Author Topic: hispano vrs. Mg151 (Read 2877 times)

Flyboy · « **on:** December 06, 2004, 09:38:01 AM »

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 ?

Urchin · « **Reply #1 on:** December 06, 2004, 10:23:14 AM »

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

Zanth · « **Reply #2 on:** December 06, 2004, 11:38:57 AM »

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)

Flyboy · « **Reply #3 on:** December 06, 2004, 01:54:23 PM »

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

Meyer · « **Reply #4 on:** December 06, 2004, 02:51:47 PM »

http://www.geocities.com/CapeCanaveral/Hangar/8217/fgun/fgun-in.html

http://www.quarry.nildram.co.uk/WW2guneffect.htm

Urchin · « **Reply #5 on:** December 06, 2004, 03:12:16 PM »

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%.

HoHun · « **Reply #6 on:** December 06, 2004, 03:13:06 PM »

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)

bunch · « **Reply #7 on:** December 06, 2004, 07:34:25 PM »

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?

tikky · « **Reply #8 on:** December 06, 2004, 09:58:16 PM »

I head that Soviet pilots say that their ShVAKs are better than hispanos and Mg151. What makes Shvaks better than those 2?

Tony Williams · « **Reply #9 on:** December 07, 2004, 12:05:36 AM »

Quote

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 and Discussion forum

Charge · « **Reply #10 on:** December 10, 2004, 04:59:52 AM »

"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+

GScholz · « **Reply #11 on:** December 10, 2004, 08:59:45 AM »

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.

GScholz · « **Reply #12 on:** December 10, 2004, 09:05:51 AM »

Btw. Charge. Much if not most of the KE goes to waste unless the shell hits something capable of absorbing the energy.

Angus · « **Reply #13 on:** December 10, 2004, 09:10:22 AM »

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...

GScholz · « **Reply #14 on:** December 10, 2004, 09:17:51 AM »

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.