There's some folklore in the radar world about the Nazi fighters doing a roll before engagement to mark them to a German radar operator. This makes a lot of sense because it allows you to change your backscatter signature and give a basic "friend or foe" signature to a radar operator.
I've been unable to find an authoritative source on this in the radar context; however, I have found reports of Nazis doing a roll, which leads me to two questions:
- Does anyone know of an authoritative source?
- Would a roll be executed for some other reason?
Edit: The origin of this folklore is the following: 1) I heard about this from a lecturer when I was first doing basic radar design. 2) I heard about it from an American WWII pilot who was over Germany because I asked him after #1 (note: this was 20-some years ago). 3) I am currently reading a book that discusses radar and it is mentioned but unreferenced. I asked around to other analog designers who do radar-type tracking, and we've all heard this folklore. It's fundamentally how we do RFID tracking and the initial work was 1930s.
To that end, it seems that this isn't a very good question, and perhaps I need a historian. It seems to be a question that if the Nazis rolled all as some initial move and then someone just assumed it was for radar.