50 cal vs rail stock

[MeoW.Scharfi]

33 minutes ago, Denum said:

Also comparing a 30mm auto cannon to the 20/30mm gatling guns of today was pretty funny Oc. I got a chuckle out of that. 

 

You know they use big weapons now because the aircraft are substantially larger and more powerful then what we had in WW2 right? Weight and space is much less of a concern.

 

Many planes get home after being hit by manpads and enemy gunfire today.

[Eisenfaustus]

19 minutes ago, =RS=EnvyC said:

 

You're over estimating the impact of German cannon shells. They were super low velocity and did more localised skin damage than area blast damage. PETN isn't all that powerful when combined with poor velocity.

 

A spread of .50 AP incendiary was more effective as when it hit it penetrated the aircraft, had a greater chance of setting fire to said aircraft, and a battery of 6 guns puts out ~90 rounds a second leading to a far higher instance of hitting the target for the average pilot.

 

That philosophy follows the USAF to this day with the 20mm Vulcan, which provides a wall of lead at a super high RPM with a large spread making the chance of hitting a target far more likely than say, the repeater cannons of the modern Russian 30mm.

 

You can also see that philosophy in all the OICW programs for infantry during the 80s and 90s, it's recognised that being able to get more light rounds on, or near, the target at a high ROF beats slower ROF heavier cartridges for the regular GI. The Russians admitted this when they designed the 5.45mm round as well.

1) Mg151/20 shells weren’t that much slower then .50 BMG. Being considerably heavier they had more energy

2) mine shells were absolutely devastating. 3-5 hits of 20mm and 1 hit of 30mm were on average enough to shoot down fighter sized targets

3) 5.56mm might be great for logistics and statistics - but for the individual soldier whose life depends on the effect of his shots that calibre sucks for so many reasons. Guess the analogy is actually pretty good though. On a strategic level .50 BMG has many arguments for it. The individual pilot shooting at a specific target would have been better off with 20mm though. 
 

You do know the US Navy exchanged their .50s for cannons as soon as possible on their corsairs?

[MeoW.Scharfi]

10 minutes ago, Eisenfaustus said:

3) 5.56mm might be great for logistics and statistics - but for the individual soldier whose life depends on the effect of his shots that calibre sucks for so many reasons. Guess the analogy is actually pretty good though. On a strategic level .50 BMG has many arguments for it. The individual pilot shooting at a specific target would have been better off with 20mm though. 

 

No "individual" soldiers in these countless pilot accounts of P51 and P47 pilots ever said the 50s were too weak. So no, not a good analogy.

[Rjel]

15 minutes ago, Eisenfaustus said:

You do know the US Navy exchanged their .50s for cannons as soon as possible on their corsairs?

Wasn't that with the Dash 4B? Even the earlier Dash 4s were equipped with six .50s. These didn't go into service until sometime in 1945, so very nearly the end of the war. 

[Eisenfaustus]

4 minutes ago, MeoW.Scharfi said:

 

No "individual" soldiers in these countless pilot accounts of P51 and P47 pilots ever said the 50s were too weak. So no, not a good analogy.

I‘m not saying they did complain - I said they would have been better off with cannons.
I think p51 and p47 would have been even more effective if their .50 batteries would have been exchanged for British hispanos. 
 

 

Just now, Rjel said:

Wasn't that with the Dash 4B? Even the earlier Dash 4s were equipped with six .50s. These didn't go into service until sometime in 1945, so very nearly the end of the war. 

True. Which doesn’t change that they considered that armament superior. 

[=RS=EnvyC]

The .50 BMG is a full 1000ft/s faster out the barrel and maintains its energy far longer than MG151, they are no where near close to being similar.

[Rjel]

2 minutes ago, Eisenfaustus said:

I‘m not saying they did complain - I said they would have been better off with cannons.
I think p51 and p47 would have been even more effective if their .50 batteries would have been exchanged for British hispanos. 
 

 

True. Which doesn’t change that they considered that armament superior. 

True enough. But it also says that they had a fighter they and the Marines flew from mid 1942 until that time with .50s. They knocked down a lot of E/A before getting that superior armament.

