Junkers Jumo engines - no motor cannon?

[A.G. Williams]

I've been refreshing my memory concerning the basics of WW2 aero engines, and would appreciate a response on one point: the DB 600 series V-12s were designed to accept an engine-mounted gun firing through the propeller hub (a facility most notably made use of in the Bf 109F onwards). Was a similar mounting ever used with the Jumo 211 engine? I know that the He 112 was fitted with a 20mm C/30L cannon to its Jumo 210, and the early Bf 109 was designed for a similar installation, but was it ever used - or possible - with the bigger Jumo 211?

 

[GrauGeist]

It may have been possible, but the only fighter that had the 211, was Avia's S-199 which was armed with two MG131 and two MG151/20.
The rest of the applications were multi-place types (except the Ju87, of course).

 

[A.G. Williams]

It may have been possible, but the only fighter that had the 211, was Avia's S-199 which was armed with two MG131 and two MG151/20.
The rest of the applications were multi-place types (except the Ju87, of course).

Thanks for your response.

It seems a little odd that they didn't try to fit an engine-mounted anti-tank cannon to the Ju 87G. It would have been much more efficient and accurate than a pair of underwing guns. Possibly the aircraft engine installation didn't leave enough space for a big cannon?

I know that the Il-2 could not fit an engine-mounted gun because the engine was not designed to accommodate this.

 

[Ivan1GFP]

Hello A.G. Williams,

I don't know much about the JuMo 211, but if it was anything like the JuMo 213, then one of the problems about mounting a Motor Cannon would have been the fact that oil lines to drive the Hydraulic Propeller ran through the center of the propeller shaft.
That is why the FW 190D-9 and earlier birds did not use a Motor Cannon.
With later models of the JuMo 213, the oil lines were moved and that allowed a 30 mm MK 108 and later a 20 mm MG 151/20 to fire through the propeller shaft.

- Ivan.

 

[GrauGeist]

Thanks for your response.

It seems a little odd that they didn't try to fit an engine-mounted anti-tank cannon to the Ju 87G. It would have been much more efficient and accurate than a pair of underwing guns. Possibly the aircraft engine installation didn't leave enough space for a big cannon?

I know that the Il-2 could not fit an engine-mounted gun because the engine was not designed to accommodate this.

In the engine's "valley", there was limited room, so anything beyond the MK103/108 was out of the question.

In a fighter (Bf109, He112) having a centerline 20mm or 30mm cannon would be ideal especially for bomber hunting, but for anti-armor (Ju87), they would lack the punch.
The BK3.7 had the hitting power, but it was considerably larger than the Rheinmetall-Borsicht cannons.

 

[A.G. Williams]

Hello A.G. Williams,

I don't know much about the JuMo 211, but if it was anything like the JuMo 213, then one of the problems about mounting a Motor Cannon would have been the fact that oil lines to drive the Hydraulic Propeller ran through the center of the propeller shaft.
That is why the FW 190D-9 and earlier birds did not use a Motor Cannon.
With later models of the JuMo 213, the oil lines were moved and that allowed a 30 mm MK 108 and later a 20 mm MG 151/20 to fire through the propeller shaft.

- Ivan.

Thanks!

 

[A.G. Williams]

In the engine's "valley", there was limited room, so anything beyond the MK103/108 was out of the question.

In a fighter (Bf109, He112) having a centerline 20mm or 30mm cannon would be ideal especially for bomber hunting, but for anti-armor (Ju87), they would lack the punch.
The BK3.7 had the hitting power, but it was considerably larger than the Rheinmetall-Borsicht cannons.

There's a big difference between the MK 108 and the MK 103. The MK 108 is a very compact and light low-velocity gun, very good against bombers at close range. The MK 103 is much bigger with a long barrel, firing big, high-velocity ammunition. It is too big to fit into the Bf 109 engine mounting although a slimmed-down version, the MK 103M, could fit - a Bf 109K-10 (IIRC) was fitted with one, but not considered a success. Incidentally, the MK 103 ammunition did include very effective tungsten-cored AP rounds which would have been effective against the side, top or rear armour of most tanks.

 

[Ivan1GFP]

The space between the cylinder banks of the JuMo engines was really not the limitation to mounting of a Motor Cannon.
With the MK 108 for example, the only thing that was between the cylinder banks was part of the barrel and the blast tube.
The cannon itself sat between the pilot's feet.
A problem with the MK 103 was that it was a fairly long and very heavy gun. It was around 700 pounds. Weight certainly would have affected performance of a light fighter and recoil might have been a little much for the structure.

- Ivan.

 

[Deleted member 68059]

A problem with the MK 103 was that it was a fairly long and very heavy gun. It was around 700 pounds. Weight certainly would have affected performance of a light fighter and recoil might have been a little much for the structure.

- Ivan.

Suspect that 700lbs is incorrect there, might want to edit it.

 

[Snautzer01]

+/- 145 kg about 319.6 lbs

see my thread here Waffen Revue, German weapons explained in detail and Waffen Revue, German weapons explained in detail

 

[Denniss]

700 might be with ammo. MK 103 is somewhat useless if it can't shoot ........

 

[Snautzer01]

700 might be with ammo. MK 103 is somewhat useless if it can't shoot ........

Read my reply plse. Now pls explain how to get to 700lbs.

 

[Denniss]

145kg is weapon without ammo. 100 rounds of ammo add further 92-107kg
at least somewhat closer to 700 with ~550 lbs

 

[GrauGeist]

The MK103 was less than 400 pounds, the MK101 was just over 300 pounds.

Are you perhaps thinking of the BK3.7?
It weighed 650 pounds.

 

[tomo pauk]

MK 101 and 103 were both about 140 kg, or ~300 lbs without ammo. MK 101 with a full 30 rd drum was at 180 kg, ~400 lbs.
The BK 3.7 will probably not fit on the Ju 87 as a motor cannon, unless both Jumo 211 and whole front part are redesigned. Even the MK 101 or 103 are probably stretch, the 103M might fit, though.

As per the initial question, up to the 211B/H version (1938-40) there was a clear path for the motor cannon, and it is remarked in the engine manual as such. With 211F/J (1941 and on), the feature was lost, due to the receptacle for constant prop ancillaries. I don't think that Jumo 211 ever had the motor-cannon feature being actually used.

 

[Engineman]

I've been refreshing my memory concerning the basics of WW2 aero engines, and would appreciate a response on one point: the DB 600 series V-12s were designed to accept an engine-mounted gun firing through the propeller hub (a facility most notably made use of in the Bf 109F onwards). Was a similar mounting ever used with the Jumo 211 engine? I know that the He 112 was fitted with a 20mm C/30L cannon to its Jumo 210, and the early Bf 109 was designed for a similar installation, but was it ever used - or possible - with the bigger Jumo 211?

Hi A.G. Williams,
The Jumo 211 was designed with a Motorkanone mounting and internal blast tunnel, much in the same way as the DB601 etc. However, this function was not possible with the Junkers oil operated propeller in those versions. The Motorkanone could have been used with a suitable VDM type propeller but, I am not aware of the motorkanone being used on any aircraft that did have the Jumo 211 and the VDM prop.
The fitting of a motorkanone in this way on a Jumo or a DB requires a complete installation with the airframe design as, the gun is usually quite long and sticks out behind the engine, maybe 1.5m.
Some late versions of the Jumo 213 were equipped for the Motorkanone, with a redesigned Junkers propeller and operating system.
The S.199 was fitted with a late Jumo 211 power unit and propeller for the late model He 111 and that propeller did not have compatibility with a blast tube as it was full of its hydraulic system inside.

Cheers

Eng