.50 Cal vs 20 mm Hispano - Ground Attack

[Venturi]

By the way, @unreasonable took the wrong probabilities from the paper. He took the "type B" column - which is fail to RTB within two hours. "Type A" is defined as a kill within 5 min and is probably more reflective of what we would see in the sim.

 

The probabilities of a single hit, Type A kill on a Jug are:

 

0.50cal, API-T = 0.0170
(By the way, of the different systems which were looked at as possibly contributing to the kill, pilot kills by themselves were 0.010 - and engines were 0.0010, only 1% of the chance of a kill!)

 

20mm M97 HEI (Hispano) = 0.060

(Again, the pilot makes up 0.030, or half of the probability of a kill! The engine is only 0.005 or less than 10% of the probability!)

 

So, let's re-run the numbers NOW, using the same data as above:

 

11/53 hits for the 50BMG:

1-[(1-0.0170)^11] = 17% kill within 5min

 

5/24 hits for the Hispano =

1-[(1-0.060)^5] = 27% kill within 5min

 

We see again the same pattern - but again, more rolls of the dice, more chances to insta-kill.

Interesting to note that of the rounds tested, the 37mm as found on the P39 had extremely high chances of knocking out the engine, and the German 30mm had extremely high chances of destroying the aircraft by structural damage.

 

This should tell us that the "HE" round on the 37mm was actually very good at penetration - and the German round performed as expected with a large blastwave ripping structure to shreds.

 

Also that overall, the 37mm round was only slightly more effective on a round per round basis than the 30mm German round.

[Gambit21]

...but...but...the F-15 uses a 20mm cannon...surely that means that fewer Germans died in Belgium in 1945.

[unreasonable]

6 hours ago, Venturi said:

 

Probability doesn’t work like that.

 

It is in fact the probability that nothing happens in “x” number of tries. And so you minus that from 1.

 

 

Thus, using the CORRECT probability formula,  1-[(1-p)^x] , and the probability statistics from your post, we get the following information:

 

 

The figures I show are quite clearly labeled as the probability of surviving.  The probability of surviving n hits, each with an independent probability of killing the plane p, = (1-p)^n which is what is in the table.    The probability of not surviving n hits in this case = 1-(1-p)^n   ie 1- the figures in the table.

Or at least what was meant to be in the table - what comes of using a calculator after midnight rather than a spreadsheet.... the 50 cals need ~18 hits to equal ~ 5 1/2 20 mm hits. (not 4 1/2 as previously stated). 

 

Amended table: survival p from n shots.

 

 

n	20mm	50 cal	50/20
1	0.880	0.963	1.09
2	0.774	0.927	1.20
3	0.681	0.893	1.31
4	0.600	0.860	1.43
5	0.528	0.828	1.57
6	0.464	0.798	1.72
18	0.100	0.507	5.07

 

5 hours ago, Venturi said:

By the way, @unreasonable took the wrong probabilities from the paper. He took the "type B" column - which is fail to RTB within two hours. "Type A" is defined as a kill within 5 min and is probably more reflective of what we would see in the sim.

 

So, let's re-run the numbers NOW, using the same data as above:

 

11/53 hits for the 50BMG:

1-[(1-0.0170)^11] = 17% kill within 5min

 

5/24 hits for the Hispano =

1-[(1-0.060)^5] = 27% kill within 5min

 

We see again the same pattern - but again, more rolls of the dice, more chances to insta-kill.

 

As to whether to take the A or B numbers, as your worked example shows, it hardly matters. Look at your own results.

 

What you are showing is that 5 20mm hits have a 0.27 p of an A kill, while 11 50 cal hits have a 0.17 p of an A kill.   

That means to get the same p as the 20mm after 5 hits, the 50 cal needs more hits: 18!  Just as in my first example.

 

So you did pick up a calculation error - but you are still proving my point.

 

 

Edited September 23, 2019 by unreasonable

[JtD]

5 hours ago, Venturi said:

50BMG, 11 hits

1-[(1-0.037)^11] = 0.34 or 34% fail to RTB

 

20mm Hispano, 5 hits

1-[(1-0.120)^5] = 0.47 or 47% fail to RTB

 

This is of course, assuming that the of the extra six hits that the 50BMG has, one of them wasn’t directly through the cockpit of the target or severing the elevator control cables or pulleys... remember, statistics only work reliably when dealing with a group of data that is larger than n=30, in general. In any one particular instance, having extra hits means extra rolls of the dice to instantly disable the aircraft, which has a quality all its own.

 

True. Aircraft cannot RTB at 66% / 53%. They either do, or don't. So what you'd need is 30 aircraft randomly fired at to confirm the findings from the report. Or you go with the report, because that's not just a statistical analysis. The 3.7% / 12% figures are to some extent, and they are based on n > 30 hits.

 

The extra 6 chances of a .50 to hit something are included already, because you used ^11. The 3.7% chance of a .50 round to score a critical hit reflects exactly the chances of hitting something you mentioned. You've rolled the dice 11 times and came up with 34%.

 

However, for this topic, we'd need such vulnerabilities for a common truck, after all, this about ground attack.

