Spitfire Mk.XIV vs P-51D Mustang

[DAVIDICUS]

So as I was saying, why maintain an armament of .303's?

Originally Posted by Soren

Here's an IX.e (Notice the four .303's ):

Umm, does that plane have any guns fitted? I think this is an unarmed air-show plane, with fake .50's AND the .303 slots marked in red.

Can you show me an actual picture of a Wartime Spit IXe or Spit XIVe with .303's?

=S=

Lunatic

Originally Posted by DAVIDICUS

So as I was saying, why maintain an armament of .303's?

The reason would be that 20mm cannon are too prone to jamming to rely on just two of them. If the one jams, the other is pretty much useless. You don't want to be totally toothless, and even 4 x .303's is better than nothing.

But I really think most if not all Spit XIV's mounted .50's, not .303's. As for Spit IX's, I believe from the IXe and on, they were also mounting .50's.

=S=

Lunatic

[Soren]

Originally Posted by RG_Lunatic

As for Spit IX's, I believe from the IXe and on, they were also mounting .50's.

Thats because they were ! Both configurations were available. Ever hear about the Universal "E" and "C" armament ??

[DAVIDICUS]

I think we can all agree that the .303 machine gun was employed on British aircraft in later stages of the war.

Now, I can see why earlier produced aircraft that were still used later in the war retained their .303 armament. You fight with the weapons you have. That's not what I'm talking about. Why would any aircraft built from, say July of 1942 on, be outfitted with .303's?

Were there manufacturing/supply or installation issues related to outfitting aircraft with the .50 BMG?

Two .50's are far more effective than four .303's. So, why install a .303 armament under any circumstances?

[Soren]

Your making it sound like the .303's were useless, but they werent. And the .50's werent the most effective Fighter vs Fighter round either.

The advantage of the four .303's was that they had a much higher ROF, and at 30-120m they were more than enough to put down a fighter.

Against Bombers the .303's would be in-sufficient though, but so would the .50's.

[the lancaster kicks ass]

this is true..........

Originally Posted by Soren

Your making it sound like the .303's were useless, but they werent. And the .50's werent the most effective Fighter vs Fighter round either.

The advantage of the four .303's was that they had a much higher ROF, and at 30-120m they were more than enough to put down a fighter.

Against Bombers the .303's would be in-sufficient though, but so would the .50's.

Umm... a .50 hit is at least 6-10 times more damaging than a .303 hit. .50's had good range, .303's had poor range.

I disagree, the .50 was a decent fighter vs. fighter round. Perhaps not as good as the Hispano, but two .50's were about the equivalent of one Hispano, all factors considered. And they were almost 3 times more reliable.

=S=

Lunatic

[Soren]

Originally Posted by RG_Lunatic

Umm... a .50 hit is at least 6-10 times more damaging than a .303 hit. .50's had good range, .303's had poor range.

I disagree, the .50 was a decent fighter vs. fighter round. Perhaps not as good as the Hispano, but two .50's were about the equivalent of one Hispano, all factors considered. And they were almost 3 times more reliable.

Yes the .50 is more powerful, but the ROF is low, and at 30-120m the 4x.303's are just as good as the 2x.50's.

Anyway the Spit IX and XIV both had the "B", "C" armament, and it was sufficient.

The "A" armament (8x.303's) during BoB was sufficient for shooting down fighters, so why shouldnt the much better "B" and "C" be so to ?

[DAVIDICUS]

I realize that I'm just basing this on my opinion but still see four .303's as inferior to two .50's. Insufficient ability to penetrate armor or inflict damage on the engine or penetrate structural members, too small of a diameter to poke good holes in the fuel system, etc.

Below are relevant excerpts (for what they're worth) from "The WWII Fightet Gun Debate"
http://www.csd.uwo.ca/~pettypi/elevo...tary/fgun.html

Concerning the Supermarine Spitfire Mk.IA:

The RAF was quick to understand that heavy firepower was needed, but its initial choice was an unfortunate one. The .303 was chosen over the .50 because of its higher rate of fire and better reliability, but the .303 round lacked the power to penetrate armour, and was far too light to do structural damage. Pilots preferred to use incendiary rounds, also because they could see them hit the target. Although some pilots had their guns "synchronized" to converge at a point, it was more common to have some spreading, to simplify aiming

...

