.50 Cal vs 20 mm Hispano - Ground Attack

[ZachariasX]

There's only one reason to go to small calibers for plowing mud. This is CAS for your ground troops at point blank range. You choose small caliber precisely for not having "secondary effects". If your team is 10 yards next to the baddies you're supposed to shoot at, then you better not do too much collateral. (Or bounce of, go through wals and one of your troops.) There is no weapon like the machine gun that can help in such situations. All "smart" ammo is useless as it both lacks the time to engage and the ability to tell friend from foe during a shootout. If you're in that CAS business, it makes sense putting on .303 size caliber machine guns. The .50 is getting a bit rarge for that, as the gun is unnecessarily heavy as is the ammo for the same firing time. If the target is only remotely hard, then you can identify it, mark it and cann the big cavallery.

 

The entire point of a gun on a plane is to bring down whatever enemy plane there is with one burst. You require more than one gun for that, then it means you couldn't build a suitable gun yet. The more guns you need, the less suitable your gun. Of course you can then let go at whatever else there is. The 20 mm were very suitable because when you shoot locomotives, it punches much larger holes than .50 BMG. Same with halftracks etc.

 

Make no mistake, the .50 BMG is a great and effective heavy machine gun. But it's not what you want to strike smething big. Any "default" gun in aircrat grew in caliber for that reason. But if you are chasing sorry pesants, put on .303 gunpods and don't forget adding a bit more lead.

[Venturi]

Lol. 

[ZachariasX]

If .50 was best option in aircraft against ground targets, someone would still use it.

 

The US also gave a tangible answer to the OP:

Edited September 21, 2019 by ZachariasX

[JtD]

Even if I agree with basically all your points about the .50 so far, I think that last argument is flawed. Warfare changes, and weapon systems need to adjust. No one uses long lance torpedoes anymore, they still were the best torpedoes of WW2 (I'd say).

[ZachariasX]

1 minute ago, JtD said:

No one uses long lance torpedoes anymore, they still were the best torpedoes of WW2 (I'd say).

True, fair enough.

 

There is however a comparison made, notably in the Algerian war. The French had quiet a couple of P-47 deployed for the counterinsurgency role. Clostermann describes that in his later books. He was flying observation planes that directed the attacks. According to him, they often used the P-47, but as soon as the enemy dug in or hid otherwise, they would call for the jets armed with karger caliber cannons using HE rounds for CAS, something they considered much harder hitting.

[US63_SpadLivesMatter]

How many of the aircraft using .50's for ground attack were initially (primarily) designed as ground attackers?

[JtD]

The US (or the British) didn't really have ground attack aircraft such as the Il-2 or Hs129 in their arsenal. What's getting closest outside of converted fighters might be the attack aircraft, like the A-20, A-26, B-25, B-26 - all of which made extensive use of the .50 in the ground attack versions.

 

We shouldn't forget that the US strapped the .50 onto everything, because that's the weapons they got. They took the 4 Hispanos out of the Mustang when they adopted it into their service. OTOH, the British didn't have an own .50, so they didn't use it in anything (with a few exceptions). You use what you've got.

[SCG_OpticFlow]

1 hour ago, ZachariasX said:

If .50 was best option in aircraft against ground targets, someone would still use it.

 

The US also gave a tangible answer to the OP:

 

Don't forget this terrifying US ground attack weapon:

[LColony_Kong]

.50cals were extremely effective for both air to air and air to ground use during ww2. The reason cannon gradually overtook machine guns is because cannons gradually gained higher rates of fire and higher muzzle velocities.

 

During ww2 everyone except the USAF and USN generally tried to combine both gun systems together as a solution. The U.S. simple banked on large numbers of 50 cals, which i would argue is the best solution for a general purpose fighter at the time.

 

Several things happened after ww2 that made 20mm cannons the ideal solution and the 50 cal was eclipsed.

 

-Aircraft become larger and far more durable.

-Larger planes could carry more practical loads of 20mm cannon rounds.

-20mm Cannons gain higher rates of fire (revolver and gatlings)

-20mm shells gained much higher muzzle velocities

-Gun sights changed to allow MUCH easier tracking of a target (lead computing radar)

 

In other words, the 20mm evolved to give you the best of both worlds....and alot of capability neither caliber had before.

 

So 50 cals didnt fall out of vogue because they sucked thats why no one still used them today. Todays fighters carry armament that is nothing like ww2. A single gun with a rate of fire 4-5 times faster than any ww2 gun or cannon that is aimed with lead computing sight out to ranges no ww2 fighter could dream of engaging out to effectively.

 

 

 

Back to ww2. The 50 cal is the best a2a gun system for anti fighter work, and its generally good enough against bombers. You have much longer firing time. You have much lower lead need to high the target. You have a wider spread due to 6-8 guns which makes it much easier to hit the target with a good harmonization pattern. I would take a 6-8 50 cal armed plane over a pair of 20mm cannon any day of the week. And I take 1 20mm cannon with more ammo over a pair of them mixed with two useless guns I could have used for ammo space.

