IMPORTANT: Huge undefended "empty" zone in AA coverage!

[Apollo11]

Hi all,

ORIGINAL: jwilkerson
Before we get too bent out of shape here we might consider that there is historical justification for this AA gap ... to wit the B29 strikes where reconfigured to go in at low altitudes in part to exploit this suspected gap ( and to avoid effects of winds and other reasons ) .. here is a first tid bit on this .. more from the "effects" side saying the gap existed ... specifically page 616 "auto-weapons fire was generally too low and heavy AA fire too high ... "

https://www.airforcehistory.hq.af.mil/Publications/fulltext/aaf_wwii-v5.pdf

In all books I read the B-29's attacked from lower altitudes due to so-called "jet stream effect" that made precision bombing impossible due to fact that bombs were heavily dispersed.

Also I never heard of massive B-29 (or other 4 engine or 2 engine bomber) low altitude attacks at day... [;)]


Leo "Apollo11"

[jwilkerson]

ORIGINAL: Apollo11

Hi all,

ORIGINAL: jwilkerson
Before we get too bent out of shape here we might consider that there is historical justification for this AA gap ... to wit the B29 strikes where reconfigured to go in at low altitudes in part to exploit this suspected gap ( and to avoid effects of winds and other reasons ) .. here is a first tid bit on this .. more from the "effects" side saying the gap existed ... specifically page 616 "auto-weapons fire was generally too low and heavy AA fire too high ... "

https://www.airforcehistory.hq.af.mil/Publications/fulltext/aaf_wwii-v5.pdf

In all books I read the B-29's attacked from lower altitudes due to so-called "jet stream effect" that made precision bombing impossible due to fact that bombs were heavily dispersed.

Also I never heard of massive B-29 (or other 4 engine or 2 engine bomber) low altitude attacks at day... [;)]


Leo "Apollo11"

There were more factors than just the jet stream ...

He reviewed the pros and cons over and over. Misjudg-
ing it would mean unprecedented losses.
Pros:
a. accuracy, bomb pattern
b. greatly improved bomb capacity due to less fuel
required to climb to high altitude
c. less strain on still troublesome engines due to
shorter climb
d. eliminate 200 MPH head wind at altitude
e. pressurization problems eliminated
f. fly under clouds (possibly)
g. better radar resolution
h. element of surprise
i. Arnold wanted results
Cons:
a. fighters (maybe)
b. flak (maybe - Japan's AA guns optimized for high
altitude)
c. failure would mean an end to career and serious
setback to 20th Air Force

LeMay was most worried about the flak:

Only LeMay and a few operations duty types were
staying up. After a brief exchange of small talk, LeMay told
McKelway,
I'm sweating this one out myself. A lot could
go wrong. I can't sleep. I usually can, but not
tonight. If this raid works the way I think it will
we can shorten the war.
In a war you've got to try to keep at least
one punch ahead of the other guy all the time. A
war is a very tough kind of proposition. If you
don't get the enemy, he gets you. I think we've
figured out a punch he's not expecting this time.
I don't think he's got the right flak to combat
this kind of raid and I don't think he can keep
his cities from being burned down - wiped right
off the map. He hasn't moved his industries to
Manchuria yet, although he's starting to move them,
and if we can destroy them before he can move them,
we've got him. I never think anything is going to
work until I've seen the pictures after the raid,
but if this one works we will shorten this damned
war out here.(32)

Link http://www.globalsecurity.org/wmd/library/report/1986/CTJ.htm


As to lower level day raids ... page 634 of volume 5 referenced in my first post above "B29s went in at lower levels than in days strikes at heavily defended targets, at altitudes from 10,000 to 18,000 feet" [ these were the April B29 strikes against Kyushu airfields in support of Okinawa campaign ]


Page 637 ... " altitudes ranging from 12,000 to 20,500 feet" [ these were daylight raids on Nagoya/Mitsubishi ]

Page 640 ... " unusually low for a day light strike ... altitudes from 13,650 to 18,000 ... " [ Kobe on 5 Jun 45 ]

Page 649 ... " over Tachikawa ... bomb visually from 12,000 feet"

None of this is to "prove" there should be an invariable flak gap ... but to offer up possible explaination as to why there might be one in the game. I'd suspect that LeMay's fire bombing attacks, in part, exploited a temporary hole in the defenses, which like most tactical exloits can be adjusted for ( eventually ) by the defenders ... looking at all the B29 attacks LeMay over saw .. it seems that Japanese flak was rarely effective at any altitude. Perhaps their most effective defense was 25 May Tokyo night attack in which 26 B29s were destroyed by all causes though crews reported the heaviest flak of the campaign ( page 639 )

[Apollo11]

Hi all,

ORIGINAL: jwilkerson

There were more factors than just the jet stream ...