[ZachariasX]

7 hours ago, Gambit21 said:

Beyond words inane and silly

Beyond some digressions, is it silly to say both configurations get the job done but one configuration weights less? And that would be a preferable one for the shooter?

 

@Venturi also showed that the lighter configuration is more efficient in other business than ground attack. Clearly that would also be grounds for my decision on how to arm a fighter aircraft. But that is just me.

 

In contrast to him, personally, I wouldn‘t hope that much for the „insta kill“ that would turn everything for the better. Especially since the BMG has less penetration than the Hispano, in an air combat situation I’d expect less insta kills under normal situations. But I also wouldn‘t want to argue about that point. I‘ve seen some things shot up by HMG as well as what the 20 mm Oerlikon can do. And when I compare fist sized torn holes done by 20 mm HE and compare that to neat little holes where i can stick my little finger through, this gives me some preference. Then again, I wouldn‘t want to be on the receiving end of neither. I assume there are many here with way more experience on working these tools, so if they come up with a different take on that, I certainly respect that.

[LColony_Kong]

12 minutes ago, ZachariasX said:

Beyond some digressions, is it silly to say both configurations get the job done but one configuration weights less? And that would be a preferable one for the shooter?

 

@Venturi also showed that the lighter configuration is more efficient in other business than ground attack. Clearly that would also be grounds for my decision on how to arm a fighter aircraft. But that is just me.

 

In contrast to him, personally, I wouldn‘t hope that much for the „insta kill“ that would turn everything for the better. Especially since the BMG has less penetration than the Hispano, in an air combat situation I’d expect less insta kills under normal situations. But I also wouldn‘t want to argue about that point. I‘ve seen some things shot up by HMG as well as what the 20 mm Oerlikon can do. And when I compare fist sized torn holes done by 20 mm HE and compare that to neat little holes where i can stick my little finger through, this gives me some preference. Then again, I wouldn‘t want to be on the receiving end of neither. I assume there are many here with way more experience on working these tools, so if they come up with a different take on that, I certainly respect that.

You can save weight in other places, and the increase in weight doesnt mean its not worth doing. Design choices are obviously more complex than who has the most efficient gun package from a weight standpoint.

 

I mean just in considering the gun package alone, its not just about weight. also about size, and the ammunition for 20mm cannons takes up alot more space. Which is why I can have 8 fifties with more rounds per gun even though the 50s and 20mm guns are about the same in weight.

 

If I know that my design is going to have adequate performance already, it makes complete sense to gain some weight to get more firepower. And the biggest difference between US fighters and other nations with regards to weight isn't even remotely down to the choice of gun package.

[JtD]

54 minutes ago, Lord_Flashheart said:

also about size, and the ammunition for 20mm cannons takes up alot more space.

 

On a per gun basis, yes. On a three .50 vs. one 20mm not so much. So space is not that limiting a factor, you just need to adjust the ammo spaces (which is not as easy as it sounds, but possible).

 

What I understood was that the maximum belt length of the 20mm was more limited than that of the .50. I'm not that much into these guns to remember the reason, but it could simply have been the handling of the belts by the ground crews, which was manual. A 200 rounds belt of Hispano weighs about 60kg. Roughly the same as for a 425 rounds belt of .50.

But it could also have been belt feed limits.

Edited September 23, 2019 by JtD

[ZachariasX]

55 minutes ago, Lord_Flashheart said:

I mean just in considering the gun package alone, its not just about weight.

In principle, I'm with you on this, especially since they found a .50 BMG in every drawer an under every rug. And it certaunly was a working package. Hence, itwas straightforward piling them up in strafer noses of an A-26 or a B-25. But If I was to equip a fighter aircraft, 100 kg would be a worry to me, as I couldn't save any weight in other places, because I would have done so already befor installing the guns. I just don't like the idea of trading blows with an aircraft half the weight but almost equal engine power and firepower.

 

When the Jug was designed, it was so much more powerful up to where it belonged than the competition that you could well install may guns that catually work instead of cannons that don't work (yet). Going for 8 guns was both logic and reasonable in the case of the Jug. But not in case of other fighter aircraft. As the war progressed, the Jug just found a new lease of life because the enviroment was permissive for it to workt out well, not because it was the ideal solution.

[LColony_Kong]

2 hours ago, ZachariasX said:

Going for 8 guns was both logic and reasonable in the case of the Jug. But not in case of other fighter aircraft. As the war progressed, the Jug just found a new lease of life because the enviroment was permissive for it to workt out well, not because it was the ideal solution.

All strike planes need a permissive environment to function. A P-47 was a better attacker than any of the dedicated planes made for this purpose during ww2 (il2, hs129, stuka, etc) this doesn't start to become untrue until you get to much larger planes, like the a-20, b-25, bf110. Even then its not always a big difference. A P-47 can carry more bombs, longer distances, with better performance than any of the dedicated strike planes that dont have multiple engines or bomb bays. And whether the disagreement of 50cal vs 20mm is ever resolved here regarding specific effectiveness, whatever advantages 20mms have does not warrant a entirely different airplane unless its going to be a completely different design. (like a B-25) At which point I could put in much bigger guns than 20mm, or have 10 of them.