Edited September 21, 2019 by Lord_Flashheart

[JtD]

22 minutes ago, Lord_Flashheart said:

.50cals were extremely effective for both air to air and air to ground use during ww2.

 

Because there were six to eight of them installed. Using high numbers of mediocre performers will always make 'effective'. On an aircraft, you'd also want 'efficient', and that's something they weren't. US M2 0.50 armament typically was twice as heavy as that of aircraft with comparable hitting power based on 20mm cannons. That waste of perfomance only affordable if you have large fighter aircraft with powerful engines and the logistics available to operate and supply them. A Yak-3 can't carry six Brownings, no place to stick them, no power to support a 5% weight increase.

 

As we've pointed out already, four typical 20mm guns weigh as much as six Brownings and can do a lot more damage, decent ammunitions provided. Same conclusion the US arrived at in a postwar study.

[cardboard_killer]

Do not underestimate the power of nostalgia on facts. For many the M2 was the best thing since canned beer and no one will ever argue them out of that faith. If it's any consolation, it isn't just in flight sims you get the argument over.

Edited September 21, 2019 by cardboard_killer

[HagarTheHorrible]

I suspect many of you aren”t coming at this from the correct perspective. You’re all just considering it from the perspective of the damage each weapon can do.  

 

Being shot at, especially if you aren”t expecting to be shot at is very likely to put you off your cup of tea regardless of the size of bullet, it’s just not nice.

 

When  we talk about weapon effectiveness the main consideration is a good risk to reward ratio.  You don’t enter a bears pit with a tickling stick.  If you’re entering a high threat, high risk area, you wan’t to inflict maximum damage for the risk taken, you go loaded for bear.  On the other hand if the threat is minimal than even just buzzing around can have some disruptive effect.

[LColony_Kong]

3 hours ago, JtD said:

 

Because there were six to eight of them installed. Using high numbers of mediocre performers will always make 'effective'. On an aircraft, you'd also want 'efficient', and that's something they weren't. US M2 0.50 armament typically was twice as heavy as that of aircraft with comparable hitting power based on 20mm cannons. That waste of perfomance only affordable if you have large fighter aircraft with powerful engines and the logistics available to operate and supply them. A Yak-3 can't carry six Brownings, no place to stick them, no power to support a 5% weight increase.

 

As we've pointed out already, four typical 20mm guns weigh as much as six Brownings and can do a lot more damage, decent ammunitions provided. Same conclusion the US arrived at in a postwar study.

Multiple 50s was better than multiple 20s. 4 20mms doesnt give you the ammo or the lead advantage of the 50s, or the rate of fire. Plus 4 20mm was a fairly rare setup, with 1 or 2 being the norm for cannon armed planes.

 

A large fighter with lots of logistics sounds pretty much like the US situation. If other nations couldn't duplicate that, it hardly makes the setup less ideal.

 

Ill gladly trade 5% weight difference for 4 times the ammo capacity while being less than 4 times less potent. Ill also trade it for having an easier time aiming. Especially when the only performance metric that really matters for a ww2 fighter is speed, and then climb.

 

Why would I ever want to trade far more ammo and much less drop with plenty of hitting power so I can lose 5% weight.....when I DO have the engines to have comparable performance to enemy planes? And when the performance metrics that are going to win the air war are range, speed, and the ability to hit targets at range and at high speeds?

 

I dont care if I lose 5% weight so I cant gain a slight edge in turn performance when 99% of the time I either wont be in that kind of fighter or when I am, the pilots make the difference anyhow. The 109 can out turn the P-51, but the difference was small enough under practical conditions that most 51 pilots came away with the opposite impression.

https://imgur.com/h3pWMkM

 

Good Luck doing deflection shooting like this with a ww2 cannon, especially with the most common 2 gun or 1 gun set up with only 100-200 rounds.

Edited September 21, 2019 by Lord_Flashheart

[Bremspropeller]

The 50s worked, but just barely and only when clustered in battleship-numbers.

 

Everybody else went up un caliber and was glad they did. Including the Navy/ Marines.

Their Corsairs went from 6x0.50'' to 4x20mm. Including the taylor-made CAS AU-1 for the Marines.

 

1 hour ago, Lord_Flashheart said:

Multiple 50s was better than multiple 20s. 4 20mms doesnt give you the ammo or the lead advantage of the 50s, or the rate of fire. Plus 4 20mm was a fairly rare setup, with 1 or 2 being the norm for cannon armed planes.

 

Nope. 4x20mm gives you more effect for less rounds. The round will go plonk-boom, instead of just going plonk.

 

4 20mm was standard in the Fw 190 - and they even downsized to two 20mm guns for ground-attack. Go figure.

It also was standard in the Hurricane IIC, the Typhoon Ib, the Tempest II and V and the Sea Fury.

