Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: bustr on April 23, 2009, 02:22:02 PM
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Recently I was looking at some technical drawings of a Do335 focusing on the nose mounting of the Mk103 through the Dailmer-Benz DB-603E engine. The drawing left out one detail of the mounting, Elevation. The tube that the 30mm round travels through to exit out the spinner looks like it is fixed to the datum line, and not of a diameter to allow the Mk103's barrel itself to be raised and lowered to change the down range impact point of the 30mm round. If this is true, what is the actual range of the bore sighting in this configuration?
Are cannons that fire through the spinner in fact restricted to the axis of the spinner and cannot have their elevation changed?
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Very much more limited, yes.
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Are cannons that fire through the spinner in fact restricted to the axis of the spinner and cannot have their elevation changed?
I find this very hard to believe. This would prevent not only vertical, but lateral adjustments as well. Are you convinced that the ID of the tube thru the spinner, as well as the ID of the centerline opening in the reduction gear assembly is really that tight? You know, depending on the depth of the spinner and reduction gear, an ID of only slightly more than 30mm might still allow you significant elevation/windage adjustment by moving the rear of the gun.
Just a thought. :)
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Someone once posted info from some documents.. It had something like just 2 different angles. This was for one of the Me 109s.
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The Luft46 website states that Mk108 installations in the prop were fixed at the factory. 400 yard(meter) convergence was set and could not be changed. I'm not sure if MG151 or Mk103 installations would be the same, but I'm guessing that they would.
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Cthulhu,
I was looking at the extension tube from the barrel of the Mk103 to the spinner and thinking how littel clearance in reality you would have to work with to not have any friction from the prop and spinner assembly rotating around it. You would have to account for vibrations from many sources that could cause the spinner end of the extension tube to touch the rotating assembly. In the real world of WW2, 30mm range and accuracy in air to air engagement would have enormous forces limiting general accuracy to very close shots, or from flying straight and level lobbing at bombers from behind.
I've seen pictures of the 20mm nose cannon taken out of 109's and set on static display next to them. The barrel and receiver are long enough to equal the length of the engine, spinner and then some. So yes some movement of the breech housing anchor points would be possible to get rounds shooting straight with a bit of elevation. In the Mk103 diagram for the nose mounting on the Do335 there was an extension tube which made me wonder how much manipulation would be engineered into the overall mounting as opposed to the forces that are generated by rounds cycling through it. Most of the aircraft mountable Mk103 pictures I've seen show short barrels. I would venture the guess this is a trade off over weight to be able to use the Mk103 in a fighter.
Is it possible from responces to this thread that HiTech is being genrous to us with convergence settings available to nose mounted guns?
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You would have to account for vibrations from many sources that could cause the spinner end of the extension tube to touch the rotating assembly.
I'm guessing that muzzle deflection due to firing the MK 103 (barrel harmonics), would be greater than deflections due to all other sources at that location. If it was me, I'd just add a bushing or bearing to constrain the muzzle, and see how much it degraded accuracy. But that's just a shot in the dark on my part. You've actually seen the 335 drawings.
Is it possible from responces to this thread that HiTech is being genrous to us with convergence settings available to nose mounted guns?
I think you're right. According to Stoney (and his data is usually very accurate), the centerline mounted 108's were non-adjustable. I'd assume the spinner-mounted Mk 103 on the Do 335 would be installed the same way. So yeah, convergence should probably be locked. In fact, HTC should probably just remove the Mk 108 entirely from the german fighters. :D (Can you tell I've had my share of "tater enema's" courtesy of the Muppets?)
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Remove the 108 and replace with 103, why that's genius Cthulhu, thank you :P
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Remove the 108 and replace with 103, why that's genius Cthulhu, thank you :P
No problem, but let's keep it accurate. Shoe-horning the 103 into your Ta 152 should jam the cannon's receiver into your groin rather nicely. :D Did the Luftwaffe issue cups?
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:lol
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Cthulhu,
2006 I spent time learning the K4 courtesy of Plantano. I reached a point I could land 2-3 each sortie. Give Moot and the Muppets their due for spending the time it takes to be good with taters. I notice your complaint is only about them. Thank god most players can't hit anything with a tater. Usualy if they can't fly the K4 or Ta with finess, you know for the most part you can ignore them in a furball. The muppets have a flying style in those tater puds you can pick out in any engagement. But Cthu aren't you an elder god or sumptin like that? Just use god mode on em...... :)
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Make them turn, cut the turn. Then as far as ballistics go.. Don't hesitate. If you have a habit of thinking about the trigger before pulling it, you need to get rid of that and start over. Press anytime it seems right.. You'll waste a lot of ammo but will relearn it correctly. It's really not that hard to see or sense the gun solution after a while.. The consistently hard part is actually pointing the nose where it ought to be.
