SAE AS391C
SAE AS391C 1993-MAY-01 Arspeed ndcator Ptot Statc Recprocatng Engne Powered Arcraft
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This Aeronautical Standard covers five basic types of airspeed instruments as follows:
Type I - 1 revolution
Type II - 1 revolution (unequal scale)
Type III - 1 1/2 to 1 3/4 revolutions
Type IV - 7 revolutions
Type V - 1 3/4 to 2 revolutions