Current PageProtractor Main PageKell-Strom Home PageAviation Tools Index
Kell-Strom Logo

KS2113 Bubble Protractor

KS2113 Universal Bubble Protractor

A useful propeller and control surface tool is the Kell-Strom KS2113 Universal Propeller Protractor. This device is used to measure the propeller blade angle or control surface at a specific station to determine proper adjustment.

The frame of the protractor is made of aluminum and has three (3) sides which are 90 to each other.  A level is mounted on one corner of the front of the frame. This corner spirit level swings out and is used to indicate when the protractor is vertical.

A moveable ring is located in the frame and is used to set the zero reference angle for blade or control surface angle measurements.


The ring is engraved with index marks which allow readings as small as one tenth (1/10) of a degree. A center disc is engraved with a degree scale from 0 to 180 positive and negative and contains a spirit level to indicate when the disc is level.

Kell-Strom has manufactured and sold the KS2113 bubble protractor for over 50 years and offers it to those who prefer it to more modern devices. It is a precision instrument.  However, even our best tools have limitations that manufacturing or new technologies eventually surpass.  Such is the case with the Universal Bubble Protractor.
Modern quality systems ask for more than analog and subjective measurements (spirit levels, as precision instruments still require an individual to judge the bubble's position between the lines).  Additionally, neither the bubble's position or the degree scales' readouts can be input directly to a computer from the protractor.
To respond to both modern quality systems' requirements and allow for true objective, digital electronics measurements, Kell-Strom promotes the use of our Pro360 and Pro3600 digital protractors. See Digital Protractor/Level/Inclinometer page for more information.

Top of Page TOP OF PAGE
TOP OF PAGE Top of Page