DaveB.inVa
Airman 1st Class
- 225
- Dec 20, 2004
Good Lord man I didnt say it was perfect!!! If its that damn bad I can delete it. I swear I knew just as soon as I posted it somebody would pick on the friggn flat 50 caliber "curve".
The Best Single Air-to-Air Weapon of the War?
- Thread starter cheddar cheese
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Anonymous
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DaveB.inVa said:
I didn't say that, I was just pointing out that it relates to the Hispano II and is not represenative of most 20mm cannon, and particularly the MG151/20.
KraziKanuK
Banned
- 792
- Jan 26, 2005
Worth reading, WORLD WAR 2 FIGHTER ARMAMENT EFFECTIVENESS
http://www.quarry.nildram.co.uk/WW2guneffect.htm
http://www.quarry.nildram.co.uk/WW2guneffect.htm
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Anonymous
Guest
KraziKanuK said:
Tony's evaluation takes into account factors such as gun weight, which are not really relevant to overall "effectiveness". Each side had what guns they had, and the weapons systems were part of the overall aircraft design. It is really a gun "efficiency" evaluation, as opposed to a weapons systems effectiveness evaluation. Furthermore, little account of the ballistic quality is considered. Finally, Tony has somewhat abitrarily chosen to use momentum as opposed to kinetic energy as a measure of impact damage. While there is some merit to this, it is a very arguable point and I feel that something about halfway between the two measurements is a more accurate evaluation.
Even so, Tony points out that in the end the Hispano 20mm was about equally damaging as compared to the MG151/20 mine round. What he does not emphasise is the much superior ballistics of the Hispano, which implies more hits, especially as range increases.
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Lunatic
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Anonymous
Guest
Grampa said:
Figures I have differ from those you list, which are 905 m/s (at the muzzel) which makes it about equal to the .50 API round (890 m/s at 78 feet) and Hispano II HE/I round, and an ROF of 500 rpm. The performance looks very good, but like the MK103 this is a big gun with a lot of recoil energy - making it more suitable for ground attack where very short bursts of fire were sufficient and aircraft were generally bigger/heavier. The Hispano was really too big a gun for the Spitfire (they barely were able to make it work), the VYa had twice the recoil energy of the Hispano!
For Air-to-Air combat, especially against fighters, the B20 looks very good to me. Figures vary on the performance of various rounds, but the most detailed account I have found gives the following ammo types:
Code:
USSR Designation Bullet Weight [g] Description
| US Abbreviation | Muzzle Vel. [m/s] |
| | | | |
OZ HEI 75,3 770 Nose fuze, 2,8g HE + 3,3g incediary
OZT HEI-T 75,8 770 Nose fuze, 2,8g HE + 3,3g incediary, tracer
OF HE-Frag. 67,6 790 Nose fuze, 6,7g HE, fragmentation grooves on shell
OFZ HEI-Frag. 68,3 790 Nose fuze, 0,8g HE + 3,8g incediary, fragmentation
grooves on shell
BZ API-HC 96,0 750 Mild steel projectile case with hardened steel core,
surrounded by 2,5g incendiary, screwed on
aluminum, or bakelite ballistic cap. A 3rd
type with swaged steel cap exists as well.
BZ API 96,0 750 Solid steel shot with incendiary in swaged steel cap
BZT API-T 96,0 750 As above but with tracer in base cavity
PU TP 68,3 790 Inert filled HEI shell with dummy fuze
PUT TP-T 68,0 790 Empty solid head projectile with swaged tracer in
base cavityThe above velocity figures are for the short barreled (1245 mm) ShVAK. Figures would be higher for the long barreled (1700 mm) engine version of the ShVAK and somewhere in-between for the B20. The B20 weighed only 25 kg. and fired at approximately 800 rpm. Ammo fit in the same belt links as the 12.7 mm ammo of the Brezin UB from which the B20 was derived.
Note: As can be seen above the weight of HE rounds is considerably less than that of AP type rounds. As with most WWII guns, you will commonly see the heavier AP type round weights associated with the lighter HE type round velocities, which is of course incorrect. The Hispano is one of the very few guns for which most types of ammo were balanced to about the same 129 gram projectile weight.
Because of its light weight and high RoF, I think the B20 was probably the best air-to-air gun of WWII, if we are looking at the guns alone and not at the planes as an overall weapons system. Certainly a P-47 or Tempest with 8-10 B20's would have had totally devestating firepower against any type of aerial target!
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Lunatic
CharlesBronson
Senior Master Sergeant
Lunatic: Your last 4 post are the kind I like to read.
I agree completely in the issue of ballistic curves. But remenber that Mauser designers was limitated by overall length of cartrigde that should be the same as 15 mm gun.