[Ehret]

11 hours ago, BraveSirRobin said:

But they still lost.  Most of these super weapons showed up too late or were not really the best weapons for the war that they had to fight.  The best weapons were probably the Liberty ship, Deuce and a Half, and an endless supply of Russian conscripts.

 

Allies thought (and Western is still) in terms of force-multipliers. They aren't as flashy or visible as "super-weapons" but they are far more powerful because they make the time to work in your favor.

 

The Liberty ships weren't alone - they benefited from the cavitron which allowed smaller ASW ships and planes to carry effective radars.

The Sherman tanks benefited by small "things" like herring-gears, stabilizer, wide choice of reliable engines and standardization of parts.

 

If you would remove the 20mm cannon from the P-38 the combat results wouldn't change much if at all. Remove turbos and counter-rotating props and you would end with a lemon like British did.

[JtD]

50 minutes ago, Lord_Flashheart said:

A P-47 was a better attacker than any of the dedicated planes made for this purpose during ww2 (il2, hs129, stuka, etc) this doesn't start to become untrue until you get to much larger planes, like the a-20, b-25, bf110. Even then its not always a big difference. A P-47 can carry more bombs, longer distances, with better performance than any of the dedicated strike planes that dont have multiple engines or bomb bays.

 

Well, the topic is 20mm vs. .50 and not P-47 vs. other aircraft.

 

But since you're going down that road, I'd like to mention that the F4U carried a bigger load than the P-47 and was more versatile in terms of ground attack. It had, for instance, dive brakes and could be used as a dive bomber. Other than that, same big engine, smaller airframe - more useful load. Plus I think it's not surprising that aircraft that big and powerful could carry more than say the smaller/lighter Hs129 which had half the power available. And if the P-47 was a 'better' attacker than the Il-2 is definitely arguable - given that one of the lessons learned by the USAAF in WW2 was that "we need a Sturmovik type aircraft". Personally I'm not a big fan of the Il-2 (I prefer general purpose aircraft such as the P-47), but it had uses where it was better suited to the task than any fighter bomber. It's also not an attackers job to carry bombs over large distances, that's what bombers are there for.

[ZachariasX]

1 hour ago, Lord_Flashheart said:

And whether the disagreement of 50cal vs 20mm is ever resolved here regarding specific effectiveness,

There is something about that you you could tell me (or maybe someone else with experience shoothing with those guns). Looking back through he thread, it was often pointed out that part of the effectivity comes from the bullets having "more spread" than the 20 mm arragnement, in the sense that you can afford something like a larger hitcone due to a higher population of bullets there. Looking at the diagram of the P-47 gun harmonization pattern, it doesn't look to me as a "spread", but more likely the arrangement where at least one gun shoots at where you point your gunsight. It is the most "precise" arrangement and it uses those many guns to the effect of precision rather than just plain hitting power. It results in a very long range where some bullets precisely strike where aiming aiming at. If I wanted a shotgun pattern, I would choose a different arragngement.

 

So my question is, is my observation correct? Or wold there be a better way to arrange the guns if all I wanted is hitting with most bullets where I aim at? I have no such diagram for the Tempest, although that oone would be intersting as well.

 

I mean, intutitvely, I'd have all gun trajectories converge at ~200 meters. So if I'd hit, it would make short work of the target. But at 400 meters, it would be impossible to hit anything and for plowing mud I must be able to shoot at least 600 meters. I'd be almost harmless to ground targets because at these speeds I would certainly not go in to 200 meters distance if there's just a remote chance that the other guy can bite back.

 

I'm asking this because for any rifle I consider spread the worst. It makes you miss. But if you aim in the wrong place, it doesn't make you miss the wrong place and hit the right place instead. At least I've never seen such in my life.

 

 

[Ehret]

I just noticed something... it's not only US who employed machine guns. The I16 has quad fast firing 0.30"; the Il-2 - twin 0.30"; the Mig-3 can carry four 13mm MGs; LaGG, Yaks, the Zero with paltry 60 rpg for the 20mm so pilots had to depend on the 0.303s all the time. Many LW's twin engine planes had rifle caliber equip turrets when US bomber carried 0.50" by default. So what is the argument, again?

 

The US planes weren't generally out-gunned by the opposition. And if they were they had other things going for them. There were more important things to worry about. Like effective intelligence services - an example - the double cross system which allowed British to easily fool Germans (you had to use spies to correct fire) into undershooting with the V1/V2.

 

And it goes on and on. Who was "wise differently" and wrong, then?

Edited September 23, 2019 by Ehret

[JtD]

2 hours ago, ZachariasX said:

So my question is, is my observation correct? Or wold there be a better way to arrange the guns if all I wanted is hitting with most bullets where I aim at?

 

In the words of the USN - "We tried elaborate solutions, but in practice with gun dispersion owing to wing flexibility and other factors, the setup really became a moot point and we went for a fixed 300 for all guns instead and let dispersion do the job."

 

In my words, yes, they tried to create a pretty large zone where at least one gun was shooting where the gunsight pointed, with the rest shooting somewhere nearby. But don't put too much thought into this. Watch guncam footage of ground attacks. You can see bullet impacts pretty well, it will give you a much better impression of the real thing than anything you can take and interpret from the books.

