uavdex 0.1.11

Unmanned Aerial Vehicle Design EXploration - A Python package for multidisciplinary analysis and optimization of electric group 1-2 UAVs.

UAV DEsign eXploration

Sammy N. Nassau, RPI DBF 2021-2026 UAVDEX Repo

UAVDEX enables rapid determination of electric aircraft propulsion quantities (i.e. thrust or efficiency) across the entire flight envelope. It is intended primarily for students competing in design competitions such as AIAA Design/Build/Fly or SAE Aero.

The tools to thoughtfully design aircraft should be accessible to all.

Example analyses using UAVDEX

Installation

Anaconda is recommended. In anaconda prompt with a desired environment (not base) activated, simply run:

pip install uavdex

PointDesign

This object allows for calculation of electric aircraft propulsion with specified components across the entire flight envelope.

Key inputs that define a single flight condition:

• Uinf: freestream velocity over the propeller
• h: altitude
  • OR rho: density
• dT: throttle setting (0-100%)
• SOC: battery state of charge (0-100%)
  • OR Voc: cell voltage (~3.5-4.15 for LiPo)
  • OR t: runtime

Runtime assumes constant current. This is valid when designing an aircraft that spends most of its flight time in a single condition (i.e. cruise). The inputs support most common units including

Input Type	Name in Code	Units	Input Type	Name in Code	Units
Velocity	Uinf_mph	miles per hour	Throttle	dT	0-100%
Velocity	Uinf_fps	feet per second	Altitude	h_ft	feet
Velocity	Uinf_mps	meters per second	Altitude	h_m	meters
Velocity	Uinf_kmh	kilometers per hour	Density	rho_kgm3	kg/m$^3$
Velocity	Uinf_kt	knots	Density	rho_slugft3	slug/ft$^3$
State of Charge	SOC	0-100%	Density	rho_lbft3	lbm/ft$^3$
Battery Cell Voltage	Voc	Volts	Runtime	t_s	seconds
Runtime	t_m	minutes	Runtime	t_hr	hours

Velocity, throttle, altitude/density, and state of charge/cell voltage/runtime must all be specified as shown in PointResult Example.

Component initialization

import uavdex as ud

design = ud.PointDesign() 			                    # initialize PointDesign object
design.Motor('C-4130/20', nmot = 2)                     # add a motor, and specify the # of motors (nmot = 1 by default)
design.Battery('Gaoneng_8S_3300', discharge = 85)     # add a battery, and specify the maximum discharge (default is 80%)
design.Prop('16x10E')                                   # add a propeller

To view and edit the databases use

design.OpenMotorData()      # opens an editable csv
design.OpenBatteryData()    # opens an editable csv
design.OpenPropellerData()  # opens a folder containing .dat files from https://www.apcprop.com/technical-information/performance-data/?v=7516fd43adaa

Alternatively, for a list of options printed to the console:

design.MotorOptions()
design.BatteryOptions()
design.PropellerOptions()

All values required are typically provided by the manufacturer, meaning users can add whatever components they desire.

PointResult

A simple function to get propulsion quantities (called 'propQ' in the code) at a specified flight condition.

PointResult example

import uavdex as ud

# Component Initialization
design = ud.PointDesign() 			   # initialize PointDesign object
design.Motor('C-4130/20', nmot = 2)    # add a motor, and specify the # of motors
design.Battery('Gaoneng_8S_3300')      # add a battery 
design.Prop('16x10E')                  # add a propeller

# PointResult
# Uinf_mps:	velocity in m/s   (alternatively use Uinf_fps, Uinf_mph, Uinf_kmh, Uinf_kt)
# dT: 	throttle (0-100%)
# h_m: 	altitude in m         (alternatively use h_ft, rho_kgm3, rho_slugft3, rho_lbft3)
# t_s: 	runtime in s          (alternatively use t_m, t_hr, SOC, Voc)
propQs = design.PointResult(Uinf_mps = 15, dT = 70, h_m = 50, t_s = 30, 
                            verbose = True) # this returns propQs as an array and also prints to console. To stop printing, set verbose = False.

which prints the following to the console:

At: t = 30 s, Uinf = 15 m/s, dT = 70 %, h = 50 m
Total Thrust (N)               = 51.281
Total Thrust (lbf)             = 11.528
Total Thrust (g)               = 5229.235
Total Thrust (oz)              = 184.456
Total Torque (N-m)             = 1.806
Total Torque (lbf-ft)          = 1.332
RPM                            = 6298.030
Drive Efficiency (%)           = 54.775
Propeller Efficiency (%)       = 64.581
Gearing Efficiency (%)         = 100.000
Motor Efficiency (%)           = 91.515
ESC Efficiency (%)             = 93.000
Battery Efficiency (%)         = 99.657
Mech. Power Out of 1 Motor (W) = 595.549
Elec. Power Into 1 Motor (W)   = 650.770
Elec. Power Into 1 ESC (W)     = 699.752
Waste Power in 1 Motor (W)     = 55.221
Waste Power in 1 ESC (W)       = 48.983
Waste Power in 1 Battery (W)   = 4.810
Current in 1 Motor (A)         = 29.138
Current in 1 ESC (A)           = 21.932
Current in Battery (A)         = 43.864
Voltage in 1 Motor (V)         = 22.334
Voltage in 1 ESC (V)           = 31.905
Battery Voltage (V)            = 31.905
Voltage Per Cell (V)           = 4.002
State of Charge (%)            = 88.923

