BF-109f4 Convergence

[Slade]

For you BF-109f4 Pilots,

I like to generally put convergence close on 109s (275-300).  It can sometimes be hard to get a shot at that range with vulchers and speed demons around you.

Where do you hard core 109f4 pilots put your convergence?

Thanks,

Slade 

[Krusty]

Set it for a moderate range (i.e. 350). Fight for that moderate-range-killshot. If you MUST take a shot furhter out, adjust your pipper higher to compensate for the drop.

No sense in setting them out to 600 and missing all your shots at the most common range because the "lob" sent the rounds over your target. Remember with nose mounted guns you aren't converging horizontally but you are converging vertically.

[BuckShot]

I set all of my 109s at 250 because that's where most of my kills happen.

[popeye]

Just started flying it this tour, started at 300 and am now trying 450.  Since all the guns are close together it doesn't seem to make a lot of difference.

[horble]

I have all guns at 400 for every plane.

[bustr]

After 15 years of trying with Hitech, I still wish he would set the motor cannon locked to 0 elevation inside of the motor like the were set in real life. The MG fired parallel to each other and could be adjusted for elevation, not convergence. That was only possible with with wing mounted guns or gondola mounted. It amazes me no one is ever curious how a gun barrel can be elevated up inside of the engine without destroying it. In the case of the ShVAK, it's bolted down to the top of the block and passes through the center of the reduction gear. With the Daimler-Benz it's a 57mm dia. tube that passed through the engine to the reduction gear. You cannot tilt the barrel if you want it to fit clean through the reduction gear and the MK103 is inserted into the same tube as the MG151\20. The same restriction held for the P39 and it's reduction gear housing in the nose.

[oakranger]

Always wonder how that was set up.  Thanks for the pics, Bustr.

[JOACH1M]

400 yards.

[wil3ur]

I keep all my centerline cannon at 225 from 109 to KI61 to Yaks...  I pull the trigger when they're under my gun sight and watch them fly into view in flaming pieces.

[FBKampfer]

250 for all centerline armament, regardless of ballistics.

Teach yourself to use holdover and you'll be much happier.

[trap78]

Great pics of the DB engine Bustr; it was a very advanced design for the day. Using dual overhead camshafts, the block was still cast with the through hole for a push rod / camshaft arrangement. This allowed a means for passing the cannon barrel through the engine. I agree the in game convergence should be fixed for this type of design. I set my convergence at 275, based on hours of filmed sorties most of my shots are in the 250 - 300yd range.

[Krusty]

But it wasn't just fixed "flat"... The angle of the gun along the engine wasn't flat to your path of motion and Bf109s still harmonized the gunsight so that it was actually between 3 and 5 degrees upward to the line of the engine itself. Remember when you're talking distances of 250 yards (700+ feet), a VERY tiny half a degree had a large impact in final impact of the round.

Further, even if the gun is rigidly fixed, your viewpoint relative to the nose of the craft changes where that bullet/shell impacts. So even IF it were 100% fixed all you need to do is adjust your pipper on the reflective gunsight and you can still adjust your convergence -- effectively -- without touching the gun at all.

Germans were rather fastidious about their standards and practices and they could and did make adjustments to such things through one means or another.

What does it matter HOW it was done? The end result in AH is that you are pulling off the same effect.

Bf109Fs, from what I remember reading, were harmonized at 400m, but on the upward lob of the trajectory would also pass through the aimpoint at 200 yards, and German studies (unrelated topic) were noting the most effective ranges were 200m or less.

The fixed convergence and harmonization wasn't that different from US or RAF convergences -- it was a standard and the pilots were forced to fly it until that standard was changed or unless somebody had enough clout to break the standard. I have read anecdotal accounts of Luftwaffe aces that had custom convergences, but for the most part the fixed harmonization/convergence was for all the green pilots with no skill that couldn't hit the broadside of a barn. It didn't mean you COULDN'T change it, it meant they were anal retentive and didn't allow it in most cases.

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

This is really a non-issue. It's taking the information and drawing the wrong conclusions from it.

