amount of practical damage mere two 20mm cannons would do.
To make matters worse, the sheer number of armament would mean the guns needed to be placed at the wings, and were very sensitive to harmonization. Dispersion and spread would scatter the limited number of hits even more on the Fw190.
And if you were in a typical BnZ pass, you're window of chance would be small due to the quick approach speeds.
Now, imagine if it was a Spitfire, landing only two cannon hits whereas a P-51D would land 10~15 hits all over the Fw190. Only two hits it is, but it would blow whole chunks off the enemy plane, immediately effecting its flight capabilities.
With the .50s, you have to hope one of the 10~15 hits achieved snagged a delicate internal system. With the 20mms, it doesn't matter - you land even one hit, and the enemy plane will be forced to fly with a hole the size of your computer monitor on its surface.
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Originally posted by 63tb
If the 20mm was superior (especially the Hispano) to the .50, why didn't the British and Americans use them for bomber defense? I see that they might be tough for hand-held positions but they would work in a turret mount, right? Wouldn't a 20mm be a better defensive weapon too?
63tb
Yes. The problem was that 20mm guns required a much bigger turret design, able to take the recoil. And it was not a simple task to fit a bigger turret to an existing plane - the bombers were usually designed around a certain size of turret.
In contrast, it was a relatively simple task to strap a bigger gun onto a fighter, so fighters were always able to keep ahead in the firepower race.
Furthermore, better turrets were a relatively low priority for the RAF because they bombed mainly at night, but even so they were working on some 20mm-armed bombers right at the end of the war.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Hi Suntracker,
>HoHun, I don't believe your table takes into account the different factors of aerial gunnery. Muzzle velocity, shell trajectory, recoil vibrations.
Well, the latest table lists bare firepower and includes muzzle velocity for the calculation of energy.
Well, the MG151, the Hispano II and the MK103 are superior to the 12.7 mm Browning in each of these respects, and have the weight and firepower advantges typical for cannon.
I actually did analyze trajectory - which is given a vastly exaggerated importance in most discussions as realistic firing ranges were 200 - 300 m. The same applies to projectile flight times - effective range against manoeuvring targets is even shorter. Here are some dispersion figures:
MG-FF: 1,0*
MK 108: 1,5*
20mm Type 99-1: 1,5
20mm Type 99-2: 1,5
Ho-1 / Ho-2: 1,5
12,7mm Scotti: 1,6
Breda-SAFAT: 1,7
MG 131: 1,7
20mm Ho-5: 1,9
MG 151/20: 1,9*
MK 103: 2,0*
20mm ShVAK: 2,0
Hispano V: 2,1
37mm M4: 2,1
Ho-103: 2,2
VYa-23: 2,5
12,7mm UB: 2,7
Hispano II: 3,0*
NS-37: 3,3
MG 151: 3,4
,50 Browning M2: 4,0*
Browning ,303: 4,2
* according to historical data - these datapoints were used as a basis for calculation of the rest, see http://www.hitechcreations.com/forums/showthread.php?s=&threadid=131669&highlight=dispersion
>According to your table, wouldnt a B-25H reign supreme, with its 75mm cannon?
Probably not, because the rate of fire is so slow :-)
Regards,
Henning (HoHun)
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IIRC
From a dead 6 o'clock attack position, The RAE determined in their FW-190 vunerability analysis that 1 round of .50 cal API had 0 percent chance of:
Penetrating or igniting the Fuel tanks
Hitting the pilot
Hitting the engine
Causing any effective fuselage damage.
From 6 degrees off a dead 6 o'clock .50cal API stood a slight chance of causing effective damage.
20mm on the other hand stood a 50 percent chance of destroying the FW-190 with a one round hit to the correct spot. 20mm stood some chance of destroying the FW-190 from a dead 6 o'clock position from any hits period. From 6 degrees off dead 6 o'clock these percentages went up astronomically.
Crumpp
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"If the 20mm was superior (especially the Hispano) to the .50, why didn't the British and Americans use them for bomber defense?"
Also notice that firing to rear quarter the .50Cal's hitting power increases quite a bit as an incoming enemy fighter will "collide" with the bullet and the same fighter's bullets fired at the bomber have to go sort of up-hill to reach the bomber so the fighter has to have heavier armament than bomber to intercept it efficiently.
-C+
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Originally posted by Charge
Also notice that firing to rear quarter the .50Cal's hitting power increases quite a bit as an incoming enemy fighter will "collide" with the bullet and the same fighter's bullets fired at the bomber have to go sort of up-hill to reach the bomber so the fighter has to have heavier armament than bomber to intercept it efficiently.
-C+
That is a fallacy. The bombers projectiles gets to add the fighters speed, but must subtract the bomber's speed. The fighter's projectiles also gets to add the fighter's speed (since it is firing forward), but must subtract the bomber's speed. So the bomber's and fighter's guns gain an equal ammount of extra energy.
The only difference is added drag for the fighter's projectiles since their speed is greater relative to the air. That speed difference is equal to the bomber's true airspeed.
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"The only difference is added drag for the fighter's projectiles since their speed is greater relative to the air."
Exactly. So they slow down more rapidly whereas a rearwards fired bullet has to endure significantly less drag.
