Bounty: V1 Quiver Actuated Payload Latch

Grants / Bounties
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Status: Open

Reward: $500 USDC (milestone based, see below)

Deadline: 45 days from concept approval

Apply: Reply with a concept sketch

Technical Contact: errrks.eth, errrks@arrowair.com

Overview

Project Quiver is a 25kg MTOW open-source quadcopter with hot-swappable payload interfaces, developed by Arrow Air. More at github.com/Arrow-air/project-quiver.

The goal of this bounty is to design and prototype a reliable, lightweight, and low cost mechanical release mechanism for the Project Quiver platform. This “V1 Latch” will enable the drone to carry and remotely drop light cargo (e.g., medical supplies, water bottles, or small equipment bags) using a standard RC transmitter toggle or a Mission Planner waypoint command.

This is the first step toward a fully integrated universal cargo system and must be compatible with the existing Quick release payload interface and the Quiver Attachment Interface PCB.

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Technical Specifications

1. Mechanical Design

  • Attachment Point: Bottom attachment point only The drone has three quick release points (bottom + 2× side); this latch targets the bottom exclusively.
  • Interface Compatibility: Must clip onto the exposed face of the standard Quiver bottom quick release plate (JMRRC aluminum plate). The plate is already mounted to the drone. The bounty worker is designing what attaches to the other side of it. Reference the STEP file listed below for exact geometry. The attachment interface PCB (15.8mm × 23.5mm, 4× M2 mounting holes) is housed within this plate.
  • Mechanism Type: Servo actuated latch. The release mechanism (hook, pin, cam, or off the shelf servo latch) is left to the designer. Many suitable off the shelf drone payload release mechanisms exist and are encouraged. Search “drone payload release servo” for reference. The housing must accommodate the chosen mechanism and interface cleanly with the quick release plate.
  • Payload Rating: Safe working load of 2 kg.
  • Weight Target: Total assembly (housing, electronics, servo) under 250g.
  • Materials: 3D printed housing — PETG or Carbon Fiber Nylon preferred for durability.
  • Cargo Attachment: The hook geometry and cargo side interface (e.g., loop size, keeper design) is left to the designer but must be clearly documented so end users know how to prepare their payloads.
  • Default/Failsafe State: The latch must remain closed/locked when unpowered or on signal loss. This must be achieved mechanically (e.g., spring loaded hook) — do not rely on servo holding torque alone, as power loss will release the load.
  • Environmental Conditions: No IP rating required, but document what conditions the prototype was tested in and any known limitations.

2. Electrical & Control

  • Power Input: 12V DC from the Quiver Attachment Interface PCB (pin 10, +12V).
  • Onboard Regulation: 5V voltage regulator required for servo and MCU. Document the chosen part, efficiency at load, and any thermal considerations in the BOM.
  • Actuator: High torque metal gear micro/mini servo (MG90S or equivalent).
  • Microcontroller: Arduino Nano, ESP32, or ATTiny — must operate with 3.3V on the signal input pin. If using an Arduino Nano (5V), document the level shifting solution used.
  • Signal Input: FMU_CH1 (pin 12 on J1 Molex) — 3.3V GPIO trigger from the Pix32 V6 flight controller. High = release, Low = lock.
  • Connector to Attachment PCB: Payload must use the Molex 2045231201 mating connector to interface with J1 on the attachment PCB. The Molex locking connector provides a secure, keyed connection. Polarity and orientation are enforced by the connector housing.

3. Software Integration

  • MCU Firmware: Provide source code for the onboard MCU. The drone sends a 3.3V GPIO signal to trigger the latch — the MCU reads that signal and drives the servo accordingly. The signal must be stable for at least 50ms before the latch actuates to prevent accidental release from a noise spike. Default to locked on power on and signal loss.

Electrical Interface — Quiver Attachment PCB

The latch payload receives power and control signals through the Quiver Attachment Interface PCB. The payload connects via the 12 pin Molex locking connector (J1) on the attachment board.

