Author Topic: Analysis of Aircraft Guns (Read 4088 times)

scJazz · « **Reply #45 on:** November 09, 2003, 09:29:25 AM »

Yes I realize, but the MG/FF design was used by many countries and the variants of it are a bit different. Besides I had already tested 37 other weapon systems no real harm in testing the 38th and concluding it was no different.

scJazz · « **Reply #46 on:** December 15, 2003, 10:49:02 AM »

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.

Flyboy · « **Reply #47 on:** December 15, 2003, 11:11:37 AM »

Quote

Originally posted by scJazz

Gun Type Dam in #
13mm MG 131 0.92

[/B]

you sure about that?

shouldnt it be MORE powerfull then the 12.7mm \ 0.5cal ?

scJazz · « **Reply #48 on:** December 15, 2003, 11:34:33 AM »

I'm very certain about everything in those tables. Considering granularity issues the minimum damage is .909lbs and the maximum is .926. I used .92lbs in the table for the MG131.

Flyboy · « **Reply #49 on:** December 15, 2003, 11:59:32 AM »

this make no sense to me, why did the LW install those guns in the first place then?

scJazz · « **Reply #50 on:** December 15, 2003, 12:50:03 PM »

Flyboy this thread is not for pondering such issues.

The only thing I've done here is to post the definitive answers as to just how much damage a weapon does to a ground target as a way of showing weapon lethality. Period.

A better question would be...

Why in hell did the LW put big fat slow velocity cannons on their planes when the US idea of banks of .50s seems to work so much better?

Urchin · « **Reply #51 on:** December 15, 2003, 01:48:19 PM »

Another "issue", for me at least, is that the damage tables for objects seem to be quite different than the damage tables for planes and GVs. There is, quite simply, no way that the Hispano is only 20% more powerful than the Mg151.

At least not in the simple "test" I did of shooting drones offline.

Try it, see what results you get.

Howitzer · « **Reply #52 on:** December 15, 2003, 03:00:50 PM »

Bravo to all of you who put your time into testing this, you got very good results with a lot of effort. Great thread.

Tony Williams · « **Reply #53 on:** December 15, 2003, 03:43:04 PM »

Quote

Originally posted by Flyboy
you sure about that?

shouldnt it be MORE powerfull then the 12.7mm \ 0.5cal ?

I agree with scJazz. I'm not sure what methodology is used, but the outcomes in at least this case (I haven't checked them all) look similar to mine. See: http://www.quarry.nildram.co.uk/WW2guneffect.htm

Tony Williams: Military gun and ammunition website and Discussion forum

Tony Williams · « **Reply #54 on:** December 15, 2003, 03:44:37 PM »

Quote

Originally posted by scJazz
Why in hell did the LW put big fat slow velocity cannons on their planes when the US idea of banks of .50s seems to work so much better?

Well, if you read the 'gun effect' article I posted the URL for above, you might begin to understand why....

Tony Williams: Military gun and ammunition website and Discussion forum

scJazz · « **Reply #55 on:** December 15, 2003, 04:30:13 PM »

I read and re-read your article several times as I went and figured out the damage table presented in this thread. After cruising around in many flight sims it is definitely easier to hit a target with US .50s or the equivalent. If you can hit it you can kill it. Being able to land a few 30mms or dozens and hundreds of .50s seems like the winner goes to the .50s!

Quoting your website...
It is sometimes argued that a projectile with a high muzzle velocity and a good ballistic shape (which reduces the rate at which the initial velocity is lost) provides a longer effective range. To some extent this is true, but the greatest limitation on range in air fighting in the Second World War was the difficulty in shooting accurately. The problem of hitting a target moving in three dimensions from another also moving in three dimensions (and probably at a different speed and on a different heading) requires a complex calculation of range, heading and relative speed, while bearing in mind the flight time and trajectory of the projectiles. Today, such a problem can easily be solved by a ballistic computer linked to a radar or laser rangefinder, but at the time we are examining, the "radar" was the human eyeball and the "ballistic computer" the human brain. The range, heading and speed judgements made by the great majority of pilots were notoriously poor, even in training. And this was without considering the effects of air turbulence, G-forces when manoeuvring, and the stress of combat. These factors limited the effective shooting range to around 400 m against bombers (longer in a frontal attack) and against fighters more like 250 m.

