Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: vafiii on January 03, 2011, 05:14:00 PM
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Anyone have any drawings of the 109 engine? I'm curious to see how they were able to run the cannon through the engine block. Couldn't find much on-line on the subject. Thanks.
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ho and also explain us how is can get damaged from ack fire while the rest of the engine is ok :D
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ho and also explain us how is can get damaged from ack fire while the rest of the engine is ok :D
or when you get shot from behind and above..... if hits the cannon, with out hitting the engine or the pilot (the nose cannon is between the pilots legs)? :headscratch: :headscratch: :headscratch:
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(http://2.bp.blogspot.com/_hf92i8rLnrE/TPb0BmTC05I/AAAAAAAAAGg/o44wOd7fvwU/s1600/Meserschmidt109.SpareEngine.jpg)
Here you can see the hollow propeller shaft, through which the gun is firing, the crankshaft is located above.
(http://www.aviation-history.com/engines/db601na.jpg)
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Lusche,
Looks like that engine is sitting in someones dining room....yours perhaps? :D
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Lusche,
Looks like that engine is sitting in someones dining room....yours perhaps? :D
I don't even have a dining room :noid
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Is that a 20mm or 30mm cannon attached to that DB?
Looks like people have provided you with some of the best visual aids. As you can see the crankshaft rotates the propeller shaft which is hollow and runs through the entire engine. On the rear-end of the engine is mounted the cannon that fires through the hollow propeller shaft that runs through the entire block. From there it's on to the propeller and the hub. The cannon's barrel sits stationary inside the hollow rotating propeller shaft and the entire cannon assembly is mounted to the engine block.
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K-4 is a 30 in the nose, right?
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Some pics to help you if you still don't have it.
(http://i469.photobucket.com/albums/rr52/existentialvoid/70.jpg)
This is what it looked like behind the engine - that block thee would have a casing on it which is that block you see betwen your legs when you sit inside the cocpit of the 109. When you fired that cannon, it must have really been quite a sensation to basically have the gun shooting off between your legs. . . no pun intended.
(http://i469.photobucket.com/albums/rr52/existentialvoid/47.jpg)
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Is that a 20mm or 30mm cannon attached to that DB?
Looks like people have provided you with some of the best visual aids. As you can see the crankshaft rotates the propeller shaft which is hollow and runs through the entire engine. On the rear-end of the engine is mounted the cannon that fires through the hollow propeller shaft that runs through the entire block. From there it's on to the propeller and the hub. The cannon's barrel sits stationary inside the hollow rotating propeller shaft and the entire cannon assembly is mounted to the engine block.
In Luche's photo of the engine in the blue frame it is a 20mm Mg151/20. The shaft that the barrel (or shells in the case of the Mk108) passed through did not rotate, in Luche's cutaway diagram the left side was the place the cannon attached and the right side where the propeller was fitted. The gears you can see at the rear of the engine around the cannon tunnel are the cam drive gears (by way of the supercharger drive). The key is that the crank is on a higher level than the barrel which ran through the vee of the engine (inverted) and the reduction gear makes the hub concentric with the cannon.
I wonder at what distance the gun sight aligned with the shot in the actual aircraft (convergence)? The connector doesn't look adjustable to me.
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or when you get shot from behind and above..... if hits the cannon, with out hitting the engine or the pilot (the nose cannon is between the pilots legs)? :headscratch: :headscratch: :headscratch:
:huh :noid :bolt:
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Is that a 20mm or 30mm cannon attached to that DB?
Looks like people have provided you with some of the best visual aids. As you can see the crankshaft rotates the propeller shaft which is hollow and runs through the entire engine. On the rear-end of the engine is mounted the cannon that fires through the hollow propeller shaft that runs through the entire block. From there it's on to the propeller and the hub. The cannon's barrel sits stationary inside the hollow rotating propeller shaft and the entire cannon assembly is mounted to the engine block.
You seem very knowledgeable about this subject. Wanna come help me work on my Lycoming? I was thinking about some "extra" additions...
:devil
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that is... wow...
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"I wonder at what distance the gun sight aligned with the shot in the actual aircraft (convergence)? "
IIRC the standard convergence for guns was 450m. The shots went above the sight line at 50m and dropped below at 450m. There's a diagram of it somewhere.
-C+
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Great stuff! Thanks!
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Thanks Charge, like to see the diagram sometime if you come across it. I have a larger scale version of Luche's cutaway where you can read the labels if anyone's interested.
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...As you can see the crankshaft rotates the propeller shaft which is hollow and runs through the entire engine...
I don't *think* the prop shaft runs all the way to the rear of the engine... why would it? The only thing that needs to run more slowly than the engine crankshaft is the propeller... right? From the photos and diagrams that I've seen - including these - I think that the reduction gear housing on the front of the engine and the prop shaft *are* hollow. The gun barrel does not pass through the engine block, rather in between the two banks of the inverted V-12 and then through the reduction gear housing and the prop shaft. The axis of the propeller is below the axis of the engine crankshaft.
I *think*...?
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:rofl I went to the Doctor today to see why people keep ignoring me, and he said 'Next!'.
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Well if the blast tube didn't run in the V, then I would like those that think it didn't explain to me how the pistons and crankshaft were connected.
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I don't *think* the prop shaft runs all the way to the rear of the engine... why would it? The only thing that needs to run more slowly than the engine crankshaft is the propeller... right? From the photos and diagrams that I've seen - including these - I think that the reduction gear housing on the front of the engine and the prop shaft *are* hollow. The gun barrel does not pass through the engine block, rather in between the two banks of the inverted V-12 and then through the reduction gear housing and the prop shaft. The axis of the propeller is below the axis of the engine crankshaft.
I *think*...?
As the reduction gear has to be off-set from the crank shaft, and the barrel is center-line with the prop nose-cone, you have to be right, mechanically! :salute :cheers:
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ok, more pics to help (and because its a cool engine)
(http://i469.photobucket.com/albums/rr52/existentialvoid/61.jpg)
and this
(http://i469.photobucket.com/albums/rr52/existentialvoid/60.jpg)
the gear is in the front for sure. its basically upside down. . . and the shaft runs between the V which is more an A.
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Here is a nice picture how it was done in H.S.12Y (Klimov M100 and M105):
(http://mig3.sovietwarplanes.com/I-17/hs12y2.jpg)
-C+
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Great images. Thanks for posting! :aok
Looks to me like the gears at the rear of these Daimler-Benz engines drove things like the supercharger and the intake/exhaust valves. And with proper bevel gears and shafts! No wimpy, weak chains for DB!
Even though the hub gun did not run through the engine block, it still must've gotten pretty toasty, snuggled up inside the apex of the engine's V.
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The DB series engine is an overhead cam design. However the engine block was still cast with a through hole where the camshaft for a conventional push rod set up would go. The cannon barrel went through this hole. The cannon could not be adjusted for elevation but fired straight ahead.
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trap78,
If you can provide documentation for the fact that the cannon could not be adjusted for elevation and then what that limited the real world impact point range to, HTC could coad that and eliminate the range adjustment in the hanger. Would be interesting to know how many hub mounted cannons in WW2 had no elevation adjustment due to the their relationship with the engine.
Or country specific data to what range their hub mounted cannon was set to.
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The DB series engine is an overhead cam design. However the engine block was still cast with a through hole where the camshaft for a conventional push rod set up would go. The cannon barrel went through this hole. The cannon could not be adjusted for elevation but fired straight ahead.
the engines were mounted inverted to allow passage of a gun barrel
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trap78,
If you can provide documentation for the fact that the cannon could not be adjusted for elevation and then what that limited the real world impact point range to, HTC could coad that and eliminate the range adjustment in the hanger. Would be interesting to know how many hub mounted cannons in WW2 had no elevation adjustment due to the their relationship with the engine.
Or country specific data to what range their hub mounted cannon was set to.
wouldn't make a difference, almost all of the = 109 tator pilots, use the closest avail convergence, which I assume is the gun being level.
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I'll should still have the reference material on the DB engines around here somewhere. I'm not posting for a code change. But think about the amount of drop a 30mm or 20mm projectile has at 200 or 300 yards. It's going to take some significant elevation adjustment to compensate for that. If you've ever seen a 109 with the engine panels off everything is a very tight fit. How are you going to angle the barrel up that much without moving the propeller assembly?
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I'll should still have the reference material on the DB engines around here somewhere. I'm not posting for a code change. But think about the amount of drop a 30mm or 20mm projectile has at 200 or 300 yards. It's going to take some significant elevation adjustment to compensate for that. If you've ever seen a 109 with the engine panels off everything is a very tight fit. How are you going to angle the barrel up that much without moving the propeller assembly?
