Best armed fighter (1 Viewer)

[HoHun]

Hi Claidemore,

>I think the graphs in post #65 can be used to show that quite clearly. Move the target plane around on the graph erratically, and smaller 'circle' of the nose mounted guns will be off target more often than the larger, and often twin 'circles' of the wing mounted guns.

>Admittedly with less damage than a concentrated centrally mounted multi gun installation, but a miss is a miss and any hit is better than a miss.

Convergency/divergence or a larger pattern will not increase kill probabilities even when large errors are preset.

The reason is that the hit chances fall off with the distance to the target centre, and the average distance to the target centre is always greater with the guns off centre than with the centreline gun for a centre-weighted distribution (and you clearly have a Gaussian distribution here ... "bell curve", you're probably familiar with this one).

Regards,

Henning (HoHun)

 

[slaterat]

I tend to agree with Claidemore , once you get to the heavier armed fighters a box convergence has real benefits. I'd pick the tempest with 4 wing mounted hispanos and a good ammo load. Theres no syncronization to slow down rate of fire and varying tragedtories of different weapons to worry about. The logistics are easier too.

Slaterat

 

[HoHun]

Hi Slaterat,

>I tend to agree with Claidemore , once you get to the heavier armed fighters a box convergence has real benefits.

It's the heavier armament, not the convergence/divergence that has the benefits. In direct comparison of equal batteries, centreline armament always is superior.

As noted above, no fighter has ever been designed to mount the guns farther out in the wings than absolutely necessary. The 8-gun Hurricane's gun layout has always been considered superior to the 8-gun Spitfire's, for example.

Regards,

Henning (HoHun)

 

[drgondog]

I'd even say that the single 20 mm nose cannon was a bit on the weak side against fighters too, but before this opinion gets misunderstood, I'd like to point out that it was still a better setup than the P-51D's:

Me 109G-6: 1,8 MW
P-51D: 1,7 MW

(Not because of the neglegible 0.1 MW advantage, but because the cannon was centrally mounted and had no convergence issues.)

Regards,

Henning (HoHun)

So, against fighters you would take one centrally mounted 20mm in lieu of 6 x50 cal in wings?

One shell vs six - all capable of breaking a spar or killing a pilot or destroying an engine. Assuming each had at least one gun properly boresighted to hit what you are aiming at a 200 yards, the six gun Mustang has 5 more projectiles 'in the area' - some hitting the target -some near misses.

Interesting.

 

[Soren]

I think a single .50 cal round would have a very hard time ruining an engine from stern shots, and it wouldn't penetrate the pilots armour AFAIK. The .50 cal round wasn't at all the most destructive of rounds, and it often took alot to down a fighter.

But that having been said I'm not sure if I'd want a single central mounted 20mm cannon over six wing mounted .50 cal HMG's, the sheer amount of lead the six HMG's are spewing out should maen more hits pr. second, regardless of convergence.

Now give me two central mounted 20mm cannons, that I'd take over six .50 cal HMG's any day, the 20mm cannon simply does a whole lot more damage pr. round.

 

[KrazyKraut]

So, against fighters you would take one centrally mounted 20mm in lieu of 6 x50 cal in wings?

One shell vs six - all capable of breaking a spar or killing a pilot or destroying an engine. Assuming each had at least one gun properly boresighted to hit what you are aiming at a 200 yards, the six gun Mustang has 5 more projectiles 'in the area' - some hitting the target -some near misses.

Interesting.

You are forgetting about the two centrally mounted 13mm MGs apparently.

1x20mm plus 2x13mm centrally mounted vs. 6x12.7mm is not that different. Given the nature of '44 air combat I'd take the platform with more guns. However i'd take 2x20mm and 2x13mm centrally mounted over both any day.