He reviewed the pros and cons over and over. Misjudg-
ing it would mean unprecedented losses.
Pros:
a. accuracy, bomb pattern
b. greatly improved bomb capacity due to less fuel
required to climb to high altitude
c. less strain on still troublesome engines due to
shorter climb
d. eliminate 200 MPH head wind at altitude
e. pressurization problems eliminated
f. fly under clouds (possibly)
g. better radar resolution
h. element of surprise
i. Arnold wanted results
Cons:
a. fighters (maybe)
b. flak (maybe - Japan's AA guns optimized for high
altitude)
c. failure would mean an end to career and serious
setback to 20th Air Force

LeMay was most worried about the flak:

Only LeMay and a few operations duty types were
staying up. After a brief exchange of small talk, LeMay told
McKelway,
I'm sweating this one out myself. A lot could
go wrong. I can't sleep. I usually can, but not
tonight. If this raid works the way I think it will
we can shorten the war.
In a war you've got to try to keep at least
one punch ahead of the other guy all the time. A
war is a very tough kind of proposition. If you
don't get the enemy, he gets you. I think we've
figured out a punch he's not expecting this time.
I don't think he's got the right flak to combat
this kind of raid and I don't think he can keep
his cities from being burned down - wiped right
off the map. He hasn't moved his industries to
Manchuria yet, although he's starting to move them,
and if we can destroy them before he can move them,
we've got him. I never think anything is going to
work until I've seen the pictures after the raid,
but if this one works we will shorten this damned
war out here.(32)

Link http://www.globalsecurity.org/wmd/library/report/1986/CTJ.htm

Thanks for info - I am still DLing that huge 100+ MB PDF... [;)]

As to lower level day raids ... page 634 of volume 5 referenced in my first post above "B29s went in at lower levels than in days strikes at heavily defended targets, at altitudes from 10,000 to 18,000 feet" [ these were the April B29 strikes against Kyushu airfields in support of Okinawa campaign ]


Page 637 ... " altitudes ranging from 12,000 to 20,500 feet" [ these were daylight raids on Nagoya/Mitsubishi ]

Page 640 ... " unusually low for a day light strike ... altitudes from 13,650 to 18,000 ... " [ Kobe on 5 Jun 45 ]

Page 649 ... " over Tachikawa ... bomb visually from 12,000 feet"

None of this is to "prove" there should be an invariable flak gap ... but to offer up possible explaination as to why there might be one in the game. I'd suspect that LeMay's fire bombing attacks, in part, exploited a temporary hole in the defenses, which like most tactical exloits can be adjusted for ( eventually ) by the defenders ... looking at all the B29 attacks LeMay over saw .. it seems that Japanese flak was rarely effective at any altitude. Perhaps their most effective defense was 25 May Tokyo night attack in which 26 B29s were destroyed by all causes though crews reported the heaviest flak of the campaign ( page 639 )

RGR.

But in WitP we have gap from 0 ft to 7000 ft (or 9000 ft) for heavy AA guns.

Attacking from 12000 ft (in your examples) doesn't seem so much unreasobable when enemy was almost on his knees late at war whilst in WitP we can attack almost with impunity from mere 6000 ft when hundreads of AA guns are willing and able and ready to counter it (but they can't due to "gap limit")...

BTW, are there any sources to give us data how strong was Japanese AA at those locations you mention (i.e. how many gun barrels they had there)?

- Nagoya/Mitsubishi
- Kobe
- Tachikawa


Leo "Apollo11"

[Twotribes]

As I can tell all the Japanese AA units have at least one aa gun that does not have the minimum requirement and fires into the supposed gap. Exactly what is the problem?

[Apollo11]

Hi all,

ORIGINAL: Twotribes

As I can tell all the Japanese AA units have at least one aa gun that does not have the minimum requirement and fires into the supposed gap. Exactly what is the problem?

What's the problem... heh... that's understatement... [:D]

All they have to defend from 0 ft to 9000 ft is poor "13mm AAMG" (0.5 inch machine gun). That's like trying to put out bush fire by pissing on it... [;)]


Leo "Apollo11"

[jwilkerson]

ORIGINAL: jwilkerson


None of this is to "prove" there should be an invariable flak gap ...