The gunsight moves too.
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Posted by Blooz:
The gunsight moves too.
Okay, this makes sense. You adjust your aim point as opposed to mechanically moving the barrel. Just like adjusting the scope on a hunting rifle right?
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According to this website, the Mk 108 was fixed in the engine with a conversion of 400m...
http://www.luft46.com/armament/mk108.html
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The gunsight moves too.
How is that accomplished?
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Interesting article Stoney. Evergreen Air and Space museum is about an hour from my home. They have a 109G-10 manufactured in Austria in early '44. I'll have to make a trip up there to check out the bird and ask a few questions. I used to be a volunteer there. I also seem to remember the 109 having a rudder trim tab as well. The tab wasn't adjustable in the cockpit but rather "fixed" and could be bent to the desired angle with a special tool. Technicians at the factory would set the trim tab angle to the manufacturer's spec and once in the field, pilots could have their mechanics make additional adjustments until the aircraft felt right to them.
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Looking at it again the barrel must have been fixed. Direct your attention to the H-shaped cylindrical connection flange on the front of the cannon and then look at the diameter of the airscrew shaft at the frontmost part of the engine. Not enough room to even shim the bore up and down. You can't move the 'propeller assembly' because it's constrained by the airscrew reduction gear.
I'd imagine the barrel was fixed during manufacture and then the sight adjusted to suit. A subordinate advantage might be more accuracy (or should I say less dispersal of shot?) due to the cannon being rigidly mounted to the engine That has to be superior to wing mounting. Wonder if this announces in tests on a target in Aces High with the same armament (Bf109 / FW190 for instance)?
Cams are gear driven in the Merlin engine also.
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So with a hub mounted cannon that is bore aligned with the engine datum line between the cylanders, 20mm or 30mm. What is the point of impact range for the center of the graticule in Aces High?? Shouldnt that be set at the factory and unchangable versus a P38 or 262?
I have not seen references to reflector gunsight's bore sight center dot having a dial to allow raising or lowering it like you would for drop compensation in a rifle scope. They all seem to be line of sight to infinity for a standard torso hight human's eye and the guns are raised or lowered to achive a bullet dropping or crossing onto the line at known distances. The ring can be adjusted in diameter for distance gauging against wingspan or some set of dots or bars. There is the ability to adjust the angle of the reflector plate to lower the bore pipper on some to fire rockets or drop bombs.
The cowl MG can be adjusted for distance. But, I will ventur most hub cannon are set at the factory and left alone. So again what is the datum line bore range of the hub cannons seen by the graticule pipper? On 109 the lower stadia lines in the Revi vertical bar would seem to become very important to placing the hub cannon rounds on target.
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So with a hub mounted cannon that is bore aligned with the engine datum line between the cylanders, 20mm or 30mm. What is the point of impact range for the center of the graticule in Aces High?? Shouldnt that be set at the factory and unchangable versus a P38 or 262?
I have not seen references to reflector gunsight's bore sight center dot having a dial to allow raising or lowering it like you would for drop compensation in a rifle scope. They all seem to be line of sight to infinity for a standard torso hight human's eye and the guns are raised or lowered to achive a bullet dropping or crossing onto the line at known distances. The ring can be adjusted in diameter for distance gauging against wingspan or some set of dots or bars. There is the ability to adjust the angle of the reflector plate to lower the bore pipper on some to fire rockets or drop bombs.
The cowl MG can be adjusted for distance. But, I will ventur most hub cannon are set at the factory and left alone. So again what is the datum line bore range of the hub cannons seen by the graticule pipper? On 109 the lower stadia lines in the Revi vertical bar would seem to become very important to placing the hub cannon rounds on target.
I'm with bustr on this, I build a 109 from scratch, albeit an RC plane, but I did it by looking and basing my plans of what I could find on the internet. What I found was...
1) the nose cannons were fixed, and could not be adjusted... made them more accurate but less flexible.
2) its a super tight fit, and the cannon itself is right in front of the stick, between the pilots legs. The cannon, is behind the engine, with part of the barrel being the shaft through the engine. I'm assuming that the longer barrel increased accuracy?
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There had to be some adjustment for the Mk108 due to manufacturing tolerances between all the components (engine, motor mounts, blast tube and so on).
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Well, you may be right Milo, but what sort of adjustment? Certainly not one that would allow for a wide range of convergence. I would assume any "slop" in the mount would be merely to account for those manufacturing tolerances, not to allow pilots to adjust the convergence of the rounds. Given that the round is passing through the propeller shaft, I can't see there being a lot of variation allowable. Once the thrust line of the engine is set in the mounts, so to goes the trajectory of the cannon rounds. I.e. you can't change the trajectory without changing the thrust line of the engine. That could only be done by adjusting the engine mounts, but ultimately, the thrust line needs to be within whatever the factory specs dictate, otherwise you'd get some pretty wild performance variation out of the engine, right? While this certainly provides the gun with a much more stable mount, changing the convergence would not be possible. If someone has data that shows the thrust line of the engine, it would show what the initial trajectory would be. Obviously, the 110/163/262/190 mounts wouldn't suffer the same limitation.
Now, that being said, I don't have any serious heartburn with the way its modeled in-game, but I also would respect a choice by HTC to fix the convergence much like the 75mm on the B-25H.
[edit] And that page I linked above doesn't contain the 400m convergence setting I listed. It does support the lack of adjustment for "harmonization" I stated. I'll have to look around to find the information that stated a 400m convergence setting.
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The only point that of interest is the point at which the shell exits the prop spinner. The 50mm blast tube could be move in the x-y axis as could the MK108 as long as it was a straight line. The thrust line of the engine only sets the general line of the trajectory.
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Posted by MiloMorai
The 50mm blast tube could be move in the x-y axis as could the MK108 as long as it was a straight line.
Do you have any photos, drawings, etc. showing how this could be done so as to compensate for bullet drop at 200+ yards?
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Respectfully, I think the tolerances in mounting the cannon and having it fire through the cannon tunnel accurately are a good deal less critical than those within the engine and easily within reach of precision manufacture.
The most natural solution is to mount the cannon rigidly to the engine to take advantage of the mass to dampen the recoil and take advantage of the engine mountings, and then to make the gunsight adjustable to suit an optimal setting or a pilot preference.
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(http://i205.photobucket.com/albums/bb107/ZorinW/mk108.jpg)
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^
This looks like a ballistic chart for several different cannon rounds. If there's anything you can add in the way of an explanation of what the data means I'd be interested to hear it.
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^
This looks like a ballistic chart for several different cannon rounds. If there's anything you can add in the way of an explanation of what the data means I'd be interested to hear it.
It's a chart that shows the BF109g6 with 20mm gondolas line of fire as it relates to the line of sight.
The straight diagonal line from upper left to lower right is the pilots line of sight. Each curved line is a different ammo from the place it starts on the plane out to about 450 meters range. The dashed lines are above the line of sight. The numbers at left are the drop in centimeters. Range is across the top in hundreds of meters.
The 109g6's 30mm and the 13mm's are dead on at 400 meters. That's the "zero". The 20mm's are on at about 140 meters and are still above the line of sight at 450 and dropping back to the line of sight at probably 500 or so.
You'll notice that all converge at 275 - 300 meters. If the pilot raises his pipper up a bit, all his weapons would be dead on his gunsight at 275 meters.
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i think that the cannons and mg's had the engine built around them...not sure tho
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It's a chart that shows the BF109g6 with 20mm gondolas line of fire as it relates to the line of sight.
Okay cool thanks for the explanation. Then this graph tells us that a MG 151 round would drop about 100cm (39 inches) at 200 meters and about 180 cm (70 inches) at 300 meters. So my question is could the hub cannon be angled up enough to compensate for this trajectory. I'm guessing no but will have to verify this to be sure. The machine guns definitely had x-y adjustments for harmonization. I don't know a whole lot about the Revi sight but in the pictures I've seen there didn't appear to be an elevation adjustment.
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Okay cool thanks for the explanation. Then this graph tells us that a MG 151 round would drop about 100cm (39 inches) at 200 meters and about 180 cm (70 inches) at 300 meters. So my question is could the hub cannon be angled up enough to compensate for this trajectory. I'm guessing no but will have to verify this to be sure. The machine guns definitely had x-y adjustments for harmonization. I don't know a whole lot about the Revi sight but in the pictures I've seen there didn't appear to be an elevation adjustment.
Here's a quick-and-dirty translation of the important parts of the chart based on my spotty German abilities. It's not completely translated but I think the rest of it is fairly obvious or not really relevant to the discussion.
