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AA Gun Bofors vs 90mm range difference?

 
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AA Gun Bofors vs 90mm range difference? - 5/18/2016 2:54:37 PM   
Dili

 

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I am seeing that a land 40mm Bofors have a 6 range and a 90mm M1A1 has 4. What is the reason for this?
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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 4:20:40 PM   
BBfanboy


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I don't know, but any pictures of the 90mm gun I have seen show it pointing almost vertical. Maybe it can't get down to an angle good for horizontal distance?

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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 6:02:43 PM   
cardas

 

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No idea either, but I can give you what I assume is the answer (or in other words, pure speculation). First of all the 90 mm M1A1 has such a low range because the unit is assumed to lack any indirect fire training/support structure. The range thus represents a reasonable direct fire range on land. If you bother to go through the database then you will note that there are many other AA guns that also sits at 4 or less in range. There are some AA guns with ranges more similar to field artillery as well but I guess that's because they actually were used as such? You'd think they should be DP guns then, but maybe there are some (combat)mechanical reasons as to why they are set as AA.

Now the 40 mm isn't really a weapon that you'd use in an indirect role so here I think it's simply a data error. Someone tweaked the values on the automatic AA weapons, probably accuracy/effect, based on the ship mounted weapons. A ship based weapon should presumably have somewhat more generous ranges than the land based ones so having 6000 yards there is probably alright, but when the values were copied to the land based system they forgot to change the range to reflect the more restrictive land ranges. The only other explanation I can think of is that for some reason automatic weapons get better range despite not being used in an indirect role, but that would be quite odd.

So in short, I speculate that it's a database error and that many of the land based 20+ mm automatic AA weapons should have lower range than they currently have. A land based 40 mm Bofors should then have somewhere between 1 to 3 in range if my reasoning is sound.

< Message edited by cardas -- 5/18/2016 6:04:42 PM >

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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 6:27:44 PM   
jmolyson

 

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The difference is intended target altitude, slew rate and rate of fire. The 40MM was intended for use against fast medium to low altitude targets with high crossing rates. The land and ship mounts were able to move in azimuth and elevation at fairly high rates. This was still a standard AA gun in NATO armies in the 1990s.

The 90MM was for high altitude targets, hopefully flying in formation. The rate of fire was much lower but the shell was much bigger. The 90MM was deployed with the Marines and Army at Guadalcanal and contributed to the fairly poor bombing accuracy of Japanese bombing formations from high altitude.

The lower range for the 90MM is because the loft energy for the round is concentrated in the Y (altitude) access rather than the horizontal axis.

Joe

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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 6:40:35 PM   
cardas

 

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The range value doesn't have anything to do with AA fire in WitP:AE, does it? It's a value used purely for ground/naval combat so elevation/train rate should be pretty irrelevant. I don't think elevation/train rate is factored into any of the database values at all actually and if they are it ought to be in the effect/accuracy fields.

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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 8:00:01 PM   
Dili

 

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From what i have read in the forum cardas is correct range in AA weapons is only for surface and land combat.

AA fire is more or less this: Aircraft arrival(1st AA combat) check if aircraft inside ceiling fire. Aircraft payload delivery(2nd AA combat) check ceiling, if in, fire.

There is no way that a Bofors have a 6kyd range except in indirect fire while at 4 kyd range of 90mm will have a sizable drop but probably still can use open sights.


@ BBfanboy

It seems you are right about 90mm M1 , the mount precluded anti tank fire. But in that case 4 kyd is too much.

< Message edited by Dili -- 5/18/2016 8:05:16 PM >

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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 10:12:22 PM   
jmolyson

 

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"In U.S. Army service, the single mount Bofors was known as the "40 mm Automatic Gun M1".
The U.S. version of the gun fired three variants of the British Mk. II high-explosive shell
as well as the M81A1 armor-piercing round, which was capable of penetrating some 50 mm of
homogeneous armor plate at a range of 500 yards."