 

Related, fixed 350 yards for the P-47:

https://upload.wikimedia.org/wikipedia/commons/9/95/P-47_gun_harmonization_1945_page_35.jpg

 

With wing guns you can't have all of them hit at all ranges. Attack accuracy of P-47's were around 20 mils. Means you're hosing it in any case.

Edited September 23, 2019 by JtD

[LColony_Kong]

3 hours ago, JtD said:

 

Well, the topic is 20mm vs. .50 and not P-47 vs. other aircraft.

 

But since you're going down that road, I'd like to mention that the F4U carried a bigger load than the P-47 and was more versatile in terms of ground attack. It had, for instance, dive brakes and could be used as a dive bomber. Other than that, same big engine, smaller airframe - more useful load. Plus I think it's not surprising that aircraft that big and powerful could carry more than say the smaller/lighter Hs129 which had half the power available. And if the P-47 was a 'better' attacker than the Il-2 is definitely arguable - given that one of the lessons learned by the USAAF in WW2 was that "we need a Sturmovik type aircraft". Personally I'm not a big fan of the Il-2 (I prefer general purpose aircraft such as the P-47), but it had uses where it was better suited to the task than any fighter bomber. It's also not an attackers job to carry bombs over large distances, that's what bombers are there for.

I dont dispute the F4U was good, I didnt realize it was arguing against it. But it if was between a 4 20mm f4u and a 6 fifty f4u, my reaction to it is "meh". The increase in firepower to me is not worth the loss of trigger time.

 

You said you prefer general purpose aircraft so I dont think Ill say much on this, but in my view dedicated attack aircraft are a waste of time for any major air power. Historically speaking, the best option has always been to simply outfit your air superiority plane with bombs. Since they are already designed for performance, they can carry larger payloads. And they perform better doing it. They also dont waste air frames and pilots on planes that can only do one task. The only think an il2 could do better than a P-47 was have slightly better odds vs a tank with its cannon. And as you pointed out earlier, these were generally not the main targets.

 

Needing a dedicated strike aircraft goes under the laundry list of false lessons to include: "The sherman sucked," "The missiles dont work," "The phantom sucked," etc.

 

But now we really off topic!

2 hours ago, ZachariasX said:

There is something about that you you could tell me (or maybe someone else with experience shoothing with those guns). Looking back through he thread, it was often pointed out that part of the effectivity comes from the bullets having "more spread" than the 20 mm arragnement, in the sense that you can afford something like a larger hitcone due to a higher population of bullets there. Looking at the diagram of the P-47 gun harmonization pattern, it doesn't look to me as a "spread", but more likely the arrangement where at least one gun shoots at where you point your gunsight. It is the most "precise" arrangement and it uses those many guns to the effect of precision rather than just plain hitting power. It results in a very long range where some bullets precisely strike where aiming aiming at. If I wanted a shotgun pattern, I would choose a different arragngement.

 

So my question is, is my observation correct? Or wold there be a better way to arrange the guns if all I wanted is hitting with most bullets where I aim at? I have no such diagram for the Tempest, although that oone would be intersting as well.

 

I mean, intutitvely, I'd have all gun trajectories converge at ~200 meters. So if I'd hit, it would make short work of the target. But at 400 meters, it would be impossible to hit anything and for plowing mud I must be able to shoot at least 600 meters. I'd be almost harmless to ground targets because at these speeds I would certainly not go in to 200 meters distance if there's just a remote chance that the other guy can bite back.

 

I'm asking this because for any rifle I consider spread the worst. It makes you miss. But if you aim in the wrong place, it doesn't make you miss the wrong place and hit the right place instead. At least I've never seen such in my life.

 

 

I dont think my experience really helps with investigating the harmonization pattern.

 

My point with "spread" through really just means the cone of fire. Not the literal dispersion of the guns. This is one of the reasons that for soft targets (planes, trucks) I dont feel 20mm adds much (relative to what disadvantages it has). Any target that gets caught in the pattern of 6-8 fifties is going to get shredded.

 

You can see this in gun camera footage all the time. Virtually any time a plane gets hits with 50s you see the plane erupt in flashes all across the fuselage. Explosive filler doesnt make that big a difference when your plane or truck just flew/drove through a hail of lead. Each bullet is its own shrapnel.

 

As seen here:

 

Edited September 23, 2019 by Lord_Flashheart

[unreasonable]

 
@Ehret Airforces up-gunned from MGs to HMGs and then to 20mm cannon when they: 1) had a functioning weapon, and 2) when it would fit into the space available.  Planes kept mixed armaments mostly because they only had room for one or two cannons but could squeeze in MGs or HMGs into the remaining space. 

 

My take on the OP's question is simply would you be better off with 4 20mm or 6 or 8 50 cals, (for ground attack, although the discussion has taken in air-air use as well), assuming that you have available and working weapons of each type and the plane in question has space for them.  In the case of the P-47 perhaps neither of these is true for the cannon, but no-one is saying it was a poor ground attack aircraft: just examining the possibility that it would have been even better if it had been able to carry the Tempest's gun battery.