(http://i156.photobucket.com/albums/t5/AK_Comrade/bf109G6u4weaponstrajectories.png)
You can see that the MK108 30mm motorcannon not only is angled up high enough to intersect the sight line, it barrels over it and then drops back down. The MG151's are in wing gondolas and thus don't really matter for this discussion.
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Okay cool thanks for the explanation. Then this graph tells us that a MG 151 round would drop about 100cm (39 inches) at 200 meters and about 180 cm (70 inches) at 300 meters. So my question is could the hub cannon be angled up enough to compensate for this trajectory. I'm guessing no but will have to verify this to be sure. The machine guns definitely had x-y adjustments for harmonization. I don't know a whole lot about the Revi sight but in the pictures I've seen there didn't appear to be an elevation adjustment.
lol...you had it right two pages ago when you realized that it's the same as a hunting rifle with a telescopic sight. When sighting a rifle, you don't move the barrel to make the bullet intersect your line of sight, you move the sight to intersect your line of fire at a certain known range. That's what his chart is for. It gives the pilot the ability to know where the bullets are (high or low) for the different ammo types at different ranges. The amount of drop doesn't matter. What matters is how far the bullets are from the line of sight. In this case, at 300 meters, the bullets of all three calibers are about 60 centimeters (30 inches?) above the line of sight. So if a P51 was at 300 meters range the only need to put the pipper at the base of the Mustangs tail to get good hits with all weapons. If the P51 were at 400 meters, the 30mm and 13mm guns would hit with the pipper dead center of the target.
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If the 30mm was angled up the line of fire would curve up. No. The 30mm starts at 0 on the chart and the line of sight starts at about 70 cm above it (at the gunsight in the cockpit). The pilot is actually looking down through the lines of fire (shown by the line of sight line) and the bullets are arcing down (none go up) through the line of sight.
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(http://i205.photobucket.com/albums/bb107/ZorinW/mk108.jpg)
But we're still looking at a fixed convergence for the Mk108 at 400m, right?
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80cm = 31.496 inches
Average person's eye is aprox 80cm up from the seat of his chair.
Revi is fixed at 80cm up level with your eye so you can look to infinity.
The Revi3, 12 and 16 series had a virtual reflected light ring the was equal to a 450mm dia iron ring at about 18 inches from your eye. Or on the reflector glass itself a ring about 45mm - 50mm in diameter 18 inches from your eye.
The piper is fixed on the Revi. Maybe its housing mounts could be shimed a bit but, the reflector gunsight is just a dot at your eyeline to infinity. In the included chart it looks like the pilots line of sight is at an angle down over the top edge of the engine to about 400 meters. Or if he aims using the lower stadia ticks on the vertical line of the Revi16b graticule the first tick down would be about 200 meters for the Mk108.
I've seen one of these charts for the FW and the sight line is level out while the MG and cannon are set to arch up to the sight line. With a Mk108 in the nose of a 109 it would seem all of the MG and 20mm are set to drop their rounds rapidly out of the barrel to try and harmonise with the very rapid drop of the 30mm. The sight line's down angle to 450 meters would indicate the pilot expects to start aiming with the lower stadia marks on the verticle graticule line.
The game seems to auto level the convergence sight line for us with the MK 108 in a hub mounted configuration rather than force us to remember to aim with the lower stadia marks. Unless they elevated the Revi in the 109 and fitted a Berlin phone book under the piolts kester to raise his eyeline over the nose of the plane while flattening the top of his head to fit up against the top of the canopy. Or the late war luftweenie's were all circus midgets.....
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Does anyone have this chart but with a 20mm HUB cannon?
My thought being that the Revi and PBP russian graticules have a primary cross with stadia marks in both. Both are used with hub mounted cannon which look to not have much ability to be elevated from the engines datum line. This would mean shots past 250 meters would require aiming asistance in the form of bullet drop compensation marks. If so, HTC should have the HUB cannons fixed on the 109, 152 and Yak at about 250 meters and we learn to use the stadia marks.
Unless they were put in the graticules like some of us hang fuzzy dice from our rear view mirrors.
On one of the WW2 Warbirds forums I read a comment that 109 20mm hub cannons were fixed at 400 meters from the factory. But, thats in effect anecdotal information. The chart provided in this post shows the tragectory of the MG 151/20 dropping away rapidly at about 250 meters even if you were to superimpose its line up 40cm to the 0-datum line. You would still be aiming for the top of the rudder with the center of the graticule or placing the first stadia mark down dead center at 200-250 meters.
It would be an interesting addition in the hanger to have charts like this one generated when we adjust convergence that could be pulled up. Even have it show in real time above the aircraft and as you change the convergence the chart changes with it.
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The only point that of interest is the point at which the shell exits the prop spinner. The 50mm blast tube could be move in the x-y axis as could the MK108 as long as it was a straight line. The thrust line of the engine only sets the general line of the trajectory.
Milo, I've read that the blast tube was 70 mm, either way having a larger blast tube might have allowed some positive/negitive adjustment at the mount. I've been looking for reference on this but it seems difficult to obtain.
I hope to check with Mr.Baumer to see if he has any reference material on the subject,he has some excelent balistics and convernce settings for the FW.
:salute
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From: Schliephake
The problem with fitting large guns in engine mountings was that there had to be enough space between the back of the engine and the pilot's seat to fit the gun breech and ammunition magazine. The gun barrel wasn't a problem - there was lots of length running from the back of the engine to the prop - as long as it was less than 70mm wide (the diameter of the tube running between the cylinder banks of the 109). The problem with the MK 103 was that there was a gas duct running alongside the barrel for part of its length, and this meant that the barrel couldn't fit in the tube. The MK 103M was redesigned to avoid the need for the gas duct, so the entire barrel could fit within the 70mm tube through the engine.
http://www.ww2aircraft.net/forum/weapons-systems-tech/luftwaffe-cannons-machineguns-topic-6368-13.html
If you account for barrel wall thickness to handel preassure and not rupture, I'm betting the 70mm allowence throught the DB605 cylanders does not allow alot of play if you want to keep a straight line to get the rounds out of the extension tube. A few pages back on the forum I linked is a MK108 with adaptor for mounting in a 109. Question would then be based on the adaptor.
Is the tube running between the cylanders fixed in place with no adjustment thus requiring the adapter to mate the MK108 barrel to the tube inline to the engine 0-datum line?
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Doesn't that information pertain to the MK103? I think that was only fitted to the Do 335 and was too big for the Bf109. The Mk108 was an APIB system and hence really stumpy. I think only a tiny piece of the barrel protruded into the cannon tunnel, unlike the Mg151/20.
Yup the tube / tunnel has to be fixed, look again at the gears fore and aft.
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(http://img524.imageshack.us/img524/3166/daimlerbenzdb601n.jpg)
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Milo, I've read that the blast tube was 70 mm, either way having a larger blast tube might have allowed some positive/negitive adjustment at the mount. I've been looking for reference on this but it seems difficult to obtain.
I hope to check with Mr.Baumer to see if he has any reference material on the subject,he has some excelent balistics and convernce settings for the FW.
:salute
It is quite possible it is 70mm as it was a looong time ago when told the size of the blast tube.
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I checked with Mr Baumer and he said he doesnt have anything definitive on the subject,his TA152 manual doesnt even cover this!
Milo,NP. I suffer from the same problem,I call it sometimers,you remember sometimes...... :lol :lol
:salute
PS: I never did find that reference to the JG that requested the gondies be removed from their K4's, So we're even :rofl :rofl :rofl
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I have a copy of Janes 1945/46 edition with a section on engines in the back. Dailmer Benz engines had hollow airscrew shafts with a square mounting flang on the back end of the shaft. If the engine was used in a multi engine mount or a none hub cannon mount a cover was bolted over it.
The flang and it's four bolt points make me think the cannon is solidly fixed along the 0-datum line of the engine so that there is no chance of the barrel rubbing on the inside of the rotating hollow shaft introducing unncessary vibrations to the engine or prop.
I'm not sure if the square flang rotates with the hollow shaft or the hollow shaft rotates inside of it via a race bearing of some type.
Half way down the page here is a picture of the MK108 with a DB605 shaft adaptor.
http://www.ww2aircraft.net/forum/weapons-systems-tech/luftwaffe-cannons-machineguns-topic-6368-7.html
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Check the picture of this DB605 with motorkanon attached. I beleive the cannon is fixed to the 0-datum line of the DB605 via the hollow prop shaft so the convergence is fixed at the factory. Probably around 275-350 meters for a 20mm depending on ammo. You can calculate the drop for a 30mm based on the graph for the G6 in this thread. Probably 250 meters for the MK108.
http://historicaviationjournalandmarketrepo.blogspot.com/2010/12/for-sale-messerschmitt-bf-109-lake-find.html
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...the barrel rubbing on the inside of the rotating hollow shaft...
