Author Topic: 50. Vs. Cannons (Read 8290 times)

Meyer · « **Reply #30 on:** July 08, 2007, 12:01:08 AM »

Quote

Originally posted by Gibbage
On what mount? A fixed test bed, or a 5000lb aluminum frame held aloft in air? Look at the factors of the gun. Recoil operate, short berral, low velocity, light weight shell mounted in light fighters. Nothing there speaks of accuracy in everything I know of gunnery. Whats its MIL rating? And please make sure of the mount. Alot of pilots spoke of the Mk-108 as not being very accurate, and hated it for the recoil.

I would think you did read this thread, since you posted in it WW 2 weapons Dispersion

Gibbage · « **Reply #31 on:** July 08, 2007, 01:35:05 PM »

That thread was back in 2004, and the data source was not given. Also, please note the distance the Luftwaffe used was 100M. Thats a very short distance, and we are speaking of 650M. The Mk-108 fired Minegros shells. A light, and very thin walled explosive shell. This shell was fired at a relitivly low velocity. That means air currents will play havoc on the shells after 100M and it will loose KE very fast. Besides, how many Luftwaffe pilots got within 100M of a B-17 before taking the shot?

Waffle · « **Reply #32 on:** July 08, 2007, 03:52:39 PM »

Curiosity question...

How much play was in the mk108 mount to allow it to pitch up / down for vertical harmonization if it was mounted through the engine /prop shaft / hub on 109s?

64kills · « **Reply #33 on:** July 08, 2007, 03:54:19 PM »

screw all that stuff 50 are the best they are more accurate and the do more damage

Viking · « **Reply #34 on:** July 08, 2007, 04:45:06 PM »

Quote

Originally posted by Gibbage
That thread was back in 2004, and the data source was not given. Also, please note the distance the Luftwaffe used was 100M. Thats a very short distance, and we are speaking of 650M. The Mk-108 fired Minegros shells. A light, and very thin walled explosive shell. This shell was fired at a relitivly low velocity. That means air currents will play havoc on the shells after 100M and it will loose KE very fast. Besides, how many Luftwaffe pilots got within 100M of a B-17 before taking the shot?

First of all, learn how to spell or use a spellchecker; reading your posts is painful. Secondly, the Luftwaffe opened fire at about 400 metres (when the bomber fit into the gun sight from wingtip to wingtip). Third, the Mk 108 could fire many different types of rounds; none of them were “light” by any definition of the word. The Mk 108 round used in fact the same projectiles as the bigger Mk 101 and 103 cannon; only the cartridge was cut down. The HE(M) Minengeschoss (not “Minegros” you dolt!) projectile weighed 330 grams; compared to the 130 gram 20 mm projectile of the Hispano II cannon it was not “light” by any standard.

Gibbage · « **Reply #35 on:** July 08, 2007, 04:54:43 PM »

Quote

Originally posted by Waffle
Curiosity question...

How much play was in the mk108 mount to allow it to pitch up / down for vertical harmonization if it was mounted through the engine /prop shaft / hub on 109s?

That is a very good question! In all honesty, with the lob factor of the Mk-108, I REALLY dont thing it could be verticaly harmonized to 650M! It was mounted behind the engine, and the reciever was between the pilots legs. It had a blast tude that ran between the cylinder heads of the DB engine, and through the prop hub. If it was harmonized too 650M, it would need to blast right out the top of the coweling!!! Again, we are dealing with a large, light weight, now velocity grenade round that had a great deal of drop. A US prototype aircraft, the P-54, used a moveable nose section to compensate for the drop of its 37MM, and even it had a higher MV then the Mk-108.

