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National Advisory Committee for Aeronautics, Research Memorandum - Longitudinal Aerodynamic Characteristics to Large Angles of Attack of a Cruciform Missile

The lift, pitching—moment, and drag characteristics of a missile
configuration having a body of fineness ratio 9. 33 and a cruciform tri-
angular wing and tail of aspect ratio A ware measured.at a Mach number
of l.99 and a Reynolds number of 6.0 million, based on the body length.
The tests were performed through an angleéofaattack range of ~50 to 28°
to investigate the effects on the aerodynamic characteristics of roll
angle, wing-tail interdigitation, Wing deflection, and interference among
the components (body, wing, and tail). Theoretical lift and moment
characteristics of the configuration and its components were calculated
by the use of existing theoretical methods which have been modified for
application to high angles of attack, and these characteristics are com—
pared with experiment.

The lift and drag characteristics of all combinations of.the body,
wing, and tail were independent of roll angle throughout the angle—of—
attack range. The pitching-moment characteristics of the body-wing and
body—wing—tail combinations, however, were‘influenced.significantly by
the roll angle at_large angles of attack (greater than 10°). A roll from
0° (one pair of wing panels horizontal) to #50 caused a forward shift in
the center of pressure which was of the same magnitude for both of these
combinations, indicating that this shift originated from.body—wing inter—
ference effects.

A favorable lift—interference effect (lift of the combination greater
than the sum of the lifts of the components) and a rearward shift in the
center of pressure from.a position corresponding to that for the compo—
nents occurred.at small angles of attack.when the body was combined with
either the exposed wing or tail surfaces. These lift and center-of—
pressure interference effects were gradually reduced to zero as the angle
of attack was increased to large values. The eff ct of wing—tail inter—
ference, which influenced primfié cififififi-oment characteristics,
is dependent on the distance between the wing trailing vortex wake and
the tail surfaces and thus was a function of angle of attack, angle of
roll, and wing-tail interdigitation. Although the configuration at zero
roll with the wing and tail in line exhibited the least center-of—pressure
travel, the configuration with the wing and tail interdigitated had the
least change in wing—tail interference over the angle-of-attack range.