In the first phase (of fighter armament employment) the rifle-calibre machinegun was still important. Fighters either carried a homogenous armament of such guns, or they used a mixture of rifle-calibre guns with cannon or heavy machineguns. Examples of the first approach are the eight Browning .303s in the Spitfire and the four MG17s in the early Fw 190. Examples of the second approach are the MG FF and MG 17 weapons of the Bf 109E, the two .50 and four .303 Brownings of the early P-51, or the two 20mm cannon and two 7.7mm guns in the A6M2. The first phase ended when it was generally understood that the light machinegun was ineffective against modern combat aircraft.

In the second phase there were still two options. Either a homogenous armament of heavy machineguns was used, or a mixture of more modern 20mm cannon with machineguns. The first approach was chosen almost exclusively by the USAAF, which equipped its fighters with six or eight .50 Browning guns. The second approach was far more common, and used by fighters such the Spitfire, the Bf 109, or Ki.84. The cannon were now in general belt-fed, high-velocity weapons with a satisfactory rate of fire. The disadvantage of cannon was that their weight and recoil precluded the use of more than one or two. Hence they had to be mixed with machineguns, with different ballistic characteristics, different ammunition and different maintenance requirements. The disadvantage of an armament of heavy machineguns only was that it lacked the destructive power to be effective against anything but small fighters or lightly constructed bombers.

The third phase, which lasted well beyond WWII, was characterized by a switch to a homogeneous armament of 20mm cannon. Examples of such armament are the last Spitfire models, the Typhoon and Tempest, the Soviet La-7, and the Japanese N1K-2J. Usually four 20mm cannon were carried. This was also the standard armament for most post-war fighters, except those of the USAAF. Again, there was a second option: That of heavy "bomber killer" armament. Here the German MK 108 cannon must be mentioned, as installed in the Me 262. Such cannon were either low- velocity, low-rpm weapons, or they were extremely heavy; in either case they reduced the suitability of the fighter for combat against other fighters. Because of this and the introduction of spin-stabilized and folding-fin rockets, such armament was installed in few post-war fighters, but one that must be mentioned is the MiG-15

Originally Posted by Soren

Yes the .50 is more powerful, but the ROF is low, and at 30-120m the 4x.303's are just as good as the 2x.50's.

Anyway the Spit IX and XIV both had the "B", "C" armament, and it was sufficient.

The "A" armament (8x.303's) during BoB was sufficient for shooting down fighters, so why shouldnt the much better "B" and "C" be so to ?

The .50's had about five times the hitting power of the .303 at the muzzle. By 100 meters, this has increased to about eight to nine times the hitting power. The .303's had a hard time penetrating even the 109's armor from point blank range. The .50 AP or API round could easily penetrate the reaf of the fuselage near the tail, pass through the pilot's seat armor, pass through the firewall, and end up damaging the engine, from point blank range (or out to as much as 100 meters). From 300 meters, the .50 could still easily penetrate the fuselage and both the aluminum and steel seat armor to reach the pilot.

.303's could strike German self-sealing fuel tanks repeatedly with minimal effect. A single .50 hit to the fuel tank was usually enough to rupture it beyond its ability to self-seal, and often sufficient to cause a fire as well. And that does not consider the incendiary effect - when this is factored in the .303's simply cannot compare, they could not carry enough incendiary to be very effective, where the .50's could.

Even at point blank range the .303 was not nearly as effective as the .50, it would take at least three .303's to equal a single .50, even accounting for the RoF. The 1200 rpm RoF of the .303 was really not that much of an advantage over the 850 rpm RoF of the .50 BMG, given the poor .303 ballistics vs. the excellent .50 ballistics. And in 4 x .50 installations, such as on the P-51B, the guns were usually tweaked to fire at about 950 rpm.

Look at the facts Soren - the P-51B with 4 x .50's had very much superior armament to the Spitfires armed with 8 x .303's. There is simply no disputing it, even the British agreed.

