2 cm Flak 30, 38. WHY L/112,5??? CORRECT IS L/65!!!

Michi · Post by **Michi** » 15 Jan 2004 00:17

Can anybody share informations why on really lovely done homepages the caliber length of the 2 cm FlaK 30 and 2 cm FlaK 38 is often given with L/112,5??

The correct length of the 2 cm FlaK 30 and 2 cm FlaK 38 is L/65.
The correct length of the 2cm KwK 30 and 2cm KwK is L/50.

2 cm x 50 = 100 cm.
2 cm x 65 = 130 cm.
2 cm x 112,5 = 225 cm.

Did I miss something??

MfG Michi

Christian Ankerstjerne · Post by **Christian Ankerstjerne** » 15 Jan 2004 00:47

The 2cm. Fla.K. 38 L/112.5 did in deed have a barrel which was 225cm. long - just look at the barrel, it should be quite clear that it is more than two meters long...

Christian

Paul Lakowski · Post by **Paul Lakowski** » 15 Jan 2004 01:43

Christian Ankerstjerne wrote:The 2cm. Fla.K. 38 L/112.5 did in deed have a barrel which was 225cm. long - just look at the barrel, it should be quite clear that it is more than two meters long...

Christian

Yes its an AAA gun while the other examples are AFV weapons etc. Wonder how much difference doubling the barrel length did to the MV and accuracy?

Michi · Post by **Michi** » 15 Jan 2004 01:48

Die von der Firma Rheinmetall entwickelte 463 kg schwere 2 cm FlaK 30 besaß eine Rohrlänge von 1300 mm.

Source:
Hahn, Fritz: Waffen und Geheimwaffen des Deutschen Heeres 39/45

Das Rohr (ohne Mündungsfeuerdämpfer) der 2 cm FlaK 38 hat eine Länge von 1300mm.

Source:
"L.Dv 187/40"

Das Rohr der 2cm Fliegerabwehrkanone 30, nachgenannt 2cm FlaK 30 ist 1,30 m lang und besteht aus....

Source:
"L.Dv 1717/35"

The last two sources are primary sources.
L.Dv is short for Luftwaffen-Dienstvorschrift (~ airforce manual)

I have some 15 or 20 more sources on the 2 cm FlaK 30 and 2cm FlaK 38 with L/65.
The few sources I have for L/112,5 are English or US secondary sources.

Keep in mind that the 2 cm KwK 30 and 2 cm KwK 38 are derivates of the FlaK.
The intention of the tank troop was, the barrel should not look over the chasis of the tank.
So they made the 2 cm KwK L/15 caliber-length shorter!!

MfG Michi

Michi · Post by **Michi** » 15 Jan 2004 02:11

One last quotation of a primary source:

Das Rohr der 2 cm KwK's ist neuerdings 1300 mm lang. Es entstammt der 2cm FlaK.

Source:
H.Dv. 159/41

Results according GOOGLE.COM:

2 cm L/65 ____ 232
2 cm L/112,5 __ 076

2cm L/65 ____ 055
2cm L/112,5 __ 030

20 mm L/65 ____ 241
20 mm L/112,5 __ 075

20mm L/65 ____ 103
20mm L/112,5 __ 025

MfG Michi

PS:
The penentration of a 2 cm FlaK was about 3 mm higher than the 2 cm KwK.

Paul Lakowski · Post by **Paul Lakowski** » 15 Jan 2004 07:57

well the 'Rheimetall Handbook on weaponary ' [who made the flak 20mm twin and the RH202 for the
marder reports the calibre @ L 92

Your speaking about the bore length and the gun length. SO 88 Flak 41 is reported to be an L-74 gun so @ 88mm that makes it ~ 6.5m long. Ivan Hogg reports the gun length @ 6545mm while the bore is 6302mm.

Looking at the 20mm Flak 30 thats 2300 length or L 115 , while the bore is 1300mm or L65.

Christian Ankerstjerne · Post by **Christian Ankerstjerne** » 15 Jan 2004 10:33

Michi, look at various photographs, and you'll see that the barrel is much longer than 1.3 meter...

Christian

Michi · Post by **Michi** » 15 Jan 2004 11:21

Your speaking about the bore length and the gun length. SO 88 Flak 41 is reported to be an L-74 gun so @ 88mm that makes it ~ 6.5m long. Ivan Hogg reports the gun length @ 6545mm while the bore is 6302mm

Isn't it Ian V. Hogg?
If so, there are many, many uncountable mistakes in his book "German Artillery of World War Two". (I have only his first edition)

In the German speaking world (Germany, Austria & Switzerland) the L/xx indicates the length of the barrel, NOT the gun length!
We call it Länge in Kaliber (calibre length)

Once again a quotation from a primary source:

For the 2 cm Flak 30 and 2 cm Flak 38:
Länge der Waffe mit Rohr (length of the weapon incl. barrel)
(Maß von Vorderkante Mündungsfeuerdämpfer bis Hinterkante Puffertopf) ________ 2252,5 mm (88,6811 in) L/112,625

Länge des Rohres (length of the barrel)
(ohne Mündungsdämpfer) ____________________________________________ 1300 mm (51,1811 in) L/65

L.Dv 187/40

It has no sense to give the length of the weapon in L/.
The decisive length for penetration data or the speed is the length of the barrel.
[In the Army I was commanding a self-propelled anti-air gun M 42A1 with a twin 40mm a/a gun L/60 (barrel length), later on a 20 mm a/a gun with L/120 (barrel length)]

MfG Michi

Michi · Post by **Michi** » 15 Jan 2004 11:31

To open another "front":

How long (in L/xx) is the 2 cm KwK 30 and 2 cm KwK 38??
What's the V0 (muzzle velocity?)