 

[Juha]

Hello Kurfürst
I assume that the Hisso's shell, being heavier and faster, was better against armour and so more dangerous to things behind the armour. Also heavier shells produces higher weight of fragments or it has more HE inside, usually both. And heavier and faster shell penetrates deeper into target before exploding if fusing is same.
That doesn't necessary means that Hisso was better gun, only that the philosophies behind the two guns were slightly different, 151 counted more on blast and numerous small fragments and Hisso more on kinetic energy and fewer but heavier fragments.

Juha

 

[Kurfürst]

Hello Kurfürst
I assume that the Hisso's shell, being heavier and faster, was better against armour and so more dangerous to things behind the armour. Also heavier shells produces higher weight of fragments or it has more HE inside, usually both. And heavier and faster shell penetrates deeper into target before exploding if fusing is same.

That's the part I don't get - its not a AP or solid shell. Its a shell that blows up upon/very shortly after impact. As a result

1, Its capability is marginal against armor because of its construction, and because by the time it would reach armor the fuse blows it into tiny bits of fragments.

2, Heavier and/or faster does not particularly effect how 'deep' it penetrates into the fuselage (as this a matter of fuse timing, achieving a desired distance) and, with the fuselage being a hollow, very thin layer of aluminium skin and not some body or piece of dense, solid structure, its isn't particularly hard to punch true - I guess even a .22 LR round would be more than capable of that, not to speak of the capabilities a 20mm round.

And course, the amount of damage done is proportional to the amount of energy required to yield that damage to the structure. In the case of the same damage, the energy is the same and very likely very much smaller than the total energy the shell possesses, given light aircraft structure.

For example, if lets say, a spar flange requires 2000 Joules to have punched a 20mm diameter hole in it, in practical matter it doesn't really matter if you have 20 000 or 25 000 Joule KE round for the task, since the only difference will be that, to simplify matters, that the less powerful round will continue its path once it exited the aircraft with 18 000 Joule, while the other still has 23 000 Joule that can used for nothing else but a short and uneventful journey until it falls back to ground (or self destructs).

A heavier HE shell of course can produce more/larger fragments, but the potential of these is fairly low, usually stopped within a few layers of 'stuff' getting in their way. In any case, the KE of the fragments is dependent on the amount and energy of explosives within the shell (from where it gets its source KE), and again has no relation to muzzle velocity or shell weight.

Overall, a HE shells does damage in the following way:

1, Some damage as it enters structure, breaking things on its way, and the damage done equal the energy required to destroy the particular thing, the remainder is just surplus KE and plays no 'useful' purpose sine the projectile will blow up soon.
In this regard there won't be too much difference between a high powered and lower power round, because they both possess far greater energy than it is required to penetrate, but this KE will be soon equal to zero as

2, the projectile blows up, and it looses its KE energy. Then it will:
2a, Send small fragments in every direction with very little individual damage capability, but covering a wide area, having enough KE to damage the first light structure/component they hit (lines, wires, skin, crew). This KE is derivied from the amount of explosives in the shell - some part of which is consumed to break up the shell body into fragments. Fragments usually stop in the first thing they hit.

2b, Pressure and hot gases that again comes from the amount of explosives in the shell and will be capable of large amount of damage, quickly diminishing with distance but effecting everything nearby. Now, IIRC the Hispano HEI shell actually contained only half explosives, half incendinaries.

Actually that's why I asked - 'why'. The physics behind it simply don't explain (at least for me) how higher muzzle velocity, or higher projectile weight, can translate into higher damage done, especially as after the projectile blows up initial KE becomes irrelevant and most of the damage is done or directly related the chemical energy from the explosive charge.

Higher muzzle velocity, or higher projectile weight would factor in if we would speak of non-fused, solid rounds (like AP), but even with these there is very little practical gain I can see - with penetration figures being in the 20+ mm if armor penetrated region, and most aircraft had 4-6-8-10mm on them at a few vital places, the rest being light structure, easily punctured by any round.

That doesn't necessary means that Hisso was better gun, only that the philosophies behind the two guns were slightly different, 151 counted more on blast and numerous small fragments and Hisso more on kinetic energy and fewer but heavier fragments.