ORIGINAL: Apollo11
BTW, are there any sources to give us data how strong was Japanese AA at those locations you mention (i.e. how many gun barrels they had there)?

- Nagoya/Mitsubishi
- Kobe
- Tachikawa

(1) Well now after some more checking - I'm thinking I may be wrong about there not being an invariable flak gap ... to wit: Ian Hogg's GERMAN ARTILLERY OF WORLD WAR II, page 155 "The Germans were probably the first to realize that there was a gap in the sky between the maximum effective ceiling of the light weapons and the minimum of the heavy guns; they were certainly the first to try to plug it. " I am continuing to hunt for the existence and reason for the "flak gap" ... but at this point I certainly couldn'y say that it should not exist.

Unfortunately, despite an hour of looking, I still haven't found the reason for the minimum effective altitude of the heavier ( 75mm and up ? ) weapons. So for now my "guess" is that most of these weapons used a timed fuse ( well I know that much ) and that this timed fuse had a minimum time setting. But, I haven't been able to verify that yet. If this theory is correct, then introduction of a VT fuse would mitigate the minimum altitude of the heavy weapons ( or at least lower it as the VT fuse might still have a minimum setting to ensure no premature bursts too close to friendlies on the ground ).

(2) No, the Airforce "blue" books I'm quoting above don't give flak gun totals for the Japanese cities, but I purposely skipped any city that was called "lightly defended" and included only those that were said to be "heavily" defended. Another intangible might be late war the Japanese knew where their cities were and they didn't have to ship the flak guns and ammunition very far, so those cities were more likely to have the heaviest defence, also any integrated air defense capabilities were most likely to be here ( versus early war overseas locations ) and what radar defenses existed were more likely to be here, etc. etc.

[tsimmonds]

Isn't the main problem for heavy AAA firing at low altitude one of tracking, pointing and fuse-setting? Relative to the POV of a fixed gun, an aircraft flying at 6000 feet seems to move significantly more quickly across the sky than one flying at 26,000 feet. I can easily imagine that such a fire control problem would have been all but impossible to solve with that generation of FC technology. Only automatic weapons can effectively engage in a situation where they have to rapidly track and point while firing.

[jwilkerson]

You're very possibly right ... I do know Germans did not integrate "automatic" weapons ( 20mm 37mm ) into their directed AA fire ...

But if I throw a rock down range and it bangs into something - I would expect the something to be affected even if the something is only 1000 feet away ... I'm not an AA guy .. I was an FA guy so can speak with some authority there .. but as to AA still hoping to find attestable source that nails this one down ... but your logic is certainly sensible !!!

[Apollo11]

Hi all,

ORIGINAL: irrelevant

Isn't the main problem for heavy AAA firing at low altitude one of tracking, pointing and fuse-setting? Relative to the POV of a fixed gun, an aircraft flying at 6000 feet seems to move significantly more quickly across the sky than one flying at 26,000 feet. I can easily imagine that such a fire control problem would have been all but impossible to solve with that generation of FC technology. Only automatic weapons can effectively engage in a situation where they have to rapidly track and point while firing.

Very true!

But heavy AA can be used in one other way (i..e not directly tracking targets) - they can be set to fire directly into path of incoming enemy aircraft which would then simply fly into heavy FLAK "cloud"...

BTW German 88mm FLAK was able to fire 20+ shells a minute (that's a huge rate of fire) and we can imagine 100+ of such guns firing into area, for example, 10000 ft (3000m = 3 km) above (even if we assume that Japanese guns were 2x slower than german that's lot of shells)!


Leo "Apollo11"

[jwilkerson]

ORIGINAL: irrelevant

Isn't the main problem for heavy AAA firing at low altitude one of tracking, pointing and fuse-setting? Relative to the POV of a fixed gun, an aircraft flying at 6000 feet seems to move significantly more quickly across the sky than one flying at 26,000 feet. I can easily imagine that such a fire control problem would have been all but impossible to solve with that generation of FC technology. Only automatic weapons can effectively engage in a situation where they have to rapidly track and point while firing.

Ok another tid bit ... page 156 of Ian Hogg's GERMAN ARTILLERY OF WORLD WAR II ... [ in reference to the development of the "gap filling" 5cm F41 ] ... "After some months of service the Luftwaffe concluded that the design was a failure ... it could not track targets fast enough ... " ... [but] it showed that a weapon of this class was desirable.