(http://i1043.photobucket.com/albums/b434/trap78/DB605Drawing.jpg)
I noticed this the other day; the crankshaft is geared to drive the supercharger which in turn is geared to the "cannon tunnel" which then appears to drive the overhead cam via a shaft. It seemed to me the cannon tunnel would have to rotate at one-half the crankshaft speed (most likely) for this to work.
(http://i1043.photobucket.com/albums/b434/trap78/EngineBlockDB605.jpg)
This is a good picture of the bare block with the front of the engine facing towards us. It shows what looks to me like the through hole cast as part of the block that housed the cannon barrel. This is where a camshaft would have gone in a conventional push rod design. Since the DB was an overhead cam arrangement this "tunnel" could be utilized for the placement of the cannon barrel.
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Great links bustr.
It's way more logical in design terms to fix the cannon to the engine without any recourse for adjustment, and then simply adjust the sight, similar to a rifle as many posters have observed.
The four bolt flange was fixed (I mean non-rotating) as it also served as the bearing surface for the cam drive gear set. If the cannon tunnel had an actual blast tube within it there would be absolutely no need for it to rotate.
Hopefully this picture will help. It's from a Jumo engine manual but the similarities are sufficient. It illustrates both the cam gear (right side of the picture) and the prop reduction gear (left side of the picture). You can see the cam drive gear is just a ring which would have rotated around what would be the four bolt flange shaft on the DB engine. Sorry the picture is a little small:
(http://img811.imageshack.us/img811/458/j28k.jpg)
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Then the fixed four bolt flang being ridgid seems to make it clear that the cannon is locked to the 0-datum line of the engine. Only thing now would be to suggest that cannon in german plane HUB mountings be set to the 0-datum line with no adjustment.
After all the Revi graticules were changed to include stadia marks after the 109E Revi3c version when the motorkanon became standard armament with the 109F series that used the ReviC/12. Below center inside of the 50mm ring two stadia marks became standard which probably aproximate to roughly 400 meters and 600 meters off the engines 0-datum line.
My early comment about the Yak and its graticule referenced to stadia lines because the Yak has a HUB cannon. I wonder if any of our audience has schematics showing the russian engine/HUB cannon configuration to see if they also had a fixed flange.
If the flange is fixed and ridgid, I wonder why we have the ability to change the HUB cannon's convergence in the hanger??
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If the flange is fixed and ridgid, I wonder why we have the ability to change the HUB cannon's convergence in the hanger??
Well, we could ask HTC, but I'd assume it was for simplicity/omitted detail.
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While we're on the topic of 109s, I want my two radiators! :cry
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While we're on the topic of 109s, I want my two radiators! :cry
:aok :aok :aok
With the shutoff valve between them...
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Well, we could ask HTC, but I'd assume it was for simplicity/omitted detail.
Since the 109 and 190 seem to be the most piciunely argued over for detailed accuracy in the games aircraft offerings. This point would fit nicely with that venue and give the expertin another badge of courage in their kit for the super human requirments to master the "Way of the Jagdflieger".
But then again check this picture: http://ww2db.com/image.php?image_id=10369
My whole effort at research could be to nill by this gentelman and his bore sighter. Or he could be using it to make sure the cannon is centered in the 70mm tube.
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Remember that bore sighting is aligning the center of the barrel with a target at a specific distance. Since the technician in the photo can't look down the cannon barrel from the breach end he uses that nifty tool that allows him line up the center of the barrel with the target visually. The next step would be to adjust the sight so the pipper is on the target. At this point the weapon isn't "sighted in" but should register hits "on the paper". Then fine adjustments can be made to the sight to bring everything dead on.
In the photo you'll notice the rear of the aircraft is supported on adjustable jack stands. These could be used to move the nose up and down. The target itself could be moved left or right. This would give you x and y adjustments to bore sight the cannon.
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Yup, Trap is correct about what that person is doing.
The Bf109s modelled in Aces High have other differences from the real thing in the interests of simplicity. So do a lot of planes come to that. Why don't we just agree to not campaign against the convergence setting until there is a wide scale addressing of all those little inaccuracies?
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I'm more interested in how real life 109's were designed and worked than I am in trying to convince HTC to make changes to the game. How these aircraft functioned in "the world" I find pretty amazing. It's up to HiTech how realistic he wants the game to be.
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WW2 reflector gunsights did not have an elevation adjustment other than a few allowed a change in the angle of the reflector plate to lower the dot for use with rockets and shallow dive bombing.
They were a line of sight aid evolved from the earlier iron ring and telescopic tube sights. Gun convergence and harmonization was adjusted to cause the rounds to pass through the "line of sight" at some set distance. The gunsight nor the graticule was adjustable to compensate for bullet drop like a rifle scope. The armorer adjusted for the paralax lense table to be level while the aircraft was propped up level for gun adjustment. The guns were adjusted to patterns that converged at the line of sight based on the center pipper of the graticule. The mounting was standardised to the average hight distance from the pilots seat to his eye for a direct line of sight over the nose of the aircraft.
FW convergence charts show the line of sight level to the datum line and all of the guns adjusted to fire over the line of sight and drop the rounds in between 400 meters and 550 meters. None of the Fw A to F series had HUB mounted cannon. In the chart for the G6 with MK 108 motrkanon, the MK 108 is shown firing level to the 0-datum line while the line of sight is down over the nose to 400 meters at a point 340cm(11ft) below the 0-datum line.
The Revi installation in the 109 cockpit is preaty much fixed because there is absoultly no room to raise the pilots line of sight up any higher.(Berlin Phone book 1944 seat cusion) Thats why you have 20 mil stadia marks along the cross hair. The effective straight line of sight shot for the MK 108 is 100 meters which has a drop of about 12 inches. The line of sight angling down to a convergence of 400 meters will align with about the 40 mil (second down) stadia mark below the center of the Revi graticule(11 ft drop).
When you look at the diameter of a MG151/20 barrel and how far it extends into the cannon tube past the flange I can see up to 2 degrees of elevation possible down the 70 mm engine tube. I'm still looking for the information about factory setting of MG151/20 had two choices of 200 or 400 meters. Based on the chart I bet 200m was more common for the MG151/20. About a 24inch drop at 200meters.
With a 30mm round from a short barrel that barly makes it to the tube without an adaptor, you want it going straight down the center of the tube and not impacting the sides. Reference back to the G6 chart showing the 30mm at a flat trajectory from the left of the chart.
HiTech has been very good about fixing things over the years if you present the data or a solid argument. Pyro is interested in updating the realism of the ordenance.
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bustr - do you have a picture that illustrates what your saying? I think I understand but want to be sure.
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Here's a few pages I used along with researching concepts to other pages.
How else did I create the Reflexvisiere graticules in my Historic gunsight pack? You can use the tech graph included in this thread for the MK108 balistics related to the stadia marks on the Revi graticules. Other discussions at Historic web forums have beaten the 30mm balistics to death. Rougly 12 inches at 100 meters, roughly 11 feet at 400 meters, past that it drops down a well. You can see where stadia marks were added to the Revi graticules around the same time 20mm cannon became standard armament on fighters. The ReviC/12A without stadia marks was used in gun turrents. You notice the germans kept using iron rings on hand held manned gunner positions till the end of the war MG or 20mm.
Reflexvisiere Manuals: http://deutscheluftwaffe.de/
Reflexvisiere discusson group in german: http://208090.homepagemodules.de/t103f25-Revi-Baumuster.html
http://www.ww2aircraft.net/forum/
http://www.ww2incolor.com/forum/showthread.php?4127-Luftwaffe-Cannons-amp-Machineguns.
http://forum.axishistory.com/viewtopic.php?f=114&t=17850
Check some of the links I added to this post back a few page also. I suspect some of our membership have books with diagrams that show detailed info on the Motrkanon installation along with factory data on convergence.
I could be wrong but, the motorkanone MG151/20 bottom of the page picture in this link has a collor to fit down the hollow airscrew cannon tube on the DB601. And that looks like the 4 hole flang that bolts to the fixed flang on the back of the DB601.....
http://www.ww2incolor.com/forum/showthread.php?4127-Luftwaffe-Cannons-amp-Machineguns./page3
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(http://i1043.photobucket.com/albums/b434/trap78/DB605Drawing.jpg)
I noticed this the other day; the crankshaft is geared to drive the supercharger which in turn is geared to the "cannon tunnel" which then appears to drive the overhead cam via a shaft. It seemed to me the cannon tunnel would have to rotate at one-half the crankshaft speed (most likely) for this to work.
