Parasite Drag Functions

This group of API functions is supplemental to performing a Paraste Drag analysis through the Analysis Manager. They include functions to write out Parasite Drag Tool equations, calculate atmospheric properties, and control excrescences. Click here to return to the main page. More...

Functions
void	vsp::AddExcrescence (const std::string &excresName, const int &excresType, const double &excresVal)
int	vsp::GetNumExcrescences ()
void	vsp::DeleteAllExcrescences ()
void	vsp::UpdateParasiteDrag ()
std::string	vsp::ExportParasiteDragToCSV (const std::string &file_name)
void	vsp::WriteAtmosphereCSVFile (const std::string &file_name, const int &atmos_type)
void	vsp::CalcAtmosphere (const double &alt, const double &delta_temp, const int &atmos_type, double &temp, double &pres, double &pres_ratio, double &rho_ratio)
void	vsp::WriteBodyFFCSVFile (const std::string &file_name)
void	vsp::WriteWingFFCSVFile (const std::string &file_name)
void	vsp::WriteCfEqnCSVFile (const std::string &file_name)
void	vsp::WritePartialCfMethodCSVFile (const std::string &file_name)

Detailed Description

Function Documentation

AddExcrescence()

void vsp::AddExcrescence ( const std::string & excresName, const int & excresType, const double & excresVal )

extern

Add an Excresence to the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 );
 
AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 );
 
// Each excrescence gets its own row, so deleting them one at a time has to
// empty the table and then start being rejected.
DeleteExcrescence( 1 );
DeleteExcrescence( 0 );
 
if ( GetNumTotalErrors() != 0 )
{
    Print( "ERROR: the two excrescences were not both added" );
    __failure++;
}
 
DeleteExcrescence( 0 );
 
if ( GetNumTotalErrors() == 0 )
{
    Print( "ERROR: more excrescences were added than asked for" );
    __failure++;
}
 
// That error was raised deliberately, so take it back off the queue.
while ( GetNumTotalErrors() > 0 )
{
    ErrorObj err = PopLastError();
}

See also

EXCRES_TYPE

Parameters

[in]	excresName	string Name of the Excressence
[in]	excresType	int Excressence type enum (i.e. EXCRESCENCE_PERCENT_GEOM)
[in]	excresVal	double Excressence value

CalcAtmosphere()

void vsp::CalcAtmosphere ( const double & alt, const double & delta_temp, const int & atmos_type, double & temp, double & pres, double & pres_ratio, double & rho_ratio )

extern

Calculate the atmospheric properties determined by a specified model at input altitude and temperature deviation. This function may not be used for any manual atmospheric model types (i.e. ATMOS_TYPE_MANUAL_P_T). This function assumes freestream units are metric, temperature units are Kelvin, and pressure units are kPA.

double temp, pres, pres_ratio, rho_ratio;
 
double alt = 4000;
 
double delta_temp = 0;
 
CalcAtmosphere( alt, delta_temp, ATMOS_TYPE_US_STANDARD_1976, temp, pres, pres_ratio, rho_ratio );
 
// The ratios are against sea level standard day, so asking at sea level with
// no temperature offset has to return the sea level standard itself.
double sl_temp, sl_pres, sl_pres_ratio, sl_rho_ratio;
 
CalcAtmosphere( 0.0, 0.0, ATMOS_TYPE_US_STANDARD_1976, sl_temp, sl_pres, sl_pres_ratio, sl_rho_ratio );
 
if ( !closeTo( sl_temp, 288.15, 1e-2 ) )
{
    Print( "ERROR: sea level is not the standard day temperature" );
    __failure++;
}
 
// The density ratio carries a little rounding from the model constants.
if ( !closeTo( sl_pres_ratio, 1.0, 1e-9 ) || !closeTo( sl_rho_ratio, 1.0, 1e-4 ) )
{
    Print( "ERROR: the sea level ratios are not one" );
    __failure++;
}
 
// The atmosphere thins with altitude.
if ( temp >= sl_temp || pres >= sl_pres || pres_ratio >= 1.0 || rho_ratio >= 1.0 )
{
    Print( "ERROR: the atmosphere did not thin with altitude" );
    __failure++;
}
 
// The pressure ratio is the pressure against sea level.
if ( !closeTo( pres_ratio, pres / sl_pres, 1e-6 ) )
{
    Print( "ERROR: the pressure ratio does not match the pressure" );
    __failure++;
}