 

I hope this is a fair summary of the arguments made so far, for my own benefit as much as anyone else's.

 

That the 8*50 cal arrangement  is equal or better:

 

1) You can carry more ammunition and get a longer firing time.

2) You have a wide "shotgun" dispersion or beaten zone so a higher chance of getting at least one hit

3) It has a higher rate of fire per gun, so potentially more hit/s on top of the fact of having twice the guns.

4) It has a higher muzzle velocity, so potentially flatter trajectory and easier aiming.

5) It worked well enough in practice because the smaller the target (ground vehicles or fighter planes) the less the extra destructive force per shell of the 20mm matters

 

The arguments that the 20mm solution is better are:

 

1) One Hispano V puts out about 3 times as much KE/s as one 50 cal, plus it has chemical energy effect from HE, so it could be generating about 4-5 times the potential maximum destructive force per second, taking into account the rate of fire, muzzle velocity and weight of shell.

2) We have test evidence of the relative effectiveness of the two systems from a reputable US source which suggests 20mm HEI effectiveness of about 3 times that of 50 cal, per hit, on a P-47 and 5 times on a B-25. Ie broadly in line with the theoretical energy per hit.  

3) Effective damage = probability of hit * effect of hit, so the lower number of 20mms hits are more than compensated for by their higher effect.

4) Splinter damage from HE rounds compensates for the lower number of projectiles in the beaten zone when attacking soft ground targets.

5) Getting your damage on target as fast as possible is crucial when firing opportunities are short, which they usually are.

 

I have probably missed a couple.

 

 

 

  

[Ehret]

19 minutes ago, unreasonable said:

I have probably missed a couple.

 

I just realized another factor - if you are taking fire then the ammo boxes filled with (especially the thin-walled ones) HE shells become a serious liability. Just one unlucky machine gun hit into one of them may obliterate the plane completely.

[JtD]

36 minutes ago, Lord_Flashheart said:

The only think an il2 could do better than a P-47 was have slightly better odds vs a tank with its cannon.

 

No, that's not really the point. The feature because of which the Il-2 was considered "needed" was the armour. Simple thing, high value targets are typically well defended, if not by airforces, then by ground forces, i.e. AAA and small arms fire. The planes involved in such attacks will inevitably take damage. In April 1944 for instance, nine P-47's of the 8th Air Force were lost to light AAA, five to small arms fire (US figures). High performance fighters, even structurally strong ones, are just not built to cope with that to the same degree dedicated ground attack aircraft are. It's true, and it's a matter of preference/priorities/warfare how you deal with it.

[LColony_Kong]

Just now, JtD said:

 

No, that's not really the point. The feature because of which the Il-2 was considered "needed" was the armour. Simple thing, high value targets are typically well defended, if not by airforces, then by ground forces, i.e. AAA and small arms fire. The planes involved in such attacks will inevitably take damage. In April 1944 for instance, nine P-47's of the 8th Air Force were lost to light AAA, five to small arms fire (US figures). High performance fighters, even structurally strong ones, are just not built to cope with that to the same degree dedicated ground attack aircraft are. It's true, and it's a matter of preference/priorities/warfare how you deal with it.

Right the armor approach is a misguided one. Better not to get hit. And if you cant do this, the armor doesn't really help much and detracts from range and payload. Planes like the il2 got shot down by AAA about as easily as anything else, and any plane that takes a hit is not likely to finish the mission even if its not shot down.

 

If you are going to build dedicated general purpose strike planes, they should justify their existence by being large enough to do things a general purpose fighter cannot really do at all. Like a B-25, Pe-2, A-20, etc. Fighter sized attack planes are a total waste of space: literally, ramp space.

 

People put armor on planes. It doesnt work very well, except the small amounts of armor on fighters to protect the pilot.

[Lusekofte]

On 9/22/2019 at 5:47 PM, HagarTheHorrible said:

Which is an erroneous assumption to make.  It was found, during the Vietnam war, that despite the almost universal use of semi and fully auto weapons, hit probability went down.  

I was talking about how it works in this game. A ,50 cal simply saw down anything less than a tigertank. Just as well as any other caliber. And frankly ballistics in a 2 a is tearing up some types of planes while others seem to work well no matter what hit them. It is no accurate science. It is hitbox and caliber coding

 

[Gambit21]

3 hours ago, JtD said:

 

No, that's not really the point. The feature because of which the Il-2 was considered "needed" was the armour. Simple thing, high value targets are typically well defended, if not by airforces, then by ground forces, i.e. AAA and small arms fire. The planes involved in such attacks will inevitably take damage. In April 1944 for instance, nine P-47's of the 8th Air Force were lost to light AAA, five to small arms fire (US figures). High performance fighters, even structurally strong ones, are just not built to cope with that to the same degree dedicated ground attack aircraft are. 

 

That’s just not true.

”Dedicated” ground attack aircraft with few notable exceptions are built just like “non-dedicated” ground attack aircraft - to the extent that they exist.

 

The P-47 WAS a dedicated ground attack aircraft in Belgium 1945, as was the P-38.

Original job in 1943 is neither here nor there.