What is the V0 (muzzle velocity?) of the 2 cm FlaK 30 and 2 cm FlaK 38??

MfG Michi

Paul Lakowski · Post by **Paul Lakowski** » 15 Jan 2004 19:11

Once again a quotation from a primary source:

For the 2 cm Flak 30 and 2 cm Flak 38:
Länge der Waffe mit Rohr (length of the weapon incl. barrel)
(Maß von Vorderkante Mündungsfeuerdämpfer bis Hinterkante Puffertopf) ________ 2252,5 mm (88,6811 in) L/112,625

Länge des Rohres (length of the barrel)
(ohne Mündungsdämpfer) ____________________________________________ 1300 mm (51,1811 in) L/65

L.Dv 187/40

It has no sense to give the length of the weapon in L/.
The decisive length for penetration data or the speed is the length of the barrel.
[In the Army I was commanding a self-propelled anti-air gun M 42A1 with a twin 40mm a/a gun L/60 (barrel length), later on a 20 mm a/a gun with L/120 (barrel length)]

MfG Michi[/quote]

You miss the point...if this is the accepted form of information presentation and you wish to communicate then you must follow suit, or no one will understand what you mean?

Michi · Post by **Michi** » 15 Jan 2004 20:00

@ Paul:

You miss the point...if this is the accepted form of information presentation...

1. My post was not an information presentation.
My post was a question with -I hoped so- a corrective answer.
-> This didn't happen up to now.

you wish to communicate then you must follow suit, ?

2. Here you are correct, as I have forgotten something in my very first post.

Can anybody share informations why on really lovely done homepages the caliber length of the 2 cm FlaK 30 and 2 cm FlaK 38 is often given with L/112,5??

The correct length of the 2 cm FlaK 30 and 2 cm FlaK 38 is L/65.
The correct length of the 2cm KwK 30 and 2cm KwK is L/50.

2 cm x 50 = 100 cm.
2 cm x 65 = 130 cm.
2 cm x 112,5 = 225 cm.

Did I miss something??

MfG Michi

You should read
... barrel length of the 2 cm FlaK 30 and 2 cm FlaK 38 is often given with L/112,5??
The correct length of the barrel 2 cm FlaK 30 and 2 cm FlaK 38 is L/65.
The correct length of the barrel 2cm KwK 30 and 2cm KwK is L/50.

Your speaking about the bore length and the gun length.

Nope, I'm speaking only about the barrel length (yours bore length); never about the gun length.

OR with other words,
why do the Allied use the length of the weapon when talking of L/xx?? (e.g.: L/112,5)
why do the Germans use the length of the barrel when talking of L/xx?? (e.g.: L/65)

MfG Michi

Paul Lakowski · Post by **Paul Lakowski** » 15 Jan 2004 21:45

Michi wrote:@ Paul:

OR with other words,
why do the Allied use the length of the weapon when talking of L/xx?? (e.g.: L/112,5)
why do the Germans use the length of the barrel when talking of L/xx?? (e.g.: L/65)

MfG Michi

Cause the size of the gun overall is as important as its capability...it tells you what size fighting compartment you need...or it will tell you which gun can fit in what turret [knowing turret ring etc].

Michi · Post by **Michi** » 15 Jan 2004 22:50

Cause the size of the gun overall is as important as its capability...it tells you what size fighting compartment you need...or it will tell you which gun can fit in what turret [knowing turret ring etc].

That's a good point!!!!

But for the penetration data, the muzzle velocity and the range, the length of a barrel is more important.

As you were looking for the penetration data of 2 cm FlaK and 2cm KwK, I cann't imagine that the gun overall length is important in that case.

MfG Michi

Paul Lakowski · Post by **Paul Lakowski** » 16 Jan 2004 01:15

Michi wrote:
Cause the size of the gun overall is as important as its capability...it tells you what size fighting compartment you need...or it will tell you which gun can fit in what turret [knowing turret ring etc].
That's a good point!!!!

But for the penetration data, the muzzle velocity and the range, the length of a barrel is more important.

As you were looking for the penetration data of 2 cm FlaK and 2cm KwK, I cann't imagine that the gun overall length is important in that case.

MfG Michi

Well in modern circles the size of the breech is more important than the length of the bore..... or atleast as important. THis may have a reflection in the actual gun length.