Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Flyboy on December 06, 2004, 09:38:01 AM
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how can the hitting power of the hispano be so much greater then the Mg151.
wasthere such a difference in the real world?
i mean those are both 20mm rounds how can such awide gap ocour ?
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Believe it is primarily due to the way the guns are modelled in AH.
There have been oh... probably about a hundred threads about this topic in the 3 years I've been around here.
Short version is, the Hispano has two types of rounds, HE and Ap. Both are heavy rounds with fast muzzle velocity, therefore the composite AH round is a heavy, fast round with good AP and good HE characteristics.
The Mg-151 had HE, AP, and Mine rounds (super HE). If I recall correctly, the belting was something like 2 HE, 2 AP, and 1 Mine. The HE round was small, with a fairly low muzzle velocity, and didn't have that much explosive. The AP round was small, with a fairly low muzzle velocity. The Mine round weighed less than the other 2, but had far more explosive content. It would do damage comparable with a Hispano.
The composite round is small, slow, and doesn't have much HE.
Best thing to do to check it out yourself is take Tony Williams analysis of Aircraft Guns, and play with it some.
The Hispano is the 20X110 HE Round (he doesn't have any AP data up there).
The MG151 is the 20X82 is the MG-151. He rates the Hispano at a 201 overall, the MG151 AP at 110, the HE at 109, and the Mine at 236.
So for a average belt of 5 rounds, the average Hispano round does 201 damage (in Tony Williams damage points) per round, the MG151 does ((110+110+109+109+236)/5) or 134.8 damage (in Tony Williams damage points) per round. The MG151 is roughly 67% as effective as a Hispano. I think it is slightly less than that in AH.
Older MG vs cannon thread (http://www.hitechcreations.com/forums/showthread.php?s=&threadid=92877&highlight=Mg151+AND+Hispano)
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(http://www.quarry.nildram.co.uk/20mm1.jpg)
20x70RB Becker, 20x72RB Oerlikon FF (aka IJN Type 99-1), 20x80RB German MG-FFM, 20x82 Mauser MG 151/20, 20x94 IJA Ho-103), 20x99R ShVAK, 20x100RB Oerlikon FFL (aka IJN Type 99-2), 20x105 MG 204, 20x110RB Oerlikon FFS (and HS.9), 20x110 HS.404 (Hispano)
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well the cartige of the hispano is much bigger no doubt about it, but the projectile itself seems about the same size. so i would guess they will have around the same amount of HE content?
but hey what do i know :)
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http://www.geocities.com/CapeCanaveral/Hangar/8217/fgun/fgun-in.html
http://www.quarry.nildram.co.uk/WW2guneffect.htm
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The Hispano 20mm HE round had 8% HE by weight (per Tony Williams website), the MG151 HE had 3.2%, the API had 3.1%, and the Mine round had 22%.
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Hi Flyboy,
>well the cartige of the hispano is much bigger no doubt about it, but the projectile itself seems about the same size. so i would guess they will have around the same amount of HE content?
The trick is that the MG 151/20's mine shell is a thin-walled projectile leaving much more space. It required a different manufacturing process, and it was not easy to get it to work at all because a thin-walled projectile tended to get deformed on firing.
The energy output of the MG 151/20 was - depending on the belting - equal to or slightly superior to that of the Hispano II:
MG 151/20: 1,27 MW (at 1:1:3 API/HET/Mine)
MG 151/20: 1,16 MW (at 1:1:2 API/HET/Mine)
Hispano II: 1,06 MW (at 1:1 API/HE)
MG 151/20: 0,97 MW (at 1:1:1 API/HET/Mine)
One area that still needs more research is the belting order and especially the logic behind the belting. Technically, a pure mine shell load out would give the best results (though you'd not get any tracers :-)
For the Hispano II, the belting order does not make any difference because the chemical energy of API and HE are identical.