 

We can also talk Vipers and F-15E’s, or B-25’s, Beaufighters, Mosquitoes, Avengers, Typhoons and F4U’s (which were used extensively as ground attack aircraft in Korea) as were Mustangs for that matter.

 

The IL2 and the A-10 are the exception, not the rule. Even it’s predominantly the pilot that benefits from the armor, not the engines and airframe.

 

You talk as if ground attack aircraft are flying around with armored engines, solid ibeam wing spars and armored skins - not the case.

 

IL2 hit by Flak 38 - dead or taken out of the fight.

 

Jug hit by Flak 38 - dead or taken out of the fight.

Edited September 23, 2019 by Gambit21

[ZachariasX]

36 minutes ago, Gambit21 said:

The IL2 and the A-10 are the exception, not the rule. Even it’s predominantly the pilot that benefits from the armor, not the engines and airframe.

There are other, more suitable ways in increasing survivability of an airframe, like redundancy. It weights less and it is more efficient. The pilot is, by definition, never redundant, you have to protect him.

 

1 hour ago, Gambit21 said:

We can also talk Vipers and F-15E’s, or B-25’s, Beaufighters, Mosquitoes, Avengers, Typhoons and F4U’s (which were used extensively as ground attack aircraft in Korea) as were Mustangs for that matter.

Exactly. But just because an aircraft was used for ground pounding (even with some success) doesn‘t mean it would be well suited for it. It is only used because you either don‘t have other aircraft for the mission or you have a situation where any aircraft would do the job. The Mustang in the Swiss Air Force became a ground pounder quickly. They put on bombs and rockets. So much for the „laminar“ wing and many other things that make it a great aircraft. Even on the contrary. Flak shots tend to lag the mark, hence putting the radiator in the back of the plane is about the daftest thing you can have in a ground pounder. At least the P-47 had a turbocharger it didn’t really need in that place.

 

The reason why you have dedicated ground ponders as the exception is just corporate welfare by selling a „one size fits all“ that is mainly good at generating high running costs. There is no lobby for them, even though they are the most important aircraft you can have once you achieved air superiority. Dedicated ground pounders are cheap. They are meant and made to be shot at. It’s just not a great product to sell unless you are forced to produce it. Of course, they say it is most efficient to have „one aircraft that can do everything“ (like the fast fighter that can carry bombs too, and is invisible, and... ) as you have only to buy one aircraft. We know how that goes.

[Diggun]

2 hours ago, ZachariasX said:

We know how that goes.

*threaddrift*

 

An airforce of 13 planes that cost 10 zillion an hour each to run, 2/3rds of which are out of service at any time for maintenance or airframe life extension reasons, reliant on a specific, tech heavy and time sensitive supply chain, which could be threatened in any number of ways? 

 

Sounds rediculous. Imagine putting yourself in that position. The very thought! 

 

/threaddrift.

Edited September 23, 2019 by [_FLAPS_]Diggun

[unreasonable]

 The area of discussion I am still interested in is that of 50 cals vs 20mm for ground attack of soft targets: say personnel in the open or light cover, where we can agree that any direct hit by either weapon is effective.

 

Ignoring for now the rate of fire and ammo load issue, if you are firing one gun for a fixed time into an area that contains n targets (people), then the results of firing n 50 cal or 20mm ball rounds should be, on average, almost identical.  So obviously, in this case, 8 guns will get a better result than 4: almost twice as many hits. "Almost" because second hits on the same target do not count, and 2.5mm misses for 50 cal are hits for 20mm.

 

The question is, what happens if you are firing HE 20mm instead of ball?  For direct hits the number should be the same, but clearly some shots that would be near misses with ball would be effective with HE, due to the splinter effects.  A simple way of modeling this is just to make each target bigger and still count direct hits.

 

If a crouching person presents an area of 1m^2 for a direct hit, we can model a target size of double this, 2m^2, which is ~1.4 m on each side.  That is in effect saying that an HE round has a lethal radius - for this target - of 0.20m = almost 8 inches for the metrically challenged. 

 

If you assume that the targets have twice the area in the case of HE, you get on average almost twice the number of hits.  If the target is any larger than that, the HE becomes advantageous, on a per shot basis. You then have to scale for number of guns, rate of fire and belt mix to get the battery comparison, but clearly you do not need a very large increase in the effective target area to get the 4*20mm effectiveness up to the 8*50 cals in this scenario. 

 

So the RL question is what is the effective lethality of 20mm splinters against bodies?  I really would not want to have a 20mm HE round go off 8 inches away from me..... 

 

 

  

[Jaegermeister]

I personally appreciate all the work and research you guys have done to answer the key question here.

 

It would appear that the unanimous verdict is.... whichever round you hit the intended target with will most likely do the job. ?

[LColony_Kong]

7 hours ago, ZachariasX said:

 

The reason why you have dedicated ground ponders as the exception is just corporate welfare by selling a „one size fits all“ that is mainly good at generating high running costs. There is no lobby for them, even though they are the most important aircraft you can have once you achieved air superiority. Dedicated ground pounders are cheap. They are meant and made to be shot at. It’s just not a great product to sell unless you are forced to produce it. Of course, they say it is most efficient to have „one aircraft that can do everything“ (like the fast fighter that can carry bombs too, and is invisible, and... ) as you have only to buy one aircraft. We know how that goes.

