# Propeller Design Research Part 2

## <span style="color: rgb(53, 152, 219);">Date: 09/17/24</span>

### <span style="color: rgb(45, 194, 107);">Meeting goals</span>

- Calculator for approximate propeller thrust given motor specifications
- Learn how to use a simulator to simulate propeller performance
- Compare calculator results to simulator results

### <span style="color: rgb(45, 194, 107);">Meeting Notes</span>

- Propeller thrust can be calculated using: 
    - Thrust = (Motor power \* Propeller efficiency) / Flow velocity
    - Source: [Propeller Performance: An introduction, by EPI Inc. (epi-eng.com)](https://www.epi-eng.com/propeller_technology/selecting_a_propeller.htm#:~:text=Rearranging%20that%20equation%20to%20solve%20for%20thrust%2C%20produces%3A,as%20speed%20increases%2C%20the%20quotient%20%28thrust%29%20must%20decrease.)
- Flow velocity can be calculated using: 
    - Speed (inches/minute) = Pitch \* RPM \* (1 - Slip)
    - Source: [http://dunnritepropellers.co.nz/images/prop\_tips\_03.pdf](http://dunnritepropellers.co.nz/images/prop_tips_03.pdf)
    - **Factors contributing to propeller slip and how to reduce propeller slip**: 
        - Boat weight and design: The weight and design of your boat can affect how much resistance the propeller encounters in the water, which can impact prop slip.
        - Engine power: If your engine is producing more power than your boat can handle, it can cause the propeller to slip in the water.
        - Propeller size and design: The size and design of your boat’s propeller can impact how efficiently it moves through the water and how much resistance it encounters.
        - Water conditions: Rough water or strong currents can increase the resistance your propeller encounters, which can lead to higher prop slip.
        - Source: [How To Reduce Prop Slip: Tips and Techniques For Better Boat Performance - Waves Weekender](https://www.wavesweekender.com/reduce-prop-slip/)
        - A slip of 1 or 100% means that the propeller will not advance in water.
        - "Calculated propeller slip within the
        - range of 5% to 25% is typical and acceptable. If slip is greater than 25%, there is likely an issue with the propeller." [Prop Bite: Understanding Propeller Slip | Mercury Marine](https://www.mercurymarine.com/us/en/lifestyle/dockline/prop-bite-propeller-slip)
- **Propeller efficiency is related to propeller diameter.** The greater the diameter, the more efficient the propeller (The propeller will be able to move more water/ produce more thrust per revolution). But the greater the propeller diameter, the more drag. So for low-speed craft, a higher diameter propeller is preferred whereas for a higher-speed propeller, a smaller diameter propeller is preferred. [How Propeller Pitch and Diameter Affect Boat Performance (citimarinestore.com)](https://citimarinestore.com/citiguide/how-propeller-pitch-and-diameter-affect-boat-performance/#:~:text=With%20the%20exception%20of%20high%20speed%20%2835%2B%20knots%29,means%20a%20dramatic%20increase%20in%20thrust%20and%20torque.)
    - "The main opportunities for propulsion efficiency improvements are in hull efficiency (typically 0.95–1.3), propeller open water efficiency (typically 0.55–0.70) and relative rotative efficiency (typically 0.98–1.07)" [Propeller Efficiency - an overview | ScienceDirect Topics](https://www.sciencedirect.com/topics/engineering/propeller-efficiency#:~:text=The%20main%20opportunities%20for%20propulsion%20efficiency%20improvements%20are,improving%20the%20wake%20distribution%2C%20and%20recovering%20rotational%20energy.)
- Selected motor: [APISQUEEN 70167 7.5KW internal rotor brushless waterproof motor for hy – Underwater Thruster](https://www.underwaterthruster.com/products/apisqueen-70167-7-5kw-internal-rotor-brushless-waterproof-motor-for-hydrofoil-unmanned-boat-thruster?_pos=1&_sid=457c77898&_ss=r&variant=43896370397412)

#### <span style="color: rgb(185, 106, 217);">What was completed?</span>

- The calculator: [https://docs.google.com/spreadsheets/d/1fZU8p28u3xLca4Ge9oelJ2ioDH1f\_wty5EOEaINy\_YU/edit?usp=sharing](https://docs.google.com/spreadsheets/d/1fZU8p28u3xLca4Ge9oelJ2ioDH1f_wty5EOEaINy_YU/edit?usp=sharing)

#### <span style="color: rgb(185, 106, 217);">What is in progress?</span>

- Learn how to use a simulator to simulate propeller performance
- Compare calculator results to simulator results

#### <span style="color: rgb(185, 106, 217);">What is the goal for the next meeting?  
</span>

- Simulate a propeller and compare results with the calculator

<details id="bkmrk-images-%C2%A0"><summary>Images</summary>

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