Furthermore, it was incorporated in the Navy/ Marines Corsairs, which went from 6 fifties to four twenties. The AD was designed from ground up with four twenties.

 

Is that enough to disprove everybody's unrational preference for the fifties?

 

[LColony_Kong]

6 minutes ago, Bremspropeller said:

The 50s worked, but just barely and only when clustered in battleship-numbers.

 

Everybody else went up un caliber and was glad they did. Including the Navy/ Marines.

Their Corsairs went from 6x0.50'' to 4x20mm. Including the taylor-made CAS AU-1 for the Marines.

 

 

Nope. 4x20mm gives you more effect for less rounds. The round will go plonk-boom, instead of just going plonk.

 

4 20mm was standard in the Fw 190 - and they even downsized to two 20mm guns for ground-attack. Go figure.

It also was standard in the Hurricane IIC, the Typhoon Ib, the Tempest II and V and the Sea Fury.

Furthermore, it was incorporated in the Navy/ Marines Corsairs, which went from 6 fifties to four twenties. The AD was designed from ground up with four twenties.

 

Is that enough to disprove everybody's unrational preference for the fifties?

 

Yes it give you more effect for less rounds, which is not the only metric of firepower. You have to actually hit the target.

 

20mm corsairs were rare. The vast majority of ww2 fighters had some combination of mg and cannon, and most cannon armed fighters....especially the planes that actually gave significant service during the war, only had 1 or 2 cannon and usually only 1-200 rounds. The 190 is the only plane on that list you gave that actually gave significant service. The rest were built in modest-tiny numbers, or showed up too late to matter.

 

 

[Bremspropeller]

1 minute ago, Lord_Flashheart said:

Yes it give you more effect for less rounds, which is not the only metric of firepower. You have to actually hit the target.

 

20mm corsairs were rare. The vast majority of ww2 fighters had some combination of mg and cannon, and most cannon armed fighters....especially the planes that actually gave significant service during the war, only had 1 or 2 cannon and usually only 1-200 rounds. The 190 is the only plane on that list you gave that actually gave significant service. The rest were built in modest-tiny numbers, or showed up too late to matter.

 

 

 

If you don't hit the target with the 50s, you'll just make holes in the ground. The 20s (if HE) will burst and at least cover the area with shrapnell. The 20mm is a much superior round.

 

20mm Corsairs were the norm in Korea.

The Hurri IIC showed up too late to matter? Or the Typhoon IB?

 

Cognitive dissonance at play...

[unreasonable]

3 minutes ago, Lord_Flashheart said:

Yes it give you more effect for less rounds, which is not the only metric of firepower. You have to actually hit the target.

 

20mm corsairs were rare. The vast majority of ww2 fighters had some combination of mg and cannon, and most cannon armed fighters....especially the planes that actually gave significant service during the war, only had 1 or 2 cannon and usually only 1-200 rounds. The 190 is the only plane on that list you gave that actually gave significant service. The rest were built in modest-tiny numbers, or showed up too late to matter.

 

 

 

They generally only had 1-2 cannon because that was all the space they had and early war planes tended to be light and underpowered. Spitfire wings were a little too thin even for 2 cannon - if the RAF could have made 4 cannons work they would have done so.  Typhoons and Tempests did not give significant service? This is absurd.  Both the RAF and GAF switched to adding more cannons instead of more HMGs because, having been fighting for years, they had found out what actually works.  

 

Cannons appeared in greater numbers later in the war not because the cannons were hugely different: but because the planes were larger and more powerful, enabling the significant advantages of cannons to be fully exploited.

[LColony_Kong]

Just now, Bremspropeller said:

 

If you don't hit the target with the 50s, you'll just make holes in the ground. The 20s (if HE) will burst and at least cover the area with shrapnell. The 20mm is a much superior round.

 

20mm Corsairs were the norm in Korea.

The Hurri IIC showed up too late to matter? Or the Typhoon IB?

 

Cognitive dissonance at play...

Not sure you know what cognitive dissonance is. Nothing i said was contradictory, in particular the bit your mentioned. Cognitive dissonance is not me being wrong lol.

 

Korea was not ww2. Did I say anything about Korea? Nope. Hurricane 2c and Typhoon entered service early but in the case of the hurricane it was one of many variants and was already obsolete as an aircraft. 3500 typhoons were produced over a rather large period.

 

Most 20mm hits that don't hit the target wont do anything either. I think you have a rather inflated concept of just how much area effect a 20mm explosion has. Given that both 20mm and 50 cal are extremely effective against virtually any target both could destroy, ill take the larger ammo capacity and greater saturation of the 50 cals.

3 minutes ago, unreasonable said:

 

They generally only had 1-2 cannon because that was all the space they had and early war planes tended to be light and underpowered. Spitfire wings were a little too thin even for 2 cannon - if the RAF could have made 4 cannons work they would have done so.  Typhoons and Tempests did not give significant service? This is absurd.  Both the RAF and GAF switched to adding more cannons instead of more HMGs because, having been fighting for years, they had found out what actually works.  