(http://i1043.photobucket.com/albums/b434/trap78/EngineBlockDB605.jpg)
This is a good picture of the bare block with the front of the engine facing towards us. It shows what looks to me like the through hole cast as part of the block that housed the cannon barrel. This is where a camshaft would have gone in a conventional push rod design. Since the DB was an overhead cam arrangement this "tunnel" could be utilized for the placement of the cannon barrel.
yup, good picture.... right through the upper reduction gear to exit the nose cone/prop. :salute
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Page 15 of the 109-G6/U4 manual says the MK108 fits parallel to the engine and is not adjustable. Roughly translated. 0-datum line convergence.
http://deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Messerschmitt/Me%20109/Bf%20109%20G-6%20U4%20Bedienungsvorschrift%20-Wa.pdf
109F2-F4 manual shows similar things by the fact it shows the MG151/20 round drops 8cm at 100 meters out the barrel. But it says roughly the ReviC/12b is line of sight to 400 meters. ReviC/12b graticule introduced stadia marks on the cross hairs at every 20 mil.
http://deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Messerschmitt/Me%20109/Bf%20109%20%20F-2%20F-4%20Wa.pdf
I will venture the motorkanone is mounted inline with the engine datum line fixed and there is no elevation adjustment. The inverted "V" mounting of the engine allowed an unobstructe line of view down over the nose to 400 meters. One would think then in the game the HUB cannon on german fighters should be locked at about 100-125 meters due to no adjustemt possible in the engine tube mounting..
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Isn't that rather unfair to players who have spent a long time learning to fire, especially in the case of the Mk-108 equipped aircraft, what is generally accepted to be a difficult set of ballistic characteristics?
Is your goal to improve realism or to hobble the Bf109s modelled in the game?
I contributed to this thread because it was an interesting technical / engineering discussion. Not to join a campaign to undermine the 109s. I'm sure other aircraft weren't able to adjust their harmonisation / convergence settings from anywhere between 150-650 yards either. I had the idea that the RAF were at one point dissatisfied with the Spitfire's armament for this reason too?
Further, even if you fix the point of convergence, what's to stop people making their own custom gun sights to compensate? I doubt they could do that in the field either.
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Whether the engine cannon is adjustable or not makes no difference. It shoots where it shoots and if it is rigid then the sight line is adjusted according to it to get the sight line converge with the cannon bore sight line at desired point. After that all other guns are adjusted to converge with that point. And of course the Revi had an adjustment for X-Y shift as can be observed from this document:
http://www.cockpitinstrumente.de/archiv/Dokumente/ABC/r/Reflexvisiere/Revi%2016%20B%20Waffenhandbuch.pdf
In Revi 16B the adjustment was done from screws 20 (X) and 21 (Y). 3 degrees of adjustment is enough to move the reticle vertically 26m at 500m distance. Pretty much enough to get even the MK108 shoot to middle of reticle at 500m if the drop would be as much as 7m at 500m.
-C+
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Isn't that rather unfair to players who have spent a long time learning to fire, especially in the case of the Mk-108 equipped aircraft, what is generally accepted to be a difficult set of ballistic characteristics?
To me, the difficult part of mastering the Mk108 hub gun is the rate of fire and small ammo load. With so few rounds going down range, snap shots are tricky. But, if I'm dead six, its very easy to hit since the sight will get you on target. So ultimately, I don't think a fixed convergence setting of 400 meters is going to really change anything. I'd like to hear more about the adjustment range on the gun sight though, as Charge makes a good point.
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In Revi 16B the adjustment was done from screws 20 (X) and 21 (Y). 3 degrees of adjustment is enough to move the reticle vertically 26m at 500m distance. Pretty much enough to get even the MK108 shoot to middle of reticle at 500m if the drop would be as much as 7m at 500m.
Glad to see this. I was having trouble conceptualizing a gunsight that couldn't be adjusted.
- oldman
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The Revi16b mirror pivots in an arch on an adjustment bar also. Left and right 2.5+- and up and down 3.0+-. The Revi is mounted with its center 4.5cm right of center. That is not the point of this.
In the game the 109F-K Motorkanone 20-30mm lines are set to elevate up to the level line of sight if you pull them back to 150 convergence or arch over level line of sight out to farther ranges so that when you choose your long convergence range on the target you will see your motorkanone rounds hit center of your graticule and the target. This is impossible if you read the armorers installation instructions in the manuals. The Motorkanone is locked at the engine's zero line with the rounds almost emeidiatly arching down per gravity influence once they leave the spinner. The MG's and wing pod cannons are set to pattern with the motorkanone.
In the hanger the Ta152 30mm line stays level when pulled back to 150 yards. But, if you fire at the offline target with the 30mm your rounds should be hitting below center if your aircraft is flying auto leveled. The effective Line of sight for the 109F-K was 400 meters down over the nose based on the motorkanones tragectory at a 400 meter impact point. Look at the armorers charts.
The rounds were not set to arch up but down which you should see in the offline target during auto level. Elevating the graticule will not change gravity if the offline target's center is at static "0" datum line to an auto leveled aircraft. The motorkanon datum line should be pointing directly at the center of the target and at 100 meters the 20mm should hit -8.5cm below target center and the 30mm should hit -19cm below target center.
MK108 30mm motorkanone at 0 meters the Revi center dot was at 74.5cm above 0-datum, 4.5cm right of line. At 100 meters the Revi line of sight was -29cm below the 0-datum line. The 30mm round was -6cm at 50 meters and -19cm below the 0-datumn line.
MG151/20 motorkanone at 0 meters the Revi center dot was 74.5cm above 0-datum line, 4.5cm right of line. At 100 meters the Revi line of sight was 28.5cm above the 0-datum line. The 20mm round was -2.0cm at 50 meters and -8.5cm below the 0-datum line at 100 meters.
I will venture the Yak's HUB cannons are set the same way.
So is the offline targets center staticly tied in a line to the level aircrafts center line?
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You seem very knowledgeable about this subject. Wanna come help me work on my Lycoming? I was thinking about some "extra" additions...
:devil
I don't know Von, I just learned something new today, don't think I'm quite up to snuff yet (no seriously, I thought the hollow propeller shaft ran through the entire block and rotated freely around the barrel of the cannon that also protruded into the block). The propeller is supposed to be stationary and rotate the engine and frame, right?
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You guys realise in the 109F and G6 manuals that the diagrams for adjusting the guns is the pattern if you jack up the tail so the engine is ground level and you are firing at a barrier 50M or 100M? You adjust the Revi graticule to center at 100 meters for the motorkanone impact point at -8.5cm or -19cm. Your 3.0 degree+- verticel adjustment.
Then you use the stadia marks out to 400 meters. The left and right adjustment is to cause your line of sight to point to 2.5cm left of center at 400 meters to offset for the Revi center being mounted 4.5cm right of the centerline. The MG were not set to cross each other at 400m. 400m is where they were set for their ballistics to drop the rounds and meet the motorkannone's round on a parallel plain.
Read the manuals.
It looks like the fixed 4 bolt flang for the motorkanone does not rotate. The tube looks like it has a bearing race that supports it at the end flang. I could also be worng because one page up it looks like only the forward tubeing that sticks through the reduction gear at the front rotates. Check the color schematics at the end of the document below.
http://deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Motoren/Daimler%20Benz/Handbuch%20DB%20601%20A-B.pdf
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Calm down bustr! <slap> This is becoming an obsession! We've already established the cannons were fixed and the four bolt flange tube and the cannon tunnel didn't rotate. It's been a very interesting discussion throwing up some great resources and pictures. That last link was good.
I think we all accept the conclusions of the discussion that the real 109s didn't have the option to set their convergences, nor adjust their boresights beyond what was apparently their 'ideal' setting decided upon by the factory. I gathered that the OP was asking more of a 'how did this work' question.
Are you now campaigning to have those features locked in the game, and removing the custom gunsight option for those specific aircraft? What is your motivation to campaign for added realism specifically for the 109s? Or is this to be part of a more widespread campaign for more realism? There is after all artistic license taken with the other aircraft also.
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Not really.
I'm amased at the quest for precise data and extreams for Luftwaffa aspects of this game players and HTC go to for factual realism but then in the same process ignore something this technically arcane but, important about the BF109's, Motorkanone, and the relationship of the other guns to the alignment of the Motorkanone and to the Reflexvisier as a unified system. After all the core principel here effects several other aircraft in the game.
Did you gentelmen never want to understand the technical relationship and theory behind why graticules were constructed in the manner they were and their relationship to the armament they support? HTC forces our bomber pilots to perform arcane procedures to successfully level bomb. Once I began translating the relevent information in the manuals it became obvious what the relationship was of the Reflexvisier to the tragectory diagrams in the back of the 109 manuals.