Its not different design philosophy - the RAF simply had no other gun than the licensed Hispano, nor did it have M-Geschoss type rounds for it during the war. The French who designed it originally for a single gun installation, which meant that high ballistic performance gun - along with the bulk and recoil of it - in an engine installation, for which it was ideal. And if it was, the British decided after the war for adopting Mine shells into Mauser revolver cannons...

It is noteworthy that the Germans also considered originally a 20mm 'Elephant gun', the 20mm MG C 30 for the Bf 109 but instead opted for lightweight and compact Oerlikons in the wings. All of their later designs were compact with moderate ballistic performance, and Russian designs show similar considerations; it is noteworthy that these weapons were all purpose-designed for aircraft use, rather than adapted pieces originally meant for ground installations, so the designers must have understood that typical fighter combat ranges higher ballistic performance and bulk was less desirable than compactness and high rate of fire.

 

[kool kitty89]

Kurfurst, if you're comparing the German 20mm "normal" HE shell to the Hispano's, there are some things to note. One reason for the lower weight is that it uses an aluminum fuze (introduced on the MG FF/M) to reduce the recoil closer to that of the Minengeschoss.

WORLD WAR 2 FIGHTER GUN EFFECTIVENESS
Going by the figures on Tony Williams' site, the German 20 mm HET/HEIT shell carried less than 1/2 the filler of the Hispano's HE shell. (130g HE Hispano 10.4g filler, 115g German HET 3.7g filler)

Also I beleive that the HE or HEI (115 g) shell used by the MG FF/M and MG 151/20 were all tracer types (at least that's the only one listed on Tony Wiliams' site) which explains the small capacity. There was also an unfuzed API round, but that's something of a different nature and the capacity wasn't better than the HET anyway.

The only plain HE shell for the MG 151/20 was the Minengeschoss I beleive, so the Hispano's shells cannot be compared.

However, the old MG FF (not FF/M) used a 134 g HE shell, 4g heavier than the Hispano's (and 6g heavier than the Oerlikon FFF's and FFL's), however I don't know know what the HE content of this shell was. (note this shell apears to be the same as was also used with a few different cartridges and guns like the 20x105B of the MG 204 and the 20x138 flak round)

 

[drgondog]

You are forgetting about the two centrally mounted 13mm MGs apparently.

1x20mm plus 2x13mm centrally mounted vs. 6x12.7mm is not that different. Given the nature of '44 air combat I'd take the platform with more guns. However i'd take 2x20mm and 2x13mm centrally mounted over both any day.

If you will take the time to read HoHum's post...he said specifically ONE 20mm over P-51D armament.

 

[kool kitty89]

On the armament of the Bf 109, there were sests with a single, synchronized, MG 151/20 mountd in a pod under the fuselage. This was considered superior to the twin wing pods. (on impact of a/c performance as well as assed weight would be roughly 1/2 and roll rate would not be penalized, and prag would be less)

The reason given for it not reaching service was due to the possibility of mix-up between the electric and non-electric primed ammo for the two guns (the hub cannon being unsynchronized and percussion primed), which doesn't make sense to me, particularly given that both types of MG 151/20 were used together on the Fw 190. (wing root plus outer wing)

A more likely reason is that this configuration elliminated the centerline drop-tank/bomb pylon.

I can't seem to find the original sourse for this, I beleive it was brought up on this forum a while back, maybe Kurfurst knows.

 

[drgondog]

I think a single .50 cal round would have a very hard time ruining an engine from stern shots, and it wouldn't penetrate the pilots armour AFAIK. The .50 cal round wasn't at all the most destructive of rounds, and it often took alot to down a fighter.

I believe you would be wrong about a.) penetrating pilot's armor, and b.) inability to ruin an engine. The reason the SpecWar guys use the Barrett .50 is not only long range sniping but the ability to penetrate > 1/2 steel at 1200 yards to get to an engine. When the circumstances existed that it took a 'lot' of rounds it was usually because a.) not such a great shot or pilot in front is not making it easy - or the ranges start out at 300+ yards and a long ranging chase occurs.

