Ejected shells vs pusher props

[pigeon]

Maybe it should be in the "What If" section considering how rare pushers were, idk... But SAAB J21 had 20mm + 13.2mm nose guns, DO 335 had 15mm/20mm in the nose plus a really big high velocity 30mm firing really big shells. Then there's also prototypes like SO 8000 (6 x 20mm) etc. All of which should be sucking empties right into prop.

Was this ever a problem, and if, then what solutions did it have?

 

[Engineman]

They had to retain the links and cases in an internal bin.

Eng

 

[Snautzer01]

Curtiss-Wright XP-55 Ascender - Wikipedia

en.m.wikipedia.org

 

[pigeon]

I hazily remember a forum discussion somewhere (might be even here, it was a long time ago), about something with 20mm(?) in wing roots, that had ejection chutes going diagonally through wings so the crap exited outside of propeller arc (might have been outside of tail booms). Using the pressure differential above/below wing to generate the airflow in chutes, with chute doors being operated by guns recoiling on their mountings.

Does anyone else here remember what it was, or am I just going retarded?

 

[z42]

Speaking of ejecting spent shell cases, the Wikipedia article on the Mk 108 says:

instead of simply ejecting the spent cartridge case, the 108 reinserts it into the empty link in the ammunition belt.

However if one looks at e.g. a picture of a Me 262, one can clearly (?) see the ejection ports on the underside of the nose. So what gives? Were there Mk 108 versions with the system described in Wikipedia or is it just nonsense?

 

[CATCH 22]

Speaking of ejecting spent shell cases, the Wikipedia article on the Mk 108 says:



However if one looks at e.g. a picture of a Me 262, one can clearly (?) see the ejection ports on the underside of the nose. So what gives? Were there Mk 108 versions with the system described in Wikipedia or is it just nonsense?

Wasn't this the system on all Me 109G with MK 108 (U4 sub-variant):

First photo shows the top and second photo shows the underside (no bottom) of the spent cartridge cases container (Leerhulsenbehalter).

 

[spiralcopter]

Some of the Italian Breda machine guns, notably the Breda 37 and the Breda 20/65 20mm autocannon offer a unique potential solution; instead of ejecting cases clear of the weapon's receiver, the spent cases were re-inserted into the feed strip!


View: https://www.youtube.com/watch?v=6QM11u2R-zA

In principle a system like this could be used with a belt-fed weapon (provided it used non-disintegrating belts rather than disintegrating links, of course), although I have only ever heard of this having been done in the context of an experimental machine gun intended for use in tanks (no spent cases bouncing around the inside of the tank and causing a mess, you see). Of course, such a thing could reasonably be applied to an aircraft installation as well.

 

[z42]

Some of the Italian Breda machine guns, notably the Breda 37 and the Breda 20/65 20mm autocannon offer a unique potential solution; instead of ejecting cases clear of the weapon's receiver, the spent cases were re-inserted into the feed strip!


View: https://www.youtube.com/watch?v=6QM11u2R-zA

In principle a system like this could be used with a belt-fed weapon (provided it used non-disintegrating belts rather than disintegrating links, of course), although I have only ever heard of this having been done in the context of an experimental machine gun intended for use in tanks (no spent cases bouncing around the inside of the tank and causing a mess, you see). Of course, such a thing could reasonably be applied to an aircraft installation as well.

These sort of systems are common in modern aircraft guns, called 'linkless feed systems'. They came about due to a number of different issues making 'traditional' belt feed systems untenable:

• Ejector openings cause a lot of drag on a supersonic aircraft.
• Again on supersonic aircraft, the cases ejected are decelerated very rapidly, and if they tumble and hit the aircraft there's enough velocity differential to risk damaging the aircraft skin.
• A Gatling gun at 6000rpm would just rip a traditional belt to pieces. Or if the links are sturdy enough to handle that kind of acceleration, they're probably also stiff enough that the de-linker risks damaging the shell cases. So there needs to be some mechanism to supply to the shells to the gun rather than just relying on the gun pulling the belt.

I believe such systems have also been developed for autocannons on IFV's. In this case I think it's more about not having the empty cases bouncing around inside like you say, and also to provide the capability to switch ammo types easily.

 

[tomo pauk]

Were there Mk 108 versions with the system described in Wikipedia or is it just nonsense?

Second option is true.

 

[z42]

Some of the Italian Breda machine guns, notably the Breda 37 and the Breda 20/65 20mm autocannon offer a unique potential solution; instead of ejecting cases clear of the weapon's receiver, the spent cases were re-inserted into the feed strip!


View: https://www.youtube.com/watch?v=6QM11u2R-zA

In principle a system like this could be used with a belt-fed weapon (provided it used non-disintegrating belts rather than disintegrating links, of course), although I have only ever heard of this having been done in the context of an experimental machine gun intended for use in tanks (no spent cases bouncing around the inside of the tank and causing a mess, you see). Of course, such a thing could reasonably be applied to an aircraft installation as well.

Oh, and have to hand it to whatever bird is chirping there in the background of that video. Not missing a beat despite a frickin' autocannon going off in the vicinity!

 

[spiralcopter]

These sort of systems are common in modern aircraft guns, called 'linkless feed systems'. They came about due to a number of different issues making 'traditional' belt feed systems untenable:

• Ejector openings cause a lot of drag on a supersonic aircraft.
• Again on supersonic aircraft, the cases ejected are decelerated very rapidly, and if they tumble and hit the aircraft there's enough velocity differential to risk damaging the aircraft skin.
• A Gatling gun at 6000rpm would just rip a traditional belt to pieces. Or if the links are sturdy enough to handle that kind of acceleration, they're probably also stiff enough that the de-linker risks damaging the shell cases. So there needs to be some mechanism to supply to the shells to the gun rather than just relying on the gun pulling the belt.

I believe such systems have also been developed for autocannons on IFV's. In this case I think it's more about not having the empty cases bouncing around inside like you say, and also to provide the capability to switch ammo types easily.

Not exactly. A linkless feed system is like a big industrial conveyor which often, but not necessarily re-packs the spent cases inside it.

Some systems do re-stow the cartridges, some don't. It's not an intrinsic feature of a linkless feed system. For instance, the M230 chain gun on the AH-64 boots the spent cases overboard:

While on most fast-moving jets the cases are recycled for the reasons you mentioned.


Linkless feed systems are not a prerequisite for very high rates of fire. Some versions of the M134, for instance, fire at a frosty 6,000 RPM using standard M13 linked ammo. The Italian system shown above isn't a linkless feed system either; it's a solid feed strip (which works the same way as a belt... just dumber because it isn't flexible) where, rather unusually, the cases are re-packed.

 

[z42]

Not exactly.

Indeed, "not exactly". Which is why I wrote "sort-of", to mean systems that put the empty cases back into the magazine, not that they would work exactly the same..

A linkless feed system is like a big industrial conveyor which often, but not necessarily re-packs the spent cases inside it.

Yes. BTW, somebody made a 3D model of how the 30mm gun feed system on the A-10 works at
View: https://www.youtube.com/watch?v=UH07uffv26M

Looking at the real thing at

View: https://www.youtube.com/watch?v=5Uh1Ix9wG8w
it seems that one thing that 3D model lack is that each shell is apparently placed in a kind of plastic socket as it moves along the conveyor belt.