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Cthulhu,
2006 I spent time learning the K4 courtesy of Plantano. I reached a point I could land 2-3 each sortie. Give Moot and the Muppets their due for spending the time it takes to be good with taters. I notice your complaint is only about them. Thank god most players can't hit anything with a tater. Usualy if they can't fly the K4 or Ta with finess, you know for the most part you can ignore them in a furball. The muppets have a flying style in those tater puds you can pick out in any engagement. But Cthu aren't you an elder god or sumptin like that? Just use god mode on em...... :)
Bustr, if I mentioned everyone who could kick my arse in a fight, we'd be here for weeks. I'm sure I'd be adding your name to that list if the Pigs weren't so damned loyal to the perennial losing country. ;)
As far as God Mode goes, I take a more modern approach. I've got a custom skin that pushes a rootkit out to guy's machines when they fly close. Then I just make a few remote registry additions and poof! "Unexplained InstaDeath".
BTW, you really need to defrag your HD. (and you probably should move the child porn to a hidden partition) :D
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"Most of the aircraft mountable Mk103 pictures I've seen show short barrels."
I'm not sure what that means but the only shortening there was was the deletion of the muzzlebrake from engine mounted 103s. Even the engine mounted 103's barrel was as long as the whole 108 cannon, with the breech it was nearly double as long as 108.
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Is this telling me any and all nose hub cannon mounted planes should not have the ability to set the cannon fall off distance?
109's 39's .ect
If so i would like the option removed on my 39's, i don't care for gaming a game, but..for realism's sake it would be nice.
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Ammo counters, combat trim, etc.
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Is this telling me any and all nose hub cannon mounted planes should not have the ability to set the cannon fall off distance?
109's 39's .ect
If so i would like the option removed on my 39's, i don't care for gaming a game, but..for realism's sake it would be nice.
Not necessarily. The unique layout of the P-39 may mean that elevation is adjustable. Someone needs to research it to verify if it is fixed.
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Is this telling me any and all nose hub cannon mounted planes should not have the ability to set the cannon fall off distance?
The only one I feel confident about are the hub mounted Mk108. I've not seen any documentation about the others, though I suspect that while they're may be some adjustment available, its probably limited. How limited I don't know. There may be some information in America's Hundred Thousand about the P-39; I'll have to check.
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Sorry for the hijack, but how exactly was the P39's cannon mounted? The cannon's barrel going through the engine block makes sense to me, but the Airacobra's was in front of the engine, wasn't it? How was the propeller hooked up to the engine?
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I would think a drive shaft that goes through the plane into the back of the prop, then the 37mm was mounted against the front of the prop
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I would think a drive shaft that goes through the plane into the back of the prop, then the 37mm was mounted against the front of the prop
The propeller hub is like, what, one foot deep, and 2-3 feet across? No way you could fit a 37mm auto-cannon and 30 rounds of ammunition in there.
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The reduction gear is located to the nose in the P-39 allowing the canon installation.
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Guys, the crankshaft is not on the same axis as the prop for most inlines. There is an offset due to the reduction gear. The spinner mounted cannon is nestled down in the "Vee" of the engine between the two cylinder banks.
Here's a Merlin to illustrate the point:
(http://img13.imageshack.us/img13/7093/merlin1d.jpg) (http://img13.imageshack.us/my.php?image=merlin1d.jpg)
The reduction gear is located to the nose in the P-39 allowing the canon installation.
Yep, but really it's the longish distance from the firewall to the prop that let Bell get that big gun in there.
Here's a picture I found illustrating the P-39 drivetrain & cannon:
(that baby blue housing behind the prop is the reduction gear)
(http://img7.imageshack.us/img7/5994/p39drivetrain.jpg) (http://img7.imageshack.us/my.php?image=p39drivetrain.jpg)
That cannon appears to be canted up slightly doesn't it? ;)
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Cool, thanks Cthulhu! I always thought that the MK108/ MG151 just fired through a hollow drive shaft or whatever you call it.
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Cool, thanks Cthulhu! I always thought that the MK108/ MG151 just fired through a hollow drive shaft or whatever you call it.
Someone with the resource is going to post a picture or drawing I would imagine, but the Mk108 cannon installation was not set up the same way the P-39 was. The P-39 installation is rather ingenious, as it allows full manipulation of the weapon with interfering with the prop shaft. I went looking online to see if I could find the information I saw a few years ago that showed the installation; I could not find it. Regardless, I'm sure someone does, and you will see how the short barreled cannon, and the way it was wedged in with the engine, made a fixed mount pretty much mandatory.
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Someone with the resource is going to post a picture or drawing I would imagine, but the Mk108 cannon installation was not set up the same way the P-39 was. The P-39 installation is rather ingenious, as it allows full manipulation of the weapon with interfering with the prop shaft. I went looking online to see if I could find the information I saw a few years ago that showed the installation; I could not find it. Regardless, I'm sure someone does, and you will see how the short barreled cannon, and the way it was wedged in with the engine, made a fixed mount pretty much mandatory.
Agreed Stoney. I think we'll find the P-39 is the only plane with an adjustable gun mount.
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http://img111.imageshack.us/img111/6848/2smallow5.jpg
http://www.quarry.nildram.co.uk/AMgundrawJ.jpg
http://img486.imageshack.us/img486/8414/1small2io1.jpg
http://img465.imageshack.us/img465/8109/me209v5cutaway5no.gif
Quick check in Google provided these.
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