(Values are approximations based on a standard energy for the explosive content. MG 151/20 mine shells also came in a variant with a reportedly 40% more powerful explosive substance, but I neglected that for the sake of simplicity as the chemical energy didn't actually increase by 40% and the greater effect was due to a more rapid detonation. You've got to draw a line somewhere :-)
Regards,
Henning (HoHun)
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IMO the simple answer is that based on muzzle velocity & projectile mass, the Hispano Mk.II, per hit, is 50% more powerful than the MG151/20, thus the Hispano Mk.II is likley to bring down an opponent with fewer hits. The MG151/20 makes up for about half of this difference by having a rate of fire 25% greater than the Hispano Mk.II, so in any given attack, the MG151/20 is likley to score more hits. Getting into the qualities of explosives complicates the issue beyond my knowledge....On a similar topic, which of the LW 20mm mine shells were the ones with time delay fuses (time to explode after firing, like flak, not time to explode after impact) MGFF-m, MG151/20 or both? Also did the Mk108 shells have this capability also?
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I head that Soviet pilots say that their ShVAKs are better than hispanos and Mg151. What makes Shvaks better than those 2?
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Originally posted by tikky
I head that Soviet pilots say that their ShVAKs are better than hispanos and Mg151. What makes Shvaks better than those 2?
Soviet wishful thinking :) The only clear advantage is a slightly higher rate of fire.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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"The Hispano 20mm HE round had 8% HE by weight (per Tony Williams website), the MG151 HE had 3.2%, the API had 3.1%, and the Mine round had 22%."
"You've got to draw a line somewhere :-) "
Well if you don't and calculate 151/20 power by using the correct power output of Mine with PETN what would be the result for 151/20?
Where did U get that 40% increase in explosive power? Mine over normal HE per grams or compressed Mine over normal Mine per grams or what?? What was the difference on axis and allien normal HE filling?
Ring had a nice page on this subject but it seems to be down so I cannot calculate them myself.
I think that in terms or 5 round having 3 compressed Mine rounds would give a quite hefty punch compared to any other 20mm if chemical power is considered...
Edit: From another forum:
Hispano
AP, KE = 45 855 Joule
HEI, KE = 47 705 Joule
HEI, CE = 25 751 Joule
HEI, Total = 73 456 Joule
Mauser
AP, KE = 28 985 Joule
HE, KE = 28 580 Joule
HE, CE = 8461 Joule
Total HE = 37 041 Joule
MG, KE = 27 630 Joule
MG, CE = 68 425 Joule
MG, Total = 96 055 Joule
KE for Kinetic Energy
CE for Chemical Energy
-C+
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IIRC the MG151/20 belting was initially AP - HE(M) - HE(T) - HE(M). Later they changed it to AP - HE(T) - HE(M) - HE(M) which would give the HE(M) better grouping, thus better chance of causing catastrophic damage to bombers.
However in both loadouts half the belt is mineshells.
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Btw. Charge. Much if not most of the KE goes to waste unless the shell hits something capable of absorbing the energy.
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How is the ballistic of the mineshell. Same?
Oh, and for your info (you probably already know?), some Spittys had the late Orlikon cannon.
Pilots were highly impressed with it. Just a couple of hits...
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From what I've read the Orlikon was a simpler weapon than the Hispano. Heavier and more reliable it was favoured over the Hispano in the anti-aircraft role. However the Hispano's lower weight made it more suitable as an aircraft armament. Firepower wise they would have been pretty similar.
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does AH modell diferent shells? do we have both HE and AP rounds when we fire our guns?
that can explain alot of irregularity in the DM. sometimes it takes 20 rounds sometimes 2
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Hi Charge,
>Edit: From another forum:
Hm, I calculate about the same kinetic energy, but twice the chemical energy. I'm using Tony's data, 4.184 J/cal, 1.335 kcal/g for chemical energy.
>Well if you don't and calculate 151/20 power by using the correct power output of Mine with PETN what would be the result for 151/20?
Well, I've not gone into exact chemical compositions because
a) It's not easy to find out which explosive what used in which shell.
a) There is a certain uncertainty about the exact composition of each explosive.
b) Chemical energy and destructive capability are not always linear for different explosives anyway. (The improved mine shell had less than 40% more energy for 40% more destructiveness.)
I looked at blast front velocities and the like and then decided to leave it at a standard energy content since more detail was as likely to introduce new errors as to improve accuracy.
>Where did U get that 40% increase in explosive power?
For example a reproduction of WW2 weapon data in the German Waffen Revue magazine.
