Propeller selection (student version)#

Written by Marc Budinger (INSA Toulouse), Scott Delbecq (ISAE-SUPAERO) and Félix Pollet (ISAE-SUPAERO), Toulouse, France.

Design graph#

The following diagram represents the design graph of the propeller’s selection. The max thrust is assumed to be known here.

../../_images/DesignGraphs_propeller_student.svg

Fig. 16 Propeller design graph#

Exercise 8

  • Give the main sizing problems you are able to detect.

  • Propose one or multiple solutions (which can request equation manipulation, addition of design variables, addition of constraints)

  • Orientate the arrows

  • Give equations order, inputs/outputs at each step of this part of sizing procedure

Sizing code#

Exercise 9

Propose a sizing code for the propeller

import numpy as np

# Specifications
rho_air = 1.18  # [kg/m^3] Air density
ND_max = 105000.0 / 60.0 * 0.0254  # [Hz.m] Max speed limit (N.D max) for APC MR propellers

# Reference parameters for scaling laws
D_pro_ref = 11.0 * 0.0254  # [m] Reference propeller diameter
M_pro_ref = 0.53 * 0.0283  # [kg] Reference propeller mass

# Assumptions
F_pro_to = 15.0  # [N] Thrust for 1 propeller during Take Off
F_pro_hov = 5.0  # [N] Thrust for 1 propeller during hover

# Design variables

## To be completed

# Equations
## To be completed

%whos

Variable    Type      Data/Info
-------------------------------
D_pro_ref   float     0.2794
F_pro_hov   float     5.0
F_pro_to    float     15.0
M_pro_ref   float     0.014999
ND_max      float     44.449999999999996
np          module    <module 'numpy' from '/op<...>kages/numpy/__init__.py'>
rho_air     float     1.18

Optimization#

Exercise 10

Adapt the sizing code for the optimal selection of propellers of a drone with the following:

  • requirements: Payload mass (1 kg), Hovering time (20 min), Take off acceleration (1 g)

  • Design assumptions: Number of propellers per arm (1), Number of arms (4), Battery discharge margin (20%), ESC power efficiency (0.95), Motor efficiency (0.80)., a Structure+Motor / Load mass ratio (1).

# Reference battery parameters for scaling laws
M_bat_ref=0.273 # [kg] Reference mass of battery
E_bat_ref=133200 # [J] Reference Energy of battery
P_max_ref=1850 # [W] Reference max power of battery