I think that requeriment was caused by the continuos delays in the production, for example a prototipe was installed in the nose of Do-17e in 1938 for ground strafing in Spain, but in early 1941 was only a few of these in service.
Anyway the mine shell have a initial speed of 785 meters second and carry a lot of high explosives, more than Hispano 20 mm shell.
His only real defect was his nill anti-armour capabilities even in thin plates.
And yes I do some skeet ,but I like more Hunting, Partrigdes and rabbits wich a plague around here.
I agree completely in the issue of ballistic curves. But remenber that Mauser designers was limitated by overall length of cartrigde that should be the same as 15 mm gun.
I think that requeriment was caused by the continuos delays in the production, for example a prototipe was installed in the nose of Do-17e in 1938 for ground strafing in Spain, but in early 1941 was only a few of these in service.
Anyway the mine shell have a initial speed of 785 meters second and carry a lot of high explosives, more than Hispano 20 mm shell.
His only real defect was his nill anti-armour capabilities even in thin plates.
And yes I do some skeet ,but I like more Hunting, Partrigdes and rabbits wich a plague around here.
NightHawk
Senior Airman
Yes, the Me-262a-a1\U4 Pulkzersturer(bomber formation destroyer),Carried a long barreled 50mm cannon, this big gun protruded 7 feet ahead of the nose and slowed the aircraft by 15 mph,But provided sufficient punch to destroy any air or ground target it coult hit.evangilder said:
The 262 could carry about 50 rounds for it,I think....
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Anonymous
Guest
CharlesBronson said:
Thank you
I will be redoing my guns and ballistics pages into a single page sometime soon and reposting them. If you'd maybe like to help in this endevour let me know. Running the ballistics software is a nightmare so I probably won't add any new guns to that analysis. You can see the relevant table at http://members.cox.net/rg_lunatic/gunpage/. This is actually an incomplete page, I lost a hard drive sometime back and could only recover this preliminary version, which I posted for access to the tables. Note also that the ShVAK comments at the end were made in ignorance of the larger 1700 mm barrel of the ShVAK engine cannon, which would improve velocity and range.
CharlesBronson said:
It was more than just the length of the cartridge. In order to use the same basic gun with a larger projectile, the velocity must be reduced. The overall energy to run the gun must be approximately the same, or the gun must be re-designed which the German's did not want to do. They simply necked up the cartridge to 20mm and replaced the barrel such that the operational energy was correct.
CharlesBronson said:
I've seen lots of conflicting data on the MG151/20 mine rounds. But the most compelling is that from RML tests, which indicate a weight of 92 grams and typical muzzel velocity of about 765 m/s, with a max velocity of 785 m/s, and an HE/I payload of 16 grams of high explosives and 2.5 grams of electron incendiary metal.
One big issue with the mine rounds had to be round integrity. Delay the fuse timing so the round would penetrate meant the round would indeed penetrate further before detonation. But in so doing the round would have to pass through the aircraft skin and possibly contact structure or armor. Because the round walls are so thin they would be subject to destruction and once the HE is seperated from the fuse it will not detonate. For this reason, I believe the mine rounds were probably not genrally setup with delayed action fuses (such as those used on the Hispano and German non-mine type rounds). I've not been able to find any info indicating that mine rounds were setup with delayed action fuses which seems to confirm this belief. The end result is that the MG151/20 round would tend to do most of its damage to the surface of the target. The core explosion area is about the size of a baseball, and it must recruit mass from the target as it does not carry much of its own (like the Hispano), and the mass it is likely to recruit is aluminum - a poor sharpnel. On the 30mm mine rounds, the core of the explosion is more that of a 10-inch softball, and this is enough to reach pretty deeply into a target and do substantial damage even on a surface detonation. For these reasons I think the Germans generally found their theory behind the mine round somewhat flawed w.r.t. 20mm ammunition, but valid for 30 mm ammunition.
Note: the core of an HE (such as RDX) explosion involves supersonic expansion of approximately 1000x. This means that a sugar cube sized piece of HE would expand to about the size of a 10x10x10 block of sugar cubes. Beyond this there is a shock wave through the air (much more significant at low altitude than high altitude) and possibly through the targets structure. In the right circumstances you can also achieve a "confined space" effect which can blow apart the container if sufficient energy is involved for the size of the space.
The Hispano carried about 11.5 grams of HE/I composition, but weighed ~129.5 grams and had an initial velocity of ~890 m/s. It was a significantly bigger round with signficantly higher initial velocity. Furthermore, it had superior ballistic shape (the MG151/20 mine round has a very flat nose) and about a 30% higher sectional density, resulting in much better long range performance. On the downside, the gun was so powerful that unless very firmly mounted (such as in the Typhoon, Tempest, or especially in the P-38) the cone of fire was relatively large.