See also

ATMOS_TYPE

Parameters

[in]	alt	double Altitude
[in]	delta_temp	double Deviation in temperature from the value specified in the atmospheric model
[in]	atmos_type	int Atmospheric model enum (i.e. ATMOS_TYPE_HERRINGTON_1966)
[out]	temp	double output Temperature
[out]	pres	double output Pressure
[out]	pres_ratio	double Output pressure ratio
[out]	rho_ratio	double Output density ratio

DeleteAllExcrescences()

void vsp::DeleteAllExcrescences ( )

extern

Delete all Excresences from the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 );
 
AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 );
 
AddExcrescence( "Percentage Example", EXCRESCENCE_PERCENT_GEOM, 5 );
 
DeleteAllExcrescences();
 
if ( GetNumExcrescences() != 0 )
{
    Print( "ERROR: DeleteAllExcrescences left excrescences behind" );
    __failure++;
}
 
// Clearing an empty table is not an error.
DeleteAllExcrescences();
 
if ( GetNumTotalErrors() != 0 )
{
    Print( "ERROR: DeleteAllExcrescences complained about an empty table" );
    __failure++;
}

See also

AddExcrescence, DeleteExcrescence, GetNumExcrescences

ExportParasiteDragToCSV()

std::string vsp::ExportParasiteDragToCSV ( const std::string & file_name )

extern

Write the Parasite Drag Tool buildup table out to a CSV file, the way the Export CSV button on the tool does. The same table is also placed in the Results Manager under the name "Parasite_Drag", so the returned ID gives access to it without going through the file.

string pod_id = AddGeom( "POD", "" );
 
Update();
 
// The table is filled in by running the buildup, so do that first.
ExecAnalysis( "ParasiteDrag" );
 
string res_id = ExportParasiteDragToCSV( "ParasiteDragExample.csv" );
 
if ( res_id.length() == 0 )
{
    Print( "ERROR: ExportParasiteDragToCSV returned no results" );
    __failure++;
}
 
// The buildup carries one row per Geom, so the Pod has to be in there.
array< string > @labels = GetStringResults( res_id, "Comp_Label" );
 
if ( labels.size() == 0 )
{
    Print( "ERROR: the buildup table is empty" );
    __failure++;
}

See also

UpdateParasiteDrag

Parameters

[in]

file_name

string Name of the CSV file to write

Returns

string Results ID for the buildup table

GetNumExcrescences()

int vsp::GetNumExcrescences ( )

extern

Delete an Excresence from the Parasite Drag Tool

AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 );
 
AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 );
 
AddExcrescence( "Percentage Example", EXCRESCENCE_PERCENT_GEOM, 5 );
 
DeleteExcrescence( 2 ); // Last Index
 
// Three were added and one was deleted, so index 2 no longer exists and
// asking for it again has to be rejected.
DeleteExcrescence( 2 );
 
if ( GetNumTotalErrors() == 0 )
{
    Print( "ERROR: DeleteExcrescence accepted an index past the end" );
    __failure++;
}
 
// That error was raised deliberately, so take it back off the queue.
while ( GetNumTotalErrors() > 0 )
{
    ErrorObj err = PopLastError();
}

Parameters

[in]

index

int Index of the Excressence to delete

Get the number of Excresences in the Parasite Drag Tool

if ( GetNumExcrescences() != 0 )
{
    Print( "ERROR: a new model starts with excrescences" );
    __failure++;
}
 
AddExcrescence( "Miscellaneous", EXCRESCENCE_COUNT, 8.5 );
 
AddExcrescence( "Cowl Boattail", EXCRESCENCE_CD, 0.0003 );
 
if ( GetNumExcrescences() != 2 )
{
    Print( "ERROR: GetNumExcrescences did not count what was added" );
    __failure++;
}
 
DeleteExcrescence( 1 );
 
if ( GetNumExcrescences() != 1 )
{
    Print( "ERROR: GetNumExcrescences did not follow DeleteExcrescence" );
    __failure++;
}

See also

AddExcrescence, DeleteExcrescence, DeleteAllExcrescences

Returns

int Number of excrescences

UpdateParasiteDrag()

void vsp::UpdateParasiteDrag ( )

extern

Update any reference geometry, atmospheric properties, excressences, etc. in the Parasite Drag Tool

WriteAtmosphereCSVFile()

void vsp::WriteAtmosphereCSVFile ( const std::string & file_name, const int & atmos_type )

extern

Calculate the atmospheric properties determined by a specified model for a preset array of altitudes ranging from 0 to 90000 m and write the results to a CSV output file

