Detailed Lecture Notes on Radio Control Boat Power Systems

Introduction

• Series of videos on power systems for specific applications.
• First application: Radio control boat power systems.
• Objective: Understand steps to select the best power system for a radio control boat.

Steps to Select Power System

1. Know the Hull Type
   • Different hull types affect performance:
     • Monohull
     • Hydroplane
     • Outrigger
     • Catamaran
     • Tunnel hull
2. Measure Hull Length
   • Measured in inches.
   • Conversion from mm:
     • Formula: mm ÷ 25.4 = inches
3. Calculate Wattage
   • Formula: Power (W) = 4.279 * (Hull Length (in))² - 163.1 * Hull Length (in) + 1901.5
   • Example: 34-inch catamaran gives approx 1300 watts.
4. Determine Voltage and Current
   • Voltage primarily determined by battery selected.
   • Example: 2S battery gives 7.4 volts nominal, leading to 175 amps.
5. Select Battery Pack
   • Recommended 6S battery setup: 22.2 volts nominal, 60 amps.
6. Calculate kV Value for Motor
   • Maximum unloaded RPM: 22,500 - 33,000 rpm, pick 26,000 rpm for catamaran.
   • Formula: kV = RPM ÷ Nominal Voltage
7. Select Brushless Motor
   • Motor wattage = calculated wattage * 1.4.
   • Motor size formula: Motor Size (g) = Wattage ÷ 4.5 (in runners), 3-3.5 for out runners.
8. Select ESC (Electronic Speed Control)
   • Must match voltage and current requirements.
9. Select Propeller
   • Use formula: Prop Diameter (mm) = 11.452 * (Wattage) ^ 0.1787
   • Keep pitch ratio of 1.4.
10. Testing Setup

• Run boat for short duration, monitor temperatures (max 60°C or 140°F).
• Data log to verify performance and power draw.

Detailed Breakdown

Selecting the Hull Type

• Understand performance variations among hulls.
• Start with hull type known for power system selection.

Measuring Hull Length

• Ensure accurate measurement in inches.

Calculating Wattage

• Example shows how to compute wattage for a given hull length.

Voltage and Current Selection

• Voltage affects current requirements for desired wattage.

Battery Pack Selection

• Recommended to select a 6S battery for this setup.
• Consider capacity and C rating for battery reliability.

Calculating kV Value

• Importance of kV value based on hull type and performance needed.

Brushless Motor Selection

• Ensure motor has adequate wattage and size for the setup.

Selecting ESC

• ESC must match the voltage and be rated for more than the expected current.

Propeller Selection

• Use calculated diameter as starting point; test different prop sizes for performance.

Testing the Setup

• Importance of monitoring temperatures and current draw during test runs.

Conclusion

• This lecture covers complex details on power system selection for radio control boats.
• Future videos may cover power systems for RC cars and airplanes.