Bomber gun dispersion chart

[davidpt40]

Does anyone here have a link to the (real life) B-17 and B-24 gun station dispersion charts?  I have seen it years and years ago, but cannot seem to find it using the search feature.  I'm currently in a discussion on how accurate (or rather innacurate) bomber guns were at 500 yards.

[MiloMorai]

a 2 sec search

[davidpt40]

Thanks for the effort. I'm actually looking for the table that lists the mils of dispersion at 500 yards.

[guncrasher]

Thanks for the effort. I'm actually looking for the table that lists the mils of dispersion at 500 yards.

ask  999, he's gotten it down.

semp

[Oldman731]

Does anyone here have a link to the (real life) B-17 and B-24 gun station dispersion charts?  I have seen it years and years ago, but cannot seem to find it using the search feature.  I'm currently in a discussion on how accurate (or rather innacurate) bomber guns were at 500 yards.

Found this:

For those so interested, the following comes from AF Manual 335-25 FIGHTER GUNNERY, dated Dec 1950 -

QUOTE -

With an F-80 harmonized at 350mph IAS for a 1,000 foot range, the trajectory of the bullet will cross the sight line the first time at 1,000 feet. The trajectory will rise gradually to a height of 7 inches above the sight line and then will fall, recrossing the sight line again at 2,000 feet. (snip) With a cone of dispersion (the cone of bullet dispersion from a caliber .50 machine gun is about 4 mils for 75 percent of the rounds and 8 mils for 100 percent of the rounds) of 8 mils, or 16 feet at 2,000 feet, 6 guns (M2) firing 72 rounds per second give a bullet density of one bullet per 2.8 square feet per second, ...

- UNQUOTE

https://forums.ubisoft.com/archive/index.php/t-10877.html

Of course (and if true), that would be for a fixed installation in the nose of a jet.  WWII bomber guns, particularly the hand-held mounts, I would expect to be much less accurate.

- oldman

[MiloMorai]

Testing done by the USAAF found that the bullet pattern from a B-17 during ground testing had the following results for 12 rounds to 600yds:

ball turret > dia. 15' - 8.3mils
upper turret > dia. 21' - 11.7mils
chin turret > dia. 23' - 12.6 mils
waist(closed) dia. 26' - 14.3mils
side nose > dia. 34' - 18.7mils
tail turret > dia 45' - 25mils

For the B-24 it was:

ball turret > dia. 15' - 8.3mils
upper turret > dia. 20' - 11.2mils
nose turret > dia. 23' - 12.9mils (Emerson)
nose turret > dia. 35' - 19.3mils (Motor Prod.)
waist(closed) dia. 23' - 12.9mils
waist(open) dia. 63' - 35.6mils
tail turret > dia 35' - 19.3mils

Can you imagine what the results would be while shooting at a real a/c traveling at high speed?

taken from: "Gunner" ISBN 1-55046-332-2

**************************

Attacks and hits on B-17s and B-24s, Jan - May 1944

Distribution according to direction of origin in azimuth

B-17 % distribution of 3585 attacks and 441 hits whose direction could be determined

12 - 20.2/15.6
1 - 12.5/9.3
2 - 5.9/6.7
3 - 4.5/3.9
4 - 5.7/4.0
5 - 9.1-9.2
6 - 20.7/15.6
7 - 5.9/6.6
8 - 3.8/2.7
9 - 3.9/2.9
10 - 3.7/3.9
11 - 10.4/10.3

B-24 % distribution of 10425 attacks and 102 hits whose direction could be determined

12 - 21.6/17.6
1 - 12.7/8.4
2 - 3.9/5.2
3 - 2.9/5.4
4 - 3.0/3.6
5 - 7.7/7.8
6 - 20.7/15.6
7 - 19.6/20.6
8 - 11.0/6.9
9 - 3.1/2.0
10 - 6.9/3.4
11 - 11.9/7.8

Note: might not total 100% as the graphic was hard to read

[davidpt40]

You found it! I had done an advanced search in Aircraft and Vehicles but couldn't find it.  I owe you one.

Testing done by the USAAF found that the bullet pattern from a B-17 during ground testing had the following results for 12 rounds to 600yds:

ball turret > dia. 15' - 8.3mils
upper turret > dia. 21' - 11.7mils
chin turret > dia. 23' - 12.6 mils
waist(closed) dia. 26' - 14.3mils
side nose > dia. 34' - 18.7mils
tail turret > dia 45' - 25mils

For the B-24 it was:

ball turret > dia. 15' - 8.3mils
upper turret > dia. 20' - 11.2mils
nose turret > dia. 23' - 12.9mils (Emerson)
nose turret > dia. 35' - 19.3mils (Motor Prod.)
waist(closed) dia. 23' - 12.9mils
waist(open) dia. 63' - 35.6mils
tail turret > dia 35' - 19.3mils

Can you imagine what the results would be while shooting at a real a/c traveling at high speed?

taken from: "Gunner" ISBN 1-55046-332-2

**************************

Attacks and hits on B-17s and B-24s, Jan - May 1944

Distribution according to direction of origin in azimuth

B-17 % distribution of 3585 attacks and 441 hits whose direction could be determined

12 - 20.2/15.6
1 - 12.5/9.3
2 - 5.9/6.7
3 - 4.5/3.9
4 - 5.7/4.0
5 - 9.1-9.2
6 - 20.7/15.6
7 - 5.9/6.6
8 - 3.8/2.7
9 - 3.9/2.9
10 - 3.7/3.9
11 - 10.4/10.3

B-24 % distribution of 10425 attacks and 102 hits whose direction could be determined

12 - 21.6/17.6
1 - 12.7/8.4
2 - 3.9/5.2
3 - 2.9/5.4
4 - 3.0/3.6
5 - 7.7/7.8
6 - 20.7/15.6
7 - 19.6/20.6
8 - 11.0/6.9
9 - 3.1/2.0
10 - 6.9/3.4
11 - 11.9/7.8

Note: might not total 100% as the graphic was hard to read