I will venture HTC is probably not 100% modeling Motorkanone and secondary autoguns based on the armerors diagrams in the manuals. If so the MG on the 109 are set to arch down parallel generaly to the Motorkanone out of the barrel to make a concentrated fire pattern........read the manuals. The Revi16b has an H and S adjustemnt screws inside of the case which corrisponds to the H and S values in the 109's ballistics tables. H was set to the Motorkanone at 50 or 100 meters just like zeroing a rifle scope for 100 or 200 yards then relying on the mildots or drop marks for ranges past the zero distance.
I was under the impression HTC wants to be technicaly correct where they can in the original manufactuers standard armament specifications in this game for each vehical or aircraft. Then again this is just a game and no one argues real world tech physics data in this forum with HiTech over the flight physics models of his creations....... :rolleyes:
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It's a good bit of research and ideally it would be incorporated into the game. I think it would be best done at the same time as similar improvements in realism across the planeset. Rather than one in particular.
Ultimately you can only forward these findings so far. Look at our recent discussion regarding the weights of the Ki-61 and Ki-100. We found documentation from three separate sources that the Ki-61 in Aces High is overweight. And? What can we do further than that?
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I'll venture a number of things.
1. Nobody in the game so far has cared to understand the intimate relationship between the Reflexvisier and the wheapons.
2. Too many players now are invested with the one size fits all relationship of gunsights to wheapons in the game.
3. English language information has generaly been freely available for the allied N3, N9 and MkII based reflector sights and wheapon systems that were the sighting technology for them.
4. The german military tech manuals from WW2 I have been reading have only recently been available for free download I suspect since no one in this forum knew the motorkanone is mounted parallel to the engine 0-datum line and is unadjustable.
5. I've seen the armerors 50/100 meter gun pattern guides in WW2 forums all over the internet but, it was obvious no one understood the relationships of H S and V to the installation of the MG, kanone and Revlexvisier. Or how to align them all at 100 meters from the manuals. Or even realised the 109 zero line is off the kanone but the FW190 zero line is off the center of the Revi. N3, N9 and MkII the zero line is off the gunsight center line and rounds arch up to it like the FW190. This makes me beleive the Yak are aligned the same as the 109 especially with the stadia marks on the cross hairs of the PBP1 graticule.
6. Players would be more interested if I had read a german WW2 manual that shows how to make the K4 out turn an A6m through 6-360 degree TnB circles.
7. I may have to remake my Revi graticule circles to reflect 50mm which is about 100mil with our current POV in the cockpit. Lots of drop at 400 meters accounted for that way via the lower stadia marks.
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Bustr,
this is kinda off topic, but do you have any info on k4s that used C3 instead of B4 fuel?
-Ty
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posted by bustr:
...The inverted "V" mounting of the engine allowed an unobstructe line of view down over the nose to 400 meters....
This makes sense with what I've been reading. The inverted engine configuration goes all the way back to the prototype. Apparently the designers felt the over the nose view would be better and servicing the engine could be made simpler. The two large Y shaped cantilever legs which held the engine were magnesium alloy forgings. Just getting the metallurgy right on these components is pretty amazing for the late 1930's. The cutoff valve that allowed the pilot to isolate the radiators is also a well thought out design. I'm looking forward to making the trip up to Evergreen and taking a look at their G-10 and see what other 109 factoids I can find.
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I'll venture a number of things.
1. Nobody in the game so far has cared to understand the intimate relationship between the Reflexvisier and the wheapons. I did. Four pages ago.
2. Too many players now are invested with the one size fits all relationship of gunsights to wheapons in the game. Yup because in the end..... it's a game.
3. English language information has generaly been freely available for the allied N3, N9 and MkII based reflector sights and wheapon systems that were the sighting technology for them. Yes and?
4. The german military tech manuals from WW2 I have been reading have only recently been available for free download I suspect since no one in this forum knew the motorkanone is mounted parallel to the engine 0-datum line and is unadjustable. I did. Four pages ago.
5. I've seen the armerors 50/100 meter gun pattern guides in WW2 forums all over the internet but, it was obvious no one understood the relationships of H S and V to the installation of the MG, kanone and Revlexvisier. Or how to align them all at 100 meters from the manuals. Or even realised the 109 zero line is off the kanone but the FW190 zero line is off the center of the Revi. N3, N9 and MkII the zero line is off the gunsight center line and rounds arch up to it like the FW190. This makes me beleive the Yak are aligned the same as the 109 especially with the stadia marks on the cross hairs of the PBP1 graticule. This is AH not TW. Little Jimmie fighter pile-it doesn't care. Looks like something for the "Wish List" though.
6. Players would be more interested if I had read a german WW2 manual that shows how to make the K4 out turn an A6m through 6-360 degree TnB circles.Much more. Know why?
7. I may have to remake my Revi graticule circles to reflect 50mm which is about 100mil with our current POV in the cockpit. Lots of drop at 400 meters accounted for that way via the lower stadia marks. Knock yourself out. I'll just set my convergence at 300 in the hanger and be done with it.
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I suspected the cannon was fixed a long time ago when I found the Flight International picture I posted. I thought of bringing it up once in another thread about the 109. I decided not to because of the nature of this forum.
I'm all for having the game steered more towards realism and away from AirQuake too but I think players can do little more than present information and hope the HTC management sees it and agrees with it. Suggesting the 109 series has the convergence option fixed is a departure from the policy of offering that option across the whole plane set. Interesting if that policy was further extended to cover something like flaps for instance.
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Bustr,
this is kinda off topic, but do you have any info on k4s that used C3 instead of B4 fuel?
-Ty
It is not known if and how many units had converted to 1,98 ata manifold before that order came, but it should be noted these units, in particular III./JG 27, III./JG 53 and IV./JG 53 were the major users of the Bf 109 K-4 in the Lufwaffe. The other units effected are not known at present, but given the abundance of photograph depicting G-10 and K-4 fighters belonging to other units, marked for C-3 fuel use - a likely sign of the DC engine at 1,98 ata - the boost increase was likely not limited to JG 27 and JG 53 alone.
http://kurfurst.org/Engine/Boostclearances/605D_clearance198.html
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It is not known if and how many units had converted to 1,98 ata manifold before that order came, but it should be noted these units, in particular III./JG 27, III./JG 53 and IV./JG 53 were the major users of the Bf 109 K-4 in the Lufwaffe. The other units effected are not known at present, but given the abundance of photograph depicting G-10 and K-4 fighters belonging to other units, marked for C-3 fuel use - a likely sign of the DC engine at 1,98 ata - the boost increase was likely not limited to JG 27 and JG 53 alone.
http://kurfurst.org/Engine/Boostclearances/605D_clearance198.html
It is rather strange that Barbi says III./JG27 is a major user of the K-4, yet his list has III./JG27 flying G-10s. It is best to take what Barbi says with a great deal of skepticism.
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It is rather strange that Barbi says III./JG27 is a major user of the K-4, yet his list has III./JG27 flying G-10s. It is best to take what Barbi says with a great deal of skepticism.
If you hadn't said that, I was going to... :cheers:
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It is best to take what Barbi says with a great deal of skepticism.
So as it stands this the definitive source when it comes to 109K+fuel topic, right?
http://www.spitfireperformance.com/spit14v109.html
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If you read the 109F manual for installing and using the RZ65 65mm rockets they mention an assumption that the Revi has been adjusted for the 100m H setting to see 7.5cm above the MG151/20 motorkanon 0-datum line at 100 meters. In our game that means if our line of sight between the center of our graticule and the offline target center is fixed then when we fired the 109 20mm motorkanone we should be seeing its rounds hitting 82.5cm below center at 100 yards and the 30mm 93.5cm at 100 yards.
With the MG151/20 the H setting raised the graticule to allow seeing 7.5cm above kanone 0-datum line at 100 meters and the MK108 it was 19cm below that line at 100 meters. In the 109 seriese the Revi graticule was adjusted to a point at 100 meters that would corrispond to an endpoint at 400m describing a point on a level cross line to which the motorkanone rounds idealy would impact. The MG were set to bisect this line harmonised with the motorkanone.
Essentialy they knew the ballistics of the motorkanone fireing from the datum line out to 400 meters and adjusted the 2 MG to 400 meters harmonised with it. Then adjusted the Revi graticule to account for the drop to 100 meters. The pilots learned how to use the graticule in gunnery school to determine range and ballistic drop.