Tony Williams · « **Reply #56 on:** December 15, 2003, 11:23:56 PM »

There is certainly no point in having a devastatingly effective gun if you can't hit the target, but nor is there any point in having guns which can always hit if the hits do negligible damage. The problem is to get the balance right.

The six .50 armament was at one end of the 'acceptable' scale, three MK 108s (for the same total gun weight) were at the other. Against lightly constructed fighters, the .50s were clearly superior. Against heavy well-protected bombers, the MK 108s were clearly superior. The optimum was somewhere in between.

The experience of those air forces which enjoyed the benefit of a range of different weapons (HMGs and cannon) led them to move to cannon as their primary fighter armament well before the end of the war: the USAAF was the only exception, partly because they no real option; there was no other reliable weapon available to them. Fortunately for them, their opponents were generally small fighters and they had no tough bombers to deal with.

IMO the best all-round armament to see service during the war belonged to the later Tempests: four 20mm Hispano Mk V. This weighed slightly less than six .50s and was about twice as destructive. The ballistics at effective fighting ranges were very similar to the .50s, and while the rate of fire was only two-thirds as much, each hit did about three times as much damage.

Tony Williams: Military gun and ammunition website and Discussion forum

Flyboy · « **Reply #57 on:** December 16, 2003, 08:46:23 AM »

sorry for the "hijacking" of the threat but did the Mg131 was so weak in comparison to the allied 0.5cal Mgs?
i would assume it would be morepowerfull cause the larger caliber, but what do i know

scJazz · « **Reply #58 on:** December 16, 2003, 09:30:49 AM »

Flyboy please check Tony's website linked in this thread. For all intents and purposes to this discussion we can say that Tony is the expert on how things really were and I am the expert on how these real things are being modelled in AH.

I would like to answer this one to test my own knowledge. I might screw this up, Tony please correct my mistakes.

The MG131 used a 13mm cartridge the .50 M2 is a 12.7mm cartridge. Although cartridge diameter or caliber is nearly equal the length of the cartridge is not. The 13mm cartridge is roughly 2/3rds the length of of the .50 cartridge. This basically allows the .50 to pack about 50% more propellant than the 13mm. This extra propellant give the .50 projectile a much greater muzzle velocity. In addition the aerodynamics of the .50 were slightly superior allowing the projectile to maintain striking power over greater distances. Looking at Tony's table and using his Damage values for the two rounds we see that the 13mm x64B round has a Damage of 34 while the 12.7mm x 99 round (.50 M2 Aircraft mounted if I remember correctly) has a Damage of 46.

Adding to the complexity is the fact that the US generally did not use explosive ammunition for sub-cannon rounds. Instead they had an incendiary tip. The Axis forces almost always used HE content in their bullets. While an excellent idea in some respects it has the added effect of lowering the bullet weight and density. Explosives are less dense and hence weigh less than lead. This again shortens the range and accuracy of a round that already had a lower muzzle velocity to begin with.

Generally what you see from Axis weapons and Axis design philosophy is the idea that hitting with even a few slow, short-range rounds was adequate since they were almost invariably HE rounds. The MK108 30mm gun is a perfect example of this idea.

The US had quite a different idea in that they tried hitting a target with a whole bunch of incendiary tipped fast moving, long range bullets. The .50 M2 is a perfect example of this idea.

The British lucked out when they developed a cannon that was way ahead of its' time in many respects. The 20mm Hispano MK II an V. This combined the best of all worlds and is without a doubt the pinnacle of WWII guns. The round had a muzzle velocity that was 95% that of the US .50 so it was long range and accurate. It also used HE and hence caused considerable damage to anything it hit.

scJazz · « **Reply #59 on:** December 16, 2003, 09:47:16 AM »

Tony your point about 3 MK108s weighing as much as 6 .50s is noted. However in almost no cases were highly produced aircraft fitted with 3 MK108s. The exception to this would be the ME 262s. However as you point out since it was the human brain that acted as the ballistics computer the ME 262 presents some extreme problems.

Since it had an attack speed well in excess of the speed of its' target (bombers) managing to land hits with a MK 108 round became difficult at best. For less weight and probably even less volume the ME 262 could have been fitted with 12 MG 131s. In a nose mounted arrangement with no convergence problems this would have been devestating! Longer ranged and faster slugs would have made the odds of actually landing a hit extremely probable. Roughly 6 MG151s could have also been used and this would have worked out almost as well. Considering LW design concepts it would have been the most likely choice besides the MG131. However I don't think it would have been as effective.