  • Attachment PCB connector: Molex 2077601281 (12 pin, on the attachment board)
  • Payload side mating connector: Molex 2045231201 — pre crimped cables available from Mouser PN 538-79758-1149, no crimping required

Relevant Pins (J1 — 12 pin Molex 2077601281)

Pin Signal Description Notes
6 GND Ground reference Pin 8 is also GND — both available
10 +12V Main 12V supply (always on) Use for servo power via regulator
12 FMU_CH1 Flight controller trigger signal 3.3V GPIO — High = release, Low = lock

Power Notes

  • The +12V rail (pin 10) is always on when the system is powered. Use +12V as your primary power input for the latch assembly.
  • FMU_CH1 is a 3.3V GPIO signal. If using an Arduino Nano (5V MCU), a level shifter is required on the signal input pin. ESP32 or ATTiny85 (at 3.3V) are recommended to avoid this complication.
  • A 5V regulator is required on the payload side to power the microcontroller and servo from the 12V rail. Factor this into the weight budget.
  • Estimated current budget: MG90S stall current ~500mA at 5V, plus MCU ~100mA. Size your regulator for at least 1A continuous at 5V.

Deliverables

  1. CAD Files — Complete assembly in .step or Fusion 360 format, including 3D printable housing. The release mechanism itself may be off the shelf. Document the chosen component in the BOM.
  2. BOM — Full bill of materials including every component, supplier, part number, and unit cost. Must be sufficient for another DAO member to independently source and replicate the build.
  3. Wiring Diagram / Schematic — Clear diagram showing: J1 (Molex 2077601281) → Molex 2045231201 harness → voltage regulator → MCU → servo. Include the signal path from FMU_CH1 (J1 pin 12) through the MCU to the servo.
  4. Firmware/Code — MCU source code with comments. Must handle: GPIO input reading, closed on startup, closed on signal loss.
  5. Information Note — Brief document following AIP-5 standard covering:
    • Assembly steps
    • Test results (see Evaluation Criteria)

Milestone Payment Schedule

Milestone Payout Trigger
M1 — Concept Approval $150 (30%) Concept sketch, CAD, and electronics reviewed and approved by errrks.eth
M2 — Working Prototype $150 (30%) Video demonstration of latch actuating under 2 kg load submitted
M3 — Final Acceptance $200 (40%) All deliverables submitted and 20 cycle test passed, signed off by errrks.eth

Payment is in USDC. Each milestone must be approved before the next begins.

Claim Process

This bounty operates on a claim and lock basis:

  1. Reply with a concept sketch.
  2. errrks.eth will review and approve or provide feedback within 5 business days.
  3. Once approved, the bounty is locked to that contributor and the 45 day clock starts.
  4. If the deadline is missed or the contributor withdraws, the bounty reopens.

Only one active claim at a time. Concept sketches from other contributors are welcome as community input for future iterations.

Revision Policy

If a submission does not pass evaluation at M3, the contributor has 14 days to address the feedback and resubmit. errrks.eth will provide written feedback specifying what must be corrected. If the revised submission still does not pass, errrks.eth will determine whether to extend, renegotiate, or reopen the bounty.

Evaluation Criteria

Evaluator: errrks.eth (errrks@arrowair.com)

Criteria Requirement
Reliability Latch must successfully actuate (open and close) 20 consecutive cycles under a 2 kg static load without jamming or failure. Dynamic drop conditions should also be considered and documented.
Failsafe Latch must remain mechanically closed on power loss — spring or gravity assisted, not servo torque dependent.
Fit Assembly must physically mount to the Quiver attachment plate without modification to the plate.
Signal Full open/close cycle must be achievable via the 3.3V GPIO trigger on FMU_CH1.
Simplicity Preference for commonly available off the shelf components to ensure DAO replicability.

Open Source Requirement

All work produced under this bounty must be released as open source upon submission. This includes CAD files, firmware, schematics, and documentation.

Submitting this bounty constitutes agreement to release all deliverables under the above licenses. Files should be contributed to the Arrow community repository or linked from a public GitHub repository.

Reference Files

Arrow Payload Systems

Quick-Release Plate (Mechanical Interface)

Information Note Standard

Attachment Interface PCB

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