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-[HRAF]Roland_HUNter

Hispano MK II "OP"?

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Hello everyone!

I'm curious, why the british 20mm, can almost 1-2 shot everything?
I mean, what is that factor?
The Hispano HEI has 6g to 11 g explosive filler and its stronger than the  Minengeschoß what has 18g explosive filler.
What is that factor I missed? ūüėĘ

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1 minute ago, 71st_AH_Barnacles said:

Probably muzzle velocity. The 23mm Russian cannon is very effective for the same reason.

Hispano Mk V: 840 m/s(in the game UK has the MKII)
Mg 151/20: 785 m/s

Edited by -[HRAF]Roland_HUNter

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Is already neat difference  does that have more penetration? 

 

Where can I read the information?

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4 minutes ago, Hobel said:

Is already neat difference  does that have more penetration? 

 

Where can I read the information?

It has more penetration, indeed, but for planes penetration is "useless" because it will overpen your plane. because the plane has no armor, only around the cockpit.(except IL-2 and bombers)

Edited by -[HRAF]Roland_HUNter

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24 minutes ago, -[HRAF]Roland_HUNter said:

Hispano Mk V: 840 m/s(in the game UK has the MKII)
Mg 151/20: 785 m/s

As kenetic energy is proportional to the square of the velocity, and the British round has more mass, there's probably a significant amount of extra kenetic energy in the hispano's hits compared to the mg151/20, enough for you to notice the increased lethality in game.

Edited by 71st_AH_Barnacles
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1 minute ago, 71st_AH_Barnacles said:

As kenetic energy is proportional to the square of the velocity, and the British round has more mass, there's probably significant amount of extra in the hispano's hits compared to the mg151/20, enough for you to notice the increased lethality in game.

 

It's a bigger round, more energy, less charge but more shrapnel, and so on. It was historically a very effective weapon.

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1 minute ago, 71st_AH_Barnacles said:

As kenetic energy is proportional to the square of the velocity, and the British round has more mass, there's probably significant amount of extra in the hispano's hits compared to the mg151/20, enough for you to notice the increased lethality in game.

Agreed, but a heavier rock should not do more damage(but should more penetration as it have) than a bigger explosive  rock. I guess.

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1 minute ago, -[HRAF]Roland_HUNter said:

Agreed, but a heavier rock should not do more damage(but should more penetration as it have) than a bigger explosive  rock. I guess.

I think that the way explosive rounds in this game are modelled means that you seem to get a lot of fireworks but not much effect with some mineshell hits. The new physiology model means that they can knock the pilot unconscious though. I think that I've been knocked unconscious a lot more in allied planes.

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Just now, 71st_AH_Barnacles said:

I think that the way explosive rounds in this game are modelled means that you seem to get a lot of fireworks but not much effect with some mineshell hits. The new physiology model means that they can knock the pilot unconscious though. I think that I've been knocked unconscious a lot more in allied planes.

A big exploding should not damage the plane heavily? MK 108 working the same way but with 72-85g of explosive filler.
In the game your pilot is unconscious by a hit, because he got heavily wounded.

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5 minutes ago, -[HRAF]Roland_HUNter said:

A big exploding should not damage the plane heavily? MK 108 working the same way but with 72-85g of explosive filler.
In the game your pilot is unconscious by a hit, because he got heavily wounded.

No, it should. 

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In my experience the Hispano doesn't "1-2 shot" often, it's a powerful cannon but the number of hits for a kill tends to be higher, around 5-6 if I had to take a guess. The smoke effect is much smaller than the German cannons and usually it's 2 or 4 cannos firing at the same time so more rounds are hitting than what it seems.

Edited by -=PHX=-SuperEtendard
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It’s useless against ground targets.  Seems less effective than 4 mg151s from the a8 to me but they are still really good in air to air.  

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56 minutes ago, -=PHX=-SuperEtendard said:

In my experience the Hispano doesn't "1-2 shot" often, it's a powerful cannon but the number of hits for a kill tends to be higher, around 5-6 if I had to take a guess. The smoke effect is much smaller than the German cannons and usually it's 2 or 4 cannos firing at the same time so more rounds are hitting than what it seems.

