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National Advisory Committee for Aeronautics, Technical Notes - Full Scale Drag Tests of Landing Lamps

Drag tests were conducted in the N. A. C. A. full—scale
wind tunnel on full-scale models of two Army Air Corps
type A~6 landing lamps mounted on an 8 by 48 foot airfoil.
Drag measurements were made with the lamps in the Iéading
edge and attached to the lower surface at the 5 and 10
percent chord positions. The drag of the lamps when
faired into the airfoil was also measured.

The results sh.oz that at 100 miles per hour and at
the angle of minimum drag of the airfoil the unfaired
lamps in the leading edge produced an increase in drag
of 5. 5 pounds and that the unfaired lamps on the lower ' _
surface at either position increased the airfoil drag 22. 5
pounds. These increases represent 6 and 24 percent of the
minimum drag of the airfoil, respectively. Fairing the
lamps into the airfoil reduced the drag of the lamps about
50 percent for the_leading~edge position and about 60 per—
cent for the two lower surface positions.

With the rapid increase being made in the speed of
modern transport and military airplanes, greater attention
is being given by airplane designers to the effect of va-
rious types of wing protuberances. The National Advisory
Committee for Aeronautics has conducted several investi—
gations to study this effect. (See references 1 to 5.)

The investigation reported herein was requested by
the Bureau of Aeronautics, Navy Department, to determine
the drag of the Army Air Corps type A—G landing Iamp lo—
cated in the leading edge and upon the lower surface of a _
wing. The tests were conducted in the ET.A. C. A. full-scale
wind tunnel with the lamps mounted on an 8 by 48 foot air.

Two dummy wooden lamps were constructed to the dimen—
sions of the Army Air Corps type A—G landing lamp (fig. 1)
and cylindrical wooden fairings were made for fairing the
lamps into the airfoil at three locations (fig. 2). A
smooth metal~covered 8 by 48 foot Clark Y airfoil was used.
The tests were conducted in the full—scale wind tunnel de—
scribed in reference 6.