[354thFG_Drewm3i-VR]

1 hour ago, oc2209 said:

 

Except a mixed belt of AP/HE 20mm will cause explosive structural damage as well as having a good chance of penetrating vital areas.

 

So it's still not a matter of .50 being better in any way than cannons. It's just that API mitigates the .50's tendency to punch holes in a target without actually setting anything on fire.

 

I don't understand why people try to defend the .50 when it fundamentally shares the same weaknesses as the .30. They both lack explosive potential. They both require banks of redundant guns and concentrated hits on target. Cannons can get away with 'glancing blows' to cripple targets.

 

The British were able to win the Battle of Britain with .303s. Still doesn't mean it was a smart idea. And as soon as they reasonably could, they transitioned to having cannons in all their fighters.

You do realize planes with .50s had 6 or 8 guns going simulations with over 2000 API rounds in a box dispersion pattern vs 1x20mm + 2x13mm HE/AP/I mix and 2 13mm with only 200 rounds or so per gun? Taking this plus muzzle velocity, rate of fire, and bullet drop into consideration, and all of a sudden the 6 or 8 gun .50s platform with API and tons of ammo becomes the superior weapons platform FOR SHOOTING DOWN LIGHTLY ARMORED TARGETS LIKE FIGHTERS...of course heavy bombers are different. Thus, we are not simply comparing the guns in a vacuum, we are comparing total weapons platforms.

[=621=Samikatz]

Just now, Eisenfaustus said:

I‘m not saying they did complain - I said they would have been better off with cannons.
I think p51 and p47 would have been even more effective if their .50 batteries would have been exchanged for British hispanos.

 

iirc the Hispano had issues with freezing at high altitude, hence why Spitfires kept carrying machine guns even though the C/E wings were perfectly capable of fitting 4 cannons. HMGs were definitely right for the 8th AF at least

[=RS=EnvyC]

7 minutes ago, =621=Samikatz said:

 

iirc the Hispano had issues with freezing at high altitude, hence why Spitfires kept carrying machine guns even though the C/E wings were perfectly capable of fitting 4 cannons. HMGs were definitely right for the 8th AF at least

 

Lots of nations had various issues. The M2/AN would jam under certain conditions, the variety of German 30mms would jam when firing under high g etc.

 

Would be interesting to see how people change the way they fly if it broke their weapons...

[Jaws2002]

1 hour ago, =RS=EnvyC said:

Convergence is everything, the box spread was core to the M2/AN weapon system.

 

And nothing in the world would stop you from using the same convergence for 20mm guns.

Edited February 7, 2022 by Jaws2002

[LukeFF]

5 hours ago, oc2209 said:

damn well not anything smaller than 20mm

 

There are a few light strike counterinsurgency aircraft that are fitted with sub-20 mm weapons.

[=RS=EnvyC]

54 minutes ago, Jaws2002 said:

 

And nothing in the world would stop you from using the same convergence for 20mm guns.

 

Except there is, 109s only have one of them and 190s max have four, the majority with only two, firing a slower round (at the muzzle and ballistically) at a slower rate of fire with less ammunition.

 

More to the point the Germans practiced point convergence specifically because they had so few guns. A 109 puts out 13 rounds a second of cannon fire, versus 112 from a 8 gun P47.

 

Remember, IL2 does not accurately simulate USAAF A2A gunnery doctrine. Keep in mind we're talking about the M2 in its historically used fashion, not the unrealistic representation in game.

 

 

 

[oc2209]

2 hours ago, Denum said:

Also comparing a 30mm auto cannon to the 20/30mm gatling guns of today was pretty funny Oc. I got a chuckle out of that.

 

Not as much of a laugh as I got from imagining a real life Tempest pilot wishing he had six .50s instead of quad 20mm, like you evidently would.

 

2 hours ago, Denum said:

6 to 8 guns firing AP/API vs at best 4 20mm cannons that were shooting mostly HE?

 

Does math elude you or am I missing something...? 

 

Every .50 round fired has the potential of penetrating armor and killing the pilot. 

 

The 20mm guns that at best, shot AP every second round with a slower rate of fire has less of a chance of killing the enemy.