I strongly disagree. The only type of airplane you need is a strike eagle type. Anything else is highly inefficient. No other airplane types should be made unless their design is required to do a completely different and necessary role, or that design could do a role several orders of magnitude better. The "muh CAS" lobby is huge. There has been a huge lobby for reformer ideas ever since the dumbest man ever to grace the USAF (John Boyd) left his hideous mark behind. That lobby you say doesn't exist has been doing nothing for the last 10 years but distribute misinformation to slow down a certain extremely important aircraft project. An aircraft program whose costs and delays are not what the detractors say they are.

 

So I guess the answer to the 20mm vs .50cal debate is F-35??

 

 

Edited September 24, 2019 by Lord_Flashheart

[JtD]

15 hours ago, Lord_Flashheart said:

Right the armor approach is a misguided one. Better not to get hit.

 

It surprises me to hear that from you of all people. After all, you want "firing time" over anything else, which necessitates repeated low speed passes to make use of it. That means you will get hit, and then you may wish your pilot had armour all around, not just front and back.

 

But as it is off topic and I'm also not the best person to make a pro Il-2 case, I'll leave that part of the discussion at that.

 

12 hours ago, Gambit21 said:

IL2 hit by Flak 38

 

Interesting choice for small arms fire which the Il-2 was armoured against. Probably no point in using tanks as well, because that 200mm rifle the grunts are carrying will go through 100mm of armour just like it goes through canvas.

 

5 hours ago, unreasonable said:

due to the splinter effects

 

I think once the projectile hits the dirt, splinters won't do that much. They typically extend forward in a cone shape, behind what triggered the fuze. Means they'd mostly get stuck in the dirt, where the projectile is when it explodes. So you'd need something to trigger the fuze prior to the projectile hitting the ground (say a vehicle). Or a rebound that leaves the projectile intact enough to explode. Shallow angle of attack may help.

Hypothetically, if it was in the same league as fragmentation bombs, just smaller, and hit vertically exploding upon impact, at 2 feet distance you'd get 0.5 useful fragments per square foot. But it doesn't, so the actual effect will be considerably smaller.

Edited September 24, 2019 by JtD

[ZachariasX]

2 hours ago, unreasonable said:

So the RL question is what is the effective lethality of 20mm splinters against bodies?  I really would not want to have a 20mm HE round go off 8 inches away from me..... 

From the case I‘ve heard, at arms length you are in for a nice recovery vacation at the hospital. And you have to deduct one hand from the bottom line.

 

53 minutes ago, Lord_Flashheart said:

I strongly disagree. The only type of airplane you need is a strike eagle type.

I should be most interested in hearing you out on this... in another thread, another time.

 

2 hours ago, Jaegermeister said:

It would appear that the unanimous verdict is.... whichever round you hit the intended target with will most likely do the job. ?

Indeed. So the question is, which arrangement gives you a result that you can label as „hit“.

 

I agree with unreasonable on this:

3 hours ago, unreasonable said:

You then have to scale for number of guns, rate of fire and belt mix to get the battery comparison, but clearly you do not need a very large increase in the effective target area to get the 4*20mm effectiveness up to the 8*50 cals in this scenario. 

Not necessarily because it is the almighty truth, but because I believe it to be more effective, giving me more confidence. In the end, the boots on the ground have to do some walking and the more confident they are, the faster they are. And, speculating, this has probably a bigger impact on the whole thing. The soldiers in these boots happily take care of whatever you didn‘t hit with the supposedly inferior solution, as long as you convince them to move. If the small whistle does the job, fine.

 

Personally, I‘d always go with the cannons, for technical and personal reasons. I find the effect ball rounds frustratingly boring on structure. Just tiny holes, and then you have to clean your gun for that. Cannons... are more Hollywood.

[unreasonable]

2 hours ago, JtD said:

I think once the projectile hits the dirt, splinters won't do that much. They typically extend forward in a cone shape, behind what triggered the fuze. Means they'd mostly get stuck in the dirt, where the projectile is when it explodes. So you'd need something to trigger the fuze prior to the projectile hitting the ground (say a vehicle). Or a rebound that leaves the projectile intact enough to explode. Shallow angle of attack may help.

Hypothetically, if it was in the same league as fragmentation bombs, just smaller, and hit vertically exploding upon impact, at 2 feet distance you'd get 0.5 useful fragments per square foot. But it doesn't, so the actual effect will be considerably smaller.

 

I agree that other things being equal, the softer the ground the less effect splinter damage will have, without proximity fuzes or other airbursts.  But otherwise I think this underestimates the effect.  HE shell splinter patterns are a typically a butterfly shape (in section) - a shallow, hollow cone with very little going straight forward: the initial velocity of the splinters is much higher than that of the projectile.  Clearly some proportion will go in the ground, but how many?   For a typical strafing angle of less than 45 degrees and a surface detonation (rock) you will get ~50% of the fragments effective (plus richochets from those headed down). For a delayed detonation in softer ground clearly much less and no richochets, but still potentially a significant number.