Gibbage · « **Reply #36 on:** July 08, 2007, 05:09:04 PM »

Quote

Originally posted by Viking
First of all, learn how to spell or use a spellchecker; reading your posts is painful. Secondly, the Luftwaffe opened fire at about 400 metres (when the bomber fit into the gun sight from wingtip to wingtip). Third, the Mk 108 could fire many different types of rounds; none of them were “light” by any definition of the word. The Mk 108 round used in fact the same projectiles as the bigger Mk 101 and 103 cannon; only the cartridge was cut down. The HE(M) Minengeschoss (not “Minegros” you dolt!) projectile weighed 330 grams; compared to the 130 gram 20 mm projectile of the Hispano II cannon it was not “light” by any standard.

There is no reason what-so-ever to resort too insults here. I was hoping this forum was more friendly then some of the others I visit. Yes, I do have a spelling problem, but you seem to be able to read just fine and get the point of my post.

The only shells used in Mk-108's were MG shells (Info from Tony Williams of "Flying guns of WWII"). They were thin walled and filled with explosives. Making them far less dense then an AP shell or a normal HE shell. Thats why im saying they were light. Please compare a 30MM MG shell with a normal 30MM HE or AP round and you will see what I mean. Those are around 500G+, so yes, the MG shells are light for 30MM shells. Were do you get your info that they also fired the the same rounds from the Mk-103 and 101?

Lusche · « **Reply #37 on:** July 08, 2007, 05:09:42 PM »

Quote

Originally posted by Gibbage
The Mk-108 fired Minegros shells. A light, and very thin walled explosive shell. This shell was fired at a relitivly low velocity. That means air currents will play havoc on the shells after 100M and it will loose KE very fast. Besides, how many Luftwaffe pilots got within 100M of a B-17 before taking the shot?

Aaaargh.. I won't comment further on "Minegros"

While the thin walled "Minengeschoss" round was considered light, it's only lighter in comparison to some other 30mm round. Actually it was no light round at all, having still a tremendous sectional density.

Concerning to the "will loose KE very fast" look at the two tables. First shows the 20mm MG 151/20, the second one the MK 108. Both rounds are comparable "Minengeschosse". The last colummn shows the remaining KE. After 700m, the MK108 round has dropped to 50% of its original KE, while the 20mm round has dropped to a mere 12%. You can clearly see that the 108 round retains its energy much better at long ranges. At mentioned 700mm the 108 rounds has a much higher speed than the 151 round.

So while being far from supreme and noticeably worse than contemporary 20mm guns, the MK108's ballistics are not that bad as it is generally believed.

Viking · « **Reply #38 on:** July 08, 2007, 05:15:37 PM »

And comparing the 1,770 fps muzzle velocity of the Mk 108 to that of a grenade launcher is just inane. A M203 grenade launcher has a typical muzzle velocity of 250 fps. The Mk 108 is much closer to the M1 Carbine rifle in terms of muzzle velocity, and at the muzzle it has 23 times the kinetic energy of the .50 cal.

Gibbage · « **Reply #39 on:** July 08, 2007, 05:17:21 PM »

Quote

Originally posted by Lusche
Aaaargh.. I won't comment further on "Minegros"

While the thin walled "Minengeschoss" round was considered light, it's only lighter in comparison to some other 30mm round. Actually it was no light round at all, having still a tremendous sectional density.

Concerning to the "will loose KE very fast" look at the two tables. First shows the 20mm MG 151/20, the second one the MK 108. Both rounds are comparable "Minengeschosse". The last colummn shows the remaining KE. After 700m, the MK108 round has dropped to 50% of its original KE, while the 20mm round has dropped to a mere 12%. You can clearly see that the 108 round retains its energy much better at long ranges. At mentioned 700mm the 108 rounds has a much higher speed than the 151 round

Sorry for my bad German, but its not my native language. Im sure you would excuse a German poster for his bad english. Please extend the same courtesy for me, but again you seem to understand what I was trying to say.

Now, you say at 700M, the Mk-108 looses 50% of its KE, but the MG-151/20 only looses 12%. That seems to illustrate my point perfectly, not dispute it! I said the Mk-108 shell looses KE fast. It seems this document you posted agrees with me, but you dont for some reason. Can you explain that?

