/// <summary>
/// Computes the required takeoff distance.
/// </summary>
/// <exception cref="Exception"></exception>
public static double TakeOffDistanceMeter(AirbusPerfTable t, TOParameters p)
{
var tables = GetTables(t, p);
if (tables.Count == 0)
{
throw new Exception("No data for selected flaps");
}
var pressAlt = ConversionTools.PressureAltitudeFt(p.RwyElevationFt, p.QNH);
var inverseTables = tables.Select(x => GetInverseTable(x, pressAlt, t, p));
var distancesFt = inverseTables.Select(x =>
x.ValueAt(p.WeightKg * 0.001 * Constants.KgLbRatio))
.ToArray();
var d = (distancesFt.Length == 1) ?
distancesFt[0] :
Interpolate1D.Interpolate(
tables.Select(x => x.IsaOffset).ToArray(),
distancesFt,
IsaOffset(p));
// The slope and wind correction is not exactly correct according to
// performance xml file comments. However, the table itsel is probably
// not that precise anyways.
return(Constants.FtMeterRatio * (d - SlopeAndWindCorrectionFt(d, t, p)));
}
// Use the length of first argument instead of the one in Parameters.
private static double SlopeAndWindCorrectionFt(double lengthFt,
AirbusPerfTable t, TOParameters p)
{
var windCorrectedFt = lengthFt + WindCorrectionFt(lengthFt, t, p);
return(windCorrectedFt - lengthFt + SlopeCorrectionFt(t, p, windCorrectedFt));
}
/// <summary>
/// Error can be None, NoDataForSelectedFlaps, or RunwayTooShort.
/// </summary>
/// <exception cref="RunwayTooShortException"></exception>
/// <exception cref="Exception"></exception>
public static TOReport TakeOffReport(AirbusPerfTable t, TOParameters p,
double tempIncrement = 1.0)
{
var d = TakeOffDistanceMeter(t, p);
var primary = new TOReportRow(p.OatCelsius, d, p.RwyLengthMeter - d);
if (primary.RwyRemainingMeter < 0)
{
throw new RunwayTooShortException();
}
var rows = new List <TOReportRow>();
double maxOat = 67;
for (double oat = p.OatCelsius + tempIncrement; oat <= maxOat; oat += tempIncrement)
{
try
{
var q = p.CloneWithOat(oat);
d = TakeOffDistanceMeter(t, q);
var remaining = q.RwyLengthMeter - d;
if (remaining < 0)
{
break;
}
rows.Add(new TOReportRow(oat, d, remaining));
}
catch { }
}
return(new TOReport(primary, rows));
}
private static double WetCorrection1000LB(double lengthFt,
AirbusPerfTable t, TOParameters p)
{
if (!p.SurfaceWet)
{
return(0.0);
}
return(t.WetCorrectionTable.ValueAt(lengthFt));
}
private static double WindCorrectionFt(double lengthFt,
AirbusPerfTable t, TOParameters p)
{
var headwind = p.WindSpeedKnots *
Math.Cos(ToRadian(p.RwyHeading - p.WindHeading));
return((headwind >= 0 ?
t.HeadwindCorrectionTable.ValueAt(lengthFt) :
t.TailwindCorrectionTable.ValueAt(lengthFt)) * headwind);
}
// The table is for limit weight. This method constructs a table of
// takeoff distance. (x: weight 1000 LB, f: runway length ft)
// Wet runway and bleed air corrections are applied here.
private static Table1D GetInverseTable(TableDataNode n, double pressAlt,
AirbusPerfTable t, TOParameters p)
{
var table = n.Table;
var len = table.y;
var weight = len.Select(i =>
table.ValueAt(pressAlt, i) - WetAndBleedAirCorrection1000LB(i, t, p));
return(new Table1D(weight.ToArray(), len.ToArray()));
}
private static double SlopeCorrectionFt(AirbusPerfTable t, TOParameters p,
double windCorrectedLengthFt)
{
var len = windCorrectedLengthFt;
var s = p.RwySlopePercent;
return((s >= 0 ?
t.UphillCorrectionTable.ValueAt(len) :
t.DownHillCorrectionTable.ValueAt(len)) * -s);
}
private static double BleedAirCorrection1000LB(AirbusPerfTable t, TOParameters p)
{
if (p.PacksOn)
{
return(t.PacksOnCorrection);
}
if (p.AntiIce == AntiIceOption.EngAndWing)
{
return(t.AllAICorrection);
}
if (p.AntiIce == AntiIceOption.Engine)
{
return(t.EngineAICorrection);
}
return(0.0);
}
// Returns best matching tables, returning list can have:
// 0 element if no matching flaps, or
// 1 element if only 1 table matches the flaps setting, or
// 2 elements if more than 1 table match the flaps, these two tables are
// the ones most suitable for ISA offset interpolation.
private static List <TableDataNode> GetTables(AirbusPerfTable t, TOParameters p)
{
var allFlaps = t.AvailableFlaps().ToList();
if (p.FlapsIndex >= allFlaps.Count)
{
return(new List <TableDataNode>());
}
var flaps = allFlaps.ElementAt(p.FlapsIndex);
var sameFlaps = t.Tables.Where(x => x.Flaps == flaps).ToList();
if (sameFlaps.Count == 1)
{
return(sameFlaps);
}
var ordered = sameFlaps.OrderBy(x => x.IsaOffset).ToList();
var isaOffset = IsaOffset(p);
var skip = ordered.Where(x => isaOffset > x.IsaOffset).Count() - 1;
var actualSkip = Numbers.LimitToRange(skip, 0, ordered.Count - 2);
return(ordered.Skip(actualSkip).Take(2).ToList());
}
private static double WetAndBleedAirCorrection1000LB(double lengthFt,
AirbusPerfTable t, TOParameters p) =>
WetCorrection1000LB(lengthFt, t, p) + BleedAirCorrection1000LB(t, p);