Secondly, there were probably more hits (a lot more) from Mustangs in slight to great off angle shots than exactly 6 o'clock.. you may feel differently. Further on six o'clock shots there are slightly below to slightly above angles that would present nothing but ~ .032-.050 aluminum skin as a barrier to cylinder block/Supercharger to the .50 API. If you want to argue that a .50 can't defeat an engine under those circumstances from 200 yards, fire away.

But that having been said I'm not sure if I'd want a single central mounted 20mm cannon over six wing mounted .50 cal HMG's, the sheer amount of lead the six HMG's are spewing out should maen more hits pr. second, regardless of convergence.

I agree, that was my single point, along with the destructive power of a .50 against sheet metal, spars, and with unobstructed angle, to an engine

Now give me two central mounted 20mm cannons, that I'd take over six .50 cal HMG's any day, the 20mm cannon simply does a whole lot more damage pr. round.

I think I would prefer two centrally mounted 20's also, particularly the 151/20

The USAF finally figured out better approach to both worlds with the M-61 which puts out the same number of rounds as 10 Ma Duece's, but in 20 mm (or 3000+ in 30mm)

 

[kool kitty89]

However the performance of the M61 is fairly comperable 4x M39's. Of course the M61 would weigh less than half that of the 4x M39's, though it is fairly bulky by comparison. (and of course requires power feed and spool-up time) The M61A1 is actually slightly less powerful than a battery of 4x M39's. (slightly lower rate of fire, both guns use same ammo)


Somthing that may be significant (or at least a bit odd) is that relatively few modern guns seem to use a Minengeschoss like shell. At least judging by the capacities listed here: Modern Fighter Gun Effectiveness
The exception would seem to be some 30 mm weapons like the ADEN and DEFA, though they still don't seem to manage to pack as much HE as with the WWII 30 mm German shells, even the streamlined ones -wich only hels slightly less filler in any case and much of this was due to the tracer as well. (on possible reason for the lower capacity is the use of significantly shorter -thus smaller- shells than the WWII german ones, so the streamlined fuze takes up proportionally larger space)

And indeed, cut-away pictures of the ADEN shell does look similar to the Minengeschoss.

 

[Soren]

I believe you would be wrong about a.) penetrating pilot's armor, and b.) inability to ruin an engine. The reason the SpecWar guys use the Barrett .50 is not only long range sniping but the ability to penetrate > 1/2 steel at 1200 yards to get to an engine.

Maybe, but remember that today we use far better armour piercing projectiles.

AFAIK the WW2 .50cal AP projectile wasn't capable of penetrating the pilots armour of LW fighters.

When the circumstances existed that it took a 'lot' of rounds it was usually because a.) not such a great shot or pilot in front is not making it easy - or the ranges start out at 300+ yards and a long ranging chase occurs.

Well considering the amount of rounds fired in one second by the six .50 cals I'd say it usually took a very good amount of rounds to down an enemy fighter.

 

[kool kitty89]

As to AP capability, remember that the rounds have to go through the aircraft's skin first (and possibly part of the structure) before the armor is reached. The amount of energy lost to the skin will probably not be enough alone to prevent the penetration (depending on the round), but it will probably cause the projectile to tumble. (lighter projectiles will lose proportionally more energy than heavier ones of course)

Also the projectile will probably not be hitling close to perpendicular. (in fact the closer to perpendicular you get, the more fuselage structure you have to go through)

 

[HoHun]

Hi Koolkitty,

>As to AP capability, remember that the rounds have to go through the aircraft's skin first (and possibly part of the structure) before the armor is reached. The amount of energy lost to the skin will probably not be enough alone to prevent the penetration (depending on the round), but it will probably cause the projectile to tumble. (lighter projectiles will lose proportionally more energy than heavier ones of course)

You're right - Tony mentions this effect repeatedly in his books on fighter guns, and it has a dramatical effect on the penetration abilities of armour-piercing rounds.