=S=

Lunatic

[DAVIDICUS]

In case anyone is interested in calculating energy of gun projectiles in foot pounds, the following is the equation:

Take the weight of the bullet/projectile in grains and divide by 7,000. (There are 437.5 grains to an ounce.)

Take that figure and multiply by the velocity in feet oper second.

Take that figure and multiply again by the velocity in feet per second.

Take that figure and devide by 64.32 (Two atmospheres in pounds per square inch.)

So, for instance, my .338 Winchester Magnum can drive a Federal High Energy load consisting of a 225 grain bullet at 2,940 feet per second for a whopping (trust me, its quite nasty on both ends) 4,319 foot pounds of energy. That's considered quite a powerful rifle and more than adequate for hunting the largest and most dangerous species (Moose, Brown Bear) in North America. It's power exceeds the .303 British (less than 2,500 fpe)by a very wide margin yet pales compared to the .50 BMG(more than 12,000).

[Soren]

Originally Posted by RG_Lunatic

Look at the facts Soren - the P-51B with 4 x .50's had very much superior armament to the Spitfires armed with 8 x .303's. There is simply no disputing it, even the British agreed.

=S=

Lunatic

I never stated that the 8x.303's were better than 4x.50's RG, so stop putting words into my mouth !

The 4x.303's with incendiary rounds coupled with 2xHispano's was just as effective in their own right against enemy Fighters, as the 2x.50's coupled with 2xHispano's at 30-120m or so.

Also the .303's did't have to make any serius internal damage to the enemy fighter, just the airframe or wings, wich they were more than capable of !

Also the Browning .303 had an ROF of 1140 rpm, whereas the Browning .50 M2 had an ROF of 750 rpm.

4x.303's will litterally 'Rain' bullets at you ! wich will make any enemy fighter look like a 'Filter' of some sort.

In terms of ballistics and penetrating power, sure the .50's were much better, but penetrating power aint all, infact the Germans pretty much demonstrated that their incendiary rounds were more effective if they hit home.

Originally Posted by Soren

I never stated that the 8x.303's were better than 4x.50's RG, so stop putting words into my mouth !

Ahh but you are. Even in this post in your next statement you say exactly that! 4 x .303's are, in your estimation, equal to 2 x .50's (out to 120 m).

Originally Posted by Soren

The 4x.303's with incendiary rounds coupled with 2xHispano's was just as effective in their own right against enemy Fighters, as the 2x.50's coupled with 2xHispano's at 30-120m or so.

I very strongly disagree. The .303's were largely ineffective against mid-war and late-war fighters. The deWilde incendiary rounds were known to even bounce off the relatively thin skins of German fighters. When they did penetrate, they had no energy remaining to do any damage, and they carried so little incendiary that they had a hard time starting fires unless a very large number of hits were scored.

Originally Posted by Soren

Also the .303's did't have to make any serius internal damage to the enemy fighter, just the airframe or wings, wich they were more than capable of !

No, they weren't. It took a large number of hits, often a hundred or even more, to down enemy fighters with .303's.

Originally Posted by Soren

Also the Browning .303 had an ROF of 1140 rpm, whereas the Browning .50 M2 had an ROF of 750 rpm.

Why is it that when people compare the .50 Lightweight Aircraft M2 to other guns, they always choose the maxium RoF of the other gun, but the minimum for the M2? The .303 Browning had a RoF of from about 1040-1140 rpm. The .50 M2 Browning had an RoF of from 750-850 rpm (modified with a nickel in place of the fiberous buffer pad it could make 950-1000 rpm). To be "fair" you need to compare them equally, the .50 fired at about 800 rpm (the standard setting for all 6 gun US fighters), the .303 fired at about 1100 rpm.

Using these figures we see that at the muzzel the energy is 3052.64 jouls/round for the .303, and 16746.43 joules for the .50. A difference of about 5.5:1 in favor of the .50. Factoring in the RoF of the guns, the .303 does a little better at 55,965 joules/sec vs. 223,286 joules/sec for the .50, but still this is a difference of 4:1. And then you have to factor in the range effect. At 100 meters the .50 BMG has lost a wopping 5.2% of its velocity (at sea level), compared to the .303 which has lost over 15% of its velocity, so at that range the .50 holds about 90% of its initial energy, where the .303 holds only about 72% of its energy. So at 100 meters we are looking at 44,000 joules/sec for the .303 as compared to about 201,000 for the .50, and we are almost back at a 5:1 advantage for the .50. And by 200 meters, the .303 is practically worthless, but the .50 BMG is still quite potent.

