Baumer, Saxman - Theory Behind Graticule Construction

[bustr]

Baumer and Saxman,

I knew it would happen. Someone finally asked for the HowTo of using the hisoric gunsights. I can muddle through it. But, I suspect you gents know it better than I.

Somerled has asked in one of the update posts of my Historic Pack for the technical usage of the "graticule". Instead of me doing my bang up rendition of the village ideot, could you guys post a few words here about how to use the:

1. range rings
2. cross hair lines
3. range bars
4. range stadia marks
5. bombing\rocket stadia marks
6. attiude lines
7. bore sight dot
8. range dots

WW2 reflector gunsight graticule are virtual representations of the iron ring gunsight. On some aircraft you will see an iron ring sight next to or mounted as a fold away on the reflector gunsight body. Historicly that was in case the reflector gunsight malfunctoned. On the german Reflexivisor it was eventualy reduced to two metal tabs on the left top of the box that you lined up like iron sights.

The reflected graticule was to replicate aproximently a 3 to 4 inch diameter iron ring mounted about 18 inches to 2 feet away from your eye. The outer diameter of the ring is set to represent some standard wingspan of an enemy aircraft at about 150 meters. If there is a second inner ring it usually was for that wingspan at about 300 meters. In the game we have auto range via the Icon. but, the AvA has turned that off. So knowing on most of the historic graticule the main ring is a fighter at about 200 yards will help your gunnery there.

No reflector graticule was ever very good for determining lead on snap shots. Before the Gyroscopic Compensating gunsights like the British GGS "Ace Maker" near the end of the war, only a very small percentage of pilots from any country could hit a moving aircraft other than being on its dead 6. These men were either natural marksmen or had grown up shooting running game.

There I got the ball rolling...

[Saxman]

My understanding is:

For the cross, the horizontal line serves to indicate your wing angle, while the vertical line above the cross references your lift vector. I believe the theory is it's a quick reference to make sure you're "wings level" to the target when pulling the trigger in a tracking shot.

As far as the ranging hash marks (as seen in the Mk. VIII) the theory is that you can use those to determine how much lead to give the target if you know the:

Bullet Flight Time (determined by bullet velocity + shooter airspeed, range to target)
Target airspeed
Deflection Angle

In the case of the Mk.VIII, each hash mark is at 5mil increments, so you can, in theory, place your sight on the correct hash mark for how much lead you need to give. However the math involved is INCREDIBLY complicated, so you're probably best off shooting from dead reckoning, anyway.

The hash marks below the cross on the Mk.VIII could also be used as an aim point for bombs and rockets. Just as with leading a target, there's some equation of dive angle, relative altitude, speed, etc. that would tell you on which hash to put the target when aiming.

As far as the angled lines on the Mk.VIII (below the cross and at a 45 degree angle) I'm not sure what purpose they was meant to serve, but I find them useful to help estimate my bank angle.

Bore sight is pretty simple. More or less says "Bullets go Here" when shooting a stable or 0 deflection target.