<DOC>
<DOCNO>
1092
</DOCNO>
<TITLE>
wing-nacelle-propeller interference for wings of various
spans . force and pressure distribution tests .
</TITLE>
<AUTHOR>
robinson,r.g. and herrnstein,w.h.
</AUTHOR>
<BIBLIO>
naca r.569, 1936.
</BIBLIO>
<TEXT>
  an experimental investigation was made in the
n. a. c. a. full-scale wind tunnel to determine the effect
of wing span on nacelle-propeller characteristics and,
reciprocally, the lateral extent of nacelle and propeller
influence on a monoplane wing .  the results provide a
check on the validity of the previous research on nacelles
and propellers with 15-foot-span wings tested in the
  the scale propeller and the n. a. c. a. cowling
used in the former researches were tested in three typical
tractor locations with respect to a thick wing of 5-foot
chord and 30-foot span .  the span was progressively
reduced to 25,20, and 15 feet and the same characteristics
were measured in each case .
  the efficiency factors--propulsive efficiency, nacelle
drag efficiency, and net efficiency--were obtained for each
wing length by means of force tests and the values are
compared to determine the effect of span .  pressuredistribution
measurements show the lateral extent of the
nacelle interference and the propeller-slipstream effect
on the span loading for the various conditions .  complete
polar curves and curves showing the variation of nacelle
drag with lift coefficient are also included .
  force and pressure-distribution tests concur in indicating
that, for engineering purposes, the influence of a
nacelle and of a propeller, in a usual combination, may
be considered to extend laterally on a wing the same maximum
distance, or about five nacelle diameters or two propeller
diameters outboard of their common axes .  all
important effects of scale nacelle-propeller combinations
may be measured within practical limits of accuracy
by tests of a 15-foot-span wing .
</TEXT>
</DOC>
