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

[Shortround6]

It appears that both may be correct.

Magazine (belt box) for the 15mm and 20mm cannon in the wing.
Magazine (belt box) for the 30mm MK 108 on top of the gun.

Making installation in an older fighter even easier. Remove the chute/feedway from the wing to the gun and leave the box in the wing.
Install 30mm gun with the magazine (belt box) on top.

If you have a 109 with a 30mm cannon that ground looped you may have the parts you need to put the cannon in a fighter that was built with a 20mm gun.

 

[MiTasol]

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.

Yes the MLG was attached to the through spar on the fuselage but the wing panel close to the fuselage requires enough strength to prevent it folding under high g loads. Cutting holes in the lower skin for the MLG to retract into requires the remaining skin (which is in tension in flight) and structure in the area to carry higher loads than they would if there was no MLG cutout. While that is common it does add weight and structural complexity.
Now start cutting into the top surface in the same area and you are introducing additional high compression stress areas and greatly increase the chances of structural failure so require more structure to compensate and more structure means more weight.

Add to that the G forces on a serpentine ammo belt during high g maneuvers would almost certainly cause misfeeds to the gun when the aircraft is turning to the side where the ammo box is not fitted. The belt chutes would not be straight and would require bends to bring the ammo up through the floor and then again to feed into the gun. Both would cause high friction at any time, let alone under high g turns.

Obviously from Shortrounds post they did do this on 20mm armed aircraft and that really surprises me

 

[MiTasol]

It appears that both may be correct.
View attachment 596456

Magazine (belt box) for the 15mm and 20mm cannon in the wing.
Magazine (belt box) for the 30mm MK 108 on top of the gun.

Thanks - you have solved both the OP question and confirmed how/where the 30mm ammo was stored.

 

[Juha3]

Yes the MLG was attached to the through spar on the fuselage but the wing panel close to the fuselage requires enough strength to prevent it folding under high g loads. Cutting holes in the lower skin for the MLG to retract into requires the remaining skin (which is in tension in flight) and structure in the area to carry higher loads than they would if there was no MLG cutout. While that is common it does add weight and structural complexity.
Now start cutting into the top surface in the same area and you are introducing additional high compression stress areas and greatly increase the chances of structural failure so require more structure to compensate and more structure means more weight.

Add to that the G forces on a serpentine ammo belt during high g maneuvers would almost certainly cause misfeeds to the gun when the aircraft is turning to the side where the ammo box is not fitted. The belt chutes would not be straight and would require bends to bring the ammo up through the floor and then again to feed into the gun. Both would cause high friction at any time, let alone under high g turns.

Obviously from Shortrounds post they did do this on 20mm armed aircraft and that really surprises me

There was a problem with the belt. The ammo box could take 230 rounds but there was a tendency of belt breakage about mid belt. Finns asked from Germans had they any solution to the problem and later in Finland it became customary to load 130 cartridges into the ammo box and 25 more into the feed chute.

There was only a small hatch on the upper surface at the wing root for loading.

 

[Juha3]

a double

 

[Peter Gunn]

a double

I'd say.

 

[GrauGeist]

I'd say.

View attachment 596539

Maryann for the win!

 

[Daniel BASTIEN]

Hello, Thank you all for your precious contributions Best regards

 

[Denniss]

AFAIR swapping was not possible without modifications as the MK 108 required compressed air to cock