If you use 200-230 m convergence, and you hit the target at 200-230m, then 1-2 ll be enought. Trust me. Test it.

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The Hispano is a powerful 20mm cannon that seems to be overshadowed in reputation but certainly not in performance. There were all kinds of problems adapting the cannon to be used in wing mounted stations (it was meant to be fitted in an engine) but those were gradually overcome.

 

The things that suggest to me why this cannon is consistently extremely powerful in successive combat flight sims are the following:

 

High muzzle velocity: 880 m/s  - Highest of the WWII 20mm cannons (the Hispano Mark V is a bit slower at 840m/s)

Projectile weight: 130 grams - One of the highest projectile weights. Heavier than the ShVAK (95 grams) and the MG151/20 (105 grams)

Large cartridge: 20 x 110 - Larger than the MG151/20 (20 x 82) and ShVAK (20 x 99R)

 

Combine those with average to excellent fire rates (600 rpm for the Mark II and 750 for the Mark V) and fairly average explosive potential and you have yourself a potent cannon that is easy to lead. IMHO, there are reasons that the MG151/20 and the ShVAK are also excellent cannons but I think the Hispano is possibly the best of WWII if we ignore the reliability issues that plagued it through 1943 and even 1944.

http://users.skynet.be/Emmanuel.Gustin/fgun/fgun-pe.html

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7 hours ago, ShamrockOneFive said:

The Hispano is a powerful 20mm cannon that seems to be overshadowed in reputation but certainly not in performance. There were all kinds of problems adapting the cannon to be used in wing mounted stations (it was meant to be fitted in an engine) but those were gradually overcome.

 

The things that suggest to me why this cannon is consistently extremely powerful in successive combat flight sims are the following:

 

High muzzle velocity: 880 m/s  - Highest of the WWII 20mm cannons (the Hispano Mark V is a bit slower at 840m/s)

Projectile weight: 130 grams - One of the highest projectile weights. Heavier than the ShVAK (95 grams) and the MG151/20 (105 grams)

Large cartridge: 20 x 110 - Larger than the MG151/20 (20 x 82) and ShVAK (20 x 99R)

 

Combine those with average to excellent fire rates (600 rpm for the Mark II and 750 for the Mark V) and fairly average explosive potential and you have yourself a potent cannon that is easy to lead. IMHO, there are reasons that the MG151/20 and the ShVAK are also excellent cannons but I think the Hispano is possibly the best of WWII if we ignore the reliability issues that plagued it through 1943 and even 1944.

http://users.skynet.be/Emmanuel.Gustin/fgun/fgun-pe.html

Agreed but then the MG-FF should be strong aswell. Its just slower than the Hispano, but the proj. weight heavier.
And the large cartridge, will just give you more starting muzzle velocity, because the cartridge case is bigger with bigger amount of explosive what ll make the bullet faster in the cannon barrel.
Still we not calculated the high amount of explosive for the minengeschoß.
The true difference I guess will be the british ammunition. The birts used SAPI(Semi-Armor-Piercing-Incendiary) and SAP-HEI
(Semi armor piercing high explosive shell.) And the SAP has more shrapnel as a Yankee said.
1.PNG.bbb8a950cd689d185e703bd2ea6a8dc1.PNG

PS:But I still think something is not "okey" with Minengeschoß, why?

http://quarryhs.co.uk/RAF guns.htm

 

"The Modern Era

 

At the end of the Second World War, there was, as usual, very little money for new armament developments and the Hispano remained in service until the mid-1950s, not just in fighters but also in the Shackleton MR plane. However the Allies did have a new gun to play with; the Mauser MG 213C.

 

 

The German firm had designed a new type of gun to meet a Luftwaffe requirement for a very fast-firing, high-velocity 20 mm cannon. This addressed the main restriction on rate of fire ‚Äď ammunition handling ‚Äď by breaking it down into several stages. Instead of one chamber formed as a part of the rear of the barrel, five chambers were used within a cylinder whose axis of rotation was parallel with the barrel, so that as the cylinder rotated, each chamber was brought into line with the barrel in turn, and its cartridge fired. At the same time, the other chambers were engaged with loading a fresh cartridge or ejecting a spent case. This allowed rates of fire of well over 1,000 rpm to be achieved. As this layout bore some resemblance to the traditional revolver type of handgun, it became known as the revolver cannon.¬† During the development of the MG 213C a low-velocity 30 mm version was also produced, considered more suitable for bomber destruction. This became the focus of interest in both the UK and France, who continued the development of the gun. It took several years before the resulting Aden and DEFA guns were ready for service, but they were eventually introduced using slightly different versions of the 30 mm ammunition.