 

Yeah, and every couple of 20mm HE hits has a chance of de-winging the goddamn target and locking the pilot into his seat as he spins earthward to his death. 

 

Like I said, believe whatever you want. I'll go on believing that every other major nation in WWII aside from America, and the vast majority of airborne weapons systems designed across the world in the last 8 decades, settled on the cannon over the HMG because it was the more logical choice.

[MisterSmith]

Roll back the vitriol. Discuss the topic all you want but this personal stuff is a little over the top and will get, yet another, .50 topic locked.

[oc2209]

3 hours ago, =RS=EnvyC said:

It is quite amazing to see the lengths you'll go to to ignore historical fact and deny reality over a videogame.

 

Am I? Funny, because I could say the exact same thing about statements like this:

 

3 hours ago, =RS=EnvyC said:

You're over estimating the impact of German cannon shells. They were super low velocity and did more localised skin damage than area blast damage. PETN isn't all that powerful when combined with poor velocity.

 

Hey everyone, did you all know that being hit by a 30mm shell, 'tis but a scratch?' It only does skin damage! Won't even dent a spar.

 

You're showing your bias right here, plainly, because I'm not even talking about German shell efficacy anymore, and neither was @Jaws2002 in the post you quoted. The discussion has moved to overall cannon versus HMG performance. But I can tell right where your bias laser-focuses on.

 

I mentioned the British, the Japanese, and the Russians, all using cannons as their primary offensive weapons in aircraft. And the long history of attack aircraft since WWII also using cannons instead of HMG.

 

As long as people keep ignoring the point that everybody but the US preferred cannons even during WWII, and still prefers cannons nearly a century later, I'll keep repeating myself.

 

Don't argue with me anymore. Go back in time and tell the British they were wrong for up-gunning their fighters with cannons, and not just stopping at the utterly perfect solution of putting 6-8 .50s on everything.

 

2 minutes ago, MisterSmith said:

Roll back the vitriol. Discuss the topic all you want but this personal stuff is a little over the top

 

I agree, which is why I'm leaving the discussion right now.

Edited February 7, 2022 by oc2209

[MisterSmith]

15 minutes ago, MisterSmith said:

Discuss the topic all you want but this personal stuff is a little over the top and will get, yet another, .50 topic locked.

 

Want to make sure the full quote is emphasized.....

[Denum]

Oc, you need to pick up a history book. Seriously. Or don't. Either is fine. The latter is much more fun. 

Early war British aircraft had significant success with the .303. Few German aircraft were armored enough to provide adequate protection from the machine guns. 

 

The British had the Vickers .50, But felt that having 8 guns was more effective then 6 (As they'd have to drop two machine guns to carry the Vickers). So little time was put into creating a gun that worked in the aircraft. 

They were also working the H.S 404 as their next planned aircraft mounted weapon so they saw little need to work on the .50 caliber. They went from the .30 to the 20mm.

As German aircraft began to carry more armor the .303s were incapable of penetrating fully, or as they put it in their test documentation "Completely in-effective". 
By 1941 the RAF began supplementing their machine guns with the 20mm. As time went on cannons became their main stay armament. 

When the Americans entered the war, by their OWN RESEARCH  said the cannons were more effective.

 

But they still used the .50cal. 

 

Why?

As its been stated MANY many many many many times the USA never managed to make their cannons work. The RAF didn't build them weapons. They gave them the information and they attempted to make their own. The American version jammed with nearly impossible frequency and was only used on the P38 and P61 where the pilot or crew could re-rack the weapon and clear the jam. 

The Americans didn't need a cannon to be effective. In the Pacific they could have gotten away with rifle caliber offensive armaments and in Europe their main job was shooting down fighters. A Tempest with 4 cannons is lighter and more destructive then 6 .50cals sure. But the Mustang wasn't fighting the Tempest. It was fighting a 109 with a single 20mm or at best a 190 with 2 of them. Anyone flying with gunpods is a free kill in straight combat. 
 
 

Edited February 7, 2022 by Denum

[=RS=EnvyC]

My bias? I'm literally a 190 fanboy, I just understand the historical fact rather than wishing something is true because it's on my favorite plane.

