Author Topic: hispano vrs. Mg151  (Read 3039 times)

Offline MANDO

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hispano vrs. Mg151
« Reply #30 on: December 10, 2004, 07:48:55 PM »


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.

Offline Wotan

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hispano vrs. Mg151
« Reply #31 on: December 11, 2004, 02:36:05 AM »

Offline MANDO

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hispano vrs. Mg151
« Reply #32 on: December 11, 2004, 05:25:26 AM »
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.

Offline Kurfürst

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hispano vrs. Mg151
« Reply #33 on: December 11, 2004, 07:02:24 AM »
Quote
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 and Discussion forum



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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Offline HoHun

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hispano vrs. Mg151
« Reply #34 on: December 11, 2004, 09:31:31 AM »
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)

Offline MANDO

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hispano vrs. Mg151
« Reply #35 on: December 11, 2004, 12:42:35 PM »
Quote
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.

Offline Tony Williams

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hispano vrs. Mg151
« Reply #36 on: December 11, 2004, 02:50:46 PM »
Quote
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 and Discussion forum

Offline Tony Williams

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hispano vrs. Mg151
« Reply #37 on: December 11, 2004, 02:56:10 PM »
Quote
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 and Discussion forum

Offline Tony Williams

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hispano vrs. Mg151
« Reply #38 on: December 11, 2004, 03:01:11 PM »
Quote
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 and Discussion forum

Offline HoHun

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hispano vrs. Mg151
« Reply #39 on: December 11, 2004, 04:14:45 PM »
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)

Offline HoHun

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hispano vrs. Mg151
« Reply #40 on: December 11, 2004, 04:37:29 PM »
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)

Offline Charge

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hispano vrs. Mg151
« Reply #41 on: December 13, 2004, 04:24:57 AM »
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?

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Offline Flyboy

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hispano vrs. Mg151
« Reply #42 on: December 13, 2004, 06:34:26 AM »
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

Offline Charge

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« Reply #43 on: December 13, 2004, 07:09:04 AM »
"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...

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Offline MANDO

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hispano vrs. Mg151
« Reply #44 on: December 13, 2004, 11:33:32 AM »
Quote
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.