Okay, here is the abstract and summary for the provided transcript:
Abstract:
This video details the design and construction of the guidance package for a high-powered rocket intended to reach Mach 3 with active control surfaces (fin tabs) for yaw, pitch, and roll stabilization. The system centers around the custom "Ava" flight computer. A key design feature is the use of a standard VGA (hd15) cable to connect the flight computer to the four high-torque servos in the booster, leveraging its pin count for power and signal redundancy while allowing for clean disconnection at apogee. The construction involves building a carbon fiber avionics bay with a fiberglass switch band, integrating three modified GoPro Hero 10 cameras (with custom heat sinks and potting) for multi-angle recording, and fabricating robust carbon fiber bulkheads. Significant attention is paid to safety and redundancy, including separate power switches for the main avionics and servos, and careful power system design to handle high peak currents. The video documents troubleshooting a flight computer failure attributed to improper hot glue application and the subsequent fix using silicone conformal coating. Finally, it touches upon the simulation (CFD, Simulink) and validation process for the control system, emphasizing the importance of responsible development practices in amateur rocketry active control.
Building the Mach 3 Rocket's Brain: Guidance Package Construction & Testing
0:00 Introduction: A high-powered rocket designed for Mach 3 needs active control via fin tabs for yaw, pitch, and roll to improve stability and reduce landing dispersion.
0:41 Guidance System Overview: Control is managed by the custom "Ava" flight computer housed in a dedicated guidance package containing telemetry, GPS, three GoPro Hero 10 cameras, and the servo connection.
1:03 Servo Connection - VGA Cable: An hd15 (VGA) connector is unconventionally used to link the guidance package to the four servos in the booster section.
1:36 VGA Cable Redundancy: The 16 pins are utilized with redundancy: 4 pins for 8.4V power, 4 pins for ground (doubled up for reliability), and 4 signal pins, each duplicated to another 4 pins (total 16) to mitigate high-vibration connection issues. This also allows for clean disconnection at apogee.
3:00 Avionics Bay Construction: The bay is made from carbon fiber tubing with an integrated fiberglass section for external switches. Safety precautions (respirator) for carbon/fiberglass dust are highlighted.
5:16 Camera System: Three GoPro Hero 10 cameras are stripped down, fitted with large aluminum heat sinks (improving recording time from ~4 mins to 45 mins at 4K 120fps), potted in epoxy, and integrated into the bay for up, down, and horizon views.
6:00 Camera Control: Cameras are powered and triggered (shutter/record) via PWM cables connected to the Ava flight computer.
8:21 Safety Switches: Two external switches are installed: one for main avionics power and a separate one exclusively for servo power. This allows disabling active control on the pad if issues are detected, enhancing safety.
11:23 Power System Design: High peak current draw is anticipated (~13A intermittent max, including servo stall current). An oversized 8000mAh, 100C LiPo battery is chosen and modified to fit, providing ample margin for flight and potential ground delays.
13:55 Bulkhead Fabrication: Thick carbon fiber plates are CNC machined to create robust bulkheads for the avionics bay, despite using a non-ideal (carbide) endmill. Dust collection and PPE emphasized.
15:36 Bulkhead Integration: The lower bulkhead incorporates connectors for parachute charges and a structural threaded rod. The upper bulkhead holds GPS and telemetry antennas, requiring holes since carbon fiber blocks RF signals. VNA (Vector Network Analyzer) is used to verify antenna performance.
17:20 Camera Recording Verification: Current sensing resistors are added in series with the GoPro power lines, allowing Ava to measure current draw and verify via telemetry if the cameras are actually recording.
18:27 Wiring & Axis Checks: Careful labeling of control axes (Yaw, Pitch, Roll) is performed. Wiring connections use heat shrink, and continuity is checked frequently. A diagram aids in mapping servo connections through the VGA cable colors.
20:44 Flight Computer Installation: The "Red Ava" board is installed on a 3D printed sled, along with the telemetry radio.
21:30 Hot Glue Application Error: In an attempt to protect against shorts from debris (FOD), hot glue is liberally applied over the entire Ava PCB, including ICs.
22:34 Troubleshooting Failure: During integrated testing, the hot-glue-covered Ava exhibits power cycling issues and significant processor overheating, eventually confirmed as a hardware failure.
24:43 Failure Analysis & Solution: The hot glue is determined to be the cause of the failure (likely causing shorts or thermal issues). The damaged Ava is replaced with a new, clean board.
26:05 Proper Board Protection: Silicone conformal coating is correctly applied to the new Ava board to protect against moisture and shorts without causing the issues seen with hot glue. Its UV fluorescence aids application.
26:54 Simulation and Control Development: The process involved CFD analysis to match fin tab authority to servo torque, creating data tables, simplifying these into polynomial/linear functions for the code, using Simulink for actuator checks, and performing extensive software-in-the-loop (SITL) axis verification.
30:16 Call for Responsibility: A strong emphasis is placed on the need for careful simulation, testing, and responsible practices when implementing active control in high-power rocketry due to potential regulatory consequences of accidents.