 

It's called living in reality. The reality is at the time batteries of .50s were better for fighter to fighter combat. As technology improved and the threats changed the US moved to cannons.

 

No onea arguing that a singular cannon is better than a singular HMG, however when you put 6+ of them together into a single battery with a harmonisation pattern that doesn't require amazing marksmanship to deliver kills you end up with a superior weapons system for fighter to fighter combat.

 

That's reality.

Edited February 7, 2022 by =RS=EnvyC

[Eisenfaustus]

5 hours ago, =RS=EnvyC said:

The .50 BMG is a full 1000ft/s faster out the barrel and maintains its energy far longer than MG151, they are no where near close to being similar.

Muzzle velocity:

MG 151/20: 810 m/s

AN/M2 .50: 890 m/s

HS 404: 840-880 m/s depending on variant

 

What are you talking about?

 

4 hours ago, =RS=EnvyC said:

Except there is, 109s only have one of them and 190s max have four, the majority with only two, firing a slower round (at the muzzle and ballistically) at a slower rate of fire with less ammunition.

Mustang wing could have carried 4 HS 404 - so yes, you could have used the same convergence pattern that was used in P51 Bs. And further more - from the A6 onward the Fw 190 carried 4x MG 151 + 2 MG (from A7 onward two heavy MG). You can't claim more firepower for the P51. The P51 was the superior dogfighter - no doubt. But the same would have been true if it was equipped with cannon.

 

4 hours ago, =RS=EnvyC said:

More to the point the Germans practiced point convergence specifically because they had so few guns. A 109 puts out 13 rounds a second of cannon fire, versus 112 from a 8 gun P47.

Not true for the Fw 190. Though not called box pattern each gun pair had different setting so that at no point all six guns converged. For the Dora even one pair of 20mm was dropped because 2 cannon plus two HMG seemed sufficient.

 

2 hours ago, Denum said:

Early war British aircraft had significant success with the .303. Few German aircraft were armored enough to provide adequate protection from the machine guns. 

Absolutely - but despite their guns, not because of it. BoB pilots definetly complained about their lack of firepower, especially against bombers. And the British box pattern was turned into close point convergence by many british aces btw.

 

2 hours ago, Denum said:

The Americans didn't need a cannon to be effective. In the Pacific they could have gotten away with rifle caliber offensive armaments and in Europe their main job was shooting down fighters. A Tempest with 4 cannons is lighter and more destructive then 6 .50cals sure. 

I'm absolutely with you - the .50s were good enough. Yet working 20mm would have been even better.

[messsucher]

It would be best to admit that .50 cals were not a miracle weapon.

[JtD]

4 hours ago, =RS=EnvyC said:

No onea arguing that a singular cannon is better than a singular HMG, however when you put 6+ of them together into a single battery with a harmonisation pattern that doesn't require amazing marksmanship to deliver kills you end up with a superior weapons system for fighter to fighter combat.

 

The markmanship is a good point, but doesn't really hold up to scrutiny. If you check gun camera evaluations on firing solutions in air combat, it becomes evident that what you really need is raw and accurate firepower - not distributing it over a large number of guns and not harmonization patterns. These help on the psychological side and that shouldn't be underestimated. Basically never, but in particular not in WW2 air combat as it was. In actual firing, however, API ammo and gyro sights helped a lot more.

 

With regards to raw firepower, the USN and the USAAF both switched to the 20mm gun where they needed a bigger punch - in night fighting and in Kamikaze interception.

[Alexmarine]

10 hours ago, Eisenfaustus said:

10 hours ago, Rjel said:

Wasn't that with the Dash 4B? Even the earlier Dash 4s were equipped with six .50s. These didn't go into service until sometime in 1945, so very nearly the end of the war. 

You do know the US Navy exchanged their .50s for cannons as soon as possible on their corsairs?

 

The USN desire to switch to 20mm guns was more geared toward the ground attack role, with less consideration to air to air combat.

 

Moreover, the Corsair fleet never switched entirely to the 20mm even as late as the Korean War as on carriers it was found that servicing the cannons armed Corsairs was troublesome compared to the .50cals one. The majority of cannons armed Corsairs were usually land based with USMC units.