 

img309.jpg

 

30 mm Aden gun

 

Further joint development saw the ammunition altered to fire a lighter shell at a higher muzzle velocity, and this became the NATO 30mm round still used by the Aden Mk 4 and DEFA 550 series guns, and by the M230 Chain Gun used on the Apache AH-64 attack helicopter in British Army service. However, the Aden, DEFA and M230 all use slightly different versions of the ammunition which are not completely interchangeable.

 

The 30 mm Aden Mk 4 was the standard RAF and FAA gun from the late 1950s until the 1980s, and remains in service with the Hawk trainer (the last combat aircraft to carry it being the Sea Harrier and the Jaguar). It was exceptionally hard-hitting for its day, firing shells weighing twice that of the Hispano's at an only slightly lower muzzle velocity, but at a much higher rate of about 1,300 rpm. The difference in destructive effect compared with the Hispano was even greater than these figures indicate, because the Allies also benefited from another German development; the Minengeschoss or mine shells.

 

FGMGFFcart.jpg

 

Luftwaffe 20mm MG-FF ammunition: HE-T, Minengeschoss and API


 
The Minengeschoss were high-capacity shells with very thin walls which approximately doubled the HEI content of the shells, as you can see in the above picture of sectioned Luftwaffe 20 mm ammunition: compare the space for explosive in the HE-T and the Minengeschoss, even allowing for the tracer in the former. When used in the Aden, this resulted in the 30 mm shells having four times the blast effect of the Hispano's. Aden ammunition also used another German development, tungsten-cored AP projectiles."

They copied the Minengescho
ß, so it should be effective.

Edited by -[HRAF]Roland_HUNter

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8 hours ago, -[HRAF]Roland_HUNter said:

If you use 200-230 m convergence, and you hit the target at 200-230m, then 1-2 ll be enought. Trust me. Test it.

Just what you said... 2 cannon hits in the same place for hispanos. Aim good and you'll be prized with this DM. Lots of hits all over a target are less effective than 2 cannon hits in the same place. And has for penetration not to be a factor in planes i do not agreed with you. A shell detonating after penetrating is far more effective than a shell detonating over a surface. You can found al the informations you need here http://www.quarryhs.co.uk/WW2guneffect.htm. As you can see a Hispano mkII as double efficiency than a mg151...

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3 minutes ago, =GEMINI=marbessi said:

As you can see a Hispano mkII as double efficiency than a mg151.

 

That's the 15mm MG151. The 20mm MG151/20 is about as effective as a Hispano MkII.

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I spent a few hours in QMB smashing AI with the Tempest.  My general purpose air-to-air convergence is 300.  Even though I got many concentrated hits right in the cockpit/engine area of the planes I shot, I never saw total obliteration like can happen with the German cannons.  BTW a single 1-click and release shot let's off about 12 rounds.  If all of them hit, or even half, I'd expect that a dead on center of the plane shot would leave a massive hole where the cockpit used to be. 

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2 minutes ago, JtD said:

 

That's the 15mm MG151. The 20mm MG151/20 is about as effective as a Hispano MkII.

Yup sorry. DM btw prizes a lot convergence shot as i said before. Try simply shot outside convergence with Hispanos and you'll lose all the performance

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2 minutes ago, =GEMINI=marbessi said:

Yup sorry. DM btw prizes a lot convergence shot as i said before. Try simply shot outside convergence with Hispanos and you'll lose all the performance

 

Doesn't real life also prize convergence shots though?  I don't think there's a lot of muzzle velocity lost 230m out of the gun barrel either.  

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3 minutes ago, =GEMINI=marbessi said:

Yup sorry. DM btw prizes a lot convergence shot as i said before. Try simply shot outside convergence with Hispanos and you'll lose all the performance

In dogfight, why would you do that? Btw shot outside the convergence and lose all the performance, is true for all the wing cannons.

