def speedForLift(F, liftSurfaces = [], AoAdegrees = 0, altitude = 0, planet = planet.kerbin):
"""
Return the speed we need to go in order to get a given lift force.
Useful to figure out the liftoff speed of a plane.
F is in kN
liftSurfaces is a list of triples (n, liftType, AoA) with AoA being relative to your craft.
- you can elide n to mean 1, or elide AoA to mean 0
"""
coeff = 0
for item in liftSurfaces:
if item is wing:
coeff += item.liftCoeff(AoAdegrees)
else:
try:
(n, x, AoA) = item
coeff += n * x.liftCoeff(AoA + AoAdegrees)
except:
try:
(n, x) = item
coeff += n * x.liftCoeff(AoAdegrees)
except:
# last-ditch; this may throw
(x, AoA) = item
coeff += x.liftCoeff(AoA + AoAdegrees)
# coeff is the lift coefficient of the whole craft
return F / (coeff * planet.pressure(altitude))
def zeroThrustForces(self, flightPitchDegrees, AoADegrees, v, altitude, planet):
"""
Return the forces other than thrust that this part produces.
Returns a tuple (drag, lift, apparentGravity) with quantities in kN.
Lift and drag are vectors; gravity is a number (just the y coordinate, positive means up).
"""
Cd = self._staticCd
Clift = 0
if isinstance(self._parttype, lift.wing):
Cd = self._parttype.dragCoeff(self._AoA + AoADegrees)
Clift = self._parttype.liftCoeff(self._AoA + AoADegrees)
elif isinstance(self._parttype, jets.intake):
Cd = self._parttype.dragCoeff(self._AoA + AoADegrees)
elif isinstance(self._parttype, jets.jetengine):
Cd = 0.2
elif isinstance(self._parttype, engine.engine):
Cd = 0.2
dragMagnitude = planet.dragForce(altitude, v, self.mass(), Cd)
liftMagnitude = v * planet.pressure(altitude) * Clift
flightPitchRad = math.radians(flightPitchDegrees)
cosPitch = math.cos(flightPitchRad)
sinPitch = math.sin(flightPitchRad)
horizontalSpeedSrf = v * cosPitch
horizontalSpeedOrb = horizontalSpeedSrf + planet.siderealSpeed(altitude)
vOrbit = planet.orbitalVelocity(altitude)
centrifuge = horizontalSpeedOrb * horizontalSpeedOrb / (vOrbit * vOrbit)
gravity = planet.gravity(altitude)
downForceMagnitude = self.mass() * (centrifuge - gravity)
dragVector = physics.vector(-cosPitch * dragMagnitude, -sinPitch * dragMagnitude)
liftVector = physics.vector(-sinPitch * liftMagnitude, cosPitch * liftMagnitude)
return (dragVector, liftVector, downForceMagnitude)
def _liftFactor(self, AoAdegrees, altitude = 0, planet = planet.kerbin):
return self.deflectionLift(AoAdegrees) * planet.pressure(altitude) * self.lift
def liftForce(self, AoAdegrees, v, altitude = 0, planet = planet.kerbin):
return v * planet.pressure(altitude) * self.liftCoeff(AoAdegrees)