[MeoW.Scharfi]

2 hours ago, JtD said:

With regards to raw firepower, the USN and the USAAF both switched to the 20mm gun where they needed a bigger punch - in night fighting and in Kamikaze interception.

 

First of all they didn't all switch to 20mm, second If they don't need something then it's a bigger gun for japanese planes which already get complettly penetrated by 50. bullets.

No matter if Ki61, A6M or Ki84 the bullet went through the entire plane already at a range of 1000m, let alone the fires it made to them.

 

And to be honest I usually prefer 20mm especially ingame, but against japanese i would never take anything else than 50s which literally kills anything in the pacific already from long ranges with a wall of death.

20mm sounds complettly misplaced in that theatre in air to air roles. You have to light up the entire sky and flight path of the better maneuvering japanese planes. So nope these 20mm were intended for ground support.

 

4 hours ago, messsucher said:

It would be best to admit that .50 cals were not a miracle weapon.

 

Exactly, it's not a miracle weapon, it's a calculated killer that leaves a pink cloud in the cockpit. ? ?

 

1 hour ago, Alexmarine said:

The USN desire to switch to 20mm guns was more geared toward the ground attack role, with less consideration to air to air combat.

 

Moreover, the Corsair fleet never switched entirely to the 20mm even as late as the Korean War as on carriers it was found that servicing the cannons armed Corsairs was troublesome compared to the .50cals one. The majority of cannons armed Corsairs were usually land based with USMC units.

 

^ this ?

[Eisenfaustus]

1 hour ago, Alexmarine said:

 

The USN desire to switch to 20mm guns was more geared toward the ground attack role, with less consideration to air to air combat.

 

Moreover, the Corsair fleet never switched entirely to the 20mm even as late as the Korean War as on carriers it was found that servicing the cannons armed Corsairs was troublesome compared to the .50cals one. The majority of cannons armed Corsairs were usually land based with USMC units.

Hm this might actually be a case correlation without causality. At the time the problems with American hispanos were solved the Japanese air forces were basically beaten already. So the main task at that time was ground attack. They could and would fly successful ground attack with HMG as well. So I think more a question of timing than reason. In Korea afterwards ground attack was almost the only mission. 
 

The anecdote about ease of service only confirms that the main advantage of HMG lay in the logistics (which is of course an excellent argument!). But in the moment you line up a target 4 cannons ripping apart your target are preferable over 6-8 HMG shredding the target even though the latter are adequate for the job as well (which no one doubts)

[Alexmarine]

53 minutes ago, Eisenfaustus said:

 

The anecdote about ease of service only confirms that the main advantage of HMG lay in the logistics 

 

Actually not generally related to that, the 20mm shells had two issue related to both the handling the shells themselves and to an issue specific to Corsairs:

 

1)For some reason the 20mm ammunition was supplied as loose shells, that meant that servicing crews had to belt them themselves, given that the F4U with cannons were more prevalent to the light carriers with way less personal than the fleet carriers this meant that there was a lot of overwork involved for it

 

2)By the Korean war many USN planes (Panthers, Banshees, Skyraiders) had alrady switched to 20mm guns, so servicing them at first wouldn't constituted an issue but, specifically for the Corsair there was one: as a matter of SOP planes were usually serviced with wings folded as to save on space but while the before mentioned planes had their guns in the nose or in the fixed part of the wings the Corsair guns were all situated in the folded up part of the wings, meaning that the 20mm belts had to be raised and worked on while the wing was vertical. This seems to have been a particularly bothersome and time consuming procedure (allegedly having HE shells mixed in the belts required extra care during handling) compared to the handling of the .50cals belts in which the personal was well trained in handle over the folded Corsair wings.

 

This two points means that, even in the 50s when the entire Navy was well on it's way to completely phase off the 50cals armed planes altogether, the Corsair wasn't well liked with the 20mm guns on for fleet service.

 

In any case I just wanted to clarify the situation regarding the post war USN, not going to delve too much on the cannons vs 50cals debate which can easily become a sterile one.

