109 nose cannon

[nrshida]

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.

[Charge]

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+

[Stoney]

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.

[Oldman731]

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

[bustr]

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?

[Babalonian]

You seem very knowledgeable about this subject.  Wanna come help me work on my Lycoming?  I was thinking  about some "extra" additions...

 

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?

[bustr]

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

[nrshida]

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.

[bustr]

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.......

[nrshida]

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?

[bustr]

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.

[Ardy123]

Bustr,
this is kinda off topic, but do you have any info on k4s that used C3 instead of B4 fuel?
-Ty

[trap78]

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.

[Blooz]

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.
 
  
 

[nrshida]

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.