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JWE -> RE: AA Reprise (8/4/2011 5:27:56 PM)
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Knew this would happen. Getting pms from folks saying why is this gun’s ceiling xx,xxx. I have a website that says it is yy,yyy.
There’s 5 or 6 different max ceilings in a gun’s specs. Many sites just say max ceiling (altitude), or max effective ceiling. Don’t say squat about which they are talking about. And, of course, all are vastly different.
In Babes, we use “Max Effective Ballistic Vertical Range” as defined by the US Army Coast and Antiaircraft Artillery (Field Manual Series FM-4) as a basis. This is a good basis for two reasons: consistency and how the game code treats high altitudes.
Consistency, because this parameter is readily available for most Allied guns from their official trial statistics. Many Axis weapons were also tested and specified to the same standards. The tube/shell/ballistic parameters of this value are very well established such that any weapon can have this value calculated from first principles from its service specs.
Game effects, because a gun’s effectiveness drops off as a function of altitude. Just because a gun a max ceiling of 41,000 doesn’t mean it can hit anything up that far. Altitude % chance drop off is a quasi inverse square function of max ceiling, and is very severe at the top 20-25%. So the code just happens to convert max vertical effective into honest to gosh max effective (imagine that, maybe GG knew what he was doing?).
This isn’t ultimate max ballistic ceiling. That is even larger, and ya’ll can see where and why we picked the effective max ballistic. And then there were the fuse parameters; fuses were set on time, and muzzle velocity, atmospherics, shell aerodynamics, and slant range were supremely important. Some guns had much better ballistic parameters than their fuse characteristics would seem to suggest. Believe me, as much of that as humanly possible is incorporated into the Ceiling value in Babes.
The Ceiling value is set up to give relative altitude based % hit efficiencies in accord with the Field Manual performance plots, and normalized to Nigel Evans’ ballistics.
Just for grins, your basic 3” M3 AA gun had many different max ranges:
Max Ballistic Altitude Ceiling: 32,200 feet
Max Effective Vertical Range: 30,300 feet
Max Effective Slant Range: 28,500 feet
Max Effective Fire Control Range: 25,000 feet
Max Fuse Time: 15 sec (M2 with M4/M5 Setting Director), at 2,700 f/s FTMV
I think on this particular gun we used max slant, because it was further limited by FC and fuse constraints.
Your basic 90mm M1A1 AA gun had:
Max Ballistic Altitude Ceiling: 36,000 feet
Max Effective Vertical Range: 33,000 feet
Max Effective Slant Range: 34,500 feet
Max Effective Fire Control Range: 30,000 feet
Max Fuse Time: 15 sec (M2 with M4/M5 Setting Director), at 2,700 f/s FTMV
On this one we used MEVR instead of slant, because it was smaller and worked better with the FC and fuse limitations.
I guess this is just a polite way of saying why we are not particularly interested in what some website has to say. Folks find something from Ft Sill, Woolwich, Sydney, etc .. we are all ears. Otherwise ....
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