Kofed:
The first Fok.D.VII that
Hptm.
Rudolf Berthold had was was a Fokker built D.VII from the first production order, D. 227/18 t0 D.526.18. The serial number has to be in the range prior to D.374/18. The machine that
Ltn. Oliver Frhr. von Beaulieu-Marconnay had that was Berthold's was from at least serial number range of Fokker built D.VII 4250/18 to D.4299/18.
We know
Hptm. Berthold, had at least three, the early Fokker built, The Fokker built that
Ltn.Beaulieu-Marconnay got and the one he was shot down in. I would imagine that he had probably twice that number in 1918.
I can say, that I would expect Berthold to be flying a BMWIIIa powered D.VII, however, there is nothing in the photo that makes the statement that it it had a BMWIIIa, it could of had a Mercedes D.IIIaü 180 Ps with the dual cylinder air pump. There is no difference in the machine gun mounts on a Fokker D.VII with either a Mercedes D.IIIaü or a BMWIIIa engines. That is a lot of baloney. The machine gun mountings are exacty the same, for either engine. The forward machine gun mounting is fixed in the vertical height.
For you information, I have identified nine variations in the airframe, cowlings and engines for Fokker built D.VII, seven in Albatros Built D.VIIs and ten in OAW built D.VII. To this you would have to add a large numer of variations in the covering and finish by the three manufacturers of the D.VII.
Blue skies,
Dan-San