CharlesBronson said:
Yes but skeet shooting experiance with a variety of shot will give the feel for what I'm talking about. Small shot will slow down much faster than large shot, requiring the shooter to lead more than proportionally to the range. With small shot, double the range you may have to lead 3x as much, and at double that range (i.e. 4x) you may have to lead 10x as much to hit the pidgeon. It is hard to make such a calculation in your head. With larger shot, which has a higher sectional density (frontal cross-section area increases as the square of the diameter where weight increases as the cube) and thus superior ballistic performance, the lead becomes more proportional to the distance and so the lead relationship becomes more linear and is much easier to deal with.
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Lunatic
- Thread starter
- #32
cheddar cheese
Major General
NightHawk said:
It sure did, great weapon 8)
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Anonymous
Guest
What I remember of the BK 50 was that it was mandated by Hitler who believed such a "standoff" weapon would allow Luftwaffe' pilots to kill heavy bombers from a safe distance. In fact, it was nearly useless as the very low rate of fire made hitting even a strait flying B-17 next to impossible.
It was much more apporpriate as a anti-tank gun.
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Lunatic
It was much more apporpriate as a anti-tank gun.
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Lunatic
Erich
the old Sage
do a study for the Me 410A's with the Bk 5cm and you maybe surprised as to the bomber successes of the Geschwader ZG 26. Yes 1-2 hits was very destructive to the Allied bombers as well as 3.7cm's used by Bf 110G-2s of the Zerstorers.
The Mauser 50mm in the Me 262 never fired in anger. A sole Me 262 fitted with the unit (I have covered this elsewhere on this board) was flown only by JV 44 under Nachtjagd ace Willi Herget. Both missions in the spring of 45 against B-26 twin engines was failed to be executed as the Mauser cannon jammed............
v/r E ~
The Mauser 50mm in the Me 262 never fired in anger. A sole Me 262 fitted with the unit (I have covered this elsewhere on this board) was flown only by JV 44 under Nachtjagd ace Willi Herget. Both missions in the spring of 45 against B-26 twin engines was failed to be executed as the Mauser cannon jammed............
v/r E ~
mosquitoman
Master Sergeant
Lucky for the B-26s!
NightHawk
Senior Airman
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Anonymous
Guest
Erich said:
Can you document any cases of the BK50 actually hitting a flying target?
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Lunatic
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Anonymous
Guest
NightHawk said:
It would depend on where it hit and if the fuse was effective. Remember, approximately 1 in 4 rounds were duds. In general though, I'd say if it was not a dud and it hit a B-17 just about anywhere except the tip of a wing or fin, one round would have a very good chance of destroying the target.
However, I know of no documented cases of the BK50 being successfully used against flying targets. With an RoF of less than 1 round per second, it is effectively a semi-automatic weapon.
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Lunatic
Erich
the old Sage
as I said before have you delved in any German documentation on ZG 26 and 76 that used the Me 410 with the 5cm weapon. ther are several known fotos copyrighted that showing multi-kill rings on the barrel of the 5cm weapons as well as documented gun cam films. I know your next question and no I do not have the gun cams otherwise they would be posted here. I do have a gun cam film copyrighted (37mm) showing a Bf 110G-2 ripping the guts out of a B-24 from the rear at extremely long range.
It is obvious through photgraphic reference that the 5cm on the Me 410 had to be somewhat successful as there are multiple a/c with the weapon in staffel strength. personally I think as you believe it or not, that it was a fools weapon. the multiple useage of 6 2cm forward was much more effective and proved to be so under leadership such as Fritz Stehle in ZG 26 who scored a minumum of 7 US heavies with the Me 410 and there were a couple of others. I mention only a couple of others and many of the twin engine personell lost their lives due to .50's from P-51 escorts in 44.
The 5cm weapon on ZG 76 Me 410's actually did better ground attack work on the Ost front. Still a suicidal idea in my thoughts...
It is really of no help but I have all the losses records of both ZG 26 and 76 from the Freiburg archiv's.
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It is obvious through photgraphic reference that the 5cm on the Me 410 had to be somewhat successful as there are multiple a/c with the weapon in staffel strength. personally I think as you believe it or not, that it was a fools weapon. the multiple useage of 6 2cm forward was much more effective and proved to be so under leadership such as Fritz Stehle in ZG 26 who scored a minumum of 7 US heavies with the Me 410 and there were a couple of others. I mention only a couple of others and many of the twin engine personell lost their lives due to .50's from P-51 escorts in 44.
The 5cm weapon on ZG 76 Me 410's actually did better ground attack work on the Ost front. Still a suicidal idea in my thoughts...
It is really of no help but I have all the losses records of both ZG 26 and 76 from the Freiburg archiv's.
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