>Well if you don't and calculate 151/20 power by using the correct power output of Mine with PETN what would be the result for 151/20?
An inaccurate figure ;-)
But I could pretend the improved mine shell had 40% more energy (which it hadn't) to arrive at the following comparison:
MG 151/20: 2,25 MW vs. 1,71 MW (at a pure Mine shell loading)
MG 151/20: 1,59 MW vs. 1,27 MW (at 1:1:3 API/HET/Mine)
MG 151/20: 1,43 MW vs. 1,16 MW (at 1:1:2 API/HET/Mine)
Hispano II: 1,06 MW (at 1:1 API/HE)
MG 151/20: 1,15 MW vs. 0,97 MW (at 1:1:1 API/HET/Mine)
Regards,
Henning (HoHun)
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Hi Gscholz,
>IIRC the MG151/20 belting was initially AP - HE(M) - HE(T) - HE(M). Later they changed it to AP - HE(T) - HE(M) - HE(M) which would give the HE(M) better grouping, thus better chance of causing catastrophic damage to bombers.
Four mine shells in a row have yet better chances of causing catastrophic damage, so why stop at two?
There's little data with regard to belting, and the Luftwaffe calculations regarding bomber destruction seem to assume a pure mine shell loadout.
(By the way, one MG 151/20 mine shell carries pretty much the same explosive energy as two Hispano HE shells.)
Regards,
Henning (HoHun)
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Why stop at two?
Good question.
Reliability? AP desire for things like fuel tanks and armour?
Don't really know.
Hope Tony pops in and informs us.
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Originally posted by HoHun
Four mine shells in a row have yet better chances of causing catastrophic damage, so why stop at two?
May be because the nature of the mine itself. The mine is going to provoke a blast of very high pressure air. The HE is going to provoke the same at minor scale, but, at the same time, is going to spread very fast metal fragments able to penetrate any non armoured part of the plane nearby.
For example, if a mine explodes near a fuel tank, the fuel tank may end fully deformed. The same case with HE will result in a perforated fuel tank.
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How does the fusing of a mine shell differ from that of an impact fused HE round? I must admit I have never heard of the type.
shubie
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Originally posted by MANDO
May be because the nature of the mine itself. The mine is going to provoke a blast of very high pressure air. The HE is going to provoke the same at minor scale, but, at the same time, is going to spread very fast metal fragments able to penetrate any non armoured part of the plane nearby.
For example, if a mine explodes near a fuel tank, the fuel tank may end fully deformed. The same case with HE will result in a perforated fuel tank.
Both mine and ordinary HE produces fragments, but these fragments when speaking of 20mm shells are tiny and very weak. I have detailed report on the german MG C30 20mm cannon, a far more powerful weapon than either the Hissy or the Mauser. One would expect bigger fragments from it, but even that 20mm gun`s fragments stopped after piercing a few layers of very thin dural plates. In fact, most fragments stopped after the 1st or 2nd dural plate. On an aircraft, I`d suppose the framents would stop immiadately at the first heavier structure encountered - main spar, ribs, radios, any kind of armor or thicker plate etc.
The german mix of ordinary HEI with mine shells was probably due to increase the incendinary effect of the mix, and to add heavier fragments, but remind you, the explosive in the mine shells was already highly potent at that, the mix itself being incendinary to start with, and so were the hot fragments it spread out in the nearest vicinity. British live fire tests showed fairly high, and comparable fire probability with either type of HEI or Mine shells.
I have did some calculation on the Hissy/Mauser subject a while ago, and the numbers were very convincing. The combination of 25-33% higher ROF, the use of much higher percantage of explosive shells (80% vs. 50%, ~50% higher), and the fact that the Mines carried about 3-4 times the explosive than an Hispano HEI shell (plus the LW`s explosives were somewhat more potent than the RAF`s choice).. you have very high advantage on the Mauser`s side on Chemical Energy, and it most likely translates to greater overall energy.
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Kurfürst, looking at the section of a mine round, it really dont have anyway to produce destructive metal fragments, it has a very very thin metal cover. HE rounds are really different in design. Both are different rounds for different purposes.
