bool
BallastDumpManager::Update(GlidePolar &glide_polar, unsigned dump_time)
{
assert(IsEnabled());
// We don't know how fast the water is flowing so don't pretend that we do
if (dump_time == 0) {
Stop();
return false;
}
// Milliseconds since last ballast_clock.Update() call
int dt = ballast_clock.Elapsed();
// Update ballast_clock for the next call to BallastDumpManager::Update()
ballast_clock.Update();
// How many percent of the max. ballast do we dump in one millisecond
auto percent_per_millisecond = 1. / (1000 * dump_time);
// Calculate the new ballast percentage
auto ballast = glide_polar.GetBallast() - dt * percent_per_millisecond;
// Check if the plane is dry now
if (ballast < 0) {
Stop();
glide_polar.SetBallastLitres(0);
return false;
}
// Set new ballast
glide_polar.SetBallast(ballast);
return true;
}
void
GlidePolarTest::TestBallast()
{
polar.SetBallast(fixed(0.25));
ok1(equals(polar.GetBallastLitres(), 25));
ok1(equals(polar.GetBallast(), 0.25));
polar.SetBallastLitres(fixed(50));
ok1(equals(polar.GetBallastLitres(), 50));
ok1(equals(polar.GetBallast(), 0.5));
ok1(equals(polar.GetTotalMass(), 368));
ok1(equals(polar.GetWingLoading(), 37.551020408));
ok1(polar.HasBallast());
fixed loading_factor = sqrt(polar.GetTotalMass() / polar.reference_mass);
ok1(equals(polar.polar.a, polar.ideal_polar.a / loading_factor));
ok1(equals(polar.polar.b, polar.ideal_polar.b));
ok1(equals(polar.polar.c, polar.ideal_polar.c * loading_factor));
ok1(equals(polar.SinkRate(Units::ToSysUnit(fixed(80), Unit::KILOMETER_PER_HOUR)),
0.640739));
ok1(equals(polar.SinkRate(Units::ToSysUnit(fixed(120), Unit::KILOMETER_PER_HOUR)),
0.928976));
ok1(equals(polar.SinkRate(Units::ToSysUnit(fixed(160), Unit::KILOMETER_PER_HOUR)),
1.722908));
ok1(equals(polar.GetVMin(), 21.44464));
ok1(equals(polar.GetVBestLD(), 27.78703));
polar.SetBallast(fixed(0));
ok1(!polar.HasBallast());
}
static void
OnBallastData(DataField *Sender, DataField::DataAccessKind_t Mode)
{
DataFieldFloat &df = *(DataFieldFloat *)Sender;
switch (Mode) {
case DataField::daSpecial:
SetBallastTimer(glide_polar.HasBallast() &&
!XCSoarInterface::GetComputerSettings().ballast_timer_active);
break;
case DataField::daChange:
glide_polar.SetBallastLitres(df.GetAsFixed());
changed = true;
SetButtons();
SetBallast();
break;
}
}
