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SUAVE
2.5.2
An Aerospace Vehicle Environment for Designing Future Aircraft
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SUAVE
2.5.2
An Aerospace Vehicle Environment for Designing Future Aircraft
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| def | SUAVE.Methods.Flight_Dynamics.Static_Stability.Approximations.Tube_Wing.taw_cnbeta.taw_cnbeta (geometry, conditions, configuration) |
| def SUAVE.Methods.Flight_Dynamics.Static_Stability.Approximations.Tube_Wing.taw_cnbeta.taw_cnbeta | ( | geometry, | |
| conditions, | |||
| configuration | |||
| ) |
This method computes the static directional stability derivative for a
standard Tube-and-Wing aircraft configuration.
CAUTION: The correlations used in this method do not account for the
destabilizing moments due to propellers. This can lead to higher-than-
expected values of CnBeta, particularly for smaller prop-driven aircraft
Assumptions:
-Assumes a tube-and-wing configuration with a single centered
vertical tail
-Uses vertical tail effective aspect ratio, currently calculated by
hand, using methods from USAF Stability and Control DATCOM
-The validity of correlations for KN is questionable for sqrt(h1/h2)
greater than about 4 or h_max/w_max outside [0.3,2].
-This method assumes a small angle of attack, so the vertical tail AC
z-position does not affect the sideslip derivative.
Source:
Correlations are taken from Roskam's Airplane Design, Part VI.
Inputs:
geometry - aircraft geometrical features: a data dictionary with the fields:
wings ['Main Wing'] - the aircraft's main wing
areas.reference - wing reference area [meters**2]
spans.projected - span of the wing [meters]
sweep - sweep of the wing leading edge [radians]
aspect_ratio - wing aspect ratio [dimensionless]
origin - the position of the wing root in the aircraft body frame [meters]
wings ['Vertical Stabilizer']
spans.projected - projected span (height for a vertical tail) of
the exposed surface [meters]
areas.reference - area of the reference vertical tail [meters**2]
sweep - leading edge sweep of the aerodynamic surface [radians]
chords.root - chord length at the junction between the tail and
the fuselage [meters]
chords.tip - chord length at the tip of the aerodynamic surface [meters]
symmetric - Is the wing symmetric across the fuselage centerline?
origin - the position of the vertical tail root in the aircraft body frame[meters]
exposed_root_chord_offset - the displacement from the fuselage
centerline to the exposed area's physical root chordline [meters]
fuselages.Fuselage - a data dictionary with the fields:
areas.side_projected - fuselage body side area [meters**2]
lengths.total - length of the fuselage [meters]
heights.maximum - maximum height of the fuselage [meters]
width - maximum width of the fuselage [meters]
heights.at_quarter_length - fuselage height at 1/4 of the fuselage length [meters]
heights.at_three_quarters_length - fuselage height at 3/4 of fuselage
length [meters]
heights.at_vertical_root_quarter_chord - fuselage height at the quarter
chord of the vertical tail root [meters]
vertical - a data dictionary with the fields below:
NOTE: This vertical tail geometry will be used to define a reference
vertical tail that extends to the fuselage centerline.
x_ac_LE - the x-coordinate of the vertical tail aerodynamic
center measured relative to the tail root leading edge (root
of reference tail area - at fuselage centerline)
leading edge, relative to the nose [meters]
sweep_le - leading edge sweep of the vertical tail [radians]
span - height of the vertical tail [meters]
taper - vertical tail taper ratio [dimensionless]
aspect_ratio - vertical tail AR: bv/(Sv)^2 [dimensionless]
effective_aspect_ratio - effective aspect ratio considering
the effects of fuselage and horizontal tail [dimensionless]
symmetric - indicates whether the vertical panel is symmetric
about the fuselage centerline [Boolean]
other_bodies - an list of data dictionaries containing bodies
such as nacelles if these are large enough to strongly influence
stability. Each body data dictionary contains the same fields as
the fuselage data dictionary (described above), except no value
is needed for 'height_at_vroot_quarter_chord'. CAN BE EMPTY LIST
x_front - This is the only new field needed: the x-coordinate
of the nose of the body relative to the fuselage nose
conditions - a data dictionary with the fields:
v_inf - true airspeed [meters/second]
M - flight Mach number
rho - air density [kg/meters**3]
mu - air dynamic dynamic_viscosity [kg/meter/second]
configuration - a data dictionary with the fields:
mass_properties - a data dictionary with the field:
center_of_gravity - A vector in 3-space indicating CG position [meters]
other - a dictionary of aerodynamic bodies, other than the fuselage,
whose effect on directional stability is to be included in the analysis
Outputs:
CnBeta - a single float value: The static directional stability
derivative
Properties Used:
N/A
1.8.15