 

Cannons appeared in greater numbers later in the war not because the cannons were hugely different: but because the planes were larger and more powerful, enabling the significant advantages of cannons to be fully exploited.

Ill grant that I was a bit harsh on the Typhoon.

 

What I wont grant is that statement about what actually works. That is just ridiculous.

[unreasonable]

4 minutes ago, Lord_Flashheart said:

 

What I wont grant is that statement about what actually works. That is just ridiculous.

 

The read the US Ballistics Research Laboratory report on the effectiveness of these weapons - not a ridiculous report at all.

 

I am interested in your opinion on why it was that both the RAF and GAF (and later USN) emphasized cannons over HMGs.  If you are right that 50 cals or similar HMGs provide a better result, how did these two airforces that had been fighting for years get it so wrong?

[Alexmarine]

10 minutes ago, Bremspropeller said:

20mm Corsairs were the norm in Korea.

 

Can't really speak for the USMC land based squadron but, considering the Carriers Air Group, the 20mm armed ones (which were all of the F4U-5N night fighter variant) were outnumbered by the .50cals armed F4U-4 by a 7-6 to 1 margin (especially in 1950/1951), not amounting for more than a single "flight" unit for the entire air group. By 1953 the ratio usually fell down to 3:1 but only because more and more corsairs were replaced by jet units, while the Night Fighter variants kept their role due to the specific night threats of the conflict

[unreasonable]

23 minutes ago, Lord_Flashheart said:

 

Most 20mm hits that don't hit the target wont do anything either. I think you have a rather inflated concept of just how much area effect a 20mm explosion has. Given that both 20mm and 50 cal are extremely effective against virtually any target both could destroy, ill take the larger ammo capacity and greater saturation of the 50 cals.

Ill grant that I was a bit harsh on the Typhoon.

 

And another thing...    Just modeling in two dimensions, the "area of effect" of a 15mm round is 177mm^2   For a 20mm AP round it is 314.  So eight 50 cals = 1416mm^2, 4 20mm = 1256, so if firing AP only the 50 cals win. 

 

But if every other 20mm round is HE things look very different. Let us assume a very conservative area of effect or lethal radius: say 100mm. The area of effect of  the 20mm HE round is therefore 31,415mm^2.  (Powerful thing, that ^2) So two AP + two HE 20mm gives 63,458mm^ in total, compared to  1,416 for eight 50 cal. 

 

So in terms of getting a ground target into its area of effect, the 4 cannon set up is  ~45 times as likely to succeed, per salvo.  

 

 

 

 

[BlitzPig_EL]

Gents, we need to focus on WW2 here.

The .50 BMG was an excellent compromise between the rather in effective rifle caliber weapons of the intrerwar and early war period, and larger caliber machine cannons that eventually became the norm.  Another factor that is being overlooked is logistics.  Having one type of aircraft armament for all types gave a significant simplification to the US logistics train.  Do remember, logistics/supply wins wars.  Just look at those Luftwaffe and Japanese pilots peering down into an empty fuel Bowser if you think otherwise.

[JtD]

I'm starting to wonder why the IL-2 didn't come with a battery of 12.7mm UB guns, given that they were considerably better than the M2 and the M2 appears to have been the be all end all weapon. In a wing that large, they could have easily fitted a dozen UB's giving it 100% more firepower for the same weight as the eight M2's on the P-47. Which apparently is already better than 4x20, which for the same reasons must surely be better than 2x23.

 

My guess is the Soviets weren't stupid and used cannons because they were both, more effective and more efficient. Just like every nation that had a working 20mm cannon (or larger) made use of it in their aircraft - be it fighter or ground attack or anything else with front firing guns. Really, it's hard to find front line aircraft outside of the US that didn't feature 20mm+ cannons. And imho that's not because everyone outside the US was stupid, imho it is because the US failed at mass producing a reliable 20mm cannon.

[Rjel]

2 hours ago, JtD said:

I And imho that's not because everyone outside the US was stupid, imho it is because the US failed at mass producing a reliable 20mm cannon.

I don't think stupidity played into nearly as much as in some of the arguments in this thread. I think history shows that for the USAAF and Navy/Marines, the .50 cal was the perfect solution during WWII. Neither failed in the missions because of its use. Whether it was blind dumb luck or some foresight into the coming airwar the U.S. was to fight, is hard to say. But in Europe, the USAAF didn't have to face large massed formations of bombers like the British did before them or the Germans would by 1943. So the real need for a heavier caliber machine gun or cannon really is moot. The Japanese did the Allies a favor by fielding lightly constructed and highly flammable A/C. Again, the .50 cal armament was good enough to defeat them. As Blitzpig_EL stated, logistically, it simplified supply lines immensely for the U.S.A. as it fought all over the globe.  

