BF-109f4 Convergence

[morfiend]

Bustr, I 'm sure you meant the Mk108 and not the Mk103.

 I set the cowl mg's all the way out to 275 yds and I have all my engine mounted cannon set to 200,this gives me a nice pattern from point blank out to about 300 yds. Now I dont shoot until I see D0 because I cant see the target when it gets further away than that.

  I have all my convergences set in close,even wing mounts,the furthest I set the guns is 275! Mk108 I like to set to 175yds.


   

[bustr]

I think MK108 and want 103 because the MK108 came first.. and 3 comes before 8..douh.....Though the modified MK103 for the Ta152 would mount onto the back of the Junkers engine with a MoL unit and a stuzstern to keep it centered in the tube. I'll bet the round was a compromise either in propellant amount or case size to reduce the recoil that would trash the engine otherwise. Fortunately for the AAF, that never went beyond prototype. I think it was being developed for both the Do 355 and the Ta152. DB603 in the Do355 had the same panzerrohr and end flange as DB605.

Should have been there while I translated manuals first with an OCR reader plugin then through several online german to english. Half the time I had to write the words down becasue the plugin didn't know what to make of them. Many words from WW2 seem to not be in the latter 20th\21st century german lexicon. You have to break some words into parts and look at two or three meanings and a photograph of the piece of hardware. Then go Ah-Haaaa....its a 5cent lock washer, derp.

It's not fair to my brain. MK101 started in 1935, MK103 service entry 1943, MK108 started in 1940.....and I'm supposed to keep this straight in my head...weeeee.

[Slade]

Thanks for all the posts.  Learning a lot.

The challenge with the 109f is that there are so many fast planes that getting to that ideal 250 or 275 convergence is not easy.  I KNOW it can be a killer at close convergence.  I am thinking with convergence further out you may get more opportunities for a shot.  At what point though is it too far out?

Also, are there any strategies one can use to get more opportunities to get a firing solution in a 109f?


Thanks,

Slade 

[Devil 505]

Use separate triggers for your MG's and cannon. Pepper your target with the 7mm's to make them turn then fire the cannon only when you get a close shot.

[Mister Fork]

Use separate triggers for your MG's and cannon. Pepper your target with the 7mm's to make them turn then fire the cannon only when you get a close shot.

Or wait until you're just super close and fire all at once (my strategy).

[save]

The Mk103 was concidered too heavy for single engine operations, whereas the MK108 was not.
AH only have the ME-410 with the Mk103.

[bangsbox]

Thanks for all the posts.  Learning a lot.

The challenge with the 109f is that there are so many fast planes that getting to that ideal 250 or 275 convergence is not easy.  I KNOW it can be a killer at close convergence.  I am thinking with convergence further out you may get more opportunities for a shot.  At what point though is it too far out?

Also, are there any strategies one can use to get more opportunities to get a firing solution in a 109f?


Thanks,

Slade 

i set the guns of 109f to 425. I find most of my kills in it are while turning inside bad guy. and if your convergence is to close your firing solution puts bad guy well out of sight under your nose.

[morfiend]

i set the guns of 109f to 425. I find most of my kills in it are while turning inside bad guy. and if your convergence is to close your firing solution puts bad guy well out of sight under your nose.

  Not sure how this works?  You realize that the rounds dont come up to the pipper until convergence so your rounds will be low out to 425,therefore the target needs to be low to hit it.Wouldnt this make it so you need to have more lead and thus place the enemy under your nose?

  With wing mounted guns you have both horizontal and vertical to consider,central mounted guns just have the vertical. For this reason I set the conv. relatively close for central mounted guns and use a compromised conv. on wing mounted weapons,in any case I never have guns set out past 300 yds and usually have most set to 275 for wing guns.

  Rven with central mounted guns set in close,say 175,I find I still have to aim above the target on crossing shots,simply because the target is less than 100 yds and my rounds dont come up to the pipper until 175. If I had them set to 425 I would have to aim even higher because the rounds arent angled up as much.


  You can test the effects with the dot target command


 I think convergence is a personal preference,if it works for you great!  When a new player asks I usually suggest the set it to 300 and experiment as there is no one setting that works for every plane and every player!



