Table of Contents

The subsystem design phase is a smaller section of the overall detail design phase. Overall the goal of this phase is to create, choose, and come up with specific ideas for sections of the system.
Team Vision for SubsystemLevel Design Phase
Goals Thrust and power calculations should be created
 Magnetism and levitation calculations should be created
 Research on propellers
 CAD models of the propellers
 Update risks
 Improving and solidifying elements of the design
Accomplishments
 Thrust and power calculations were done and came with conclusive results.
 Spreadsheet of relationships between mass, levitation, and magnetism were created.
 Several key facts an concepts of propellers were discovered, which led to the creation of the propeller designs
 Added several new risks and assigned them to group members
 Designs were more detailed and research done on buying a DC motor.
Feasibility: Prototyping, Analysis, Simulation
PhaseAppropriate Analysis
Analysis/PrototypeQuestion: How will thrust be calculated?
Assumptions:
 is a function of vehicle speed
 incompressible fluid & flow
 exit velocity is uniform
 gain data from test runs
Analysis:
 This is a continuation of the first thrust feasibility analysis seen on the systems design page. It goes more in depth in the calculations and has several examples.
 Creating several possible areas for the propeller designs to discover the thrust values.
 Equation's displayed below
 F is the force/thrust
 p is the pressure, pte is the downstream total pressure, pto is the static pressure
 rho is the density of air or water (vicinity it is in)
 Ve is the exit velocity, Vo is velocity of the vehicle
 A is the disk area of the propeller
Below is the spreadsheet for the thrust calculations. It includes several possible disk areas and velocities.
By Bernie GarciaAnalysis
Question: How is power calculated from a propeller’s thrust?
Assumptions:
 Density of salt water
 Incompressible fluid & flow
 Uniform disk area
Analysis:
 Power of propeller through thrust
 Calculations involve density, area, and thrust
 Equation displayed below
 P is the power (J/s)
 T is the thrust
 Rho is the density of salt water
 A is the disk area
Below is a spreadsheet filled with power calculations derived from examples from the previous thrust calculations. It should be noted that the higher the thrust, then the higher the power.
By Bernie GarciaThe spreadsheets for the thrust and power calculations can be found here
Question: How much magnetic force is needed to levitate?
Assumptions:
 Solenoid model is accurate and correct
 magnetic fields are uniform and ideal
 all electrical properties are ideal
 material properties are idea
Analysis:
 This excel sheet below calculates several different, important factors for levitation.
 The first portion uses several inputs to determine the field strength, Beta, and the overall force
 This is followed by a portion that allows the number of turns for a certain Beta to be calculated
 The next portion is a reverse of the first. In this
sense it uses a known force to calculate the needed Beta.
 From this other important parameters such as the number of wire turns and distances can be found
 The spreadsheet also includes comments explaining how each column is found, along with necessary units, and images of several key equations
To the right is a link to the spreadsheet that is used. Levitation Spreadsheet
Drawings, Schematics, Flow Charts, etc.
Propeller Designs
Cad Models
 Solidworks Model of the 5 Bladed Propeller
 Solidworks Model of the 3 Bladed Propeller
 Solidworks Model of the 4 Bladed Propeller
 Solidworks Model of the Inverted Propeller
Cad Sheets
 Solidworks Sheet of the 5 Bladed Propeller
 Solidworks Sheet of the 3 Bladed Propeller
 Solidworks Sheet of the 4 Bladed Propeller
 Solidworks Sheet of the Inverted Propeller
Propeller Descriptions
 4 different propeller designs, which can all be altered to change size and blade number.
 Propeller designs 1 and 3 have hulls with either a pointed end or smoothed over end. This is a conventional propeller design.
 Design 1 has large angle twists on the blades to allow multiple blades without colliding into one another.
 Design 2 has 3 blades to be efficient and has an extruded hole throughout the hull to allow for items to be placed fully though, such as shaft.
 Design 3 has four blades and is similar to design 1, except it 's blades aren't quite angled/twisted as it.
 Design 4 is an inverted propeller, where the propeller itself can be placed within a motor.
 Hydro propellers usually have 35 blades.
 Less blades makes the propeller more efficient, but usually require large hull diameters.
 Lower number of blades also has less resistance
 Large number of blades reduces noise, but they can disrupt the water flow and cause turbulence
 More blades also equals a smoother and uniform performance, with the blades being able to be smaller because they don't have to cover as much of the disk area
Flowchart
Bill of Materials (BOM)
 Feasibility
 Construct a motor from scratch
 Purchase an ‘off the shelf’ motor
 Projected budget for designing/building a motor
 Purchase a brushless DC motor for roughly $300
Risk Assessment
Design Review Materials
Plans for next phase
Home  Planning & Execution  Imagine RIT
Problem Definition  Systems Design  Subsystem Design  Preliminary Detailed Design  Detailed Design
Build & Test Prep  Subsystem Build & Test  Integrated System Build & Test  Integrated System Build & Test with Customer Demo  Customer Handoff & Final Project Documentation