Airspeed Indicator, 900 km/h, Luftwaffe Fahrtmesser Fl.22234 Lily Bomber When the de-icing system is

When the de-icing system is engaged by flipping a toggle switch

Its a terrific historical document

used by bombardiers and technicians to check the proper operation of the Norden Bombsight

This valve was used to regulate the vacuum pressure between its source (either an externally-mounted venturi tube

where the master switch is a flat toggle instead of a push/pull switch as designed in this B-6

Airspeed Indicator, 900 km/h, Luftwaffe Fahrtmesser Fl.22234 Lily Bomber When the de-icing system isHere is a WW2 era German Airspeed Indicator FI. 22234, with a maximum airspeed of ~900 km h. As the airspeed increases, rotating the pointer clockwise from the 6 o'clock position, it rotates 360deg past 0 once 800 km h is exceeded, thus following the airspeed index on the inner scale, up to ~900 km h. According to AircraftCockpits. com, this was used in aircraft such as Do335, Fi103, FW190A7 9, Ta152, Go229, He162, He219, Ju388, Bf109G, Fi103, and