Original Posted By: "Ted Brousseau"
Kirk,I made the vane type ASI using a DeHavilland unit from a Tiger Moth asa pattern. I then put temporary marks along its scale(no numbers yet) andwent flying in the Pietenpol. I noted where the pointer was with referencethe ASI in the cockpit at different airspeeds and applied the numbers alongthe scale with a felt marker. While somewhat crude, it worked very well.Later, when I installed it on the Sperry, it agreed almost exactly with theASI on the instrument panel!Possibly one could calibrate the device by holding it out from a car windowwhile driving on a windless day, but I never tried this method.Oh yes, I forgot to mention that I tried several sizes of vane in order togetfull (or nearly so) travel of the pointer over the scale. This is easierthan try-ing different springs.Graham (CF-AUN)________________________________________________________________________________