It seems obvious to me that the guns had to point back along the flight path in order for the periscope to target the bandit instead of being angled down where the bandit is masked by the fuselage.
Found this ME-110 document with it's static test firing results with a periscope & rear firing guns it is 32 pages long & in German.
So I am just going to show the high lights.
I have not translated all of the text in this document as there is a lot. If I am wrong on any of this let me know & if you can read German I will forward the entire copy to who ever wants it.
Front cover.
One of the photos taken of the rear guns.
Horizontal firing elevation.
Measurements off of the centerline of aircraft to the periscope & guns. Periscope then to rear firing guns.
From the horizontal guns to bullet trajectory.
Another graph showing the same information.
This caught me by surprise
Mounted horizontal guns firing in a 239.3cm arc or 94.2 inches back to 400M.
Then at a range of 650 meters they fall back to the line of sight of 0 of the periscope.
Where have I seen this before?
The test firings I did with the AHII AR-234 & the above image was at 500 yards.
So based off of the 110 results it looks like the Arado guns are programmed correctly to shoot up & back & now that we can see that the periscope on the Arado had adjustment knobs as well to change the angle of the RF2C periscope.
They could adjust accordingly for targeting.
Still why is there reports from the Allies who looked at the captured AR-234's & said the guns were facing down
Looking at the 110 a little closer may have the answers?
First off why do the bullets arc upwards from a horizontal firing position?
This type of gun & bullet ballistics characteristics,turbulence from the wake of the aircraft?
Frankly I have no idea? Some one with better knowledge on this will have to chime in here.
They could not angle the 110 guns upwards in their mounts as it would just about shoot it's own tail off when fired.
So is it just possible that the downward facing guns of the Arado is correct? Arado blueprints indicate that they did.
Captured aircraft reports say they did.
But why?
May be the 20mm ballistics arced so high on the horizontal that they were useless. Maybe the danger of shooting of it's own tail?
With a little down angle however to begin with this might have helped with the arc?
The upward pattern certainly would have helped with visibility through the periscope since the aircraft would not obscure the view as much.
All speculation on my part at this point.
Would be nice though to have the static firing results on the AR-234B.
There is only a brief bit on the C model static tests that I could find.