[cardboard_killer]

4 minutes ago, Rjel said:

I think history shows that for the USAAF and Navy/Marines, the .50 cal was the perfect solution during WWII.

 

I think history shows quite the opposite. The USA struggled to put a 20mm in production that was reliable on its a/c and didn't get it right until after the war was mostly over. The differences were not material to the war overall. The US could have put 30.06s in their planes and the differences would not have been material to the war.

[Rjel]

5 minutes ago, cardboard_killer said:

 

I think history shows quite the opposite. The USA struggled to put a 20mm in production that was reliable on its a/c and didn't get it right until after the war was mostly over. The differences were not material to the war overall. The US could have put 30.06s in their planes and the differences would not have been material to the war.

That wasn't my point at all. My point was, the .50 caliber did EVERYTHING the U.S. needed it to do during WWII. Short of stopping Tiger tanks as we all know. There truly wasn't a need for them to field a cannon armed fighter. Find the tests done on a 78thFG P-47 with two 20mm cannon slung under the wings. It was found that the two extra cannon really did not contribute to the overall effectiveness of the P-47 in ground attack and in that configuration, degraded performance just as it did for the Bf-109.

Edited September 21, 2019 by Rjel
spelling

[Bremspropeller]

4 hours ago, Alexmarine28 said:

Can't really speak for the USMC land based squadron but, considering the Carriers Air Group, the 20mm armed ones (which were all of the F4U-5N night fighter variant) were outnumbered by the .50cals armed F4U-4 by a 7-6 to 1 margin (especially in 1950/1951), not amounting for more than a single "flight" unit for the entire air group. By 1953 the ratio usually fell down to 3:1 but only because more and more corsairs were replaced by jet units, while the Night Fighter variants kept their role due to the specific night threats of the conflict

 

Rephrasing then: By Korea, all new Corsairs were cannon-armed exclusively.

 

That's because the -4 was a WW2 bird and it, plus it's cannon-armed development, the -4B, got cut back in the immediate aftermath of WW2.

Starting with the -4B, all subsequent Corsairs were cannon-armed. That includes all -5 variants, the AU-1 and the french F4U-7 (used in Indochina).

 

Incidentally, all Corsair A-A kills in Korea were by 20mm.

 

 

[Ehret]

2 hours ago, JtD said:

My guess is the Soviets weren't stupid and used cannons because they were both, more effective and more efficient. Just like every nation that had a working 20mm cannon (or larger) made use of it in their aircraft - be it fighter or ground attack or anything else with front firing guns. Really, it's hard to find front line aircraft outside of the US that didn't feature 20mm+ cannons. And imho that's not because everyone outside the US was stupid, imho it is because the US failed at mass producing a reliable 20mm cannon.

 

Yes. However, still missing (mostly) that IRL people weren't robots. Personally, I would feel threatened the same if the enemy would shot 0.30" or 20mm. It really takes little to disable a human; just enough stress can do it.

The same goes for many planes - one small hole in sensitive place can ensure that the machine will not be able to return... That's not flashy as big caliber HE bangs but will decide course of the war the same.

 

There is problem with how score is counted in sim games - you have obliterate the target quickly to ensure someone else will not get the score, instead. That's poor mechanic.

[JtD]

44 minutes ago, Rjel said:

The Japanese did the Allies a favor by fielding lightly constructed and highly flammable A/C. Again, the .50 cal armament was good enough to defeat them.

 

It were the Japanese that reminded the USN that the 0.50 was insufficient on occasion. Kamikaze aircraft had to be brought down quickly, something 6x0.50 did not accomplish. And no, the US using a 20mm cannon instead of the 0.50 wouldn't really have mattered much in the big picture, as it was sufficient overall. But sufficient is not perfect.

 

14 minutes ago, Ehret said:

The same goes for many planes - one small hole in sensitive place can ensure that the machine will not be able to return.

 

Interestingly, there are much more sensitive places on an aircraft when you use a cannon than if you use an hmg. And as a bonus, cannons produce a lot more holes. Which all nations realized and most nations made use of.

Edited September 21, 2019 by JtD

[Sublime]

Ironically and Im.only a virtual combat pilot but if I was picking a2g loadout for a warbird Id take .50 cal.and lots for ground attack while Id take 20mm cannon and the less rounds for air targets. Hm

[Rjel]

43 minutes ago, JtD said:

 

It were the Japanese that reminded the USN that the 0.50 was insufficient on occasion. Kamikaze aircraft had to be brought down quickly, something 6x0.50 did not accomplish. And no, the US using a 20mm cannon instead of the 0.50 wouldn't really have mattered much in the big picture, as it was sufficient overall. But sufficient is not perfect.

 

Considering the mountains of lead thrown up by the Navy AA during Kamikaze attacks and the air patrols circling the fleet, nothing short of walls of steel could've prevented some airplanes getting through. I don't remember saying the .50 cal was perfect, only that it helped to accomplish the U.S. air mission in WWII. Sufficient as it was, no it was not perfect. But then, if the 20 and 30mm cannon used by the Luftwaffe were perfect in contrast, why are we not arguing this in German??