Originally Posted by Soren

4x.303's will litterally 'Rain' bullets at you ! wich will make any enemy fighter look like a 'Filter' of some sort.

Yeah, and they won't have much more effect than rain either!

Originally Posted by Soren

In terms of ballistics and penetrating power, sure the .50's were much better, but penetrating power aint all, infact the Germans pretty much demonstrated that their incendiary rounds were more effective if they hit home.

Where do you get this from? US and British incendiaries were superior to those used by the German's throughout the war. To be effective, an incendiary has to be able to "hit home", and that requires penetration or an absolutely huge amount of incendiary material.

=S=

Lunatic

[Soren]

Ahh but you are. Even in this post in your next statement you say exactly that! 4 x .303's are, in your estimation, equal to 2 x .50's (out to 120 m).

Yes in their own right they are, and coupled with the 2xHispano's they were very effective. But i wasnt suggesting 8x.303's vs 4x.50's !

I very strongly disagree. The .303's were largely ineffective against mid-war and late-war fighters. The deWilde incendiary rounds were known to even bounce off the relatively thin skins of German fighters. When they did penetrate, they had no energy remaining to do any damage, and they carried so little incendiary that they had a hard time starting fires unless a very large number of hits were scored.

No, they weren't. It took a large number of hits, often a hundred or even more, to down enemy fighters with .303's.

Well you see with 4-8x guns with 1100 rpm, over 100 hits are very plausible ! And although the 8x.303's proved insufficient against Bombers, they proved more than enough against the Me-109's over Britain in 1940 !

Why is it that when people compare the .50 Lightweight Aircraft M2 to other guns, they always choose the maxium RoF of the other gun, but the minimum for the M2?

As far as I remember, you mentioned the .303 to have an ROF of 1200rpm ! and the M2 950rpm.

The .303 Browning had a RoF of from about 1040-1140 rpm. The .50 M2 Browning had an RoF of from 750-850 rpm (modified with a nickel in place of the fiberous buffer pad it could make 950-1000 rpm). To be "fair" you need to compare them equally, the .50 fired at about 800 rpm (the standard setting for all 6 gun US fighters), the .303 fired at about 1100 rpm.

Using these figures we see that at the muzzel the energy is 3052.64 jouls/round for the .303, and 16746.43 joules for the .50. A difference of about 5.5:1 in favor of the .50. Factoring in the RoF of the guns, the .303 does a little better at 55,965 joules/sec vs. 223,286 joules/sec for the .50, but still this is a difference of 4:1. And then you have to factor in the range effect. At 100 meters the .50 BMG has lost a wopping 5.2% of its velocity (at sea level), compared to the .303 which has lost over 15% of its velocity, so at that range the .50 holds about 90% of its initial energy, where the .303 holds only about 72% of its energy. So at 100 meters we are looking at 44,000 joules/sec for the .303 as compared to about 201,000 for the .50, and we are almost back at a 5:1 advantage for the .50. And by 200 meters, the .303 is practically worthless, but the .50 BMG is still quite potent.

The .50 cal round itself was about 4.2-4.6 times as destructive as the .303.

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Look at table 2 :GUN POWER AND EFFICIENCY.

Here the Browning .303 and 50 Browning M2 are listed as equal !

Then take a look at table 3: FIGHTER FIREPOWER.

The Spit Mk.Vc with 4x.303's + 2xHispano's; Armament power= 480.

The Spit Mk.XIV.E with 2x50's + 2xHispano's; Armament power= 520.

They are very close !

Yeah, and they won't have much more effect than rain either!

Nice joke, I'll give you that !

All im trying to say is that the 4x.303's + 2xHispano's armament wasnt ineffective, and more or less on par with the 2x.50's + 2xHispano's armament against Fighters.

Also the lower weight of the Browning .303 gun was an advantage of its own.