xo. 4 



WIND TUNNEL EXPERIMENTS IN AERODYNAMICS 



II 



gage. The wind speed was then adjusted to 2, 4, 6, 8, etc., up to 40 

 miles per hour and both gages read. Some 100 readings were taken. 

 From the Chattock gage readings the true speed was taken from its 

 calculated curve ( for standard air) . The readings of the alcohol gage 

 were then plotted on true speeds. The curve so made was then a 

 calibration of the side plate and alcohol gage in combination. The 

 Pitot tube and Chattock gage may now be removed, and in future 



f<\A»\o ine"Ve<' 



Fig. I 



-Side pressure plate. 



model testing the alcohol gage readings may be used to measure the 

 velocity at the center of the tunnel. 



It is shown below that the velocity over the section varies about 

 I per cent over a 2 foot 6 inch square at the center of the tunnel. 



Chattock Micromanometer 



The Chattock gage mentioned above has been adopted as our 

 laboratory standard, but is used only for the calibration of other 

 gages which may be preferred on account of ease of reading. The 

 following notes on this gage are introduced here in the hope that 

 someone may have use for a delicate pressure gage. Working draw- 