Information: The tube in a 109 engine had little to no room for harmonization, so it should be fixed flat and drop as soon as it comes out of the nose in this game. Well it doesn't take into account other factors, the fact that all you needed was a fraction of a degree, the fact that you could still tweak the gunsight, the tales that some aces did, and the fact that the prescribed convergence was no different than other nations' prescribed/dictated convergences -- it was a rule, not a physical limitation.

Hence, IMO, the topic of the hub guns not being converged is a non-starter and not worth all the effort put into it so far.

[DaddyAce]

But it wasn't just fixed "flat"... The angle of the gun along the engine wasn't flat to your path of motion and Bf109s still harmonized the gunsight so that it was actually between 3 and 5 degrees upward to the line of the engine itself. Remember when you're talking distances of 250 yards (700+ feet), a VERY tiny half a degree had a large impact in final impact of the round.

Further, even if the gun is rigidly fixed, your viewpoint relative to the nose of the craft changes where that bullet/shell impacts. So even IF it were 100% fixed all you need to do is adjust your pipper on the reflective gunsight and you can still adjust your convergence -- effectively -- without touching the gun at all.

Germans were rather fastidious about their standards and practices and they could and did make adjustments to such things through one means or another.

What does it matter HOW it was done? The end result in AH is that you are pulling off the same effect.

Bf109Fs, from what I remember reading, were harmonized at 400m, but on the upward lob of the trajectory would also pass through the aimpoint at 200 yards, and German studies (unrelated topic) were noting the most effective ranges were 200m or less.

The fixed convergence and harmonization wasn't that different from US or RAF convergences -- it was a standard and the pilots were forced to fly it until that standard was changed or unless somebody had enough clout to break the standard. I have read anecdotal accounts of Luftwaffe aces that had custom convergences, but for the most part the fixed harmonization/convergence was for all the green pilots with no skill that couldn't hit the broadside of a barn. It didn't mean you COULDN'T change it, it meant they were anal retentive and didn't allow it in most cases.

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

This is really a non-issue. It's taking the information and drawing the wrong conclusions from it.

Information: The tube in a 109 engine had little to no room for harmonization, so it should be fixed flat and drop as soon as it comes out of the nose in this game. Well it doesn't take into account other factors, the fact that all you needed was a fraction of a degree, the fact that you could still tweak the gunsight, the tales that some aces did, and the fact that the prescribed convergence was no different than other nations' prescribed/dictated convergences -- it was a rule, not a physical limitation.

Hence, IMO, the topic of the hub guns not being converged is a non-starter and not worth all the effort put into it so far.

Based on my understanding and having studied ballistics of specific ammunition and then sighted in firearms for optimal "point blank" range for many years, Krusty, your information and reasoning rings true to me.

[bustr]

Krusty the only variation was the aircraft bouncing around in flight. There was no adjustment because the rounds had to get clear of the tube or fly off in strange directions if they touched the inside of the tube. Detonation was not an issue due to the fuse took about 100m of flight to arm. I've translated the manuals for mounting the cannons in the DB600 series. The tube is the center line of the motor, and harmonization is always the nose attitude for average combat speed at some altitude to where 700 or 400M will be for the round by "adjusting the reticle". MG151\20 were IP for 700m while MK108 for 400m. There were no shims where the MoL unit bolted to the back of the engine for the MG151 or MK103. A fraction of a degree inside of a 65mm tube will bounce a round off the inside of the tube. That is why the MoL unit centered the barrel into the tube with both cannon while with the MG151 the stuzstern(star washer) kept the longer barrel centered to is length inside of the panzerrohr(blast tube).


MG151 barrel stuzstern keeping the barrel centered.



The MoL is bolted with no shims to the end of the panzerroher mounting flange.



See how far down the barrel by the gentlman's had on the left the stuzstern is mounted to keep it dead center of the panzerrohr.

[bustr]

Because the MK103 barrel was only 23in outside of the receiver, it had to be centered to the panzerrhor so the round will clear the tube clean. The MK103 round had such poor ballistics it even had a problem with curving in it's spin direction(spin drift) of almost 2ft at 400m.

MoL unit for the MK103.