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You are right in that the material immidiately surrounding the explosive filler is very thin, so the fragments will be of very small size, but numerous. Exploding next to the pilot, cables, fuel/coolant/electric lines, they still cause damage to them. IMHO it`s not OK to think mines don`t produce fragments at all.
There`s a lot more though in the base and the head to form fragments from. Simple math tells us that substracting 18 gram explosive from the 92gram weight of the total body will still leave us 74 grams of potential fragments.
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Hi Mando,
>For example, if a mine explodes near a fuel tank, the fuel tank may end fully deformed. The same case with HE will result in a perforated fuel tank.
Well, the fragments from a 20 mm shell are very small, and self-sealing tanks are capable of sealing rifle-calibre sized leaks quite well, so that's not a case for HE over mines.
Mine shells had some fragmentation effect as well, but the main energy went into the blast, not into the fragments. 20 mm HE fragments probably were fewer but larger, but could only damage the highest-vulnerability components, such as control wires or hydraulic or fuel lines, or harm the crew.
Since the idea behind the mine shell was to avoid the necessity of having to aim for the few vulnerable components by damaging the structure itself, the benefit of the trade-off was highly favourable for the mine shells.
Regards,
Henning (HoHun)
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Came to think of this thread since I was calibrating my rifle telescope ;)
Just HE's with very thin skin will do a lot of damage under some angles, or just not.
Vice versa with the AP.
I shoot a bull with a metal cased bullet, while I use a hollow point for birds, if you see what I mean.
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Originally posted by Angus
How is the ballistic of the mineshell. Same?
Oh, and for your info (you probably already know?), some Spittys had the late Orlikon cannon.
Pilots were highly impressed with it. Just a couple of hits...
??? RAF planes never carried any 20mm cannon except Hispanos, and Spitfires never carried any other cannon of any calibre that I'm aware.
Well, all right, the F4 Phantom II had a 20mm M61 gunpod but that's a bit out of our timeframe :)
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by Charge
"The Hispano 20mm HE round had 8% HE by weight (per Tony Williams website), the MG151 HE had 3.2%, the API had 3.1%, and the Mine round had 22%."
"You've got to draw a line somewhere :-) "
Well if you don't and calculate 151/20 power by using the correct power output of Mine with PETN what would be the result for 151/20?
PETN by itself was too sensitive to be used in ammo - it was likely to detonate when you didn't want it to. Well, the Japanese used it, but then...:rolleyes:
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by Angus
Why stop at two?
Good question.
Reliability? AP desire for things like fuel tanks and armour?
Don't really know.
Hope Tony pops in and informs us.
I've popped.
Basically, the ideal aircraft projectile would penetrate deeply through any armour, have a huge blast effect, and also throw incendiary material around all over the place. You can only achieve this in one shell by going to a very large calibre, so the 20mm rounds had to specialise in one or two elements.
The belt mix was an attempt to achieve all of the above effects but it wasn't an exact science as there was a lot of luck involved. It worked fine if your AP projectile happened to strike the armour and the HE hit a fuel tank, but it wasn't much good the other way around...
Incidentally, the main reason for the Germans retaining the old HE-T design was that the 20mm mine shell couldn't take a tracer.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by Kurfürst
Both mine and ordinary HE produces fragments, but these fragments when speaking of 20mm shells are tiny and very weak. I have detailed report on the german MG C30 20mm cannon, a far more powerful weapon than either the Hissy or the Mauser. One would expect bigger fragments from it, but even that 20mm gun`s fragments stopped after piercing a few layers of very thin dural plates.
The HE shell for the C30 was similar in size to the Hisso's so the effect should be comparable. Striking velocity makes no difference to fragmentation.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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(http://www.geocities.com/Pentagon/Base/1852/MG151-20.jpg)
Left is a Mg151/20 mine HEI-SD. As you can see, most of these grams corresponds to the fuze. HE rounds (not the one at the right) have much more metal around the explosive.
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http://www.munavia-21.org/20x81mauser151.htm
Great site here
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Very interesting site Wotan.
There are two mine rounds listed, one is the 92g mine for 151/20 or MG-FF (18.6g Nitropentane), and the other is a mine ONLY for 151/20 with 25g HA41 of a total of 105g.
