ENH: distances vs positions

docs/notebooks/getting_started_colab.ipynb

@@ -320,7 +320,8 @@
     "    mass=19.197 - 2.956,\n",
     "    inertiaI=6.60,\n",
     "    inertiaZ=0.0351,\n",
-    "    distanceRocketNozzle=-1.255,\n",
+    "    positionNozzle=-1.255,\n",
+    "    positionCenterOfDryMass=0,\n",
     "    powerOffDrag=\"../../data/calisto/powerOffDragCurve.csv\",\n",
     "    powerOnDrag=\"../../data/calisto/powerOnDragCurve.csv\",\n",
     ")\n",
@@ -358,14 +359,14 @@
    },
    "outputs": [],
    "source": [
-    "NoseCone = Calisto.addNose(length=0.55829, kind=\"vonKarman\", distanceToCM=0.71971)\n",
+    "NoseCone = Calisto.addNose(length=0.55829, kind=\"vonKarman\", positionNose=1.278)\n",
     "\n",
     "FinSet = Calisto.addFins(\n",
-    "    4, span=0.100, rootChord=0.120, tipChord=0.040, distanceToCM=-1.04956\n",
+    "    4, span=0.100, rootChord=0.120, tipChord=0.040, positionFins=-1.04956\n",
     ")\n",
     "\n",
     "Tail = Calisto.addTail(\n",
-    "    topRadius=0.0635, bottomRadius=0.0435, length=0.060, distanceToCM=-1.194656\n",
+    "    topRadius=0.0635, bottomRadius=0.0435, length=0.060, positionTail=-1.194656\n",
     ")"
    ]
   },

rocketpy/Flight.py

@@ -616,7 +616,7 @@ def __init__(
         # Modifying Rail Length for a better out of rail condition
         upperRButton = max(self.rocket.railButtons[0])
         lowerRButton = min(self.rocket.railButtons[0])
-        nozzle = self.rocket.distanceRocketNozzle
+        nozzle = -self.rocket.positionCenterOfDryMassToNozzle
         self.effective1RL = self.env.rL - abs(nozzle - upperRButton)
         self.effective2RL = self.env.rL - abs(nozzle - lowerRButton)
 
@@ -1347,8 +1347,8 @@ def uDot(self, t, u, postProcessing=False):
         M = Mt + Mr
         mu = (Mt * Mr) / (Mt + Mr)
         # Geometry
-        b = -self.rocket.distanceRocketMotorReference
-        c = -self.rocket.distanceRocketNozzle
+        b = -self.rocket.positionMotorReferencePositionToCenterOfDryMass
+        c = -(-self.rocket.positionCenterOfDryMassToNozzle)
         a = b * Mt / M
         rN = self.rocket.motor.nozzleRadius
         # Prepare transformation matrix
@@ -1835,7 +1835,7 @@ def postProcess(self, interpolation="spline", extrapolation="natural"):
             * 2
             * np.arcsin(-((self.e1[:, 1] ** 2 + self.e2[:, 1] ** 2) ** 0.5))
         )  # Nutation angle
-        theta = np.column_stack([self.e1[:, 0], theta])  # Nutation angle
+        theta = np.column_stack([self.e2[:, 0], theta])  # Nutation angle
         self.theta = Function(theta, "Time (s)", "Nutation Angle - θ (°)")
 
         # Dynamics functions and variables
@@ -1905,7 +1905,7 @@ def postProcess(self, interpolation="spline", extrapolation="natural"):
         self.aerodynamicSpinMoment = self.M3
         self.aerodynamicSpinMoment.setOutputs("Aerodynamic Spin Moment (N m)")
         # Energy
-        b = -self.rocket.distanceRocketMotorReference
+        b = -self.rocket.positionMotorReferencePositionToCenterOfDryMass
         totalMass = self.rocket.totalMass
         mu = self.rocket.reducedMass
         Rz = self.rocket.inertiaZ
@@ -2142,7 +2142,7 @@ def postProcess(self, interpolation="spline", extrapolation="natural"):
                     + math.atan(abs(self.y[i][1]) / abs(self.x[i][1]))
                 )
 
-        # Store values of distance and bearing using approriate units
+        # Store values of distance and bearing using appropriate units
         # self.distance = distance      # Must be in meters
         # self.bearing = bearing        # Must be in radians
 
