How did cannon through the hub work?

[Dave Wave]

A question for the gun guys:

Some planes like the P-39, Me-109 and others had cannon that fired through the prop hub. How did this work? Where was the cannon in relation to the engine?

Pictures would be great !

Always wondered how they did it.

Thanks in advance,

-Dave

[The Inspector]

Usually the breech was behind the engine block (except on the P-39/63 where the tractor motor was behind the pilot) and the barrel was laid along the top of the engine block and went through the upper prop reduction gearbox. Perhaps a bit difficult to envision perhaps Mark can dig out a couple photos of 109 and Bell cannon mountings.

*Edited by WIXMOD-Baker to add parentheses, to make it clear what The Inspector meant.

[51fixer]

A question for the gun guys:

Some planes like the P-39, Me-109 and others had cannon that fired through the prop hub. How did this work? Where was the cannon in relation to the engine?

Pictures would be great !

Always wondered how they did it.

Thanks in advance,

-Dave

Search this website, IIRC this was discussed a while back.

[DoraNineFan]

The gun is not firing through the center line of the crankshaft. The barrel passes through the V of the engine and fires through the propeller reduction gear and a hollow propeller hub.

[The Inspector]

The gun is not firing through the center line of the crankshaft. The barrel passes through the V of the engine and fires through the propeller reduction gear and a hollow propeller hub.

Believe I already said that

[JFS61]

Here a static display of the P-39 configuration:

[JFS61]

Inverted Daimler DB605 with tunnel for nose cannon running between the cylinder banks:

[Roger Cain]

Thanks JFS61, I've never really looked at it before either, nice link for showing it.

[Dave Wave]

So if it fires through the hub, and the hub must be hollow, how was the prop pitch controlled?

Cool pictures, thanks!

-Dave

[51fixer]

So if it fires through the hub, and the hub must be hollow, how was the prop pitch controlled?

Cool pictures, thanks!

-Dave

Aeroproducts props had an external mechanism which included oil, pump and gov built onto the prop.
No engine oil was used thus the shaft could be hollow.

[51fixer]

Chk this page for illustration on the Aeroproducts Prop on a
p-51.

viewtopic.php?f=3&t=48228&p=483288&hilit=aeroproducts#p483288

[Baldeagle]

The cannon through the prop hub was I believe first used on the SPAD XII in WW1. There's a cannon Hispano Suiza engine w/37mm cannon on display at Udvar Hazy, and apparently at the AF Museum as well:
http://www.nationalmuseum.af.mil/factsh ... sp?id=9501




SPAD XII

Little known fact, the SPAD XII had a control wheel instead of a stick because the breech of the cannon stuck back into the cockpit-



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[WIXMOD-Baker]

Thread tidied up. Please play nice!

[Sasquatch]

[muddyboots]

*angel*