<DOC>
<DOCNO>
701
</DOCNO>
<TITLE>
numerical determination of indical lift of a two-dimensional sinking
airfoil at subsonic mach numbers from oscillatory lift coefficients with
 calculations for mach number 0.7 .
</TITLE>
<AUTHOR>
mazelsky, b.
</AUTHOR>
<BIBLIO>
naca tn 2562, 1951 .
</BIBLIO>
<TEXT>
the reciprocal equations for relating the incompressible circulatory
indicial lift to the lift due to harmonic oscillations have been
modified to include the noncirculatory lift associated with apparentmass
effects . although the apparent-mass effects are impulsive in
nature in incompressible flow, the lift due to apparent-mass effects in
compressible flow is a time-dependent function . the corresponding
reciprocal equations for the total compressible lift are given . by use
of the reciprocal equations for compressible flow, the indicial lift and
 moment functions due to an airfoil's experiencing a sudden acquisition
of vertical velocity are determined numerically for mach number 0.7 .
lack of sufficient flutter coefficients prevents the calculation of
these functions at other mach numbers .
although the indicial lift and moment functions due to penetration of a
sharp-edge gust may be obtained from the oscillatory tab or aileron coefficients
by a similar analysis, sufficient coefficients are not
available at the present . however, an approximate method is shown for
determining a portion of this unsteady-lift function .
when a comparison is made of the indicial lift functions at mach numbers
appears to be less rapid for the compressible case than for the incompressible
case . consequently, the calculation of the gust load factor
at high subsonic mach numbers utilizing the two-dimensional incompressible
indicial lift functions and an over-all correction for compressibility
such as the prandtl-glauert factor might be conservative .
</TEXT>
</DOC>