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11 minutes ago, -[HRAF]Roland_HUNter said:

In dogfight, why would you do that? Btw shot outside the convergence and lose all the performance, is true for all the wing cannons.

Yup, and with 190s i have no trouble in shooting down enemies if i shot properly. I think it's not a problem of shells but planes DM. I think that P51 and P47 DM should be switched as an example and i found 109s in general very fragile as Spitfire wings that could easily be cut away with mg131 if multiple shells hits same spot. As you can see in the article i linked there are many factors to be considered in guns/shells efficiency and i found them very well represented in this game so IMHO all this thread is inneffective. A thread speaking about planes DM makes a lot more sense to me...

Edited by =GEMINI=marbessi
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5 hours ago, -[HRAF]Roland_HUNter said:

Agreed but then the MG-FF should be strong aswell. Its just slower than the Hispano, but the proj. weight heavier.
And the large cartridge, will just give you more starting muzzle velocity, because the cartridge case is bigger with bigger amount of explosive what ll make the bullet faster in the cannon barrel.

 

The MG-FF has other problems. The fire rate is slow (530 rpm) and the muzzle velocity is considerably lower at 600 m/s to 640 m/s instead of 880 m/s. The cartridge size is also smaller though with the extra weight above the Hispano I'm not sure what the effects are. That's less clear cut for me. Without the Minengeschoss rounds, the MG-FF is a very average cannon and with them it moves up to pretty good.

 

In-game I find the MG-FF/M hits fairly hard when it connects but getting repeated hits, as the IL-2 damage model seems to react best to, is harder than with the Hispano.

 

I don't know if we have charts that show drag profiles but I'm curious to see what speed the Hispano is moving at say 300 meters versus what speed the MG-FF/M is moving at the same point.

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Speaking of the German cannon rounds.... how come they don’t detonate mid air like in CLoD?   Different round?   Or is that a false effect?

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11 minutes ago, spartan85 said:

Speaking of the German cannon rounds.... how come they don’t detonate mid air like in CLoD?   Different round?   Or is that a false effect?

I'm not even sure how that would work IRL. It seems counter productive for the cannon round to have a timed fuse and the Germans didn't have a proximity fuse available to them, so what would set off the explosion? I'm not an armament expert, it just seems odd.

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8 minutes ago, RedKestrel said:

I'm not even sure how that would work IRL. It seems counter productive for the cannon round to have a timed fuse and the Germans didn't have a proximity fuse available to them, so what would set off the explosion? I'm not an armament expert, it just seems odd.

Why would it be counterproductive to have a timed fuze? Makes sense to me, so you don't have explosive rounds raining down where you don't want them. 

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The only WW2 20mm cannon, that is comparable to Hispano in average punch per round is the Japanese Ho-3 (from Ki-45, not the Ho-5 from other fighters). 

However, its lower rate of fire still makes Hispano the King of 20mm cannons of WW2. 

 

I made this table a while ago, credits to A.Williams and E.Gustin:

 

 

image.png

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23 minutes ago, Jonttu1 said:

Why would it be counterproductive to have a timed fuze? Makes sense to me, so you don't have explosive rounds raining down where you don't want them. 

If you're firing at moving targets at an unknown range and speed, a single timed fuse might mean that your shell bursts too soon or even after passing completely through the aircraft if you don't hit something substantial that stops the round. Firing from a nose-mounted cannon at a heavy bomber I would be opening up at much longer range than against a fighter, but the cannon I have needs to be able to hit and destroy both targets. So the fuse needs to be long enough to engage at max range, but if its that long and I fire through an enemy fighter's wingat 200 yards, I get a 20mm hole in the wing rather than an explosion because the shell explodes seven or eight hundred yards past him. 

In ground attack its even worse as the round might penetrate pretty far into the ground before exploding rather harmlessly. I would want it exploding on impact to maximize what fragmentation effects it can.

Now, I can see it possible to have an impact fuse and a timed fuse, so that the round bursts after a certain delay and you don't have ordnance raining down. And maybe that's how it was done. It would be interesting to see a source on that for how it worked. 

I don't think I've heard of timed fuses in any air cannon on the allied side of WWII. Maybe it wasn't a concern as much of their action was over occupied/enemy territory so they didn't care as much about unexploded ordnance falling from the sky.