 

The 50cals of allied planes will surely enjoy the game finally modelling incendiary rounds and an even more detailed damage model, just as all other guns and planes will do.

 

Alex

[354thFG_Rails]

9 hours ago, Eisenfaustus said:

Muzzle velocity:

MG 151/20: 810 m/s

AN/M2 .50: 890 m/s

HS 404: 840-880 m/s depending on variant

Look at screenshots I posted earlier. In game muzzle velocity for M2 is 895@ 0 meters. 151/20 is 705@ 0 meters. That’s not even taking into account the drag profile for the round. Don’t know where you got your values. 

[[CPT]Crunch]

There was no rush to usher in 20mm systems,

 

[Denum]

1 hour ago, [CPT]Crunch said:

There was no rush to usher in 20mm systems,

 

As far as I know these were pretty limited. They were British produced aircraft. I could be wrong but I'm nearly certain these weren't USA made 

 

Used with a recon unit, they weren't common. 

 

The majority of A36s were equipped with .50cals

Edited February 7, 2022 by Denum

[BlitzPig_EL]

I've always wondered how those protruding guns affected performance.

[LukeFF]

6 hours ago, Alexmarine said:

The USN desire to switch to 20mm guns was more geared toward the ground attack role, with less consideration to air to air combat.

 

Moreover, the Corsair fleet never switched entirely to the 20mm even as late as the Korean War as on carriers it was found that servicing the cannons armed Corsairs was troublesome compared to the .50cals one. The majority of cannons armed Corsairs were usually land based with USMC units.

 

Yes, and if I recall right, during WWII only two squadrons (VF-85 and VBF-85) converted to cannon-armed Corsairs, so they were very much in the minority. There's also the reality that only 200 -1Cs were built up to November 1944.

[[CPT]Crunch]

Point is they could have gone that route right from the beginning, they had the spare capacity and actually produce and present a working 20mm model, and put it in limited service, yet deliberately chose not to continue on that route.  The British, who received most of these produced, also chose the other direction with their Mustangs, they were given choice in many of their own other development features such as engines, so why would this differ, especially when the specific set up already existed?

 

Because the guns that were supplied worked well and were more than adequate for the job at hand.

[Eisenfaustus]

2 hours ago, QB.Rails said:

Look at screenshots I posted earlier. In game muzzle velocity for M2 is 895@ 0 meters. 151/20 is 705@ 0 meters. That’s not even taking into account the drag profile for the round. Don’t know where you got your values. 

not from the game - this was from wikipedia, which corresponded somewhat with my memory...

 

But wikipedia was actually wrong about 30 m/s

 

checking historical documents I see it actually was 785 m/s for Mineshells:

 

The 705 m/s ingame would be correct for AP though. Yet mines should start of 80 m/s faster

[BlitzPig_EL]

I've always kinda wondered why the US didn't do what the IJN did, scale up the basic Browning design for 20mm? (Japanese HO-5)

 

That said I don't understand why this thread, and so many others like it, has the long legs it has.  The historical record is quite clear.  We ran with the .50 Browning.  It got the job it was asked to do done.  Why all this pointless bickering?

 

In game I find it effective, yes I hope we get API, but the thing still gets the job done.

[357th_Dog]

1 hour ago, Denum said:

As far as I know these were pretty limited. They were British produced aircraft. I could be wrong but I'm nearly certain these weren't USA made 

 

Used with a recon unit, they weren't common. 

 

The majority of A36s were equipped with .50cals

They were US produced utilizing british supplied hispanos. 

[Bremspropeller]

9 hours ago, JtD said:

With regards to raw firepower, the USN and the USAAF both switched to the 20mm gun where they needed a bigger punch - in night fighting and in Kamikaze interception.

 

This. Just wanted to write the exact same thing.

 

On top of things, the cal 50 proved to be insufficient for jet-combat.

On top of things part deux, everybody knew that, except for the US services, who actually also knew, but opted to keep things simple.

 

[354thFG_Rails]

37 minutes ago, Eisenfaustus said:

not from the game - this was from wikipedia, which corresponded somewhat with my memory...

