Gun Convergence Adjustments

[Saxman]

Currently, the Corsair's guns can be set to harmonize in a range between 300 - 500 meters.

The US wouldn't have used meters for measuring range when boresighting, and these ranges also don't fall under what the ranges used by the Americans, being much longer.

The US typically used convergence ranges between 500ft and 1000ft (Wikipedia cites works by Colgan, Bergerud, and Nijboer giving ranges of 500ft, 750ft, 900ft, and 1000ft, though I don't have the referenced books to confirm the data). According to Hammell (also cited in Wiki. I have that book, Aces Against Japan, but I don't know where my copy is off-hand) at least one Marine squadron centered the guns of their Corsairs as short as 300ft. I've seen charts for the P-47 with ranges as far as 1200ft. Well short of 500m.

I have found one harmonization chart specifically for the F4U, though I can't read any of the ranges given:

Regardless, the ranging ought to be given in yards or feet, and the range of convergence points for each gun should be brought in much closer.

[Kreutzberg]

Big +1 for this. The Corsair's guns are very dependent on convergence.

[Saxman]

Bumping this one again:

• When the labels are added, (they weren't in this patch) please use yards, rather than meters.
• Bring the availabe convergence ranges in shorter, between 100 - 400 yards.
• Also as an addendum: Can we get options for convergence in the Quick Action loadout menu, as well?

[GeoS72]

@Saxman, thanks for your research into the gun convergence problem. What was the historical preference for these range settings?

What was the yardage recommendations for outer, middle, inner guns?

Edited August 1 by GeoS72

[Saxman]

1 hour ago, GeoS72 said:

@Saxman, thanks for your research into the gun convergence problem. What was the historical preference for these range settings?

What was the yardage recommendations for outer, middle, inner guns?

The citations I have are in my OP. That's the best copy of Pattern 2 I can find, and I can't find any information on what Pattern No. 1 is at all (ww2aircraft.net speculates it's for point convergence). According to Hammel (Aces Against Japan) VMF-213 zeroed all six guns to 100 yards. That's all I have.

[-Rudel-]

Added to our new list
https://docs.google.com/document/d/1aOrQR8opRdUnNfK9aAFfXnRZUB6IGGDSYP5xXOkk9Jw/edit?usp=sharing

[Raptorattacker]

On 8/1/2025 at 8:33 PM, Saxman said:

The citations I have are in my OP. That's the best copy of Pattern 2 I can find, and I can't find any information on what Pattern No. 1 is at all (ww2aircraft.net speculates it's for point convergence). According to Hammel (Aces Against Japan) VMF-213 zeroed all six guns to 100 yards. That's all I have.

A 26 year-old Aviation Ordnance man, Staff Sergeant Michael 'Mickey' McCarthy went against regulations and took it upon himself to set the guns (the recognized harmoization 'from above' was 1000ft) on a particular plane overnight to 300ft (100 yards) and immediately improved the lethality of the guns (literally overnight!). From then on it was standard practice to set harmonization to 300ft to improve effectiveness in US planes.

 

Edited yesterday at 09:08 PM by Raptorattacker

[Bowie]

Given the F4U's 100 MIL (100' @ 1000') inner gunsight ring, and the average fighter wingspan/fuselage length of ~ 35'?

A 100 yd harmonization would equate to basically filling the 100 MIL ring with fighter, pretty handy in a fur-ball dogfight with more maneuverable Japanese A/C.

The standard 1,000' harmonization puts that same fighter into 1/3 of the 100 MIL ring, equal spacing, which is easy to recognize in an attack. 

 

This is the 70 MIL ring P-51D gunsight, so 1/2 for a 35' wingspan/fuselage length fighter.

 

The problem with the 100 yd. harmonization - is that at that short range, the angle rate of change of a maneuvering A/C is very high.

But the lead required is also very short, so it's snap shooting at best.

Bowie

Edited 17 hours ago by Bowie

[Saxman]

17 hours ago, Raptorattacker said:

A 26 year-old Aviation Ordnance man, Staff Sergeant Michael 'Mickey' McCarthy went against regulations and took it upon himself to set the guns (the recognized harmoization 'from above' was 1000ft) on a particular plane overnight to 300ft (100 yards) and immediately improved the lethality of the guns (literally overnight!). From then on it was standard practice to set harmonization to 300ft to improve effectiveness in US planes.

 

So 100 yards should at least be an option.

And good GOD that AI video thumbnail is cursed...

[Raptorattacker]

It certainly IS cursed, yeah. ANYTHING for clicks eh??!! Subject matter is interesting though I thought...