In any case I think if I was designing an air cannon round for WWII I would go with maximum simplicity for fusing to keep costs down, production up, and maximize the likelihood that the round explodes on target. 

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German projectiles generally came with time delayed impact fuses, nose and tail fuses were used. They also had a mechanism called "Zerleger", something like "disassembler", which self destructed the projectile after some time in the air. These were generally used in air to air mission, and not typically used in ground attack missions. Though it wouldn't really hurt ground attack to use Zerleger ammunition, it would just be a waste.

 

The below ZZ1505 is a fuse with self destruction, as used with 20mm mine shells, timed at about 3s air time. When used without self destruction, they were using for instance the AZ1502 instead.

 

image.thumb.png.5dae14ea3d2d8d46c72b8ff2da302fde.png

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33 minutes ago, JtD said:

German projectiles generally came with time delayed impact fuses, nose and tail fuses were used. They also had a mechanism called "Zerleger", something like "disassembler", which self destructed the projectile after some time in the air. These were generally used in air to air mission, and not typically used in ground attack missions. Though it wouldn't really hurt ground attack to use Zerleger ammunition, it would just be a waste.

 

The below ZZ1505 is a fuse with self destruction, as used with 20mm mine shells, timed at about 3s air time. When used without self destruction, they were using for instance the AZ1502 instead.

 

image.thumb.png.5dae14ea3d2d8d46c72b8ff2da302fde.png

Well, I stand corrected! Time delayed impact fuses would intend for the projectile explodes inside the enemy aircraft structure rather than against its surface, correct? Do you know if any allied forces implemented something like this?
 

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11 hours ago, Mobile_BBQ said:

 

Doesn't real life also prize convergence shots though?  I don't think there's a lot of muzzle velocity lost 230m out of the gun barrel either.  

There’s a lot lost in the first 100m , let alone 300m.

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17 minutes ago, RedKestrel said:

Do you know if any allied forces implemented something like this?

 

I'm also curious so i'm doing some digging. On the US side it appears the 37mm gun did not: 

http://www.nj7p.org/Manuals/PDFs/Military/TM 9-240 7-May-45 Scribd.pdf

 

The Hispano.404 20mm did not:

https://archive.org/details/20mmautomaticgun00unit/page/92

 

On the russian side i cant find much info on the fuses for their canons 

https://en.wikipedia.org/wiki/ShVAK_cannon#Ammunition

https://en.wikipedia.org/wiki/Nudelman-Suranov_NS-37

 

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1 hour ago, RedKestrel said:

Well, I stand corrected! Time delayed impact fuses would intend for the projectile explodes inside the enemy aircraft structure rather than against its surface, correct? Do you know if any allied forces implemented something like this?

 

Well, maybe "delayed" was a bit of an exaggeration. All these fuses qualify as direct action / impact fuses. The delay is really short, and comes more or less from the slight delays in the fuse and the ignition capsule. All nations were very soon aware that a shell detonation on the outside does a lot less damage than one detonating just on the inside. So I assume all nations had their mini-delays built in. Below a picture from a US high speed cam. It's a test of the .60 projectile, but the report says it's an example, representative for the projectiles tested. That test included standard HEI Hispano ammo (which comes with an "impact" fuse).

What was a concern is that the fuse action varied widely, in the below screen you can see one projectile exploding right behind the impact, while another one goes off 1m (more than 40") after it struck the plate. But all three go off behind the plate, as designed. This may be different when projectile velocity drops and/or material thickness goes up.

 

image.thumb.png.e3a4f46fc35b690ed4d812036b78553e.png

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I digress but just for the fun take these extreme cases.

 

The problem with very high kinetic energy is that if you do not have something in front that can absorb it  then it is useless.

 

Take the WWI wood and fabric airplanes. You can shoot a 20mm depleted uranium armor piercing round like the one of an A10 gatling gun. Muzzle velocity is 1km/sec and muzzle energy is 200kJoules. To compare with the Hispano 20mm cannon which had a muzzle energy of 47 kJ (over 4 times less).

