I have read that armored backplates for aircraft seats were introduced early in the war, as a measure of protection against ground fire. The Germans were the first,and the French soon followed suit. The British however lagged behind.
Now, I assume that the headrest seen on some aircraft, notably the SE5 and the Hanriot HD1 was a extension of this plate to cover the head fromshots from behind.
How effective was this protection? considering the penetration power of the rifle cartridges used at the time, it must have been quite thick and heavy to being able to stop bullets. Maybe it was useless against close range shots.
Were they any good? Were they just dead weight swiftly removed?
Though the headrest may have offered a degree of protection, it looks like most pilots preferred improved visibility and thus removed them. I haven't seen photos of any Albatros DVa with them.
Information about the effectiveness of these backplates will be greatly appreciated,for wargaming purposes.I'm designing a rules set and have to cover a lot of thinbgs.More esoteric questions to follow for your perusal, gentlemen