Brave Puffin ▮

2020 build: Specs

Dry, bullet style list of Brave Puffin’s main features and components

Hull

  • Canoe shaped, 1.8 meter foam filled hull with carbon fiber as outer layer
  • Inner and outer aluminum frame
  • ~22 kg full dry weight including steel ballast

Power

  • 100 W flexible Sunpower solar panel
  • 388 Wh Li-Ion battery pack (Samsung 30Q 18650 cells in 12p3s configuration, 12V nominal)
  • MPPT charging controller, balancing board
  • Dynamic adjustment of drawn vs. charging energy for optimal efficiency

Propulsion & steering

  • Two Blue Robotics M200 brushless motors for differential steering (no rudder)
  • Plastic 6 inch, 3 blade drone propellers
  • Two 30A ESC’s
  • PID controller (in software) & virtual waypoints

Navigation & routing

  • CMPS14 tilt compensated compass
  • NEO-6M GPS
  • Precomputed map of magnetic variance (declination) covering the North Atlantic
  • Hardcoded waypoints for a 5000 km Cape Cod - Ireland - Cape Cod roundtrip route
  • 25 meter accuracy target for a waypoint hit

Sensors & communication

  • Pressure, temperature, humidity (onboard)
  • Electric current, battery voltage
  • Light level
  • Globalstar Smartone C satellite tracker
  • Bluetooth and WiFi for testing (disabled during the mission)
  • RC controller for manual steering overwrite during testing (removed before the mission)

Electronics

Puffin main board labeled

  1. ESP32 as the main microcontroller (80 Mhz, 529 KB SRAM, 4 MB Flash)
  2. CMPS14 - tilt compensated compass
  3. Globalstar Smartone C - hardwired for power and data inputs, out of the enclosure to save space
  4. NEO-6M - GPS unit for navigation
  5. GPS antenna
  6. 10A MPPT solar panel controller
  7. 5V - 3.3V voltage level converters
  8. BME280 - onboard temperature, humidity and pressure sensor
  9. Serial logger with micro SD card
  10. ATmega328P programmed to reset ESP32 every 8 hours
  11. Magnetic reed switch for external launch sequence

Not shown, on the opposite side of the main board:

  • Two 30A Raptor ESC controllers
  • Two INA219 current and voltage sensors
  • 5A DC-DC step down switching regulator, set to supply 5V off the main 12V battery pack

Safety

  • Independently powered and controlled safety light
  • Custom built from multiple power LED’s for long distance visibility
  • Separate enclosure with ESP32-CAM as a controller
  • Programmed to blink the light at night
July 11, 2020 ∙ build-2020