If you are near the target the difference is unnoticeable, of course.
-C+
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At 20k+ feet it is also pretty unnoticable at any range. There is nothing "significant" about +- ~200 mph to the drag of a bullet at 20k+.
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Originally posted by 63tb
If the 20mm was superior (especially the Hispano) to the .50, why didn't the British and Americans use them for bomber defense? I see that they might be tough for hand-held positions but they would work in a turret mount, right? Wouldn't a 20mm be a better defensive weapon too?
63tb
You could more correctly say
"As the 20mm was so supperior it is not supprising that the British, Americans, Japanese and Germans worked very hard to implement 20 mm defensive turrents"
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Originally posted by SunTracker
But that brings me back to my original point. A pilot firing cannons would not have the same amount of shells in the air, nor the dispersion if firing with 1 or 2 cannons.
So basically it all comes down to this. At the average engagement distance, would it be easier to land 20-30 hits with 6 50 cals (the average U.S. Armament), or would it be easier to land 2-5 cannon hits with two cannons (the standard cannon armament)?
6X800rpm=4800rpm. 4800rpm/60=80 rounds per second. It would take a 1/4th second burst to down an enemy aircraft. Though indiviudal machine guns could be ramped up to 950 rounds per minute by armorers.
Hispano MkII= 600rpm. 600rpmx2=1200rpm/60=20 rounds per second. Figuring 2 rounds to down an enemy aircraft, it would take 1/10th of a second. Figuring 5 rounds, it would take 1/4th of a second.
The parity load out for 6 50 cals is 4 Hispanos.
The Spit, Pony, Hellcat, Corsair, etc etc etc.
could all carry 4 hispanos. So you see by your own numbers the Hispano is twice as good as the 50, because you had to cut the battery in half to show parity.
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The rear turret of the Lancaster comes to mind. That turret was fitted with 4 x 303s. Seems like they could have stuffed two 20mm in the same space (maybe even one). When shooting back at night fighters, you would want any hit to do maximum damage since you may not get another shot. Was the issue ammo storage? I guess a belt of 20mm would take alot more space than a belt of 303. Or was it that all Hispano production was allocated to fighters only?
63tb
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They could fit a pair of .50s instead of four .303s (just about - the total gun weight was still greater) but not a pair of Hissos. The 20mm weighed 50 kg, the .303 around 10 kg. It also generated much heavier recoil, needed entirely different ammo feed arrangements and so on.
TW
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4 20mm hispanos is vastly more effective and versitale armament than 6 USA 50 cal - end of story...
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Originally posted by HoHun
Here's a comparison of a selection of the above numbers to the energy of a single projectile (relative to the 12.7 mm Browning M2's API):
Gun Type Dam in # Energy
.303 Browning AC 0.296 0.20
.50 M2 AC 1.17 1.00
12.7mm Breda - SAFAT 0.95 0.55
12.7mm Ho-103 0.998 0.55
12.7mm UBS 1.15 1.28
13mm MG 131 0.92 0.64
Note that the two columns are not directly comparable - increase the right hand column by 17% for that, using the 0.50" M2 as a calibration point.
Regards,
Henning (HoHun) [/B]
can someone explain me how come the M2 0.5cal round has such higher destructive power over all the other HMG?
i can understand in the 20mm theres a room for variety in the HE content. but in the 12.7mm? the M2 is allmost twice as powerfull
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It is almost twice as powerful in terms of muzzle energy as the Japanese, Italian and German 12.7mm and 13mm guns, because they fired much smaller and less powerful cartridges (although the Russian 12.7mm is slightly better than the M2).
However, it is not twice as destructive, as the damage score shows. That is because the other guns fire HE ammunition.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Hi Flyboy,
>can someone explain me how come the M2 0.5cal round has such higher destructive power over all the other HMG?
Wel, compare the following rounds:
Round Type Mass g v0 m/s Chem% KE kJ ChemE kJ total E kJ
12,7x99 API 112 890 2 17,0 4,8 21,8
12,7x99 AP* 112 890 0 17,0 0,0 17,0
13x64B AP 76 710 0 9,7 0,0 9,7
13x64B HE 72 750 3,5 9,6 6,6 16,2
* Figures from API with 0 chemical energy for comparison purposes
The 12.7 mm M2 fires a 50% heavier shell at a 20% higher velocity, giving about 2 times the kinetic energy.
Another reason it looks good is that I have used mixed belting for some of the other guns, as for the Breda-Safat and the MG131, while only using the most powerful round for the 12.7 mm M2.
(Differently from what Tony assumed, I have figured in chemical energy in my statistics, and the damage numbers are actually derived from Aces High tests by someone else :-)
Use the most powerful round for the MG131 and the 12.7 mm M2 alike, and the firepower of the M2 is not ca. 200% of the MG131's (what you'd get looking at kinetic energy only), but rather 135% per round. Figure in the higher rate of fire of the MG131, the M2's firepower per barrel is just 117%.
(And figure in the weight of the weapon, and the M2 ends up at just 68% in the firepower comparison.)
For a heavy machine gun that's really powerful regardless of the perspective, we'd probably have to look at the Soviet UBS :-)
Regards,
Henning (HoHun)