@@ -3228,8 +3228,8 @@ def calculateFinFlutterAnalysis(self, finThickness, shearModulus):
         minDifHeight = self.z(minDifTime) - self.env.elevation
         minDifVelocity = minDif * self.env.speedOfSound(minDifHeight)
 
-        # Calculate the minimun Fin Flutter Safety factor
-        # Calculate the time and height of minimun Fin Flutter Safety factor
+        # Calculate the minimum Fin Flutter Safety factor
+        # Calculate the time and height of minimum Fin Flutter Safety factor
         minSFTimeIndex = np.argmin(self.safetyFactor[:, 1])
         minSF = self.safetyFactor[minSFTimeIndex, 1]
         minSFTime = self.safetyFactor[minSFTimeIndex, 0]

rocketpy/Motor.py

@@ -5,21 +5,10 @@
 __license__ = "MIT"
 
 import re
-import math
-import bisect
-import warnings
-import time
 from abc import ABC, abstractmethod, abstractproperty
-from datetime import datetime, timedelta
-from inspect import signature, getsourcelines
-from collections import namedtuple
 
 import numpy as np
 from scipy import integrate
-from scipy import linalg
-import matplotlib.pyplot as plt
-from mpl_toolkits.mplot3d import Axes3D
-from matplotlib import cm
 
 from .Function import Function
 
@@ -141,7 +130,7 @@ def __init__(
         distanceNozzleMotorReference : int, float
             Distance from nozzle outlet to the motor reference point, which
             for Solids and Hybrids is the center of mass of the solid propellant,
-            in meters. Generally positive, meaning a positive position in the
+            in meters. Always positive, meaning a positive position in the
             z axis which has an origin in the rocket's center of mass (without
             propellant) and points towards the nose cone.
         nozzleRadius : int, float, optional
@@ -174,7 +163,8 @@ def __init__(
         self.burnOutTime = burnOut
 
         # Geometric parameters
-        self.distanceNozzleMotorReference = distanceNozzleMotorReference
+        # Position of motor reference point relative to the nozzle exit
+        self.distanceMotorReferenceToNozzle = distanceNozzleMotorReference
 
         # Check if thrustSource is csv, eng, function or other
         if isinstance(thrustSource, str):
@@ -556,7 +546,7 @@ def info(self):
         )
         print(
             "Distance Nozzle - Motor reference point: "
-            + str(self.distanceNozzleMotorReference)
+            + str(self.distanceMotorReferenceToNozzle)
             + " m"
         )
         print(
@@ -597,7 +587,7 @@ def allInfo(self):
         print("Nozzle Throat Radius: " + str(self.throatRadius) + " m")
         print(
             "Distance Nozzle - Motor reference point: "
-            + str(self.distanceNozzleMotorReference)
+            + str(self.distanceMotorReferenceToNozzle)
             + " m"
         )
 
@@ -815,7 +805,7 @@ def __init__(
         self.burnOutTime = burnOut
 
         # Geometric parameters
-        self.distanceNozzleMotorReference = distanceNozzleMotorReference
+        self.distanceMotorReferenceToNozzle = distanceNozzleMotorReference
 
         # Check if thrustSource is csv, eng, function or other
         if isinstance(thrustSource, str):
@@ -1234,7 +1224,7 @@ def info(self):
         )
         print(
             "Distance Nozzle - Motor reference point: "
-            + str(self.distanceNozzleMotorReference)
+            + str(self.distanceMotorReferenceToNozzle)
             + " m"
         )
         print(
@@ -1275,7 +1265,7 @@ def allInfo(self):
         print("Nozzle Throat Radius: " + str(self.throatRadius) + " m")
         print(
             "Distance Nozzle - Motor reference point: "
-            + str(self.distanceNozzleMotorReference)
+            + str(self.distanceMotorReferenceToNozzle)
             + " m"
         )
 
@@ -1517,7 +1507,7 @@ def __init__(
         self.burnOutTime = burnOut
 
         # Geometric parameters
-        self.distanceNozzleMotorReference = distanceNozzleMotorReference
+        self.distanceMotorReferenceToNozzle = distanceNozzleMotorReference
 
         # Check if thrustSource is csv, eng, function or other
         if isinstance(thrustSource, str):