Thank you for all,

The spelling "Шранк" is directly from the pilot's instructions for the Як-52 at http://www.avion.ru/

It appears in the section used to describe the type of flap fitted to this machine. I am yet to see a photo of a Як-52 with its flaps down but the best I can ascertain is they are fitted with what is known in English as a "Split Flap". Launch Oleg's IL2 and have a look at the Як-3, this is a split flap design.

Can I assume Шранк = Split?

Cheer's, Ham.