Lab Objectives/Goals The objectives of this lab are: Become familiar with propulsion system efficiency ( ) Become familiar with wind tunnel testing equipment How to relate AEV to real-life objects How to link wind tunnel testing to the AEV
Piaggio Avanti! Fun Fact: The P.180 Piaggio Avanti’s wings, canard and propeller were designed and tested at The Ohio State University helping make this plane one of the world’s most efficiency propeller driven planes in the world! These tests were similar to the ones that will be conducted in today’s lab!
Recap – System Analysis 1 & 2 System Analysis 1: Time Current Voltage Input Power Incremental Energy Total Energy System Analysis 2: Distance & Position Velocity Kinetic Energy Propeller RPM The Advance Ratio Propulsion Efficiency
Wind Tunnel Testing Air drawn through Duct Simulating Thrust Direction
Configuration Selection Puller (Tractor) Configuration Pusher Configuration Thrust Line
Proper Propeller Orientation Visual confirmation of propeller orientation For either Puller or Pusher Configuration - When looking at the propeller (i.e. AEV) from the front: The propeller number designation should be visible The propeller should be rotating counter-clockwise Propeller number designation Counter-clockwise rotation
System Analysis 3 Summary 1). Perform wind tunnel testing: We’ll vary the motor speed from 60% power to 0% in 5% increments and record the following parameters: Voltage supplied to the motor controller Current supplied to the motor controller RPM measured by RPM sensor Thrust (in grams) measured by the wind tunnel scale. Remember, thrust is a force (i.e., Force = mass*acceleration). We’ll need to keep this in mind when analyzing the wind tunnel data.
3). How does this relate to the AEV? Increasing Voltage
How does this relate to AEV? Looking at a plot of Propulsion Efficiency vs Advance Ratio Where is the 2 volts A or B? 2 volts divided by a 7.4 volt battery is approximately equivalent to 27% MotorSpeed A B
Questions to consider... Things to think about during the Lab: What is the advance ratio needed to obtain the highest efficiency and how does that relate to power needed? Do all propellers have the same performance for all voltages/configurations?