Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: BaldEagl on January 18, 2008, 10:09:27 AM
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For most of this camp, I've set aside the 190's and been trying out the 109K-4. I plan on getting around to some of the others but have been having fun in this one and feel like I'm starting to really understand it (plus, I can up it and make up for a few Spit I deaths pretty easily :) ).
This morning I was wondering about the spinner mounted cannon. I did a search and really couldn't find anything on it.
How was it mounted? I would assume it was a solid mount to the fuselage forward of the engine? How was the ammo fed? Where was it stored?
It seems to have been a bit of technical wizardry to come up with this design as I try to think it out.
Beyond that, since a mounting of this type would seem to make such obvious sense, why wasn't it used in more applications (or even cowl mounts for that matter)?
Hoping someone knowlegable in this will have some answers.
Oops... wanted to post this in Aircraft and Vehicles forum. Skuzzy, can you move it please?
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Tony Williams had a thread going about the most efficient gun and gun platform (incl. gun position) for a prop warbird. I think it was in the AC forum.
As far as I can recall, the 109 and late 190s had the hub cannon sitting behind the engine, with the barrel fitting between cylinder heads.
E.G. On the Ta152, the engine block's front face is right around the aft end of the radiator gills. There's nowhere near enough room to fit the cannon on the front end.
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Originally posted by moot
Tony Williams had a thread going about the most efficient gun and gun platform (incl. gun position) for a prop warbird. I think it was in the AC forum.
As far as I can recall, the 109 and late 190s had the hub cannon sitting behind the engine, with the barrel fitting between cylinder heads.
E.G. On the Ta152, the engine block's front face is right around the aft end of the radiator gills. There's nowhere near enough room to fit the cannon on the front end.
That's what I've read, as well-the Propellor reduction gear in front has an opening through the middle, which goes' straight through the prop and hub itself.
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The hub firing cannons actually fired through a hollow crank shaft in the engine. The weapon was mounted directly behind the engine.
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Both Daimler Benz and the french Hispano Suiza firms designed their V12 fighter engines to allow a gun to fire through the centreline of the propeller. IIRC the Soviet Klimov engines were derived from the Hispano Suiza engine.
The gun barrel would sit in the vee of the engine with the breech and ammo behind the engine and supercharger. The engine's crankshaft drove the propeller shaft through a gear reduction and the propshaft itself was hollow to accept the gun blast tube.
One drawback of the arrangement was awkward packaging of the supercharger behind the engine compared to say the Merlin, where the supercharger casing merged into the crankcase of the engine.
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One interesting detail is that the 109 engines were inverted... meaning the cylinders were pointing downwards.
http://en.wikipedia.org/wiki/Daimler-Benz_DB_603
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Originally posted by Hornet33
The hub firing cannons actually fired through a hollow crank shaft in the engine. The weapon was mounted directly behind the engine.
Have you ever seen a crank shaft before? Unless they have magical bullets I don't see that one working out so well.
(http://i66.photobucket.com/albums/h252/Geary420/random%20shizzle/crankshaft.jpg)
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From a book I have about the Bf 109
Engine: DB601A ( DB 605 ACS or DB605 DC for the K 4)
Year: 1937
Type: 12 cylinder inverted 60 degree Vee supercharged liquid cooled engine
Bore: 150 mm
Stroke: 160mm
Total swept capacity:33.9 liters (2069 cubic inches)
Compression ratio: 6.9:1
Fuel: 92 octane
Maximum RPM: 2400
Reduction gearing: 1 : 1.55
Dry weight: 610 kg (1,344.7 lbs)
Lenght: 1352 mm (4 ft. 5 1/4 inches)
Width: 705 mm (2 ft. 3 3/4 in)
Height:1,027 mm (3ft. 4 1/2 in)
Takeoff power: 1,100hp.
Max continuous power: 960hp @ 5,000m (16,400ft)
The inverted V engine allowed the spinner hub cannon to fire between the cylinder heads, and the cowl mounted MG's to fire alongside the crankcase.
Impressive, but it must have been hell on the ground crews.:)
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Interesting. I always thought one of the drawbacks (in accuracy) of the wing-mounted 30mm cannons was supposed to be their relatively short barrels in the FW varients.
This would indicate that the 109's used much longer barrels and should, therefore, be more accurate. Does anyone know if this is true?
I also find the inverted engine interesting. It makes me wonder how they kept it from flooding the (normally) upper engine with oil.
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Originally posted by BaldEagl
Interesting. I always thought one of the drawbacks (in accuracy) of the wing-mounted 30mm cannons was supposed to be their relatively short barrels in the FW varients.
This would indicate that the 109's used much longer barrels and should, therefore, be more accurate. Does anyone know if this is true?
The barrel is not longer in engine mounted guns.
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Originally posted by BaldEagl
Interesting. I always thought one of the drawbacks (in accuracy) of the wing-mounted 30mm cannons was supposed to be their relatively short barrels in the FW varients.
This would indicate that the 109's used much longer barrels and should, therefore, be more accurate. Does anyone know if this is true?
I also find the inverted engine interesting. It makes me wonder how they kept it from flooding the (normally) upper engine with oil.
Side oilers.
Think of motor cycles. Older ones have dry sumps, a pump pumps oil from a seperate tank through the engine and back to the tank.
No oil flooding that way.
Same on some of the 427 "side oiler" Ford motors.