 

But wikipedia was actually wrong about 30 m/s

 

checking historical documents I see it actually was 785 m/s for Mineshells:

 

The 705 m/s ingame would be correct for AP though. Yet mines should start of 80 m/s faster

I’d have to double check the HE round but that sounds about right.

[Bremspropeller]

6 hours ago, MeoW.Scharfi said:

First of all they didn't all switch to 20mm, second If they don't need something then it's a bigger gun for japanese planes which already get complettly penetrated by 50. bullets.

No matter if Ki61, A6M or Ki84 the bullet went through the entire plane already at a range of 1000m, let alone the fires it made to them.

 

The japanese planes aren't all that durable, but you'd want to score that kill as quickly as possible, which is helped by having a good blend of ballistic performance and chemical performance of the HE shell. A 20mm will do better than both the cal 50 (not enough chemical performance) or a larger caliber (not enough ballistic performance).

 

The kamikaze would most probably be hard to catch in it's terminal dive, so you'd want maximal effectiveness from any hit you could score.

The same applies to night-fighting where you might only get one shot at a target - better make that one count.

 

Edited February 7, 2022 by Bremspropeller

[357th_KW]

From this book:

 

”Following delivery of the Mustang IA, the testing and evaluation process for the sub-type was the same as has been applied to the Mustang I in that examples were sent to the A&AEE for armament trials of its four 20mm Hispano cannon. Initial tests had been conducted at NAA in November–December 1942 with Mustang IA prototype AM190, which was fitted with what was considered by the RAF to be a prototypical armament installation for the sub-type, but differing in a number of detailed ways from the finalized armament installation in the full production aircraft. As supplied for testing, AM190 was fitted with US-manufactured AN/M2 20mm cannon built by Oldsmobile and based on a Hispano design and specifications that had been modified to suit US manufacturing processes and design tolerances.

 

 The trials with AM190 took the form of a series of ground and air firing tests. These revealed areas of weakness in the armament installation, including both the mounts in the wings and the empty case and link ejection chutes. The weakness of the armament installation revealed itself in flexing when the weapons were fired, allowing the cannon to move around to the point where they broke retaining brackets on the mounts and feeds. Other problems manifested themselves with lightly struck caps, varying lengths of recoil, irregularity in the firing rates, and eventually stoppages through cases jamming in ammunition feeds, breeches, or at the point of ejection of the empty case to the ejection chute. Similar to the issues with the empty case and link ejection chutes encountered on the Mustang I, the A&AEE identified that the empty case and link ejection chutes for the 20mm cannon installation were understrength, subject to flexing and movement, and contained “choke points” where ejected cases could jam or even rebound within the chutes. The A&AEE designed new chutes using thin sheet metal, which, during subsequent tests, proved significantly more reliable than the NAA-designed items. The A&AEE also found that the armament installation in AM190 was unsatisfactory in many aspects, but primarily that the mounting was of faulty design to the point where, under operational use, it would fail. This not only had a negative impact on the reliability of the armament, it could also cause structural damage to be inflicted on the wing.

 

A further trial was conducted using production aircraft FD446 during the period December 1942 to February 1943. Testing conducted by the A&AEE was similar to that undertaken with AM190, and it was soon suspended due to the front mounting tubes on all four wing-mounted cannon failing during testing. Following the issues with the US-manufactured 20mm cannon, the weapons were replaced by British-built Hispano Mk II 20mm weapons and associated feed mechanisms. The Hispano gun was a known, reliable cannon already in widespread use with the RAF, and its employment removed one set of variables that could have had a negative impact on subsequent trials during certain parts of the test program.
 

After modifications had been made to the armament installation, including significant “beefing up” of the cannon mounts, with a particular focus on the front mounting tubes, further testing was conducted. In conjunction with this testing, modified ammunition feeds and empty case and link ejection chute arrangements were also trialed. To add even further variety to the trials, a pair of US-manufactured AN/M2 20mm cannon was installed in one wing and British-manufactured Hispano Mk II 20mm cannon in the other.