propQs is an array containing the following propulsion quantities,

Index	Symbol	Description	Units	Index	Symbol	Description	Units
0	T_N	Total Thrust	N	14	Pin_m	Electrical Power Into 1 Motor	W
1	T_lbf	Total Thrust	lbf	15	Pin_c	Electrical Power Into 1 ESC	W
2	T_g	Total Thrust	g	16	Pw_m	Waste Power in 1 Motor	W
3	T_oz	Total Thrust	oz	17	Pw_c	Waste Power in 1 ESC	W
4	Q_Nm	Total Torque	N·m	18	Pw_b	Waste Power in 1 Battery	W
5	Q_lbfft	Total Torque	lbf·ft	19	Im	Current in 1 Motor	A
6	RPM	Propeller Speed	RPM	20	Ic	Current in 1 ESC	A
7	eta_drive	Drive Efficiency	%	21	Ib	Current in Battery	A
8	eta_p	Propeller Efficiency	%	22	Vm	Voltage in 1 Motor	V
9	eta_g	Gearing Efficiency	%	23	Vc	Voltage in 1 ESC	V
10	eta_m	Motor Efficiency	%	24	Vb	Battery Voltage	V
11	eta_c	ESC Efficiency	%	25	Voc	Voltage Per Cell	V
12	eta_b	Battery Efficiency	%	26	SOC	State of Charge	%
13	Pout	Mechanical Power Out of 1 Motor	W

LinePlot

To plot a sweep of any one of the 4 inputs (Uinf, dT, h/rho, Voc/SOC/t) with the others fixed, use a LinePlot. The output variable plotted on the y-axis will be a selected propQ from the list above.

To select a propQ output, input a single variable or a list of variables as shown below

propQ = 'T_lbf'                       # for a single plot
# OR
propQ = ['T_lbf', 'eta_drive', 'Ib']  # to create multiple plots of propQs for the same sweep

LinePlot example

import uavdex as ud
import numpy as np

# Component Initialization
design = ud.PointDesign() 				# initialize PointDesign object
design.Motor('C-4130/20', nmot = 2)		# add a motor, and specify the # of motors
design.Battery('Gaoneng_8S_3300') 		# add a battery 
design.Prop('16x10E') 					# add a propeller

# LinePlot usage
design.LinePlot(propQ = ['T_lbf','eta_drive','Ib'], 
                Uinf_mph = np.linspace(0, 100), 
                dT = 100, h_m = 100, t_s = 30)

This code opens the plots below. Datatips pop up when clicking anywhere along the line in an interactive viewer (see Python IDE notes).

np.linspace simply samples 50 points by default between the start and ending values. To sample 200 points and get a smoother curve, use

Uinf_mph = np.linspace(0, 100, 200)

Alternatively, Uinf can be set to a specific value and sweeps of another quantity (dT, h/rho, or SOC/Voc/t) used.

ContourPlot

For sweeps of two inputs, use a contour plot!

ContourPlot example

import uavdex as ud
import numpy as np

# Component Initialization
design = ud.PointDesign() 				# initialize PointDesign object
design.Motor('C-4130/20', nmot = 2)		# add a motor, and specify the # of motors
design.Battery('Gaoneng_8S_3300') 		# add a battery 
design.Prop('16x10E') 					# add a propeller

# to control the number of points used in linspace (n = 50 --> ~5s runtime, n = 200 --> ~15s runtime)
n = 120  

# ContourPlot (sweeps of velocity and runtime)
design.ContourPlot(propQ = ['T_lbf', 'eta_drive', 'Ib'],
                   Uinf_mps = np.linspace(0, 45, n), 
                   t_s = np.linspace(0, 300, n),
                   dT = 100, 
                   h_m = 100)

Thrust for velocity vs runtime

Propulsion Efficiency for velocity vs runtime

Battery Current for velocity vs runtime

At some constant velocity, the right side bound of the contour plot indicates the runtime of the propulsion system in seconds. This is determined by where SOC = (100 - discharge). Additional bounds can originate when the propulsion system cannot generate thrust at some combination of Uinf, dT, Voc, and h.

Additional ContourPlot examples

Efficiency for velocity vs throttle design.ContourPlot(propQ = 'eta_drive', Uinf_mph = np.linspace(0, 120, 200), dT = np.linspace(20, 100, 200), h_m = 50, t_s = 20)

Efficiency for velocity vs cell voltage design.ContourPlot(propQ = 'eta_drive', Uinf_mps = np.linspace(0, 45, 200), dT = 100, h_m = 50, Voc = np.linspace(3.5, 4.2, 200))

Efficiency for velocity vs altitude design.ContourPlot(propQ = 'eta_drive', Uinf_kt = np.linspace(0, 90, n), dT = 80, h_ft = np.linspace(0, 80000, n), t_s = 30)

The bounds on these plots occur when the throttle setting and battery voltage are low, meaning the propulsion drive cannot produce thrust at the given velocity. Therefore, efficiency goes to zero.

Notes on Python IDE usage

• VSCode: The best IDE for viewing UAVDEX plots and using the built-in datatips. No changes necessary.
• PyCharm: "Settings > Tools > Python Plots > Show plots in tool window" should be unchecked for interactive datatips.
• Spyder: Switch plot renderer from inline to QT. If the computer has a 4k screen, the text will be extremely small unless "Tools > Preferences > Application > Interface > Enable Auto High DPI Scaling" is selected.
• Jupyter: Displays static plots but it cannot support interactive datatips at this time.

Future updates

1. Automatic boundary selection (no input array needed, just specify which variable is the sweep)
2. Battery resistance near low SOC modeled
3. Manual limit lines based on component values (i.e. ESC waste power < 500 W)
4. Expansion of database features
5. Functions for the best Uinf, dT, h for maximum efficiency

Have any requests? Submit a ticket on the google form below or open a github issue thread.

TODO: GOOGLE FORM

Want a propulsion component added to the default package CSV sheets? Request here:

TODO: GOOGLE FORM