If you want to get a feel for gunnery with the ballistics set closer to the manuals. Set all of your 109 and Yak and P39 motorkanone to 150yds off line and see how it works to shoot at things. That will be closer to the authenticity HTC seems to want to put into most of the wheapons systems in the game but the front page only says "High fidelity flight simulation". Not technicaly accurate wheapons system.... :rolleyes:
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posted by bustr:
In the 109 seriese the Revi graticule was adjusted to a point at 100 meters that would corrispond to an endpoint at 400m describing a point on a level cross line to which the motorkanone rounds idealy would impact.
I just can't seem to wrap my brain around this bustr. Does it mean that the trajectory of the 20mm cannon round crosses the line of sight through the pipper of the Revi at 100 and 400 meters?
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Jack the rear end of the 109 up so the engine/motorkanone 0-datum line is level and the wings are level. Place a board at 100 meters in front of the 109 about 8 feet tall wingspan wide with a horizontal line across it at the same hight as the 0-datum line. Fire your guns. You should roughly get the following patterns.
Gun Patterns Based on Engine/Motorkanone 0-datum line.
109F
MG151/20 @ 100M - 8cm below 0-datum
Rumpfh MG @ 100M - 13.5cm above 0-datum cross at 400m
109G6/U4
MK108 @ 100m - 19cm below 0-datum
MG131 @ 100m - 4cm below 0-datum cross at 400m
MG151/20 gondola @ 100m - 60cm below 0-datum cross at 300m
Reflexvisier H adjustement at 100 meters.
MG151/20 7.5cm above 0-datum
MK108 29cm below 0-datum.
You use the H adjustment screw to raise the graticule center to see over the nose to a zero at 100 meters. Then you use the lower stadia marks on the vertical cross hair to fire past 200 meters.
FW's the Reflexvisier line of sight was level from the center of the graticule to infinity. The MG were set to drop into the line at 400M and the MG151/20 at 550m. The MG convergence was to never cross the guns. The root MG151/20 at 600M and the outer MG151/20 at 400m. I beleive setting that up is called harmonizing the guns.
I think our convegence and target mode for all of the aircraft in AH works like the way the FW's were setup. We lob rounds over the level to infinity graticule line to drop rounds into a target level with our graticule line at the convergence range we choose from the hanger. The motorkanone had a fixed convergence that never touched level after the round left the barrel. MG and gondola were adjusted to follow the motorkanone trajectory out to 400 meters.
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(http://farm6.static.flickr.com/5170/5362439793_25929f4182_o.jpg)
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(http://farm6.static.flickr.com/5170/5362439793_25929f4182_o.jpg)
lol whats with the cop? did the other guy park his 109 in a handicap zone or something?
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He's overseeing the forensics guy dusting for prints while they investigate the recent spate of engine thefts.
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He's overseeing the forensics guy dusting for prints while they investigate the recent spate of engine thefts.
:lol
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The pics should be pretty much selfexplanatory at this stage.
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(http://img692.imageshack.us/img692/7674/fw190gfb.th.jpg) (http://img692.imageshack.us/i/fw190gfb.jpg/)
(http://img600.imageshack.us/img600/881/fw190asch.th.jpg) (http://img600.imageshack.us/i/fw190asch.jpg/)
(http://img138.imageshack.us/img138/9859/bf109g6asch.th.jpg) (http://img138.imageshack.us/i/bf109g6asch.jpg/)
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from bustr:
Jack the rear end of the 109 up so the engine/motorkanone 0-datum line is level and the wings are level. Place a board at 100 meters in front of the 109 about 8 feet tall wingspan wide with a horizontal line across it at the same hight as the 0-datum line. Fire your guns. You should roughly get the following patterns.
Gun Patterns Based on Engine/Motorkanone 0-datum line.
109F
MG151/20 @ 100M - 8cm below 0-datum
Rumpfh MG @ 100M - 13.5cm above 0-datum cross at 400m
109G6/U4
MK108 @ 100m - 19cm below 0-datum
MG131 @ 100m - 4cm below 0-datum cross at 400m
MG151/20 gondola @ 100m - 60cm below 0-datum cross at 300m
Reflexvisier H adjustement at 100 meters.
MG151/20 7.5cm above 0-datum
MK108 29cm below 0-datum.
You use the H adjustment screw to raise the graticule center to see over the nose to a zero at 100 meters. Then you use the lower stadia marks on the vertical cross hair to fire past 200 meters.
FW's the Reflexvisier line of sight was level from the center of the graticule to infinity. The MG were set to drop into the line at 400M and the MG151/20 at 550m. The MG convergence was to never cross the guns. The root MG151/20 at 600M and the outer MG151/20 at 400m. I beleive setting that up is called harmonizing the guns.
I think our convegence and target mode for all of the aircraft in AH works like the way the FW's were setup. We lob rounds over the level to infinity graticule line to drop rounds into a target level with our graticule line at the convergence range we choose from the hanger. The motorkanone had a fixed convergence that never touched level after the round left the barrel. MG and gondola were adjusted to follow the motorkanone trajectory out to 400 meters.
Does this mean yes the MG151 trajectory crosses the pilots line of sight through the pipper at 100 and 400 meters or no it does not?
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No disrepect to HTC and I will gladly eat CROW with sand on it if I am wrong.
Charge I beleive HTC is using the method of your FW diagrams as the one size fits all convergence and gunnery model for the aircraft with fixed mounted forward firing guns to simplify gunnery as a key game process. But one would think 109 fans in the game would appreciate any amount of realism to support their image as having to work harder than the rest of the community to become better than them in the 109.
Consider what this means with the Ta152. Revi line of sight level to infinity won't work like on the FW A-D. MG151/20 set to drop off with the MK108 to pattern at 400 meters 12 feet down. Considering the line of sight over the nose is worse than the 109's, the H adjustment distance is probably performed at 50 meters and the lower stadia marks on the graticule become very important. None of the Ta152 manuals I have appear to have armerors diagrams for gunnery. I'll have to look again to see if they at least talk about setting the Revi H for zero.
If you pull the motorkanone and twin MG on any 109 back to 150 offline 20mm or 30mm birds you will find 200-250 yards is about your best range for getting rounds on a target with a 30 foot wingspan. Bombers out to about 400-600 yards. But, then that would be consistant with operational ranges in some of the after action reports. Didn't Galland complain with the 109F that loosing the wing guns made gunnery something only an Expert would be proficient at? Then he chose to keep his as a feild modification.
I was reading this weekend that the T9 37mm in the P39 had to be mounted parallel and close to the drive shaft because of the force of the recoil. Think thats why the N3 in the P39 had stadia marks below the dot? Wonder how many feet that 37mm drops at 400 meters?
ON the FW convergence diagram:
Yes the line of sight for the Revi graticule was level to infinity. The MG151/20 in the diagram arch up to the line of sight at about 120 and 135 meters per the diagram data spec and pass over it staying that way untill 550 meters. The MG131 stay above the sight line for almost their whole travel distancee to 400 meters. Your effective convergence for all 3 guns is about 250 meters 20 inches above Revi sight line with a 2 meter spread. 250 meters seems to be the effective fighter to fighter combat distance. 400-550 meters was for bombers.
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In 109 the cannon shoots straight at the center of the main lines in targeting board as the cross suggests and the drop is 11cm at 100 meters as the black spot suggests. The sight's assembly height is 74,5 cm and in actually points down to height of 5cm in 100 meters. That means that the use of stadia marks are up to pilot's discretion but he knows that the cannon shoots to the center of the reticle at around 140 meters where the Hx is roughly the same for both the cannon and for Revi, and the second crossing point is somewhere around 400-500 meters due to ballistic arching. Between those distances he can use the stadia marks above the center of the reticle to estimate how high the rounds fly before arching down again. Beyond the second convergence point at 400-500m he can again use the lower stadia marks to estimate the drop.
Ta uses the same method as the 109 because of the center cannon which is not adjustable. The 190 has more freedom to adjustments and it uses the Revi line of sight as a reference and all the weapons can be adjusted to match that.
I haven't noticed how it is done in AH though. Bustr, do you mean that in AH the cannon shell, whether it is 20 or 30mm does not cross the sight line twice if it is "converged" to 100 or 400 yards? Because in both cases it should.
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PS. The picture of the periscope that we saw earlier is used to point the cannon to center of the targeting board and with adjustable guns it can be used to optically set the hitting point to the right point in targeting board, however, it was preferred to check the calibration with live ammo as the optical system was not very accurate.
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You can go into the hanger and pull the motorkanone back to 150 yards along with the MG. The MG lines go straight out from their barrels. The Motorkanone line goes up to meet them. It should go out angeling down slightly at 137.16(150yds) meters. The MG131 should also angle down to make a pattern at about 250 meters with the 30mm and about a 12 inch separation roughly parallel to 400 meters..This convergence line patterning is repeated on all nose cannon planes in the game. Visible angle up to visual level line at 150yds.