Edited September 21, 2019 by Rjel
were not was

[Gambit21]

5 hours ago, Bremspropeller said:

The 50s worked, but just barely and only when clustered in battleship-numbers.

 

 

 

Well the aftermath on the ground as told by GI’s, forward controllers and the Germans themselves on the masses of wrecked trucks, trains, barracks, equipment etc wasn’t “well, they barely worked”

 

20mm are superior on a per round basis but let’s be fair about the actual end result of those 8 .50’s.

 

There’s too much speculation and theory in this thread and too little attention payed to the actual end results in 1944-45.

 

I’m sure the 9th AF would have loved the Devestator, but beside the point.

[Ehret]

1 hour ago, JtD said:

Interestingly, there are much more sensitive places on an aircraft when you use a cannon than if you use an hmg. And as a bonus, cannons produce a lot more holes. Which all nations realized and most nations made use of.

 

And they all stopped at about 30mm for air-to-air even thought a higher caliber would be even more efficient in raw damage output.

In practice it stops scaling after that and a fighter plane needs cycling rate and gun-endurance is a nice perk, too. Cycling rate improves both hit-rate and damage-output where the bigger caliber only improves the latter and may decrease hit-ratio and you can not shot for long.

Most nations weren't as successful in air-power as the US with the 0.50"s. It takes about three 0.50" rounds to match raw damage output of single 20mm; the P-47D carries up to 3200 rounds where Tempest about 800 of 20mm. In the Tempest if you hit you will hit harder but the P-47D driver will be able to hit sooner and more often. You can shoot longer burst in the P-47D and use tracers stream as kind of computing sight to intersect with targets. The 0.50" have incendiary effects too; targets often burned down when still flying. The Allies won Battle of Britain using fighters which many of them were equip with 0.30"s only; pilots may complained but they still inflicted serious losses to the enemy.

 

30 minutes ago, Gambit21 said:

Well the aftermath on the ground as told by GI’s, forward controllers and the Germans themselves on the masses of wrecked trucks, trains, barracks, equipment etc wasn’t “well, they barely worked”

 

Yes - the strafed targets were left pretty much dead. There lots of gun camera videos showing wrecked locomotives, trains, columns, burned ships and so on. Besides one have to stop the up-gunning at some point because of mobility and logistics. Troops and most vehicles still can carry a HMG; that's not so easy with cannons. A "barely working weapon" is exactly what you want because if you fielded something "overkill" then your more powerful weapon will have opportunity costs.

Edited September 21, 2019 by Ehret

[ZachariasX]

6 minutes ago, Ehret said:

And they all stopped at about 30mm for air-to-air even thought a higher caliber would be even more efficient in raw damage output.

Only for shooting *very* big aircraft, hence the armament of the Mig-15 that was conceived for intercepting B-29.

 

For an efficient aircraft gun, fire rate trumps everything else, given a certain minimum caliber and ballistics. The .50 BMG was good at these parameters BUT you can get the same of that with higher calibers, up to 30 mm in fact. That is where firing rate and gun weight set a maximum practical caliber size. Today, you have no more than 27 mm and 30 mm. 27 mm for the Mauser as compromise for high firing rate and reliability.

 

If you are all indifferent about weight penalties, you could put eight Hispano V in an aircraft. But you just reach a level, where you do not get anymore benefit from the extra rounds fired. The horse and the soldier are dead and they won’t get anymore dead if you keep on shooting. (Dead horse... Luke?) Conversely, you did require more than four BMG to hit really hard in a snapshot. Especially since with the BMG, you require a hit on a vital part, producing a small hole. The 20 mm HE will produce results if it hits 10 cm next to the vital part and the 30 mm gives you results 40 cm next to vital parts. Smaller caliber produces a smaller target. To compensate, you require scatter with small calibers. This shotgun method make a large portion of your guns fire besides the desired hitting point. This means, when you hit the target with 8 guns set for some scatter, you get the hits of maybe 2 to 4 guns aimed for the mark. It works, especially since the BMG is a good gun, but it comes at a price that the Hispano won‘t cost. If you design aircraft, it is up to you where you add another 200 kg just because you think it‘s cool.

 

The .50 BMG is a great gun. But same as if all you have is a hammer, everything looks like a nail.

Edited September 21, 2019 by ZachariasX

[Bremspropeller]

1 hour ago, Gambit21 said:

 

Well the aftermath on the ground as told by GI’s, forward controllers and the Germans themselves on the masses of wrecked trucks, trains, barracks, equipment etc wasn’t “well, they barely worked”

 

20mm are superior on a per round basis but let’s be fair about the actual end result of those 8 .50’s.

 

There’s too much speculation and theory in this thread and too little attention payed to the actual end results in 1944-45.