"The 90 mm Gun M1/M2/M3 served as a primary heavy American anti-aircraft and anti-tank gun,
playing a role similar to the renowned German 88 mm gun. It was 90 mm (3.5 in) in caliber,
and had a 4.60 m (15 feet) barrel, 53 calibers in length. It was capable of firing a 90×600 mm R
shell 17,823 m (58,474 feet) horizontally, or a maximum altitude of 10,380 m (34,060 feet)."

It would seem the game database is in error on comparative ranges. I have no idea what that means
in terms of a range of 4 or whatever, but it would seem that 500 yards is a lot less than 19,491 yards.

As far as accuracy, a rapid fire 40MM medium gun is inherently less accurate that a
one-shot-at-a-time heavy gun.


(Wikipedia)

Joe Molyson



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RE: AA Gun Bofors vs 90mm range difference? - 5/18/2016 10:20:13 PM   
cardas

 

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Are you sure the M1A1 couldn't depress enough to engage ground targets? From the scant information I found with a quick look through on the internet I'd say the M1A1 mount had a minimum elevation of 0 degrees. Positioning of the gun becomes important with such a restricted elevation and makes it less flexible, but it still allows it to engage ground targets if placed correctly. The M2 mount had a minimum elevation of -10 degrees.

When it comes to direct fire range it is mostly the quality of the sights available that would restrict direct fire along with the penetration if engaging an armored target. The elevation required shouldn't matter that much. Let's have a rough guess for a range of 5000 yards; the 40 mm would need an elevation of say 5 - 6 degrees and the 90 mm would use around 3 degrees, neither all that much. There's no problem using "direct" fire with a mortar either as an additional example. The problem is seeing and hitting the target. The Bofors would probably require a pretty direct hit even against a soft target while with the M1A1 a near miss could be sufficient because of a larger bursting charge. Larger guns should therefore have a longer effective direct fire range simply due to their larger shell even if the sights used are the same.

Here's one site making the 0 degrees claim, although I've also seen it at other places.
http://www.ww2gyrene.org/special_weapons_battalion.htm

---

The 500 yards figure is only for the penetration value, the Bofors had a theoretical range of around 11000 yards according to NavWeaps.

< Message edited by cardas -- 5/18/2016 10:26:21 PM >

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RE: AA Gun Bofors vs 90mm range difference? - 5/19/2016 2:32:05 AM   
Dili

 

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The references i have read is that it was necessary the M2 mount for the 90mm to be able to fire against land targets. I might be mistaken of it is the elevation.

Of course if you put a Bofors at 45 degree elevation you have the maximum range, those 11000 kyd but that doesn't matter in combat . It is needed a big gun with a explosive rounds strong enough that can compensate for the inherent error of firing that way. A Bofors firing like a 155mm is useless and an waste of ammo.
It like the maximum ceiling values for AA guns. Yeah they can reach that height but the round at that height is at 0 speed and about to fall back to earth. Such a fast deceleration of rounds speed is impossible to calculate for fire controls, so effective ceiling is much less. That don't even includes fuse timings which usually detonate the round at effective range/ceiling or less depending on setting. 3-2 kyd is about the range a Bofors start to fire against air targets. The effective range for AT work is probably 1 kyd. Usually the effective range for AT is considered no more than 1m drop in round trajectory.

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RE: AA Gun Bofors vs 90mm range difference? - 5/20/2016 4:49:19 PM   
jmolyson

 

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Both the 45MM and 90MM guns could be trained horizontal, but if emplaced inside a pit or
parapet might not be able to deflect down to 0 degree elevation.

Firing in the anti-armor role these guns would not have had to reach out for miles,
the armor would be coming to them. They would probably hold fire until discovered by the
enemy to avoid be flanked.

IMHO I think we are really in the weeds in regards to the modeling capabilities of this game.

Joe


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RE: AA Gun Bofors vs 90mm range difference? - 5/21/2016 5:40:04 PM   
cardas

 

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I have actually read claims (sorry, don't remember where) about the 40 mm being used in an indirect role to mark "danger zones", but I think that's pretty irrelevant. As I said earlier though, I'd put the range at something between 3 to 1. Probably rather 1 than 3.

This is an issue that would fit in the "AE Land and AI Issues" thread I'd think. The odds of it being fixed in the stock scenario is perhaps not all that high though.

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