No, I won't use the "N" word here (rhymes with Yahtzee) as that just brings up all sorts of ugly feelings and makes people think that one is promoting a certain political or sociological agenda.
I just have a fascination with aircraft, militaria and technology in general and thought this was a cool photo.
You have here a Messerschmidt BF-109 undergoing wind tunnel testing. It always amazes me how advanced some things were some 80 years ago, yet so undeveloped at the same time. Nowadays this would all be done in a computer or at the very least, in a computerized windtunnel. With this photo? Maybe they used high speed (film) cameras and pieces of yarn to try and get an idea of the flow of air over a vehicle. Lots of slide-rulers and pencil and paper were expended that's for sure.
I also enjoy seeing photos like these as in my minds eye, historical vehicles just kind of appear on the scene and I don't think about all the infrastructure, time, testing and calculation that went into their development. Seeing one such famous airplane in its build/testing phase just seems kinda cool--as does the scale of the huge windtunnel vs. the airplane itself and the little engineers below.