aerosandbox.library.aerodynamics.inviscid
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Module Contents#
Functions#
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Computes the induced drag associated with a lifting planar wing. |
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Computes the Oswald's efficiency factor for a planar, tapered, swept wing. |
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Computes the optimal (minimum-induced-drag) taper ratio for a given quarter-chord sweep angle. |
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Returns the ratio of 3D lift coefficient (with compressibility) to the 2D lift coefficient. |
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Gives the ratio of actual induced drag to free-flight induced drag experienced by a wing in ground effect. |
Attributes#
- aerosandbox.library.aerodynamics.inviscid.induced_drag(lift, span, dynamic_pressure, oswalds_efficiency=1)[source]#
Computes the induced drag associated with a lifting planar wing.
- Parameters:
lift – Lift force [Newtons]
span – Wing span [meters]
dynamic_pressure – Dynamic pressure [Pascals]
oswalds_efficiency – Oswald’s efficiency factor [-]
Returns: Induced drag force [Newtons]
- aerosandbox.library.aerodynamics.inviscid.oswalds_efficiency(taper_ratio, aspect_ratio, sweep=0.0, fuselage_diameter_to_span_ratio=0.0, method='nita_scholz')[source]#
Computes the Oswald’s efficiency factor for a planar, tapered, swept wing.
Based on “Estimating the Oswald Factor from Basic Aircraft Geometrical Parameters” by M. Nita, D. Scholz; Hamburg Univ. of Applied Sciences, 2012. https://www.fzt.haw-hamburg.de/pers/Scholz/OPerA/OPerA_PUB_DLRK_12-09-10.pdf
Implementation of Section 5 from the above paper.
Only valid for backwards-swept wings; i.e. 0 <= sweep < 90.
- Parameters:
taper_ratio (float) – Taper ratio of the wing (tip_chord / root_chord) [-]
aspect_ratio (float) – Aspect ratio of the wing (b^2 / S) [-]
sweep (float) – Wing quarter-chord sweep angle [deg]
fuselage_diameter_to_span_ratio (float) –
- Return type:
float
Returns: Oswald’s efficiency factor [-]
- aerosandbox.library.aerodynamics.inviscid.optimal_taper_ratio(sweep=0.0)[source]#
Computes the optimal (minimum-induced-drag) taper ratio for a given quarter-chord sweep angle.
Based on “Estimating the Oswald Factor from Basic Aircraft Geometrical Parameters” by M. Nita, D. Scholz; Hamburg Univ. of Applied Sciences, 2012.
Only valid for backwards-swept wings; i.e. 0 <= sweep < 90.
- Parameters:
sweep – Wing quarter-chord sweep angle [deg]
- Return type:
float
Returns: Optimal taper ratio
- aerosandbox.library.aerodynamics.inviscid.CL_over_Cl(aspect_ratio, mach=0.0, sweep=0.0, Cl_is_compressible=True)[source]#
Returns the ratio of 3D lift coefficient (with compressibility) to the 2D lift coefficient.
Specifically: CL_3D / CL_2D
- Parameters:
aspect_ratio (float) – The aspect ratio of the wing.
mach (float) – The freestream Mach number.
sweep (float) – The sweep of the wing, in degrees. To be most accurate, this should be the sweep at the locus of
wing. (thickest points along the) –
Cl_is_compressible (bool) – This flag indicates whether the 2D airfoil data already has compressibility effects
modeled. –
For example:
If this flag is True, this function returns: CL_3D / CL_2D, where CL_2D is the sectional lift
coefficient based on the local profile at the freestream mach number.
If this flag is False, this function returns: CL_3D / CL_2D_at_mach_zero, where CL_2D_… is the
sectional lift coefficient based on the local profile at mach zero.
For most accurate results, set this flag to True, and then model profile characteristics separately.
- Return type:
float
- aerosandbox.library.aerodynamics.inviscid.induced_drag_ratio_from_ground_effect(h_over_b)[source]#
Gives the ratio of actual induced drag to free-flight induced drag experienced by a wing in ground effect. Artificially smoothed below around h/b == 0.05 to retain differentiability and practicality. Source: W. F. Phillips, D. F. Hunsaker, “Lifting-Line Predictions for Induced Drag and Lift in Ground Effect”.
- Using Equation 5 from the paper, which is modified from a model from Torenbeek:
Torenbeek, E. “Ground Effects”, 1982.
- Parameters:
h_over_b (float) – (Height above ground) divided by (wingspan).
- Returns:
Ratio of induced drag in ground effect to induced drag out of ground effect [unitless]