 

I’m sure the 9th AF would have loved the Devestator, but beside the point.

 

A large share of devaststion was done by bombs and rockets. While a strafed column of trucks might look impressive, it's after all just a collection of holes.

The same is true for the 20mm - the holes are bigger and a good deal more jagged, though.

 

The whole point of this thread seems to be showing how devastating 8 cal 50s are.

Well, 4 20mm guns are just about as devastating in kinetic performance, plus they have additional HE capability.

 

20mm >>> cal 50.

 

Theory is hard physics.

No amount of "actual results" or some clouded memories of allegedly turning over battlehips and sinking Tiger tanks will change that.

[Gambit21]

The 50’s did the job at the time along with the 20mm - the end.

 

Reminds me of debates between 5.56 and 308. With one the target is dead, with the other more dead.

[Bremspropeller]

1 hour ago, Ehret said:

Besides one have to stop the up-gunning at some point because of mobility and logistics. Troops and most vehicles still can carry a HMG; that's not so easy with cannons. A "barely working weapon" is exactly what you want because if you fielded something "overkill" then your more powerful weapon will have opportunity costs.

 

A HMG is a useless gun for infantry and there's little logistical gains in providing aircraft with the same ammo as vehicle-mounted or even infantry-waepons.

In fact, WW2 showed that most rifle caliber guns were overpowered for normal infantry use.

 

What you want in war is overkill and not a barely adequate gun that almost needs double-digit numbers to facilitate acceptable results.

 

1 hour ago, Ehret said:

Most nations weren't as successful in air-power as the US with the 0.50"s. It takes about three 0.50" rounds to match raw damage output of single 20mm; the P-47D carries up to 3200 rounds where Tempest about 800 of 20mm. In the Tempest if you hit you will hit harder but the P-47D driver will be able to hit sooner and more often. You can shoot longer burst in the P-47D and use tracers stream as kind of computing sight to intersect with targets. The 0.50" have incendiary effects too; targets often burned down when still flying. The Allies won Battle of Britain using fighters which many of them were equip with 0.30"s only; pilots may complained but they still inflicted serious losses to the enemy

 

Most nations were more successful than the US in shooting down heavy bombers and fighters with less rounds.

How will the Thunderbolt pilot hit sooner and more often? He has to hit first, which is the magic trick. A Tempest will score the kill with less hits - that's all that is important.

 

The Allies won BoB because of lacking Luftwaffe strategical planning.

Incidentally, the RAF realized that equiping the Typhoon Ia with 12 peashooters was going to be a Monthy Python sketch well ahead of it's time.

 

1 hour ago, Ehret said:

And they all stopped at about 30mm for air-to-air even thought a higher caliber would be even more efficient in raw damage output.

 

An air to air missile has a bigger caliber and it guides itself.

Plus, a 30mm E-round will kill your target with two hits max. There was no need in scaling up beyond 30mm.

 

 

 

 

8 minutes ago, Gambit21 said:

The 50’s did the job at the time along with the 20mm - the end.

 

The 20mm did a better job.

The reasons have been made pretty clear by a lot of contributors in this thread.

[Ehret]

28 minutes ago, Bremspropeller said:

A HMG is a useless gun for infantry and there's little logistical gains in providing aircraft with the same ammo as vehicle-mounted or even infantry-waepons.

In fact, WW2 showed that most rifle caliber guns were overpowered for normal infantry use.

 

It can penetrate light armor, shoot through cover more effectively and provides anti-air. If that's useless to you then fine.

 

31 minutes ago, Bremspropeller said:

Most nations were more successful than the US in shooting down heavy bombers and fighters with less rounds.

 

Losing interceptors and pilots left and right eventually the US gaining air supremacy. Done by the latter using 0.50"s no less.

 

33 minutes ago, Bremspropeller said:

How will the Thunderbolt pilot hit sooner and more often? He has to hit first, which is the magic trick. A Tempest will score the kill with less hits - that's all that is important.

 

Because of ammo reserves in the P-47D you can shoot for twice amount the time throwing twice the number of projectiles. You can afford low probability shots where in your up-gunned 20-30mm you have to conserve ammo much more. There are pilots notes routinely doing +500 yards shots; even they miss that no big deal in the P-47D because you have generous 400 rpg.

 

Once hit in a fighter plane you are kind of... screwed, anyway. People aren't robots and there wasn't a convenient tech-chat; just being shoot at can result in defensive posture or breaking.

 

40 minutes ago, Bremspropeller said:

The Allies won BoB because of lacking Luftwaffe strategical planning.

Incidentally, the RAF realized that equiping the Typhoon Ia with 12 peashooters was going to be a Monthy Python sketch well ahead of it's time.

 

It doesn't change that those "peashooters" did enough of physical damage to inflict serious loses to the LW. Whatever the latter did wrong.