 

More to the point, to effectively double the number of guns by giving yourself a "free shot", the shell not having first made a direct hit, (or maybe even if it does) you only need one potentially disabling splinter!  

 

2 hours ago, ZachariasX said:

Cannons... are more Hollywood.

    

They certainly are that!

 

[Pierre64]

18 hours ago, Lord_Flashheart said:

You can see this in gun camera footage all the time. Virtually any time a plane gets hits with 50s you see the plane erupt in flashes all across the fuselage. Explosive filler doesnt make that big a difference when your plane or truck just flew/drove through a hail of lead. Each bullet is its own shrapnel.

 

As seen here:

 

On this video, at 5'35" (Lt. J. W. Kavanaugh flying "Missouri Banshee"), is it a belly landed P-51D ??

[JtD]

A Lt. J. W. Kavanaugh claimed a Fw190 on December 5th, 1944. He also made claims in April 1945, but then temperatures were in the region of 15 °C, so all that snow is very unlikely.

 

It could be a Fw190D model. Hard to tell from that video, but I suppose before the US used this footage for show, they made sure they weren't showing someone shooting his own side.

 

2 hours ago, unreasonable said:

Clearly some proportion will go in the ground, but how many?

 

Your guess is as good as mine. I read some ammo testing documents from the German side, they describe explosive cannon rounds as to be used against (soft) ground targets including troops with the principle of damage being splinter damage. So I'm pretty sure the effective percentage war larger than 0.

[unreasonable]

 
It looks to me as though there are invasion stripes on the belly and US national markings on the side - what with the tail fin extension and squared off top to tail I am 95% sure it is a P-51. 

Assuming the pilot was already walking off somewhere, presumably the shooter wanted to prevent the Germans getting their own relatively intact P-51. Or he just misidentified it - as in the P-38 shooting down the Mosquito PR example, which found it's way into the public domain.

 

  

[LColony_Kong]

That is most certainly a P-51. You can see the dorsal fin, the leading edge "extensions" for the gear, and the bubble canopy

[Ehret]

This is interesting video - specific situation but shows that 20-30mm may not work that well against trucks.

They needed to be burned to be sure and indeed - machine gun rounds (small and bigger) carry incendiaries.

 

edit:

The author commented (just below the YT video) that they tried 40mm and it still didn't kill trucks reliably. The problem was finally solved with the 105mm.

The author also said that thought the 20mm had HE filler the explosion/shrapnel on contact with the truck couldn't penetrate the hood or cabin - only windows broke and flattened tires. Otherwise trucks were drivable with new tires.

Edited September 24, 2019 by Ehret

[Diggun]

7 minutes ago, Lord_Flashheart said:

That is most certainly a P-51

Agreed, but it doesn't look like it's actually being shot at, does it? Is it possible that the pilot shooting the film may have been doing a 'camera pass' on a ditched buddy, to confirm tthe state of the a/c and his position?

[Ehret]

3 minutes ago, [_FLAPS_]Diggun said:

Agreed, but it doesn't look like it's actually being shot at, does it? Is it possible that the pilot shooting the film may have been doing a 'camera pass' on a ditched buddy, to confirm tthe state of the a/c and his position?

 

And have the proof that it really happened.

[LColony_Kong]

I don't know why I only thought of this just now, but everyone in this thread can go watch 30mm footage from Apaches....as well as on other weapons on youtube vs real targets. I wont post it here because I'm sure it violates some rule....but for anyone who hasnt see it it should convey pretty clearly that the explosive effect of 20-30mm is not a death ray. You will frequently see near misses fail to kill the target.

Edited September 24, 2019 by Lord_Flashheart

[Ehret]

11 minutes ago, Lord_Flashheart said:

I don't know why I only thought of this just now, but everyone in this thread can go watch 25mm footage from Apaches....as well as on other weapons on youtube vs real targets. I wont post it here because I'm sure it violates some rule....but for anyone who hasnt see it it should convey pretty clearly that the explosive effect of 20-25mm is not a death ray. You will frequently see near misses fail to kill the target.

 

Yes. The Apache carries the M230 30mm cannon and they often shoot longer bursts to saturate the area. Still, sometimes they need to do more passes to kill and destroy all original targets.

Edited September 24, 2019 by Ehret

[unreasonable]

34 minutes ago, Lord_Flashheart said:

I don't know why I only thought of this just now, but everyone in this thread can go watch 30mm footage from Apaches....as well as on other weapons on youtube vs real targets. I wont post it here because I'm sure it violates some rule....but for anyone who hasnt see it it should convey pretty clearly that the explosive effect of 20-30mm is not a death ray. You will frequently see near misses fail to kill the target.

 

No one is saying that it is a death ray or has a nuclear yield. Simply that it produces splinters capable of disabling soft targets - like people - even if there is no direct hit. It only has to produce one such splinter, if it is not a direct hit,  to be almost statistically equivalent to twice as many shots from a non - HE round in this case. Note that all  near misses from ball rounds fail to kill the target.

[Venturi]

The difference in armor penetration between the Hispano 20mm SAPI and 50BMG API is negligible.