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Lusche, are you sure about that? The MK108 was designed (IIRC) as short-barreled as it was to adress issues with the original longer barrel version's barrel related problems.
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Originally posted by Lusche
The barrel is not longer in engine mounted guns.
Can you explain this? If the gun (striking mechanism) is actually mounted behind the engine and the muzzle is in the front of the spinner, wouldn't that then be a barrel traversing the distance from the actual gun to the muzzel? Unless the part about the gun being behind the engine is wrong.
Which brings up another question... was this entire span rifled?
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Originally posted by BaldEagl
Can you explain this? If the gun (striking mechanism) is actually mounted behind the engine and the muzzle is in the front of the spinner, wouldn't that then be a barrel traversing the distance from the actual gun to the muzzel? Unless the part about the gun being behind the engine is wrong.
Which brings up another question... was this entire span rifled?
No, because it wasn't the barrel.
The actual barrel muzzle is not at the spinner.. it's inside the plane:
(http://www.bredow-web.de/Luftwaffenmuseum/Historisch/Bf_109_G-2/Rheinmetall-Borsig_MK_108/a_Bordnetz_Bf-109.jpg)
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Thanks Lusche. Great diagram.
One last question then. Was there something to guide the bullet to the spinner? Surely it didn't "free-fly" from the muzzel. That would seem pretty dangerous while manouvering but it would also seem that any type of "guidance" would also have an adverse effect and would have to be within pretty close tolerences.
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Originally posted by BaldEagl
Thanks Lusche. Great diagram.
One last question then. Was there something to guide the bullet to the spinner? Surely it didn't "free-fly" from the muzzel. That would seem pretty dangerous while manouvering but it would also seem that any type of "guidance" would also have an adverse effect and would have to be within pretty close tolerences.
As far as I know it's just a hollow tube. Any kind of "guidance" would not be different from being a barrel itself.
Remember that even a slow MK108 round has a minimum muzzle velocity of 500 m/s. Even when assuming that the distance between end of actual barrel and the muzzle at the spinner is 2m (probably more like 1m), the round would need only 0.004 seconds for that distance.
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Originally posted by BaldEagl
Thanks Lusche. Great diagram.
One last question then. Was there something to guide the bullet to the spinner?
On Yaks and Lagg3's the barrel protruded right thru the spinner.
Particularly noticable on the Yak9T (even more so on the 45mm version)
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There would have been a blast tube from the barrel to the end of the spinner to protect the engine from the muzzle blast.
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Originally posted by Geary420
Have you ever seen a crank shaft before? Unless they have magical bullets I don't see that one working out so well.
(http://i66.photobucket.com/albums/h252/Geary420/random%20shizzle/crankshaft.jpg)
Sorry was thinking prop shaft when I wrote that....oppps
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See here:
http://forums.hitechcreations.com/forums/showthread.php?s=&threadid=194726
And here (2nd link in 1st post):
http://www.xs4all.nl/~rhorta/wk4.htm
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Oddly enough, once the cannon was mounted, its BZO couldn't be changed. I believe the factory range was set for 400 meters. And yet, we can move the distance in or out in AH.
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Originally posted by Hornet33
The hub firing cannons actually fired through a hollow crank shaft in the engine. The weapon was mounted directly behind the engine.
I've always had a problem with that explanation.
If it ACTUALLY passed through the crank shaft of a DB engine then that is one strange shaped crankshaft!
And I've seen pictures of a DB crankshaft.
Don't think it's possible!
Why? Take a look at a CRANKSHAFT!
If you try to put something straight through a crankshaft then the piston rods, as they CIRCLE around will hit it, OR the crankshaft will NOT turn.
Most pictures I've seen the engine is inverted and the cannon LOOKS like it might pass through the oil pan, but looks more like it sets just above the crankshaft and passes through the reduction gear.
If I'm wrong PLEASE show me a picture of said creation.
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You have it right Wrag. The barrel passed thru the "lifter valley", between the cylinders and through the reduction assy. Although it seems, when I'm at the rifle range, the barrel of my Garand IS running thru a crankshaft. :D
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(http://rockford.yi.org/graphics/engine.jpg)
(http://rockford.yi.org/graphics/guns.jpg)
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Originally posted by Wayout
(http://rockford.yi.org/graphics/engine.jpg)
(http://rockford.yi.org/graphics/guns.jpg)
Thats like porn to aerophiles... (http://www.blackmustangclub.com/forum/images/smilies/drool.gif)
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In both the DB 601 and the DB 605, the most common versions, the cannon was installed behind the engine. Rounds fired passed through a blast tube located in the V of the block, between the cylinders and heads. Rounds exited through the hollow prop shaft in the reduction gear.
The image below is an early 109F-1, with the 15mm cannon installed. the 20mm was installed in like manner.
(http://www.geocities.com/capecanaveral/hangar/8217/fgun/bf109-b.jpg)
This image shows the DB 601 turned upside down. You can see the propshaft centerline is outside the engine block. A tube is installed in the V, through the propshaft.
(http://upload.wikimedia.org/wikipedia/commons/2/2e/DB_601_-1.jpg)
In this last image, you see a cut-away DB 601. You can clearly see that the crankshaft is well above the centerline of the propshaft.
(http://upload.wikimedia.org/wikipedia/commons/a/a7/Daimler-Benz-DB_601A_Schnitt.jpg)
My regards,
Widewing
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Thank you all. Very informative and answered most of my questions.