Grade Kleinflugmotoren built engines only for their aircraft, generally. The engine that is shown, from the year 1918, was an air-cooled, 4-cylinder V-engine giving 12 Kw (16 HP) of power at 1,600 rpm. It was used to win the "Lanz Preiss" and today it can be seen at the Deutschen Museum.

“Grade engine”

-A Grade engine with 6 cylinders in V of 90 degrees, and a power of 35 HP, was mounted on a triple Grade precisely. Until 25 years later Grade does not present another aviation engine. Hans Grade presented one at a 1932 Aeronautical Fair in Berlin.

-It was called "Igel", and it was a four-cylinder, in line, two-stroke engine that gave 30 hp at 1,800 rpm.

-Its aspect caught our attention as it was covered with cooling fins, giving it an uncommon image.

“Grade, 4-cylinder in line”

From Appendix 6: We located a photograph of a V-shaped 4-cylinder Grade engine on a glider or light aircraft with the characteristic of having seagull wings.

“Airplane and engine detail” (PiP)

-It seems that the engine used in this "reversible" airplane, in the case of having to make an inverted landing, is the Grade 4-cylinder Vee.

“4V engine in inverted position”

From Appendix 9: This Magdenburg company was specialized in 2-stroke engines.

-In 1910, it presents a single-cylinder, base for other 4V motors.

-The most distinctive feature is the automatic intake valve to the crankcase -between the carburetor and the crankcase- passing through an open port in the cylinder and the piston.

-The automatic intake valve device, between the carburetor and the engine, is used today being sheet valves, like harmonicas.

“Half cutaway drawing of the engine, with valve”

“Grade, front view”

-Motor extracted from a publication of aviation engines. Predictably it was useful for the better known V4 engines.

From Appendix 12: New view of the opposite side of the Typ-193AA "Igel" engine (hedgehog).

“The “Igel = hedgehog” from 1932”

“Grade V4 engine” (PiP-Flu)