aerosandbox.library.aerodynamics.transonic#

Module Contents#

Functions#

sears_haack_drag(radius_max, length)

Yields the idealized drag area (denoted CDA, or equivalently, D/q) of a Sears-Haack body.

sears_haack_drag_from_volume(volume, length)

See documentation for sears_haack_drag() in this same file.

mach_crit_Korn(CL, t_over_c[, sweep, kappa_A])

Wave drag_force coefficient prediction using the low-fidelity Korn Equation method;

Cd_wave_Korn(Cl, t_over_c, mach[, sweep, kappa_A])

Wave drag_force coefficient prediction using the low-fidelity Korn Equation method;

approximate_CD_wave(mach, mach_crit, ...)

An approximate relation for computing transonic wave drag, based on an object's Mach number.

Attributes#

mc

aerosandbox.library.aerodynamics.transonic.sears_haack_drag(radius_max, length)[source]#

Yields the idealized drag area (denoted CDA, or equivalently, D/q) of a Sears-Haack body.

Assumes linearized supersonic (Prandtl-Glauert) flow.

https://en.wikipedia.org/wiki/Sears%E2%80%93Haack_body

Note that drag coefficient and drag area are independent of Mach number for this case (assuming linearized supersonic aero).

Parameters:

  • radius_max (float) – The maximum radius of the Sears-Haack body.

  • length (float) – The length of the Sears-Haack body.

Return type:

float

Returns: The drag area (CDA, or D/q) of the body. To get the drag force, multiply by the dynamic pressure.

aerosandbox.library.aerodynamics.transonic.sears_haack_drag_from_volume(volume, length)[source]#

See documentation for sears_haack_drag() in this same file.

Identical, except takes volume as an input rather than max radius.

Also returns a drag area (denoted CDA, or equivalently, D/q).

Parameters:

  • volume (float) –

  • length (float) –

Return type:

float

aerosandbox.library.aerodynamics.transonic.mach_crit_Korn(CL, t_over_c, sweep=0, kappa_A=0.95)[source]#

Wave drag_force coefficient prediction using the low-fidelity Korn Equation method;

derived in “Configuration Aerodynamics” by W.H. Mason, Sect. 7.5.2, pg. 7-18

Parameters:

  • CL – Sectional lift coefficient

  • t_over_c – thickness-to-chord ratio

  • sweep – sweep angle, in degrees

  • kappa_A – Airfoil technology factor (0.95 for supercritical section, 0.87 for NACA 6-series)

Returns:

aerosandbox.library.aerodynamics.transonic.Cd_wave_Korn(Cl, t_over_c, mach, sweep=0, kappa_A=0.95)[source]#

Wave drag_force coefficient prediction using the low-fidelity Korn Equation method; derived in “Configuration Aerodynamics” by W.H. Mason, Sect. 7.5.2, pg. 7-18

Parameters:

  • Cl – Sectional lift coefficient

  • t_over_c – thickness-to-chord ratio

  • sweep – sweep angle, in degrees

  • kappa_A – Airfoil technology factor (0.95 for supercritical section, 0.87 for NACA 6-series)

Returns:

Wave drag coefficient

aerosandbox.library.aerodynamics.transonic.approximate_CD_wave(mach, mach_crit, CD_wave_at_fully_supersonic)[source]#

An approximate relation for computing transonic wave drag, based on an object’s Mach number.

Considered reasonably valid from Mach 0 up to around Mach 2 or 3-ish.

Methodology is a combination of:

  • The methodology described in Raymer, “Aircraft Design: A Conceptual Approach”, Section 12.5.10 Transonic Parasite Drag (pg. 449 in Ed. 2)

and

  • The methodology described in W.H. Mason’s Configuration Aerodynamics, Chapter 7. Transonic Aerodynamics of Airfoils and Wings.

Parameters:

  • mach – Mach number at the operating point to be evaluated

  • mach_crit – Critical mach number, a function of the body geometry

  • CD_wave_at_fully_supersonic – The wave drag coefficient of the body at the speed that it first goes (

  • supersonic. (effectively) fully) –

    Here, that is taken to mean at the Mach 1.2 case.

    This value should probably be derived using something similar to a Sears-Haack relation for the body in question, with a markup depending on geometry smoothness.

    The CD_wave predicted by this function will match this value exactly at M=1.2 and M=1.05.

    The peak CD_wave that is predicted is ~1.23 * this value, which occurs at M=1.10.

    In the high-Mach limit, this function asymptotes at 0.80 * this value, as empirically stated by Raymer. However, this model is only approximate and is likely not valid for high-supersonic flows.

Returns: The approximate wave drag coefficient at the specified Mach number.

The reference area is whatever the reference area used in the CD_wave_at_fully_supersonic parameter is.

aerosandbox.library.aerodynamics.transonic.mc = 0.6[source]#