Aircraft cannons....

[Lucky13]

Which was the best or better aircraft mounted cannon in WWII, in the 20-30mm range? How many different makes was there, that was fabricated?

[Soren]

The famous "Pneumatic Hammer", Rheinmetall's 30mm Mk108, takes the prize IMO. No'one else managed to squeeze that much firepower into such a small & light package. A truly frightening weapon!



When'ever Allied aircrew heard the tell tale deep thumbing sound of this weapon they cringed, and with good reason:

[Lucky13]

Ouch! Cheers Soren!

[Soren]

Also tested against the tail of a Spitfire:


There was a great deal of fear for this weapon among allied aircrews, understandably so as results of just one hit above illustrates.

[B-17engineer]

List of craft that used the MK108

Luftwaffe Aircraft that used the MK 108 Aircraft Number Location Notes

Craft that used the Mk108
[*]Aircraft Location Notes
[*]Bv 155 - 1 Cannon - engine mounted - prototype flown

[*]Bv 40 - 2 Cannon - wing roots mounted - glider - 6 examples built

[*]Fw 190 - 2 Cannon - wings mounted - various 190 variants

[*]Ta 152 - 1 Cannon - engine mounted - C and H models

[*]Ta 154 - 2 Cannon - fuselage mounted

[*]He 219 - 2 Cannon - wing roots mounted - 2 additional firing upwards

[*]Ho 229 - 4 Cannon - wing mounted - prototype flown

[*]He 162 - 2 Cannon - fuselage mounted - later replaced with Mg 151

[*]Ju 388 - 2 Cannon - ventral bulge mounted - J-1 night fighter version

[*]Bf 109 - 1 or 2 Cannon- under wing mounted - engine or various models from G onwards


[*]Bf 110 - 2 Cannon - cockpit mounted - firing upwards

[*]Me 163 -2 Cannon - wing roots mounted

[*]Me 209 - 1Cannon - engine mounted - never entered service

[*]Me 262 -4 Cannon - nose mounted - standard armament

[*]Me 410 - 2 Cannon - nose mounted - B-2/U2/R2 version

[Soren]

Rheinmetall Borsig 30mm MK108
Cartridge: 30x90RB
Weight: 58 kg
Action: Blowback operation
Muzzle velocity: 540 m/s
Rate of Fire: 650 rpm

Info on ammunition used:
The cannon used specially-developed 30x90RB mm ammunition—30 mm calibre, 90 mm case length, rebated/reduced rim. Unlike most other weapon rounds, which used traditional brass for the case, the MK 108's ammunition used steel cases. Several types of ammunition were developed, including practice, armor-piercing, high-explosive and incendiary. In operation, however, two major ammunition types were used: Minengeschoß ("mine-shell") and high-explosive incendiary. The Minengeschoß was made by drawn steel (the same way brass cartridges are made) instead of being forged and machined as was the usual practice for cannon shells. This resulted in a shell with a thin but strong wall, which hence had a much larger cavity in which to pack a much larger explosive or incendiary charge than was otherwise possible. The incendiary rounds were also often fitted with a hydrostatic fuse, which detonated when it came in contact with liquid. This was to ensure that the round did not merely explode on the target aircraft's skin, which would cause little damage, but instead penetrated and exploded when it came into contact with fuel or coolant inside the fuel tanks or radiators respectively.

The Mk108 also tops the list on Tony Williams site in his quest to find the best WW2 fighter armament:
http://www.quarry.nildram.co.uk/WW2guneffect.htm

His final assessment:

Gun efficiency
MG 17 = 1.75
MG 131 = 2.82
Breda-SAFAT = 1.24
12.7mm Scotti =1.64
Ho-103 = 1.96
.50 Browning M2 = 2.1
12.7mm UB = 3 - 3.9
MG 151 = 2.2
20mm Type 99-1 = 4.5
MG-FF = 4.5
MG 151/20 = 4.6
20mm Ho-5 = 4.2
20mm ShVAK = 3.4
Berezin B-20 = 5.7
20mm Type 99-2 = 3.4
HS.7 and 9 = 2.4
Hispano II = 4
Hispano V = 6
Ho-1 / Ho-2 = 2.8
VYa-23 = 3.4
MK 108 = 9.7
MK 103 = 4.9
37mm M4 = 1.7
NS-37 = 2.5
Ho-301 = 1.5

[B-17engineer]

Nice info Soren, here are some things I found..

In many ways, the Rheinmetall-Borsig MK 108 30mm cannon was considered to be a masterpiece of weapons engineering, due to it's compact size, ease of manufacture and hitting power. Although it was first designed by Rheinmetall-Borsig in 1940 as a private venture, the design was finalized in 1942. It met a later RLM requirement for a new aircraft cannon that could knock down enemy bombers with the lowest expenditure of ammunition and stay beyond the range of enemy defensive fire.
In short, the MK 108 was a blow-back operated, rear-seared, belt fed 30 mm cannon using electric ignition and was charged and triggered by simple compressed air. One drawback was that once installed, there was no method to adjust the gun's harmonization. One distinctive physical feature was the very short gun barrel, which gave the MK 108 a low muzzle velocity of 500-540 meters (1640-1770 feet) per second. The maximum rate of fire was 650 rounds per minu

[Soren]

Mk108 tested with HE/T round against Spitfire wing:
YouTube - Firing trial of 30mm German Mine-Geschoss HE/T round

[Lucky13]

Holy sh*t! Had that been in a dogfight, that Spitfire would have been history!

[Soren]

Yep, that would be a wing lost no doubt.

[davebender]

I agree.

The primitive WWII era gunsites required you to fire from 200 meters or less. At that range the low muzzle velocity of the Mk108 was not a serious problem. And the destruction of this weapon was awesome.

[Soren]

One drawback was that once installed, there was no method to adjust the gun's harmonization.

I don't think this is correct B17engineer, atleast I've never heard about it and I don't see why it would be a problem? Where is this info from?

[Milosh]

The first two examples Soren posted had the 30mm shell suspended in the fuselage.

[Milosh]

Nice info Soren, here are some things I found..
One drawback was that once installed, there was no method to adjust the gun's harmonization.

Hard to do anyway with the shell having to travel down a 50mm tube. There would certainly be adjustment necessary when first installed in the 109.

Harmonization was most certainly done for the wing mounted MK108s in the 190.

[piet]

for yoe se war is over tommy