One nose-mounted cannon longer than the other three cannons on twin-engined fighters

[etaicklen]

I noticed that with the four cannons mounted in the upper nose of the twin-engined German Messerschmitt BF-110, one of the cannon barrels protrudes out farther than the others. I then noticed that on the American twin-engined P-38 Lightning, which has a similar gun layout, it also has one barrel longer than the other three. Finally, certain versions of the twin-engined Japanese Ki-46 have that gun layout in the nose as well. I have done a large amount of searching online and have come up empty-handed, does anyone know why one barrel sticks out farther than the rest on these three aircraft? I'm hoping somebody here can answer my question, as copious browsing and ChatGPT querying has also turned up nothing.

 

[Wurger]

Welcome to the site.

To answer your question the differences in the barrel lenght is the ammo feeding system causing the offset of the MGs there, as memo serves.

 

[etaicklen]

Welcome to the site.

To answer your question the differences in the barrel lenght is the ammo feeding system as memo serves.

Does the placement of the ammo feeding system require that gun to be moved forward to make room in the fuselage? I find it interesting that the system works that way on three different aircraft from three different countries

 

[tomo pauk]

Barrel lengths were the same for the same weapons. It was ammo feed that dictated the relative positions of the guns, usualla meaning that one of the guns will be mounted further aft the another by about the depth of the ammo box. See P-38 here for example.
That way a lot more ammo could've been possible to carry.
Staggered guns were also in some wing installations, most notably on the P-47, and for the same reasons. See here for example.

 

[Wurger]

Here is the one for the Bf 110 . As you may notice the midle MG was mounted "in the full way" while the right one and left were moved forward and back to fit the ammo feeiding chutes and the ejection chutes. In the way the ammo cartriges/containers could be put one behind one getting as less room as possible.

the pic source: the net.

 

[etaicklen]

Here is the one for the Bf 110 . As you may notice the midle MG was mounted "in the full way" while the right one and left were moved forward and back to fit the ammo feeiding chutes and the ejection chutes. In the way the ammo cartriges/containers could be put one behind one getting as less room as possible.

View attachment 823132
the pic source: the net.

ahh I see. Thanks for that! It's interesting to see how that design characteristic carried across multiple countries. I wonder if one aircraft did it first and other designers took note, or if it is just another example of parallel evolution?

 

[etaicklen]

Barrel lengths were the same for the same weapons. It was ammo feed that dictated the relative positions of the guns, usualla meaning that one of the guns will be mounted further aft the another by about the depth of the ammo box. See P-38 here for example.
That way a lot more ammo could've been possible to carry.
Staggered guns were also in some wing installations, most notably on the P-47, and for the same reasons. See here for example.

Gotcha, thanks so much

 

[Wurger]

ahh I see. Thanks for that! It's interesting to see how that design characteristic carried across multiple countries. I wonder if one aircraft did it first and other designers took note, or if it is just another example of parallel evolution?

My pleasure. And here a shot of the accommadation of the four MGs for the Bf 110 ...

the source: the net.

 

[etaicklen]

My pleasure. And here a shot of the accommadation of the four MGs for the Bf 110 ...

View attachment 823135
the source: the net.

That image helps a lot, it clears things up nicely

 

[Wurger]

That image helps a lot, it clears things up nicely

 

[Airframes]

Note also that the protruding barrels on the Me.110 and the P.38 were 7.92 mm and .50 cal (12.7mm) machine guns respectively, not cannons.

 

[woodhaven]

P-38

 

[GreenKnight121]

ahh I see. Thanks for that! It's interesting to see how that design characteristic carried across multiple countries. I wonder if one aircraft did it first and other designers took note, or if it is just another example of parallel evolution?

No, it is simply an example of similar design goals (fitting 4 guns into a narrow aircraft nose) producing a similar result (the same has been said for aircraft shapes etc - they were designed using the same laws of physics, with similar materials and technological understanding, to similar desired end performance - so it is natural they look similar).