   

[bustr]

I'll post up something with screen captures if I need to show this but, all of you have it wrong because you don't know what is happening with your rounds. I built a terrain that level stands all the fighters so the center line is level with the horizontal center line of the target. I tested the F4 and K4. F4 convergences 150, 250, 600. K4 convergences 150, 300, 600. First the reticle center is level on the target at all ranges about 2ft high of center with both aricraft, and I tested the 20mm at 150,300,600yds. 30mm at 400, 600yds. After that it gets mario bros. "Gamey".

F4 - at 150 convergence, target at 150yds the 20mm hits 1ft above center, remember center of the target is the 20mm barrel center in the motor. At 300 it hits about 2ft above center and at 600 it hits center.
F4 - at 250 convergence, target 150yds the 20mm hits 3ft above center, remember center of the target is the 20mm barrel center in the motor. At 300 it hits about 4ft above center and at 600 it hits 1ft below center.
F4 - at 600 convergence, target 150yds the 20mm hits 5ft above center, remember center of the target is the 20mm barrel center in the motor. At 300 it hits about 6ft above center and at 600 it hits 4ft above center.

The real MG151\20 was locked level in the motor so leveled it shot too 100 at 4 inches low of the center line and at 400, 6.5feet low of the center line. The visual line of the reticle center was centered to 6.5feet below the center line at 400 by tilting the internal mirror of the Revi gunsight. That would be 6.5ft below the center of our offline target at 400. 400 was considered the max effective range for the MG151\20E mounted in 109.

I tested the K4 at 400 and 600yds because those ranges are critical ranges for the MK108. 400 is the max effective range while 600 was often the opening range for attacking bombers.

K4 - at 150 convergence, target 400yds the 30mm hits 1ft above center, remember center of the target is the 30mm barrel center in the motor. At 600 it hits 10ft below target center.
K4 - at 300 convergence, target 400yds the 30mm hits 4ft above center, remember center of the target is the 30mm barrel center in the motor. At 600 it hits 8ft below target center.
K4 - at 600 convergence, target 400yds the 30mm hits 10ft above center, remember center of the target is the 30mm barrel center in the motor. At 600 it hits 5ft above target center.

The MK108 was mounted level to shoot through the center of the DB605, and the round dropped as soon as it cleared the blast tube. So at 400 the round should be impacting the target at 11ft below target center and at 600, 29ft. Again the visual line of the Revi gunsight reticle was centered to 11ft below center by adjusting the tilt of the internal mirror. The same ballistic pattern should be happening with the Ta152 and Revi visual center line.

There are other reason people miss with a center-line mounted cannon, G in a turn and the fact that G to the round is not being fired under the effects of 1G. Means the IP point is now much lower and you have to account for shooting ahead of your turning con while lifting the aim point for the increase in G. Not understanding the 100mph principle where a center-line cannon is concerned. And snap shooting in TnB style combat is easier with an array of wing guns. And the big one, no one knows where their rounds are going like they thought they do. The yaks are not as bad as this to 400, but just as gamey.


See the target horizontal red line bisecting the blast tube? So on the static stand the target is centered for each fighter.




Here is the 30mm in the K4, gamey convergence setting at 600, and you can clearly see the red horizontal line that is the center line of the engine and cannon. So each ring is 10ft, you can count down to 30ft where the real life 30mm round would impact at 600. And our mario bros. 30mm round is impacting 5ft above the MK108 barrel center-line.   

   


Look at that static stand profile......

     

[EagleDNY]

Good to know.  No wonder I can't hit squat with the potato gun. 

[bustr]

I truly wish Hitech would center the Revi reticle to 400 for the MG151\20 and MK108 at their real ballistic IP and lock the cannons at "0". Same for all motor cannon guns. The Yak family 20mm and even the 37mm shoot 3-4 inches low at 200 and the reticle was centered for 200 because of that. The 20mm in the P39 dropped 43 inches at 400 while the 37mm dropped 6.5ft at 400, 49ft at 1000. The visual window to 400 for all for these planes is there to make the 400 adjustment of the reticle IP point.

