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National Advisory Committee for Aeronautics, Report - A Method for the Calculation of External Lift, Moment, and Pressure Drag of Slender Open Nose Bodies of Revolution at Supersonic Speeds

The approximate method is presented for the calculation of
the external lift, moment, and pressure drag of slender open-nose
bodies of resolution at supersonic speeds. 17w lift, moment,
and pressure drag of a typical ram-jet body shape are calculated
at M'ach numbers of 1.45, 1.60, 1.75, and 3.00; and the lift
and moment results are compared with a-railable experimental
data. The agreement of the calculated lift and moment data
with the experimental data is excellent. The pressure-drag
comparison was not presented because of the uncertainty of
the amount of skin-friction drag present in the experimental
results. It was found that the lift coeficient definitely in—
creased with increasing M'ach number, whereas the moment
coefiicie-nt taken about the midpoint of the body and the drag
coefiicient decreased with increasing llfach number. The
manner in which the method may be applied to slender bodies
of rerolution with annular air inlets is shown. The excellent
agreement of the calculated lift and moment results with experi-
mental data indicates that the approximate method may be
reliably used for obtaining the aerodynamic characteristics of
slender bodies that are required for eficient supersonic flight.

Current proposals for the design of aircraft capable of
sustained flight at supersonic speeds and utilizing the ram jet
as a method of propulsion have wtablished the importance
of knowing the aerodynamic characteristics of slender open—
nose bodies of revolution at- speeds greater than the speed of
sound. The lack of theoretical treatments and experimental
data emphasizes the need for theoretical investigation of this
problem to serve as a guide for future work and as a check on
the reasonableness of current and future experimental results.

The small-perturbation approximation was used in refer—
ence 1 to deduce the wave drag and in reference 2 to obtain
the lift and moment of slender pointed-nose bodies of revolu—
tion. No fundamental analysis is known to have been made,
however. of the characteristics of a slender open-nose body
shape, such as that required by ram—jet propelled craft. The
peculiarity of the problem, from general considerations of
similarity, is that the flow pattern is two dimensional at the
lip of the nose and approaches the three—dimensional pattern
farther along the body.