 

The only result is a slightly larger hole  (at that bullet speed fabric will have no time to react) in the fabric and that's all. There will be no energy absorption or just minimal. The bullet goes through the plane and if cuts no cable no critical structure element, then no harm. Same by the way with WWII airplanes that could be riddled with small holes and fly perfectly.

But if youluckily hit the pilot or the engine then yes for both it will be just a hole too, but deadly for the plane and you. 

 

What is 200kJoule. This is equivalent to 47 kCal. You can heat 47 liters of water by 1 degree instantaneously. When the bullet hits if stopped the kinetic energy is transferred nearly instantaneously. Or you can heat 1 liter of water by 47 degrees. Or if you take a water portion the size of the round and 10 cm thick that is 62,8 cm3 then you will heat it to 752 degrees. Now if you take a steel plate (8 times water density) of say 1 cm thickness you are at 7520 degrees. You punch a hole and vaporize the metal. 

 

If your bullet has an internal dart of very high resistance alloy, and the diameter of the internal dart is 10mm then you get enough energy on your steel plate to reach 14'968 degrees. This is why you just punch a hole like a jedi laser saber. And this why if you hit a massive engine you still go through with 14'968 degrees of energy you can melt your way through the engine.

 

All this is with muzzle energy which means at the muzzle. Air resistance will slow down the bullet as it flies, so depending on the distance to the plane the kinetic energy will diminish. 

 

As a conclusion it would have been more effective to hurl basket balls to the WWI planes at slower speed (but equivalent kinetic energy)  and you would have more guaranteed damage. The probability to cause structural damage and large fabric destruction to impact the flyability of the plane would have been much higher.

 

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Good points about the energy of projectiles. Especially how firing 30mm DU sabot rounds at WWI biplanes would be relatively less effective than shooting basketballs at them. 

 

46 minutes ago, IckyATLAS said:

The only result is a slightly larger hole  (at that bullet speed fabric will have no time to react) in the fabric and that's all.

 

Just a fun fact: at higher projectile speeds the hole in the fabric would be closer to the size of the projectile than it would be if the same-size projectile was fired with the same energy but a lower velocity. The rate of strain for fabrics is a huge factor for resisting something penetrating them -- it's a big topic in the field of kevlar vests. Fabrics rely on the yarns in-contact with a projectile to pull other yarns into bearing the load before they break.

 

Nitpicking here, but there's a few points to clarify:

 

32 minutes ago, IckyATLAS said:

If your bullet has an internal dart of very high resistance alloy, and the diameter of the internal dart is 10mm then you get enough energy on your steel plate to reach 14'968 degrees. This is why you just punch a hole like a jedi laser saber. And this why if you hit a massive engine you still go through with 14'968 degrees of energy you can melt your way through the engine.

 

1) Deformations of the material will absorb much of the energy

 

2) kinetic impacts rarely have any assistance from thermal effects, not even the famed HEAT warhead that everyone says "melts" through armor, it's all KE effects because the material wont have time to melt enough for temperature to matter. If temperature were a factor in any of these nomex or ceramics would become the end-all-be-all of armor, yet the reason that ceramic is used for is drastically different than its high temperature resistance -- we dont use tiles from the space shuttle as armor, and they'd make absolutely abysmal armor because they have little areal density. 

 

Anyways, yes a small-enough projectile like a 10mm dart with enough KE will punch clean through an engine block. Assuming an absolutely rigid material making up the dart, the hole punched through should be fairly clean.

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I find that even short bursts from cowl 13mms on the 109s are ridiculously effective at dewinging aircraft (with a bit of help from g effects). The damage system seems to be very heavily biased towards damage to KE energy as opposed to CE (explosive rounds). @IckyATLAS has already provided some excellent points why this is dubious way to work with it.

 

Primarily, that a very significant porition of that KE at the muzzle is already lost by the typical 300 m range due to speed loss of the projectile, and, due to very light and easily penetratable aircraft structures, very small amount of that energy is actually transferred to 'useful work', i.e. destroying the aircraft structure. The point being that since even the KE energy of a simple rifle round is far more than enough to go through that structure, the rest is not used for destruction, but it is kept as the projectile passes through 

 

The second issue is the relative energy content the rounds have. All the KE of the round is coming from the burning of the powder in the rounds (which itself is a rather inefficient process due to gas leakage and that much of that energy is simply wasted in generating heat), and that powder has FAR less energy stored in it to start with.