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Originally posted by Tony Williams
PETN by itself was too sensitive to be used in ammo - it was likely to detonate when you didn't want it to. Well, the Japanese used it, but then...:rolleyes:
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
Tony, the datasheet of the MG151/20`s munitions says 18.6 gram of Nitropenta for the M-Geschoss, 2.3 gram Nitropenta + 2.1 gram electrothermite for the HEIT shell.
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Hi Mando,
>There are two mine rounds listed, one is the 92g mine for 151/20 or MG-FF (18.6g Nitropentane), and the other is a mine ONLY for 151/20 with 25g HA41 of a total of 105g.
Thanks, that's quite interesting. My calculations of the MG 151/20 firepower were based on Tony's numbers so far which gave 20.24 g of explosive for the 92 g shell.
This is the old mine shell:
http://www.munavia-21.org/p008.jpg
This is the new one:
http://www.munavia-21.org/qmx0010.jpg
So the claimed 40% increased desctructiveness was not by use of a more powerful explosive alone, but also by increasing the explosive content by 30% :-)
Here's the MG 151/20 vs. Hispano comparison again, based on the new mine shell projectile and a standard energy content for all chemicals:
MG 151/20: 2,08 MW (pure mines)
MG 151/20: 1,49 MW (1:1:3)
MG 151/20: 1,34 MW (1:1:2)
MG 151/20: 1,10 MW (1:1:1)
Hispano II: 1,06 MW (1:1)
Regards,
Henning (HoHun)
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Originally posted by HoHun
So the claimed 40% increased desctructiveness was not by use of a more powerful explosive alone, but also by increasing the explosive content by 30% :-)
So, is it your oppinion that HA41 only added 10% destructiveness over Nitropenta?
HA41 is 80% RDX (Hexogen) + 20% aluminium powder.
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Originally posted by Kurfürst
Tony, the datasheet of the MG151/20`s munitions says 18.6 gram of Nitropenta for the M-Geschoss, 2.3 gram Nitropenta + 2.1 gram electrothermite for the HEIT shell.
Nitropenta was not pure PETN; it was mixed with 15% Montan wax to desensitise it.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by MANDO
There are two mine rounds listed, one is the 92g mine for 151/20 or MG-FF (18.6g Nitropentane), and the other is a mine ONLY for 151/20 with 25g HA41 of a total of 105g.
This was the MX-Geschoss, a very late-war development. There's a photo of a sectioned MX next to a sectioned M round in 'Flying Guns: World War 2'. You can see how much further the shell penetrates into the case, so there's less room for propellant. This reduced the muzzle velocity to 640 m/s.
Even more interesting was the 20mm M.44 incendiary fitted with a hydrostatic fuze. It resembled the M-Geschoss and had a similar chemical capacity, but weighed more at 117g because it had thicker walls to strengthen the shell to penetrate deeply into fuel tanks. The hydrostatic fuze was then detonated by exposure to the liquid, a bit like a depth charge. Worked very well against bombers, apparently, but again it came very late.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Originally posted by MANDO
So, is it your oppinion that HA41 only added 10% destructiveness over Nitropenta?
HA41 is 80% RDX (Hexogen) + 20% aluminium powder.
A quote from 'Flying Guns: WW2':
"The types of high explosive chemicals used in shells did vary, although not by as much as might be thought, as different names were used for similar substances. The basic HE in general use was TNT, as used in the Great War. This was often mixed with ammonium nitrate to create Amatol; cheaper but just as effective, except for increased susceptibility to damp. Some use was also made of picric acid, or Lyddite, another First World War explosive.
Before the Second World War, more powerful substances were introduced into service. One of these was PETN, also known as Penta or Penthrite. The problem was that this was generally felt to be too sensitive to use by itself, as it was inclined to be detonated by the shock of firing (although this did not deter the Japanese, as we have seen). It was accordingly usually desensitised by adding about 15% of Montan wax to produce Penthrite Wax, or Nitropenta. An alternative use was to mix PETN with TNT or Amatol to form one of the Pentolites; this actually helped with pouring TNT and Amatol into shells, as by themselves they solidified too quickly and tended to leave holes. Another new explosive, as powerful as PETN but less sensitive, was RDX (Research Department eXplosive), which was also known as Cyclonite or Hexogen.
