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 Subsystem-Level Design PhaseGoals
- 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
- 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
Question: How will thrust be calculated?
- is a function of vehicle speed
- in-compressible fluid & flow
- exit velocity is uniform
- gain data from test runs
- 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.
Question: How is power calculated from a propeller’s thrust?
- Density of salt water
- In-compressible fluid & flow
- Uniform disk area
- 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.
The spreadsheets for the thrust and power calculations can be found here
Question: How much magnetic force is needed to levitate?
- Solenoid model is accurate and correct
- magnetic fields are uniform and ideal
- all electrical properties are ideal
- material properties are idea
- 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.
- 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
- 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
- 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 3-5 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
Bill of Materials (BOM)
- 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