 

These trials showed greater reliability, with the new mounts being able to support sustained firing without any problem. From these trials a set of recommended modifications were put forward to be implemented in all operational RAF Mustang IA aircraft. It was recommended that the US-manufactured cannon not be installed in the Mustang IA, and that they be replaced by the more reliable, and more widely supported in RAF service, Hispano Mk II 20mm cannon. One external visual clue to this change in armament and mount was the lack of external recoil springs forward of the wing cannon fairings on Mustang IAs fitted with the revised mounts and Hispano Mk II 20mm cannon.
 

More armament trials, using FD446, were conducted in April 1943 utilizing the Hispano Mk II 20mm cannon in all positions and all the recommended modifications from the earlier tests, in conjunction with further refined wing mounting tubes. Attention was also paid to the reliability of the US-manufactured ammunition feeds, which were closely watched for any signs of early wear on key components. These tests proved the reliability to the required operational level of the British-built Hispano Mk II 20mm cannon, the new mounts, and US-manufactured ammunition feeds. These trials also included a program of testing under all aspects of aircraft operation, including combat maneuvers and extremes of heat and cold from sustained firing and operation at altitude.

 

A further series of tests were conducted in late May to mid-June 1943 utilizing FD438, which trialed all available types of British-manufactured 20mm cannon ammunition for use with the installed armament incorporating all the recommended A&AEE modifications in what would represent the “operational” modification status for RAF Mustang IAs. These tests were highly successful, with no stoppages due to cannon or feed problems being recorded in an extensive firing program, and only two stoppages in total being experienced – one through electrical firing circuit failure and the other caused by a projectile/ammunition failure. During service with the RAF, the Hispano Mk II 20mm cannon used by the Mustang IA was eventually replaced by the Hispano Mk V, which was an improved sub-variant of the type.

 

Early operational use of the Mustang IA still provided a few issues with the 20mm cannon armament, but significantly less than anticipated with the incorporation of the A&AEE modifications. One area of concern was the US-manufactured 20mm cannon ammunition that was being used as initial supply with the Mustang IA. Examination of the ammunition revealed a number of problems, including poorly seated primer cups, poorly seated rounds in cases, bulged or swollen cases, and a high percentage of primer cup failures, even when subjected to a heavy firing pin strike.

 

As a result, it was recommended that all US-manufactured ammunition be subject to a process of examination and physical measuring before employment. Ultimately, the RAF decided to only use British-manufactured ammunition to ensure minimal issues for operational units. As a result, the US-manufactured AN/M2 20mm cannon and associated ammunition were passed onto the RAF Regiment, which fitted them into ground mounts for anti-aircraft use. This meant that any jams or issues could be hand-cleared by the battery gunners – something that could not be done in an aircraft installation.”

 

Lots of detail in there, but with regard to the Mustang Ia with the 4x20mm cannons, they were initially manufactured with US made cannons, and while the US guns and ammo had their own issues, of equal importance were factors of how the mounts in the aircraft were designed, and feed and extraction in those mounts etc.

Edited February 7, 2022 by VBF-12_KW

[MeoW.Scharfi]

15 minutes ago, Bremspropeller said:

The japanese planes aren't all that durable, but you'd want to score that kill as quickly as possible, which is helped by having a good blend of ballistic performance and chemical performance of the HE shell. A 20mm will do better than both the cal 50 (not enough chemical performance) or a larger caliber (not enough ballistic performance).

 

Which part of 50s penetrate the japense planes all the way you didn't understand, which part of not many 20mm corsairs were deployed you didn't get?? And those that were deployed were not doing anti kamikaze sorties primary.

 

15 minutes ago, Bremspropeller said:

The kamikaze would most probably be hard to catch in it's terminal dive, so you'd want maximal effectiveness from any hit you could score.

The same applies to night-fighting where you might only get one shot at a target - better make that one count.

 

for americans hard to catch japenese in a dive, ok... ?‍♀️

First of all its not like you attack kamikaze planes before they hit the ships, you intercept them a lot further when they didn't even have visual contact to the ship so its not the last second defense against japense kamikaze fighters.

 

Its not so easy to hit something with 20mm compared to 50s spraying.

 

But what do i know, you all have ur personal bias, germoney suffers right .. ?‍♀️