A report on the Fw 190A-3 prepared by the Oxfordness Research station concludes that in an astern attack, neither 20 mm H.S. A.P., 20 mm H.E./T. (Fuze 253) nor 20 mm S.A.P./I. were able to penetrate the Fw 190's pilot armour when fired from a 10 degree sector after of the plane. The deflection of the projectiles by the aircraft skin and - when it came to the head armour - by the vertical tail was enough to reduce their penetration abilities to a fraction of the nominal value. It was not possible for any of the rounds (including 0.5" A.P.) to penetrate the engine cowling and damage the engine in this type of attack.

With regard to the fuel tanks, the effect you mention is specially stressed:

"The angle of the fuselage with this line of attack is 6 degrees and this gives 0.303" B. Mk.VIII and 0.5" B. Mk.II no chance of causing a fire. These ammunitions will for the most part be deflected or broken up on the 19 s.w.g. fuselage skin; larger angles off tail would make these ammunitions more effective. The detonation of 20 mm. H.E./I. on, or just after, passing through the skin also minimises its chances of producing a fire unless the strike is within 3' of the tank compartment bulkhead."

In fact, 20 mm H.E./I. and S.A.P./I. were the only incendiaries that could damage the tanks at all: "The smaller calibre incendiary ammunitions will either be broken up or deflected away before reaching the fuel tanks."

The RAF definitely had good reasons to leap-frog from 7.7 mm machine guns to 20 mm cannon, skipping the intermediate 12.7 mm calibre. The effectiveness of heavy machine guns for air-to-air combat was not what popular perception today would imagine ...

Regards,

Henning (HoHun)

 

[kool kitty89]

Wing mounted fuel tanks should be significantly more vulnerable though.

I'm not sure about the HMG rounds, but the RCMG incnediary bullets (at least the pyrotechnic type) tended to burst on the surface, similar to what you describe. Soren mentioned in the P-47 Fw 190 toughness thread that the German 7.92mm API would tend to leave a 20mm hole due to the explosion of the incendiary. Such rounds would probably scorch anything near the surface, but most wouldn't have the incendary material penetrate far. (the AP penetrator may continue further in API bullets, possibly carrying some remaining incendiary material with it)
Such pyrotechnic rounds do make excellent "spotter" rounds (oftem more useful than tracers in aiming, and without warning the enemy) due to the bright flash upon impact.

White phosphorus incendiaries are something different as they won't explode but rather spread slowly burning fragments all over the place. This will cause any leaking material or fumes that build up to ignite. Some aircraft at high altitude (ie US heavy bombers), after leaving enemy territory and heading home aparently safe would begin to burn when they dropped altitude.

Thermite incendiary is another different possibility as it burns hot enough to cause significant structural damage, it can melt through steel and will literaly cause aluminum to burn (the intense heat plus the added oxidizer -usu Barium Nitrate- of military thermite to the normal iron oxide aluminum powder mix).


Conversely, depending on fuel tank material, non incendiary bullets (AP/SAP, and even Ball) can cause fires by sparking (impact with steel or other components, somtimes magnesium, usually not aluminum).


There's also the guns in the .60 cal/15mm range that are on the verge of being cannons and do have significant HE+Fuze carrying ability.
As well as the upper end of the .50 cal/13mm range like the projectiles of the 13.2mm Hotchkiss and Russian 12.7x108 which seem to have above average filler capacity though still probably not worth fuzing.

And there's the question of developing drawn steel high capacity shells in the .50-.60 cal range. (which should allow in excess of 10% filler to be used, even with fuzing, probably upwards of 15% in the .60 cal's case)

 

[Juha]

Hello HoHun
Quote:" On the other hand, the Il-2 wings were just as vulnerable to mine shells as most, and the wooden wings of the early variants were highly vulnerable because wood responds with rapidly spreading cracks to blast damage that unlike shears in sheet metal consume very little energy as they propagate."

Yes, and also tail structure was vulnerable to M-Geschoss.