[nrshida]

Now imagine in AH if the Hurricanes had fixed convergences. It would be 10x worse than you think it is now!

Why would HTC fix them since they were neither physically not doctrinally fixed in real life? Unlike the 'motorkanone'.

As a counter-argument: RAF pilots in 1939/1940/1941 were hampered by the wide spread -- a 12-foot rectangle so that inexperienced pilots would hit at least with SOME bullets before they lost their shot or ran out of ammo. The problem was that the pilots who could actually aim were frustrated and hampered by this and it wasn't concentrating fire on a single point -- that came much later after much complaining and reports of better ways from other services. It meant that many Luftwaffe bombers got away with scattered hits and no real damage when otherwise a good shot would have downed them.

Looks like you're referring to the Dowding spread which was an experimental proposition employed by a single squadron of Hurricanes (in 1939 only) who were famous for attacking large Luftwaffe bomber streams head-on, on their way to their targets. This and the proportions of the 12-ft x 8-ft rectangle at 250 yards should give a clue as to the intended purpose.

In fact, there was generally a large variety in RAF gunnery preference at any given moment and not just with convergance settings. Douglas Bader famously continued to fly a Spitfire Mark VA (8 x 303 Brownings) even when the rest of his squadron upgraded to Hispano-equiped Mark VBs so he could continue his very popular 1940's YouTube series of 'Luftwaffe fighter pilots: will it blend?'.



Just a couple of remarks about fixed armament. It wasn't uncommon (or necessarily a problem) to have fixed guns, like others have said you could always adjust the sights.





I believe the P-38 and Mosquito also had fixed guns? Although not necessarily as restrictive as the 109 mount.


The two flies in the ointment regarding HTC changing the convergence modelling of the 109: Firstly remember that an aircraft's theoretical thrust vector (coincidentally also the boresight in the particular case of the 109) does not always or even necessarily line up with the resultant direction vector of the aircraft. You have to take this into account even in level flight (as I'm sure the designers did). I don't think G is a problem because it cannot effect external ballistics. Perceived shot drop has more to do with the aircraft doing something counter-intuitive when turning. Secondly should HTC meddle with the arrangement it's 60 seconds work in Photoshop for a player to refind his preferred aiming point. There are limits to realism and it's not always that interesting anyway. I think it's close enough.

Maybe there'd be a case for allowing more convergence options with wing-mounted guns, say horizontal AND vertical but frankly the effective ranges are already bracketted and I'd far rather have fun with the option to configure your own ammo belts / drums.

[bustr]

Motor cannon are fixed with no adjustment through the center line of the engine they are mounted. The Revi reticle and Russian PBP1 reticle both have stadia marks to account for a motor mounted cannon firing solutions. When an aircraft pulls a turn and the G meter increases that is the "G" under which the round drops from the barrel. Then the IP point is predetermined by that "G" influence moment.

The screen captures are from the AAF fighter gun harmonization manual 1945. Note the 60 degree banked turn diagram pulling "G" and what the bullet drop in feet is at 2,3,4 G at 1000ft. It is the same principle for all fixed armament aircraft while shooting in a turn pulling more than 1G. Just like your arm will increase in weight while pulling G, everything else in your aircraft will also including the weight of your round and the force of gravity it experiences at the moment of departure from the barrel. After that back in the 1G normal environment it's trajectory and IP point has already been effected by 2,3,4 G. One of the biggest reason players miss so much in TnB furballs, G force effect on ballistics.



 

Nose mounted ganging increases the dispersion cone very little and has disadvantages for high G and large angle deflection shooting.

[nrshida]

The lateral G on the projectile must be negligible compared to the acceleration it experiences as it travels down the barrel.

I think it's a subtle but significant point to say G affects aim rather than drop (which is a constant). An aeroplane's flight cannot influence external balistics but can affect the aiming point before the shot is made as the aircraft is not flying a tangent to its flightpath.

[bustr]

Give it a rest, you are simply trying to jam this conversation to win the point by splitting the molecules holding a hair together. Motor canon are fixed to the center line of the motor, pulling G changes the IP point due to an increase in the force of gravity. None motor mounted nose cannons could be harmonized to an IP point and was never an issue with this post.