[unreasonable]

HMGs are useless guns for infantry (on foot) because they are so heavy. M2 Browning weighs 38kg + another 20kg for the tripod. Without any ammunition. Lugging around an LMG or GPMG for hours is exhausting enough, as anyone who has had to do it knows.  HMGs are only useful in entirely static positions or mounted on vehicles. 

 

Shooting twice the projectiles might double the chance to hit, but as you agree that each 50 cal hit is about equivalent to 1/3 a 20mm hit, that still makes 4 20mm more effective. If spraying around shots is so effective, I am still waiting for an explanation as to why the Dowding Spread was abandoned.

 

The US gained air superiority because it outproduced the Germans, especially with weapons platforms that forced the Germans to engage in a battle of attrition whether they liked it or not - heavy bombers attacking deep in Germany plus long range escort fighters. They would have succeeded even if the P-51 had been armed with 303s - it might have just taken a little longer.  The RAF in the BoB would have inflicted unsustainable bomber losses on the Germans sooner if they had had Spitfires and Hurricanes with cannons at that time. 

 

I think we all agree that the multiple HMG approach could be effective enough: given the US's ability to outproduce, out train and out logistic it's enemies. But people here seem to be saying that because the US won, the HMGs were at least as good a weapons system - or better. This is absurd.  The Zulus won at Isandlwana, you can emphasize the practical effects; lines of dead redcoats; but nobody argues for ditching rifles and re-adopting spears, even if it would make logistics simpler.

 

 

[Ehret]

3 hours ago, unreasonable said:

HMGs are useless guns for infantry (on foot) because they are so heavy. M2 Browning weighs 38kg + another 20kg for the tripod. Without any ammunition. Lugging around an LMG or GPMG for hours is exhausting enough, as anyone who has had to do it knows.  HMGs are only useful in entirely static positions or mounted on vehicles.

 

I assumed US troops with combat vehicles and trucks. Not fuel starved and horse drawn Heer.

 

3 hours ago, unreasonable said:

Shooting twice the projectiles might double the chance to hit, but as you agree that each 50 cal hit is about equivalent to 1/3 a 20mm hit, that still makes 4 20mm more effective. If spraying around shots is so effective, I am still waiting for an explanation as to why the Dowding Spread was abandoned.

 

The P-47D has about 2.6x of raw destructive power of 1x 20mm; I basically said it myself. However, there are twice the projectiles in flight and guns have enough ammo to shot for twice as long. It changes how you can engage; you can take low probability shots more readily. Do you deny that?

You can afford to do posture shots to make the enemy break; something you need to do as quickly as possible if your wing-man got a six.

You can "walk" bullet stream to the target - something which happens often in historic gun camera films.

 

Most pilots weren't aces with superior marksmanship so it could be reduced just to a raw firepower. And even so then the basic common gun configuration of US fighter plane (6x 0.50"s) was worth 2x 20mm in raw destructiveness.

 

3 hours ago, unreasonable said:

The US gained air superiority because it outproduced the Germans, especially with weapons platforms that forced the Germans to engage in a battle of attrition whether they liked it or not - heavy bombers attacking deep in Germany plus long range escort fighters. They would have succeeded even if the P-51 had been armed with 303s - it might have just taken a little longer.  The RAF in the BoB would have inflicted unsustainable bomber losses on the Germans sooner if they had had Spitfires and Hurricanes with cannons at that time.

 

First, the US gained not just air superiority but air supremacy at the end. The outproducing wasn't factor at the beginning and yet P-47s done well. The other type of western fighter which did extremely well was the F6F Hellcat and even the F4Fs managed to hold their own. Both Japanese and LW's fighter carried varied armament including rifle caliber machine guns in noses for relatively long time. The US fighters with 6-8x 0.50" weren't generally out-gunned especially considering difference in fighters size and robustness.

 

3 hours ago, unreasonable said:

I think we all agree that the multiple HMG approach could be effective enough: given the US's ability to outproduce, out train and out logistic it's enemies. But people here seem to be saying that because the US won, the HMGs were at least as good a weapons system - or better. This is absurd.  The Zulus won at Isandlwana, you can emphasize the practical effects; lines of dead redcoats; but nobody argues for ditching rifles and re-adopting spears, even if it would make logistics simpler.

 

Spears weren't ever ditched; they are just named bayonets in modern armies.

 

So lets summarize comparing the Tempest to the Thunderbolt:

- 4x 20mm have about 1.54x  more of raw destructiveness than 8x 0.50"s

- 8x 0.50"s have twice the firing time; you can more readily afford low probability shots

- 8x 0.50"s have twice the cycling rate thus it's easier to score hits

- equivalent of 2.0-2.6x 20mm will make quick work of most Axis planes anyway as many of them are small vulnerable single in-lines, inline twin engine medium planes and very light build Japanese fighters

- most your fighter planes have common ballistics; your fighter pilots will have more proficiency by using single weapon system

Edited September 22, 2019 by Ehret