Hello Kurfürst
Now according to Tony's book page 42 the British Mk 1.z HE shell was expected to blow a hole between 75mm and 200mm in diameter in 12 mm armour plate, have You figures for German HE/HEI? I have somewhere very dark copies of a couple British Hispano ammo tests (I cannot even remember on what kind of ammo, one was probably a comparison of effectiveness of different types of Hisso ammo against certain a/c structures), but not time to dig them out.

Otherwise I agree with Your explanation but "Fragments usually stop in the first thing they hit." Now that depends, as is case in all hard flying objects, what is the thing and speed, weight, size and shape of the flying object.

Juha

ADDITION:
Quote:" And if it was, the British decided after the war for adopting Mine shells into Mauser revolver cannons..."

Now one tries to match his weapons to potential targets. IIRC RAF was first more interested in 20mm version of MK 213 but then the changed the priority to 30mm version. I'd not be surprised if the main reason of the change and the decision to adopt mine-shell was the emergence of Soviet heavy bombers and Soviet A-bombs.

On Hispano, IMHO RAF was satisfied on it, especially on Mk V, it weighted same as MG 151/20, had a bit higher ROF and higher MV but was a bit longer. And battery on Hissos was perfectly able to made a short work on any German plane they came across up to and incl He 177 if the pilot was able to get a burst or couple in.

 

[drgondog]

However the performance of the M61 is fairly comperable 4x M39's. Of course the M61 would weigh less than half that of the 4x M39's, though it is fairly bulky by comparison. (and of course requires power feed and spool-up time) The M61A1 is actually slightly less powerful than a battery of 4x M39's. (slightly lower rate of fire, both guns use same ammo)

The M61A2 has a slightly higher rate of fire at 6300/minute than the A1 and 50 pounds lighter - but in either case they both add up to 200-400 pounds for feed and storage depending on the ship.


Somthing that may be significant (or at least a bit odd) is that relatively few modern guns seem to use a Minengeschoss like shell. At least judging by the capacities listed here: Modern Fighter Gun Effectiveness
The exception would seem to be some 30 mm weapons like the ADEN and DEFA, though they still don't seem to manage to pack as much HE as with the WWII 30 mm German shells, even the streamlined ones -wich only hels slightly less filler in any case and much of this was due to the tracer as well. (on possible reason for the lower capacity is the use of significantly shorter -thus smaller- shells than the WWII german ones, so the streamlined fuze takes up proportionally larger space)

And indeed, cut-away pictures of the ADEN shell does look similar to the Minengeschoss.

Noted that the 30x173 on the GAU-8 is at the top of the power list and fires 3900/minute at 3,300 fps.

 

[drgondog]

Maybe, but remember that today we use far better armour piercing projectiles.

We are just recently using up all the WWII and Korean War surplus of 50 Ball and API in Iraq and Afghanistan

AFAIK the WW2 .50cal AP projectile wasn't capable of penetrating the pilots armour of LW fighters.

AFAIK it was but willing to be proven incorrect - but again recognizing that few relative shots were available with a pure 'no deflection' shot in which a lot of structure had the opportunity to deflect or cause a tumble.




Well considering the amount of rounds fired in one second by the six .50 cals I'd say it usually took a very good amount of rounds to down an enemy fighter.

True, but you see a lot of encounter repoerts in which 100-150 rounds were used to destroy a German fighter - 1.6 to 2.5 sec burst to point of stop shooting.

a six gun battery of .50 HMG did just fine against LW fighters. Go look to the LW records for multiple fighter claims in one sortie against USAAF and look to the number of Ace in a Day records for USAAF versus LW for a single sortie.

Offhand I don't recall one example of 5 US fighters claimed/awarded to LW pilot during a single mission. I could be wrong here but there is no example in Tony Wood's Lists that I have seen so far.

This isn't 'proof' of any kind but makes you think that just maybe the pitiful .50 caliber battery of 4 to six .50's worked very well against the superior armored and armed LW fighter.