Firing through the crankshaft ... or not

[djos]

I'm really not sure why some folk think clutching an mgu-h that is sitting in between the turbines would be that hard. As already mentioned you just need the mgu-h to be on a hollow shaft. It's just an engineering Problem that should be solvable with current materials.

Heck back in ww2 they fired bullets thru hollow crank shafts and out the Centre of the propeller hub.

[J.A.W.]

Heck back in ww2 they fired bullets thru hollow crank shafts and out the Centre of the propeller hub.

Ah, no.. Guns were mounted to fire through the V - longwise between the banks - of the engine block..
& out through the hollow reduction gear/propeller hub.. ..but not through the crankshaft itself..

[djos]

Heck back in ww2 they fired bullets thru hollow crank shafts and out the Centre of the propeller hub.

Ah, no.. Guns were mounted to fire through the V - longwise between the banks - of the engine block..
& out through the hollow reduction gear/propeller hub.. ..but not through the crankshaft itself..

Ah yeah, getting my wires crossed, many of these where driven by the crankshaft.

[J.A.W.]

Ah yeah, getting my wires crossed, many of these where driven by the crankshaft.

"Many of..." (what?) "...where driven by the crankshaft."
Props?
No interrupter gear needed - if firing through the hub..

[djos]

Ah yeah, getting my wires crossed, many of these where driven by the crankshaft.

"Many of..." (what?) "...where driven by the crankshaft."
Props?
No interrupter gear needed - if firing through the hub..

Ww2 aircraft Canon's - many where driven by the crankshaft via reduction gears etc.

[J.A.W.]

Ww2 aircraft Canon's - many where driven by the crankshaft via reduction gears etc.

I doubt it, but if you've got a schematic showing such to post (may be best to put it up on the engine image thread)..
.. I'll gladly stand corrected..

[djos]

Ww2 aircraft Canon's - many where driven by the crankshaft via reduction gears etc.

I doubt it, but if you've got a schematic showing such to post (may be best to put it up on the engine image thread)..
.. I'll gladly stand corrected..

I'm not saying it was common but it did happen ..... Btw I knew id read about a ww2 fighter that fired its Canon thru the crankshaft. It was the Russian yak-3

http://en.m.wikipedia.org/wiki/Yakovlev_Yak-3

And a discussion here mentions several aircraft that had crankshaft driven, (via reduction gear box's of course), machine guns.

https://groups.google.com/forum/m/#!top ... Vq91GwP4AI

[wuzak]

Ww2 aircraft Canon's - many where driven by the crankshaft via reduction gears etc.

I doubt it, but if you've got a schematic showing such to post (may be best to put it up on the engine image thread)..
.. I'll gladly stand corrected..

I'm not saying it was common but it did happen ..... Btw I knew id read about a ww2 fighter that fired its Canon thru the crankshaft. It was the Russian yak-3

http://en.m.wikipedia.org/wiki/Yakovlev_Yak-3

And a discussion here mentions several aircraft that had crankshaft driven, (via reduction gear box's of course), machine guns.

https://groups.google.com/forum/m/#!top ... Vq91GwP4AI

If you think about it for a moment you will realise that for a period either side of a piston's TDC its connecting rod will cover or partially cover the centreline of the crankshaft,making it impossible for a cannon barrel or bullet to pass through.

Not sure if engines actually drove mgs or cannon, but they certainly were connected for the purpose of synchronisation.

[gruntguru]

It could be done if the crankpin journal diameter was greater than the stroke (plus the calibre of the gun).

[wuzak]

It could be done if the crankpin journal diameter was greater than the stroke (plus the calibre of the gun).

Take a 20mm Hispano and try to put it through a Merlin sized engine.

The stroke is 6", so the journal is going to be huge!

The other issue with many engines, such as the Merlin and Allison, which were not designed to take a hub gun, is that the supercharger and accessories are in the way of the gun.

[J.A.W.]

[quote="djos"]


I'm not saying it was common but it did happen ..... Btw I knew id read about a ww2 fighter that fired its Canon thru the crankshaft. It was the Russian yak-3

http://en.m.wikipedia.org/wiki/Yakovlev_Yak-3 [quote="djos"]


Oh no, not wiki!

Its wrong.. & plainly confusing the offset reduction gear/prop hub with "crankshaft"..

No WW2 radials did even that, since in high powered fighters they weren't running offset reduction gearing..

& by WW2 most sophisticated "interrupter gear" systems - which interrupted the cowl/wing root mounted guns
that fired through the prop arc (unlike the hub gun), were controlled via electrictrickery..

Old man Honda did do engineering work for Nippon wartime aero-industries, but I don't know if he
was into this kind of stuff, & Kawasaki did licence produce D-B V12s, but AFAIR, unlike Hitler's mob, never
actually used the hub-cannon set-up..

[Sasha]

I doubt it, but if you've got a schematic showing such to post (may be best to put it up on the engine image thread)..
.. I'll gladly stand corrected..[/quote]

I'm not saying it was common but it did happen ..... Btw I knew id read about a ww2 fighter that fired its Canon thru the crankshaft. It was the Russian yak-3

http://en.m.wikipedia.org/wiki/Yakovlev_Yak-3

And a discussion here mentions several aircraft that had crankshaft driven, (via reduction gear box's of course), machine guns.

https://groups.google.com/forum/m/#!top ... Vq91GwP4AI[/quote]

If you think about it for a moment you will realise that for a period either side of a piston's TDC its connecting rod will cover or partially cover the centreline of the crankshaft,making it impossible for a cannon barrel or bullet to pass through.

Not sure if engines actually drove mgs or cannon, but they certainly were connected for the purpose of synchronisation.[/quote]

The German MK 103,MK108 and MG151 that fired thru the DB605,DB603 and Jumo 213 was electric fired and air cocked with the shell travelling thru a hollow Crank Shaft and exiting the center of the propeller spinner.

[wuzak]

The German MK 103,MK108 and MG151 that fired thru the DB605,DB603 and Jumo 213 was electric fired and air cocked with the shell travelling thru a hollow Crank Shaft and exiting the center of the propeller spinner.

The propeller hub was offset from the crankshaft through the spur reduction gearing.





The cannon was mounted in the vee. The superchargers of the DB 60X series were side mounted for the express purpose of allowing for the mounting of cannons on the engine.

As you can see from this cutaway from the Merlin 60-series engine, there was too much in the way for a motor mounted cannon.



The only way that a cannon could fire through the crankshaft is with the impractical system Gruntguru suggested.

[djos]

I stand corrected

[autogyro]

The Klimov v12 fitted in the Yak 3 had either a 20 ,23 or 45mm cannon firing through the prop hub.
The guns were mounted in the V of the engine.
On the later Yak 3 the cockpit was moved back because of the huge recoil from the cannon that even caused oil and coolant leaks when fired.

If you fired a cannon through a hollow crankshaft, you would blow away all your con rods.