Then spawn on the runway with the K4 convergence set to 150yards. Set the target to say 400 yards. Auto level the K4 till your pipper stops level on the center of the target. I beleive the center of the target is a fixed line to the level line view of your pipper when the aircraft settels in on auto level. Your 30mm rounds should hit 32.4 meters below the center of the target(pipper center line). Does anyone know what the width of the rings on the target are supposed to be?
If the MK108 is being elevated based on a line of sight line from the gunsight then at 250 yards the 30mm at autolevel should impact about 60cm high of target center. Another way to test this is to take a FW190A-8. Pick the small gun package. 2-MG and 2- wing root cannon. Set the MG151/20 to 550 yards. Setup the offline target at 400 yards, auto level, then fire the MG151/20. They should impact about 80cm above the target center at 400 yards with the convergence at 550 yards. Thats if the gunnery model is keyed off the level line of sight to infinity like a lazer line from the center of the gunsight pipper.
By the way here are some photos of the Yaks VK-105PF with the autocannon locked in. You will see a 4 bolt saddel clamped down on the barrel just in front of the receiver. : http://en.valka.cz/viewtopic.php/t/54646
Notice even with the P39 Oldsmobile T9 37mm it is mounted parallel to the drive shaft: http://engineeringjohnson.blogspot.com/2008_08_01_archive.html
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I believe the target rings are 10 mils
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Stoney you gave me a better idea.
I'm the first here to apologise to everyone for what I thought was the center of the target to aircraft zero line. Half a crow with sand please raw and no water.
I parked all of the aircraft I questioned on the runway and set the target to 3 yards. Went to F3 and zoomed and looked at the profile.
The center of the target is the 0-datum line of the engine if you raise the tail to level.
I will assume in flight whatever distance you set the target to, the target center is fixed to the engine 0-datum line at auto level.
If all MG or cannon firing fixed forward to a convergence point are calculated ballisticaly along that 0-datum line from the engine to strike the target center to match your chosen convergence distance point. The motorkanone rounds are being arched along that line to drop them into the center of the target. There sould be no setting to change the ballistic arch of a fixed MK108 or MG151/20 or Hub Cannon fireing level out of the spinner. The 30mm round at 400 yards should hit the target 30 meters below center. The MG151/20 1 meter below target center at 400 yards. I don't know the ballistic information for the P39 or Yaks.
Based on the engine 0-datum line alined with the center of the target at any distance at auto level. The FW190A/D MG151/20 set to 550 yards should hit at auto level on the target set for 200 yards about 115cm above target center. In the FWA7-A8 manual though, the FW 0-line for armament was the Revi center sight line to infinity about 80cm above the 0-datum line. With the 109's it was by raising the graticule center by tilting the reflector plate on some versions or titling an internal mirror on others to enable looking down to the the 100m sight line point below 0-datum then using the cross hair stadia marks to compensate for distances to 400 meters. To hit an aircraft past about 200 out to 400 yards you would have to raise the nose and aim off the stadia marks below the graticule center.
Maybe HiTech is tilting our reflector plates mathmaticly and virtualy on the fly as a consideration to center the pipper at whatever range we set (.target xxxx) to or covergence to.
I'm probably full of it and HiTech is letting me make a fool of myself......
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For those who are worried how what I'm arguing about would affect you in the game and your field of view through the gunsight, perform this experiment offline.
Set your K4 convergence to 150 and gunsight to a Revi gunsight with the tick marks on the cross hairs. Spawn and fly north at 1k auto level, reduce rpm until ATA is at 2. Wait for the aircraft to settel in and set (.target 600) and go to full zoom. Now lift the cross hairs to about between the 1st and 2nd or at the 2nd tick mark down and hold that on the center of the offline target. Fire only the cannon to produce a pattern.
Because convergence at 150 lofts the 30mm up to drop center of the target at 150 yards. I've chosen 600 yards to be an equivalent+- of the round having left the muzzel of the cannon level to the ground to hit the target set to 400 yards. You will notice the rounds hit about 30-35 meters low of center on the target with you aiming high by 2/3+- down the lower half of your graticule ring. About 45mil+- low of center on the graticule. This is a good approximation of what your gunnery would be like if the MK108 motorkanone in a 109 fired level from the 0-datum line of the engine as they were installed.
As you notice you would have no problem seeing and aiming at a 400 yard target. HiTech has coaded the line of view(visierlinie in the manual) angle down the line of the cowling specified by the data. Other wise you would not have been able to lift the gunsight high enough to hit the 600 yard target on center while watching the rounds impact through your available feild of view.
This can be extended to all aircraft in the game with a nose cannon bolted into the engine airscrew 0-line. The tragectory of the round 20mm, 30mm or 37mm would be compensated by the tick/stadia/hash(ladder) marks on historical gunsights out to about 400 meters. Or the abundent genius of gunsight designers in the player community.
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If our game gunsight visual angle measurment is in "Angular Mil" based on 1-mil=1/6400, the amount of elevation for 400 yard shots with the MK108 is not as great as in my offline test trying to account for the introduced elevation at 150 convergence.
Using the figures from the BF109G5/G6 & Bf109G-6/4U manuals and the formula:
Distance in Meters = (Size\100) divided by Mils * 1000
Target Distance(m) = 400 meters
Revi center to MK108/MG151 barrel center = 74.5cm
MK108 barrel center line above IP@400m = 340cm
MG151 barrel center line above IP@400m = 200cm
MK108 - Size(cm) at 400m is 74.5cm + 340cm = 414.5cm
MG151/20 - 274.5cm
400 = (414.5\100)divided by Mils * 1000
400 = (274.5\100)divided by Mils * 1000
MK108 - Mils = 10.25+-
MG151/20 - Mils = 6.75+-
If the MK108 motorkanon was locked into the motor firing parallel with the engine datum line the aircrafts nose would only have to be lifted to about the first Revi stadia mark below center to hit the target center at 400 meters(437yrds).
Based on the ballistics for the MG151/20 motorkanone at 400 meters the Mils = 6.75+-. The Revi aimpoint for 400m would be just above the first stadia mark below center. Based on the armerors schematics for the 109 series the twin fuslage MG and gondola guns are angled to fire in downward archs to pattern ballistcaly with the primary wheapon the motorkanone. With the twin Rumpf MG thier ballistic IP is with the motorkanon at 400m.
Locking the Yak9T/U engine mounted autocannon and P39 T9 cannon in this manner would result in gunsight Mil elevations in the same neigborhoods based on our Mil based gunsights.
If you need I can repost the links to the german manuals and pictures of the Klimov M105PF with autocannon mounted and P39 T9 mouning again.
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Testing offline with a K4 based on a 512x512 pixel bitmap (256 in the .mil file) and 1 mil=2 pixels. ReviC/12b graticule with stadia marks at 13mil/26pixel steps from 256x256 pixels as center.
By using the offline target and auto level while zoomed in, and the ballistics data for any of the Aces High motor mounted cannon firing through the spinner locked to the engine block. You should see a priedictable impact pattern starting at 50yards, 100yards then out in 100 yard steps to 800 yards that never crosses the 0-datum line after leaving the barrel.
From the Bf109G6/4U armerors chart the expected MK108 ballistics pattern below the 0-datum with the MK108 bolted parallel to the DB605 block and airscrew line should be aproximently:
Page 29. http://deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Messerschmitt/Me%20109/Bf%20109%20G-6%20U4%20Wa%20Beiheft%201%20MK%20108.pdf
Distance below DB605 datum Center Line At:
50M - 2 1/3in
100m - 7 1/2in
250m - 47in
400m - 11ft
500m - 18ft
Offline in a K4 fireing only the MK108 motorkanone. Convergence 150yd. Using the Mil elevations on the ReviC/12b graticule to describe impact points below graticule center as the target is set to 50yds, 100yds, 150yds then 100 yard steps to 800 yards.
Distance below ReviC/12b graticule center, convergence zeroed(0.00mil)@150yds:
50yds - 9.75mil below 0
100yds - 1.62mil below 0
150yds - 0.00-mil
200yds - 1.62mil below 0
300yds - 3.25mil below 0
400yds - 4.87mil below 0
500yds - 9.75mil below 0
600yds - 14.62mil below 0
700yds - 22.75mil below 0
800yds - 32.50mil below 0
I could be wrong but, it looks like the MK108 is tilted up inside of the DB650 engine block. It looks a bit closer the the ballistics for the nose mounted adjustable dual MK108 in the Me110-G2/R3 handbook Pg 18.
http://deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Messerschmitt/Me%20110/Bf%20110%20G-2%20R3%20Schusswaffenanlage%202%20MK%20108.pdf