Updated: 14-Oct-2020
It is "Niederrheinische Flugzeug-Bauanstalt Hilsmann u. Co." in Altenessen, a manufacturer of aircraft and engines.
"Hilsmann engine"
-Although it is indicated that the engine is a 7-cylinder (see figure), the author counts only 5.
Engines of HILSMANN
Model: Radial 7 cyl.
Arquitecture: Radial
Cooling:
Total Displacement:
Bore / Stroke:
Power:
Weight:
"Hilsmann Alfa model engine"