<DOC>
<DOCNO>
673
</DOCNO>
<TITLE>
investigation of full scale split trailing edge wing
flaps with various chords and hinge locations .
</TITLE>
<AUTHOR>
wallace,r.
</AUTHOR>
<BIBLIO>
naca r.539, 1935.
</BIBLIO>
<TEXT>
  an investigation was conducted in the n. a. c. a.
full-scale wind tunnel on a small parasol monoplane
equipped with three different split trailing-edge wing
flaps .  the object of the investigation was to determine
and correlate data on the characteristics of the airplane
and flaps as affected by variation in flap chord, flap
deflection, and flap location along the wing chord .  the
chords of the flaps were 10, 20, and 30 percent of the
wing chord and each flap was tested at deflections from 0
to 75 when located successively at 68, 80, and 88.8
percent of the wing chord aft of the leading edge .  the
investigation included force tests, pressure-distribution
tests, and downwash surveys .  the results give the lift,
the drag, and the pitching-moment characteristics of the
airplane, the flap forces and moments, the pressure
distribution over the flaps and wing at one section,
and the downwash characteristics of the flap and wing
combinations .
  an increase in flap chord or distance of the flap from
the leading edge of the wing increased the lift of the airplane
but had an adverse effect on the wing pitching
moment .  the ld ratio of the airplane decreased with
increase in flap deflection or flap chord .  flap normalforce
coefficients were primarily a function of flap deflection
and were relatively independent of flap chord, hingeaxis
location, and airplane attitude .  the location of
the flap center of pressure in percentage of flap chord aft of
the hinge axis remained practically constant irrespective
of airplane attitude and of flap deflection, chord, or
location .  flap hinge-moment coefficients varied with a
power of flap chord greater than the square so that with
regard to hinge moments narrow flaps were the most
efficient in producing a given increase in lift .
  split trailing-edge flaps materially affected the magnitude
and distribution of pressures over the entire wing
profile .  at low angles of attack the predominant effect
of the flaps was to increase positively the lower-surface
pressures ,. at high angles of attack, to increase negatively
the upper-surface pressures .  downwash surveys indicated
that horizontal tail planes located above the wing
chord line would be more effective than those below the
chord in counteracting the increased diving moment of
the airplane with flaps deflected .
</TEXT>
</DOC>
