Tachometer, Electric, Weston Type 545 Constellation 25 inches diameter and ~10

25 inches diameter and ~10 inches deep

vs wings and tailwheel) aircraft

22317 as used in the WWII-era JU-87 Stuka and JU-88 dive bombers and some ME 110 fighters of the German Luftwaffe

and then in 1950's versions

and ~16 inches by 8 inches x 1/4 inch thick when opened

Tachometer, Electric, Weston Type 545 Constellation 25 inches diameter and ~10Here is a WWII or pre WWII era electrical Tachometer measuring up to 2500 RPM, made by Weston. It is marked as being adjusted for series connection, so it may have been intended for a two seat trainer. It has two markers, yellow and red, along the dial scale that can be placed to indicate operating limits when installed. Measures 3. 25 inches diameter by ~2 inches deep.