Lusche · « **Reply #40 on:** July 08, 2007, 05:34:49 PM »

Quote

Originally posted by Gibbage

Now, you say at 700M, the Mk-108 looses 50% of its KE, but the MG-151/20 only looses 12%.

No I did not say that.
I did say that the MK 108 KE has dropped to 50%, the MG 151 KE has dropped to 12%
12% is actually a lot less than 50%, so the 108 has retained more of it's energy.

Sikboy · « **Reply #41 on:** July 08, 2007, 05:39:27 PM »

Cannons pwn MGs, but not just any cannon... must be a 37mm hammergun!

A real man uses a Nudelman. Jus' Sayin'

-Sik

Viking · « **Reply #42 on:** July 08, 2007, 05:41:40 PM »

Quote

Originally posted by Gibbage
There is no reason what-so-ever to resort too insults here. I was hoping this forum was more friendly then some of the others I visit. Yes, I do have a spelling problem, but you seem to be able to read just fine and get the point of my post.

If you know you have a spelling problem then not using a spellchecker (copy and paste from MS Word or some other word processor) is rude. It doesn’t take a lot of effort and if you’re unwilling to show other posters even that minimum amount of respect then why should we afford you any?

Quote

Originally posted by Gibbage
The only shells used in Mk-108's were MG shells (Info from Tony Williams of "Flying guns of WWII"). They were thin walled and filled with explosives. Making them far less dense then an AP shell or a normal HE shell. Thats why im saying they were light. Please compare a 30MM MG shell with a normal 30MM HE or AP round and you will see what I mean. Those are around 500G+, so yes, the MG shells are light for 30MM shells. Were do you get your info that they also fired the the same rounds from the Mk-103 and 101?

Type A 3 cm Minengeschoss Übung ohne Zerleger

Type B 3 cm Minengeschoss Übung ohne Zerleger

3 cm Sprenggranate Übung ohne Zerleger

3 cm Panzersprenggranate Leuchtspur Übung ohne Zerleger

3 cm Hochgeschwindigheit Panzersprenggranate Leuchtspur Übung ohne Zerleger

3 cm Sprenggranate Übung ohne Zerleger

3 cm Minengeschoss Übung Ausführung A ohne Zerleger

3 cm Minengeschoss 108 Ausführung A mit Zerleger

3 cm Minenbrenngranate 108 mit Zerleger

Gibbage · « **Reply #43 on:** July 08, 2007, 05:41:41 PM »

Bofors 40MM = 881M/s
T9 37MM = 661M/s
NS-23 23MM = 690M/s
NS-37 37MM = 880M/s
ShVAK 20MM = 770M/s
MG151/20 20MM = 800M/s
Mk-101 30MM = 960M/s
Mk-103 30MM = 860M/s
Mk-108 30MM = 540M/s

Now, compared too ALL of those guns, the Mk-108 has a very low MV. Almost HALF of some others like the Mk-101. Even the T9 (M4) used in the P-39 that was described as "Lobbing a watermellon with a flare" when he spoke of firing the 37MM, and it sitll had a higher MV then the Mk-108. Thats why I described it as like a grenade launcher. Its ammo, thin walled explosive shells were more like grenades then shells, and the MV caused a high firing arc, like a grenade launcher.

Viking · « **Reply #44 on:** July 08, 2007, 05:42:35 PM »

Continued:

3 cm Minengeschoss ohne Zerleger

3 cm Brenngranate ohne Zerleger

3 cm Minengeschoss Leuchtspur mit Zerleger (day tracer) / 3 cm Minengeschoss Glimmspur mit Zerleger (night tracer)

3 cm Minengeschoss Leuchtspur Übung ohne Zerleger

http://www.xs4all.nl/~robdebie/me163/weapons15.htm