F4U Harmonization Charts

[Ambaryerno]

Has anyone seen a larger version of this:

This is about as high resolution I can find for this chart, but I still can't read the ranges.

It also says it's for "Pattern No.2." Are there charts for other patterns?

 

[Greyman]

Tough to read but my guesses would be:

- Ranges are in yards, a line every 50 yards (ie: the final line is 600 yards)
- Pattern No.1 is simple point harmonisation (wild guess)

 

[Ambaryerno]

Tough to read but my guesses would be:

- Ranges are in yards, a line every 50 yards (ie: the final line is 600 yards)
- Pattern No.1 is simple point harmonisation (wild guess)

Would you really see a pattern where one set of guns was centered 200 yards closer than the remaining guns?

 

[Greyman]

200 yards is a wider range than I've seen before, but, I've never seen a USN pattern until now.

A 150-yard 'gap' would be pretty typical for the RAF and the USAAF.

 

[GreenKnight121]

Rarely were the guns set for a single precise "point of convergence" - the optimum was to create a "beaten zone" where none of the bullet paths were away from the pattern, but the pattern was large enough to compensate for variations in aim and the like from the aircraft bouncing in the air, but tight enough to ensure enough bullets were passing through the area to do useful damage to an aircraft in that "beaten zone".

 

[Ambaryerno]

Rarely were the guns set for a single precise "point of convergence" - the optimum was to create a "beaten zone" where none of the bullet paths were away from the pattern, but the pattern was large enough to compensate for variations in aim and the like from the aircraft bouncing in the air, but tight enough to ensure enough bullets were passing through the area to do useful damage to an aircraft in that "beaten zone".

IIRC that's only because the patterns were intended to guarantee at least some hits for novice pilots. But veterans DID prefer a point zone for greater hitting power.

 

[Greyman]

IIRC that's only because the patterns were intended to guarantee at least some hits for novice pilots. But veterans DID prefer a point zone for greater hitting power.

Fighter pilot psychology at work.

The data showed that the primary reason pilots failed to bring down a target was due to a lack of accuracy, errors in aiming, not a lack of bullet density. The vast majority of successful firing was done at ranges of 150 yards or less -- and at these ranges the various 'spread' patterns had little effect on density anyway.

When looking at shooting from medium to long ranges, the spread patterns materially increased the chances of a 'kill' -- hot-shot veteran or not.

edited for clarity

 

[mad_max]

Don't know if either of the 2 I have for the F4U are better than what you have, but use what I've saved through the years; follow the google drive folder link and download them. There's also convergence charts for a number of other American fighters, 109E and 190 in the folder. Enjoy.

Gun Convergence – Google Drive

drive.google.com

 

[Ambaryerno]

Unfortunately that looks like the same image from my OP, so it still doesn't solve the issue of being illegibly small.

 

[Greyman]

Googling around ...

It looks like the original document is from:

CONFIDENTIAL TECHNICAL NOTE NO. F-43​

BORESIGHT PATTERNS FOR FIGHTER AIRPLANES​

WITH DISCUSSION OF FACTORS AFFECTING AIMING ALLOWANCES​

4 June 1943​

Apparently found at:

National Archives & Records Administration, Seattle Branch
"Commandant's Office, Central Subject Files, 1942-43"​

 

[Barrett]

From the history of VF-11: circa 1942 the navy more or less standardized on the "pattern foresight" with six-gun fighters.
One pair sighted at 200 yds
One pair sighted at 250
One pair sighted at 300.

Theory being that an average pilot could get more hits than with a tighter harmonization.
However
I was fortunate to know Dave McCampbell well. He was told to build VF-15 for air-air and determined that six .50 cals in a three-mil group (three feet at 1000 ft) would do the job.
And of course it did.

 

[Ambaryerno]

From the history of VF-11: circa 1942 the navy more or less standardized on the "pattern foresight" with six-gun fighters.
One pair sighted at 200 yds
One pair sighted at 250
One pair sighted at 300.

Theory being that an average pilot could get more hits than with a tighter harmonization.
However
I was fortunate to know Dave McCampbell well. He was told to build VF-15 for air-air and determined that six .50 cals in a three-mil group (three feet at 1000 ft) would do the job.
And of course it did.

I mean that may as well be point convergence at that point.

CONFIDENTIAL TECHNICAL NOTE NO. F-43BORESIGHT PATTERNS FOR FIGHTER AIRPLANESWITH DISCUSSION OF FACTORS AFFECTING AIMING ALLOWANCES4 June 1943

Does anyone have access to a version that's large enough the patterns are actually legible? And has whatever "Corsair Pattern No. 1" is?