BMW Fokker D.VII's

[Bletchley]

Thanks for that information on patents, Dan-San - the Allies were much more commercial, and ad hock in their arrangements I think

It looks a bit as if the "v" designation might have been used to distinguish an engine that was overdimensioned, in much the same way as "ü" was used for one that was overcompressed, where there was a need to distinguish it from a previous or co-existing version - so we get D.III, D.IIIa, D.IIIaü, D.IIIav, D.IIIavü (for the standard D.III, the improved D.IIIa, the overcompressed D.IIIaü, the overdimensioned D.IIIav, and a further overcompressed and overdimensioned D.IIIavü).

An engine such as the BMW IIIa, however, would not require these additional suffix letters as there would have been no need to disinguish it from a previous version.

Bletchley

[Kacey]

Originally Posted by Dave_Watts

Hi all,
...............................

I didn't list the High Altitude and Over-compressed rotaries, but can if desired.

This list is quite inclusive, including several one-off motors, as well as different Mercedes motors with superchargers or turbochargers. Some of the above motors are not to be found on the other lists I have, but I'm sure they are from 1918, so this latest Cross & Cockade list is quite good. One reason I think this list may be of Allied origin is the usage of "ü" designations throughout their list. As I've said before, internally I've never been able to find usage of "ü", as in D.IIIaü within Daimler-Mercedes. If you will notice on the two lists posted so far, (from what we know to be of definite German origins), there was no usage of "ü" designation. Even though that's the case, we know it's for "über-kompressed" or over-compressed. Maybe the usage of "ü" found its way into German usage after the war and this C&C list is postwar.

Best wishes,
Dave W.

Dave,


I to have not seen may references from German sources using the ü designation. But I cannot say all. I have the Adlershof data tables as I call them (which I acquired from Koloman Mayrhofer sometime ago) this OFFICIAL looking document written in German uses the following notations:

on the fourth page under:

d) Flugmotoren August 1914 bis Ende 1916
#
123 Daimler D.IIIa
.............
130 Daimler D.IVa
..............
135 NAG Conrad C.IIIa

all fairly standard notation.

However, on the fifth page under:

e) Flugmotoren 1917 bis 1918
#
168 Daimler D IVa
169 Daimler D IIIaü
170 Daimler D IIIavü
171 Daimler D IVb
172 Daimler D IIIb
..............
.............
174 Benz Bz IIIa
175 Benz Bz IIIavü
176 Benz Bz IVsü
177 Benz Bz IIIbo
178 Benz Bz IIIbm
179 Benz Bz IIIbv
............
181 Benz Bz VIv
182 Benz Bz Vb
............
188 Basse u. S. BuS IVa
............
190 BMW IIIa
............
196 Mana IIIav
...........
199 Maybach Mb IVa
200 NAG C IIIb NAG

From this listing it appears that at least Adlershof was utilizing a ü designation on the Daimler and Benz "über-kompressed" aeroengines. Why they did not use it on the other manufacturers my guess is the same as Bletchley had. If the original engine was already "über-kompressed" then it was not given the ü designation and any further versions were not given it either (i.e. BMW, Mb .etc.)

Dechamps & Kutzbach also a German language document uses the ü designation sporadically. By this I mean it uses it on:

Benz Bz IIIa ü ..(on the 140mm bore version without the usual 'v' designation)
Benz Bz IIIb v .. (without the 'ü' designation)
Benz Bz IV ü ....(without the usual 's' designation)
Benz Bz Vb ......(without the 'ü' designation
Benz Bz VIv .....(without the 'ü' designation
Bus V ü ...........(here's an original version with the 'ü' designation)
Daimler III a ü ...(on the 140 bore)
Daimler III a v ...(on the 145 bore version without the 'ü' designation)
Maybach Mb IV a(of course without the 'ü' designation)

So we can see it was utilized by some German organizations, people, and in certain documents but certainly not on any consistent basis.

Yes, I'd be interested in your listing of "über-kompressed" Umlaufmotoren.

Regard,

KC

[Dan_San_Abbott]

Hi Bletchley:
The "v" is the abreviation of verstaerken, (it is umlaut a) it means augmented or strengthened or increased. This is added when the bore and/or stroke have been increased.
Blue skies Bletchley,
Dan-San