Print( "Starting USAF Atmosphere 1966 Table Creation. \n" );
 
WriteAtmosphereCSVFile( "USAFAtmosphere1966Data.csv", ATMOS_TYPE_HERRINGTON_1966 );
// The call above should have produced a file with content in it.
file __f;
if ( __f.open( "USAFAtmosphere1966Data.csv", "r" ) < 0 )
{
    Print( "ERROR: WriteAtmosphereCSVFile wrote no file" );
    __failure++;
}
else
{
    if ( __f.getSize() <= 0 )
    {
        Print( "ERROR: WriteAtmosphereCSVFile wrote an empty file" );
        __failure++;
    }
    __f.close();
}

See also

ATMOS_TYPE

Parameters

[in]	file_name	string Output CSV file
[in]	atmos_type	int Atmospheric model enum (i.e. ATMOS_TYPE_HERRINGTON_1966)

WriteBodyFFCSVFile()

void vsp::WriteBodyFFCSVFile ( const std::string & file_name )

extern

Calculate the form factor from each body FF equation (i.e. Hoerner Streamlined Body) and write the results to a CSV output file

Print( "Starting Body Form Factor Data Creation. \n" );
WriteBodyFFCSVFile( "BodyFormFactorData.csv" );
// The call above should have produced a file with content in it.
file __f;
if ( __f.open( "BodyFormFactorData.csv", "r" ) < 0 )
{
    Print( "ERROR: WriteBodyFFCSVFile wrote no file" );
    __failure++;
}
else
{
    if ( __f.getSize() <= 0 )
    {
        Print( "ERROR: WriteBodyFFCSVFile wrote an empty file" );
        __failure++;
    }
    __f.close();
}

Parameters

[in]

file_name

string Output CSV file

WriteCfEqnCSVFile()

void vsp::WriteCfEqnCSVFile ( const std::string & file_name )

extern

Calculate the coefficient of friction from each Cf equation (i.e. Power Law Blasius) and write the results to a CSV output file

Print( "Starting Turbulent Friciton Coefficient Data Creation. \n" );
WriteCfEqnCSVFile( "FrictionCoefficientData.csv" );
// The call above should have produced a file with content in it.
file __f;
if ( __f.open( "FrictionCoefficientData.csv", "r" ) < 0 )
{
    Print( "ERROR: WriteCfEqnCSVFile wrote no file" );
    __failure++;
}
else
{
    if ( __f.getSize() <= 0 )
    {
        Print( "ERROR: WriteCfEqnCSVFile wrote an empty file" );
        __failure++;
    }
    __f.close();
}

Parameters

[in]

file_name

string Output CSV file

WritePartialCfMethodCSVFile()

void vsp::WritePartialCfMethodCSVFile ( const std::string & file_name )

extern

Calculate the partial coefficient of friction and write the results to a CSV output file

Print( "Starting Partial Friction Method Data Creation. \n" );
WritePartialCfMethodCSVFile( "PartialFrictionMethodData.csv" );
// The call above should have produced a file with content in it.
file __f;
if ( __f.open( "PartialFrictionMethodData.csv", "r" ) < 0 )
{
    Print( "ERROR: WritePartialCfMethodCSVFile wrote no file" );
    __failure++;
}
else
{
    if ( __f.getSize() <= 0 )
    {
        Print( "ERROR: WritePartialCfMethodCSVFile wrote an empty file" );
        __failure++;
    }
    __f.close();
}

Parameters

[in]

file_name

string Output CSV file

WriteWingFFCSVFile()

void vsp::WriteWingFFCSVFile ( const std::string & file_name )

extern

Calculate the form factor from each wing FF equation (i.e. Schemensky 4 Series Airfoil) and write the results to a CSV output file

Print( "Starting Wing Form Factor Data Creation. \n" );
WriteWingFFCSVFile( "WingFormFactorData.csv" );
// The call above should have produced a file with content in it.
file __f;
if ( __f.open( "WingFormFactorData.csv", "r" ) < 0 )
{
    Print( "ERROR: WriteWingFFCSVFile wrote no file" );
    __failure++;
}
else
{
    if ( __f.getSize() <= 0 )
    {
        Print( "ERROR: WriteWingFFCSVFile wrote an empty file" );
        __failure++;
    }
    __f.close();
}

Parameters

[in]

file_name

string Output CSV file