Aluminium powder was often added to HE, as this both increased the brisance (shattering effect) and enhanced the incendiary effect; an important issue as, for example, some 90% of RAF bomber losses in the war were attributed to fire rather than structural damage. A typical German HEI mix was 63% Penthrite, 29% aluminium and 8% wax, although these proportions did vary. Shell fillings for the 30 mm M-Geschoss typically consisted of 75% Hexogen, 20% aluminium and 5% wax. The (rarely used) M-Geschoss for the BK 3.7 contained a mix of 45% Hexogen, 40% TNT and 15% aluminium. Much use was made of HA.41, a mixture of 80% Cyclonite and 20% aluminium.
Allied explosive fillings included Pentolite, Torpex (a mixture of RDX, TNT and aluminium) and Tetryl or CE (Composition Exploding). The Japanese used several types, with TNT, Pentolite and Cyclonite all being recorded, by themselves or in various combinations. The Soviets used a mixture of RDX and aluminium.
These explosives exhibited some differences in the characteristics, as shown below. The most powerful have not been much exceeded in destructive power since."
There follows a chart showing the various characteristics of the common HE types. RDX/Cyclonite/Hexogen was about 60% more powerful than TNT and slightly more powerful than pure PETN.
Tony Williams: Military gun and ammunition website (http://www.quarry.nildram.co.uk) and Discussion forum (http://forums.delphiforums.com/autogun/messages/)
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Hi Mando,
>So, is it your oppinion that HA41 only added 10% destructiveness over Nitropenta?
Well, that would be the logical conclusion from the claim +40% destructiveness and the observation +30% charge mass. I have no personal opinion in that matter though.
Regards,
Henning (HoHun)
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Hi Tony,
>RDX/Cyclonite/Hexogen was about 60% more powerful than TNT and slightly more powerful than pure PETN.
Thanks, that seems to confirm the information we have on the MX shell.
Correcting to the lower muzzle velocity you provided, I get the following comparison (slightly expanded):
MG 151/20 (MX): 1,4 MW (1:1:3 MX belting)
MG 151/20: 1,27 MW (1:1:3 Mine belting)
Hispano V: 1,23 MW (1:1 belting)
Hispano II: 1,06 MW (1:1 belting)
MG-FF: 0,78 MW (1:1:3 Mine belting)
.50 Browning M2: 0,28 MW (pure API)
Regards,
Henning (HoHun)
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What is the distance in your calculations HoHun? Do your calculations show the values at 0 yds ie. the power with the initial muzzle velocity?
-C+
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learn some new things reading the replys guys, thanks! :)
but that doesnt explain why the hispano cannon is vastly superior to the Mg151\20 cannon, on the contrary it just arise more questions.
i hope HTC will look it up
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"why the hispano cannon is vastly superior to the Mg151\20 cannon,"
Maybe because it is more easy to comprehend how kinetic energy that a "ball" round has affects the structures it hits? The chemical energy is a bit more complicated in that sense, but if you keep it simple the chemical energy is easier as its damage remains relatively constant despite the round velocity and there is no need to consider airspeed differences and impact velocities when the damage is calculated.
It gets hairy when you need to decide how much effective mass the HE round has after detonation. So would it be fair to calculate only the chemical energy for the His and Maus HE rounds? Probably not , but that is one approach. That would make the Mauser to gain considerably in power by the use of M-schoss.
Dunno how HTC has modelled those weapons, though...
-C+
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Originally posted by Flyboy
but that doesnt explain why the hispano cannon is vastly superior to the Mg151\20 cannon
I would say it was clearly the opposite.
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I think he meant in AH, Mandoble.
I'd agree with him, by the way, but it is clearly explained by the way the ammunition is modelled.
At least relatively clearly... my first post in the thread details how it is modelled, to the best of my knowledge.
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Its simple.
Here's my hypothesis:
In AH impact velocity is more important then chemical energy.
The Hispano 'hits harder' (retains velocity at greater range) then the mg151 or mgff. Because mg151 and mgff have a lower mv and lose energy faster their potential damage falls off with range. Test the mgff at sat 200 yards then at 250 then at 300 for example.
