Could a Bf-109 with a 20 mm integrated gun, have its engine replaced by an engine equipped with an integrated 30 mm gun?

Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules

79
21
Dec 17, 2016
France
Hello, I am part of a group investigating WW2 Bf-109 crash sites in North-eastern France related to the May 27 1944 air battle, in which the following JGs, equipped with Bf-109s, had been involved: JG3, JG5, JG27, JG53. On a crash site where we should normally find 20 mm bullets of Bf-109 normally equipped with 20mm guns, we have found 30 mm bullets. That could mean that this specific aircraft had his engine (equipped with a 20 mm gun- Motorkanone) replaced by another engine equipped with a 30 mm gun. Was such an engine change possible? Did that ever happen in those JGs? Thank you for your help. Best regards. Daniel
 
1601140428691.png
 
Also:
The G-10/U4 was equipped with a MK108 30mm motorkanone.
The G-14/U4 was equipped with a MK108 motorkanone.
The Bf109G series also had the option of being equipped with Rüstatz kits (R4) that were two MK108 canons in an underwing pod (one pod for each wing).
 
According to the book "Day Fighters in Defence of the Reich-A War Diary 1942-45", on May 27, 1944 the Luftwaffe lost 23 aircraft from the following JG's...
  • III/JG 3 - 6
  • I/JG 5 - 7
  • II/JG 27 - 6
  • II/JG 53 - 4
All were Bf 109G's
 
Don't need a new motor. Just swap out the cannon as it's not a part of the motor.
No, wiring will be different. It is not only the gun but everything that makes it go boom. From fuses to cable lenght to etc.
 
Bf 109 with the engine removed.

bf109-b-jpg.jpg


The engine had very little to do with the cannon, I believe the tube through the engine would take any barrel under 70mm in diameter.
Once you have planes in production with the 30mm MK 108 the parts needed to convert an older fighter become more available. Either from the factories or scrounged from wrecks (landing accidents would be the most convenient.) Parts would be the gun mounts, charging system, firing system, ammo boxes/chutes. How much of this type "stuff" could be fabricated by good armourers/mechanics I don't know. Might depend on the base they were at and access to equipment.
 
'Engine cannons' were fixed to mounts (lavettes), not on the engines themselves (possible/likely exception being H-S engines and their spin-offs). Lavettes also included the blast tube.
 
Bf 109 with the engine removed.

bf109-b-jpg.jpg


The engine had very little to do with the cannon, I believe the tube through the engine would take any barrel under 70mm in diameter.
Once you have planes in production with the 30mm MK 108 the parts needed to convert an older fighter become more available. Either from the factories or scrounged from wrecks (landing accidents would be the most convenient.) Parts would be the gun mounts, charging system, firing system, ammo boxes/chutes. How much of this type "stuff" could be fabricated by good armourers/mechanics I don't know. Might depend on the base they were at and access to equipment.
Excellent photo showing that the cannon is inside the fuselage with only the barrel extending forward through the engine V.
If the rounds are longer than the 20mm rounds that means the structure retaining the ammo box must be changed to accept the new box and I doubt that would be an easy change given there is little waste space in the 109.
You must remember that the MK108 is mounted between the rudder pedals and the whole area is very tight as shown below.
1601243423263.png

1601243600412.png

1601243723087.png

German readers will be able to clarify this as they will be able to read this manual
1601243851266.png

from www.109lair.com
 
109F-2, F-4, G-1... Motorkanone MG 151 cartridge 15x96 mm, MG 151/20 20x82 mm, MK 108 30x90 mm, so 30 mm cartridge was shorter than the original 15 mm.
 
The cartridge case was shorter, the overall length of the round was not.
However we may be arguing over a couple of inches (5cm). I believe the ammo belt container was in the wing root?

Pictures of Bf 109F cockpits show a large housing for the breech of a cannon between the rudder pedals.

ajoC3prTjncD23Ry9BrlX9Z1x7wkIWc_BeTPmV4zAl_AzCMevQb6PKksh_3XKJ6OLjBQsf4os-xUs6TESsqAN2nkX73QZHxE.gif


MK108 2nd from bottom
MG 151/20 5th from bottom.
CuXjVG5g6qgAa0Dc7tG3vz2GPbj0O9-C1Xg593kO2xoFMoY-3uRl47epgQJvETFmiiDnCPXY9vJMjvJ_2imeMKW156yA.jpg

G is the 30mm MK 108 round.
F is the 20mm MG 151/20 round
D is the 15mm MG 151/15 round.
 
Item 13 in the first picture in post 11 is the Gurtkasten MK108 which google translates as beltbox. This therefore should be the MK108 ammobox though it may be just a feed chute as Shortround is usually accurate in his posts. Looking at walkaround photos on 109lair I can see no fuselage access panels in the right area so that also suggests Shortround is correct. Someone with the ability to read German will probably be able to resolve this from the manual linked in the same post.

This is the MG151 installation in the 109F-2 - again no indication of where the ammo is stored but it does show what I am guessing is the spent casing chute on the side of the gun just above the number 18.
1601274053730.png
 
Last edited:
The ammobox for the MG 151 & 151/20 was inside the left wing
 
Making mountains out of molehills. Did you need to change a some parts to accommodate the MK108? Of course, but not as much of a problem as some believe.
 
Going by that diagram the 20mm ammo drum is above the gun and behind the firewall which makes sense given putting it in the wing would put it very close to the main landing gear where you cannot afford to weaken structure but now two people say it is in the wing.
I went back to the manual and that shows this picture with the caption
1601318053929.png

1601317992250.png

1601318292566.png

1601318527710.png

1601318642397.png

To me that suggests the ammo box sits on top of the gun and is pulled aft using ropes attached to those handles to remove it. Sounds very clumsy but????


Further in the book it shows
1601319417960.png

1601319494996.png

1601319318182.png

1601319722894.png

1601319225326.png

which leaves me totally confused

Hopefully someone like GrauGeist GrauGeist can translate this properly so it makes sense to those of us who cannot understand a Google translation
 
Last edited:
Going by that diagram the 20mm ammo drum is above the gun and behind the firewall which makes sense given putting it in the wing would put it very close to the main landing gear where you cannot afford to weaken structure but now two people say it is in the wing...

How? The landing gear was attached to the fuselage, this made it possible to remove the wings so that the machine was still on its landing gear, e.g. it could be towed behind a truck so that the wings were on the platform and the rest of the machine was towed tail-up tail first.
 

Users who are viewing this thread

Back