 

Looking at the classic 2cm Minengeschoss round, we see that all KE is coming from a powder loading of 19,5 gram of Nitrocelluose, which has a RE rating (TNT equivalent factor of ca. 1.10. That is to say, it's explosive power is equivalent to ca. 21.45 gram of TNT. The explosive shell fired itself is, however, loaded with 18.6 gram of Nitropenta (Pentaerythritol tetranitrate, PETN) witn an RE factor of about 1.60, about the same RE effectiveness of Hexogne (RDX) that was also used in Minengeschoss. That's an equivalent of 29.76 gram of TNT explosive power.

 

So you already have less energy to start with for KE than for CE, but it gets worse. A firearm is, effectively a piston engine (the round fired being the piston) with about 30% efficiency, i.e. about 30% of the energy used (burning propellant) is actually transferred to KE, the rest is being wasted on friction, gas leaks, heating of the 'exhaust' gases and so on). This means that the 21.45 gram of TNT equivalent force you started with is now about 6.435 gram TNT equivalent in KE when the projectile exist the barrel at 755 m/sec muzzle velocity (27 000 Joule KE).

 

However, by the time it actually hits it target, an aircraft at 300 meter, the velocity of the round has decreased to just 481 m/sec (11 000 Joule KE), in other words, another 60% of the initial energy has been lost to air resistance when it strikes home. If we stick to express energy in TNT equivalent force, the gun now has 40% of that 30% of energy you had when your round exited the barrel.

 

That's 2.61 gram of TNT equivalent you have left in KE. Against the 29.76 gram of TNT equivalent explosive force that goes boom just about now.

In other words, the potential CE energy of the Mineshell is about TWELVE times that of it's potential KE of the round when it strikes the target.

 

Calculations of course could be made for other HE rounds, but there's no way where KE will trumps the CE energy potential of the explosives inside the shell upon impact.

You'd simply blow up your gun if you stuffed so much powder in the shell casing..

 

Now of course CE has its own losses of energy (energy required to tear apart the shell body, which is admittedly very small with thin walled M/Geschoss but greater with normal HE rounds, heat transfer losses), but the point is that's its potential is far, far greater to start with.  This is also shown by the level of visual destruction brough about by pure KE rounds (small hole) and pure CE shells (structure completely destroyed on a relatively large area). The primary limit is for CE rounds is the very quick drop of otherwise incomparably higher initial energy - tiny fragments and gas pressure loose force (pressure/velocity) fast due to poor ballistic coefficients of small fragments and decrease of gas pressure with the increase of the volume they fill. 

p151minegr.JPG

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Interesting discussion and valid points, however planes (especially fighters) are not empty boxes as implied by some posts here. Imagine you're shooting AP bullets at this airplane:

six.png.b7ee0857635d331c9a12b48988a5cf6c.png

 

Most kills were achieved shooting from six o'clock or similar angles. It's not easy to find spots where you won't hit something solid and vital - pilot, tanks, engine, radiators, ammo, wing structure.

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4 hours ago, VO101Kurfurst said:

In other words, the potential CE energy of the Mineshell is about TWELVE times that of it's potential KE of the round when it strikes the target.

 

 

This is roughly correct, for a mineshell.  BTW - the energy content of PETN is 1.24 times that of TNT: the RE of 1.66 includes other variables in demolition power, and is a relative weight, not a relative energy. So closer to ten times than twelve in your example.

 

An HS MKII HE hit is a different case. The shell is heavier, (120g vs 95g) so it has better ballistics, losing less speed for a given range from an initially higher MV. It has less HE filling.   The HS has about 45% of the explosive CE of the 20mm mineshell: at the muzzle it's KE and CE are roughly equal.  Even if it slows at about the same rate as your mineshell, at impact it will have 2-3 times the CE compared to the KE.  Assuming it's fuze is not a dud.

 

I think anyone who has looked that this recognizes that a mix of HE effect and AP effect gives the best results overall. If you get a shot lined up from behind you want some of your hits to pass through the length of the plane, not just nibble the tail. On a snap shot for a plan view, an HE hit is much less likely to pass through without hitting anything useful.   

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