Chemical energy makes up a smaller portion of the damage 'value' (correct word...?).
Il2 is having similair issues, so has wbs.
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AH? Well, IMO, in general, the main problem is the structural damage of AP rounds. Here, a P51 can cut a Lancaster wing with a single long burst, or even cut the lancaster in half. With the example of P51 50s (AP only), just imagine what hipanos can do.
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What you have is a lot of high velocity HMG rounds hitting the wings accumulating damage. After so many hit the wing falls off. They are no wing spars or cables to be cut through etc...
Its the same reason why you fly at high speed and get hit by the bomber defensive guns and very few hits kill you.
You high speed + the velocity of the 50s coming at you = greater impact velocity ir greater damge.
We tested this somewhat for the first BoB event. We had our ju88s slow down so that the attackers closure rate was as fast as possible when they dove from high 6. This increased the effectiveness of the ju88s guns and as such the ju88s had more kills and a higher k/d the any other aircraft.
Of course the ju88s were being shot at by 303s and you wont get the same results in a b24 when attcked by 3cm.
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Hi Charge,
>What is the distance in your calculations HoHun? Do your calculations show the values at 0 yds ie. the power with the initial muzzle velocity?
Roger that. However, if you figure in speed loss while the projectile is going downrange, the balance hardly changes.
Assumptions: Hispano rounds down to 500 m/s velocity, German rounds (1:1:3 mine shell belting) down to 300 m/s (subsonic!). That's pretty far down the range, and though I have no idea on whether the two points coincede, I consider these assumptions pessimistic for the German cannon.
MG 151/20 (MX): 1,16 MW (300 m/s)
MG 151/20: 0,97 MW (300 m/s)
Hispano V: 0,89 MW (500 m/s)
Hispano II: 0,74 MW (500 m/s)
MG-FF: 0,64 MW (300 m/s)
The results have not changed much - while the German shells have retained less speed than the Hispano projectiles, kinetic energy is only the smaller contributor to total energy, so it doesn't matter much.
The MG 151/20 with standard mine shells at subsonic speed is still within 10% of the Hispano II at full muzzle velocity.
Regards,
Henning (HoHun)
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Table from Luftwaffe Shooting guide, the Schiessfibel (http://rafiger.de/Homepage/Pages/Schiessfibel.html)
Sprenggranate= HE shell
Brandgranate= Incendiary shell
Panzersprenggranate= Armor-Piercing Explosive shell
Panzerbrandgranate= Armor-Piercing Incendiary shell
Panzergranate= Armor-Piercing shell
Durchschlagsleistung= Penetration power
Sprengwirkung = Explosive effect
Brandwirkung= Incendiary effect
Keine =None
Gering= Small
Mittelmassig= Average
Gut = Good
Sehr Gut = Excellent
(http://img.photobucket.com/albums/v424/timppa/Muni1.jpg) (http://img.photobucket.com/albums/v424/timppa/Muni2.jpg)
MG151/20 belting for missions against heavy bombers:
1 Mine+ 1 Incendiary+1 API
Against other planes:
3 Mines+1 Incendiary+ 1 API
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Hi Timras,
>MG151/20 belting for missions against heavy bombers:
>1 Mine+ 1 Incendiary+1 API
>Against other planes:
>3 Mines+1 Incendiary+ 1 API
Thanks a lot, that sort of confirms my assumptions about belting!
Page 14 also re-inforces I point I've made in some other threads: Dispersion doesn't help you. The Schießfibel:
"Accordingly [referring to example illustrations for faulty deflection shooting], don't rely on weapon dispersion - it won't help you if your aim is flawed! You can see here clearly how ACCURATELY you have to know and to apply deflection, or your fire will miss. But if you think now that you could simply adjust your MGs for a larger pattern to hit more reliably, then you're making a mistake. Your experience will be similar to that of the wild hunter in the picture on the right."
The latter advice is repeated on page 28:
"Another thing: Please don't invent new harmonization patterns, for example by adjusting the trajectory cross-over 100 m out etc. The ordered harmonization has been carefully devised by combat veterans and is good."
Regards,
Henning (HoHun)