Recall from above that per page 155 "The Germans were probably the first to realize that there was a gap in the sky between the maximum effective ceiling of the light weapons and the minimum of the heavy guns; they were certainly the first to try to plug it. " which lead to the development of the 5cm F41 in the first place.

So this shows that tracking WAS one of the issues. And that the first attempt to ameliorate was a failure.

Also on page 156, we have "[the fuze on this gun] ... was unusual in having two settings: short ... 5 to 8 sec and long ... 14 to 18 sec ... "

I am still looking for fuze timmings on heavier AA but haven't been able to locate those yet - but it seems reasonable that they would have one ( since 2 is said to be unusual ) and that it would be in a higher range ( to be effective against high flying bombers - the main target of these pieces. But am still looking.

So we have strong indications of tracking and fuze issues as being the cause of the flak gap at this point ... thanks for pointing this out Ir !!!

[spence]

From roughly Oct 42 onwards there should be no "flak gap" for the 5"/38 in any case with the introduction of the VT proximity fuze. This particular fuze exploded the AA shell at the closest point of approach to an enemy aircraft due to a radar transponder in the fuze itself. It thus was effective from the muzzle (well almost) of the gun to the maximum ceiling/range of the gun. It was a major contributor to the deadliness of USN flak. It meant for one thing that the large caliber artillery could still engage a target that was rapidly changing the range. Older style AA fuzing required a manual time-fuze setting which could not be done fast enough to deal with a dive bomber which had already tipped over (for instance).
This technical Allied innovation has been ignored in this game and its predecessors (Pacwar/UV).

[Sharkosaurus rex]

The minimum altitude for heavy flak in BTR is 7500ft.

[Speedysteve]

I think it's 2500 feet in BTR Sharky not 7500 feet.

[Sharkosaurus rex]

it's 7500ft.
you need to have some 37mm (14000ft) at a base as the 20mm only has 6000ft max.

[Speedysteve]

Hi,

I've always classed HAA as being 88mm and above and in the latest versions of BTR i've played its not 7500 feet - JCL V1.6 etc

[Sharkosaurus rex]

sorry I might have been unclear.
the heavies (88, 105, 128mm) have a min alt of 7500ft.
the 37mm has a max alt of 14000ft and no min alt
the 20mm has a max alt of 6000ft and no min alt.

[demonterico]

Spence, while readind this thread, the idea of the proximity fuse also came to me. Although I could imagine a minimum altitude could be necessary for such a fuse to set, not that I actually know anything about this topic. It just seems logical to me that a fuse on a warhead of any type should be designed to set after the projectile has been fired, or droped, or whatever.

General question; I'm still playing UV does the AA gap exsist in this game as well? Seems to me like it should.

[Speedysteve]

Hi Sharky,

I may have been too and apologies for that.

I've always classed 2500 feet s being the minimum I would fly due to flak.

TRUE minimum AKAIK are:

6500 feet for HAA flak and unlimted for LAA. As such 88's etc will not be effective until 6500 feet.

However, as a player of BTR. I will fly raids at less than this provided I know there is no quad 20m or 37mm +

I'm sorry but if you want to take in true minimums then 6500 feet is it for HAA but for realistic effecriveness levels I have found 2500 feet is ok WITHOUT heavy LAA being present.

Even below 6500 feet with HAA due to tracking times I have found it not too bad at bombing especially with Boston's due to their speed.

In short unless things have changed since JCL's last major works then the TRUE HAA limit is 6500 but I find the realistic operational without significant flak is 2500 feet.

Regards,

Steven

[Dereck]

People seem to be forgetting that the night B-29 raids over Japan were low-level and they DID fly beneath the flak.

[Nikademus]

ORIGINAL: spence

From roughly Oct 42 onwards there should be no "flak gap" for the 5"/38 in any case with the introduction of the VT proximity fuze. This particular fuze exploded the AA shell at the closest point of approach to an enemy aircraft due to a radar transponder in the fuze itself. It thus was effective from the muzzle (well almost) of the gun to the maximum ceiling/range of the gun. It was a major contributor to the deadliness of USN flak. It meant for one thing that the large caliber artillery could still engage a target that was rapidly changing the range. Older style AA fuzing required a manual time-fuze setting which could not be done fast enough to deal with a dive bomber which had already tipped over (for instance).
This technical Allied innovation has been ignored in this game and its predecessors (Pacwar/UV).

Sea based heavy flak guns have no minimum altitude.