Skip to content

CAD Models

Status: requirements fixed, no finished models yet

There are no completed CAD models at this point. This page pins down the design requirements each mount has to satisfy, the planned Tinkercad workflow, and the checklist a mount must pass before it flies. It will grow STL downloads and photos as the parts get modelled and printed.

Design ground rules (all parts)

These follow directly from the frame constraints:

  • Mass is the budget. On a 3.5" CineWhoop every gram costs hover margin — prefer thin ribs and cut-outs over solid slabs, and weigh every printed part.
  • Keep mass central. Place parts so they balance around the frame centre; the payload bay sits directly under the CG.
  • Use the provided M3 hardware. M3 standoffs plus M3x9 and M3x12 screws are available for a stacked platform on the frame's existing M3 pattern — design bolt patterns around M3, not glue.
  • Fail without collateral damage. The crash tore off the GPS module and its wiring likely took the FC's single I2C bus down with it (incident report). Mounts must stay inside the frame's protective outline or break away without ripping wires out of the FC.
  • Strain relief everywhere. Downwash from the ducted props will flutter any loose cable; every wire gets a tie-down point on its mount.

Per-mount design requirements

MTF-01P mount (underside)

The optical flow + LiDAR unit is the only indoor position source — its mount has the strictest requirements:

  • Level and pointing straight down. A tilted sensor scales flow and range wrong; the mounting face must be parallel to the FC plane (the aircraft's level reference).
  • Free optical path for both the flow camera and the LiDAR aperture — no frame edge, cable or payload anywhere in view.
  • ~2 cm ground clearance, kept permanently clear. Nothing may ever slide under the sensor, on the ground or in flight; the rangefinder is configured to read down to centimetres (RNGFND1_MIN_CM = 1), so an intruding object produces a confidently wrong height.
  • Wiring runs to FC SERIAL5; route it upward away from the lens with strain relief at the mount.
  • Exact sensor footprint and hole positions will be taken with calipers from the physical unit before modelling — no dimensions are guessed here.

AI camera mount (nadir view)

  • Straight-down view. The pad detector runs on the IMX500 sensor itself; the approach logic assumes a nadir image.
  • The full field of view (66° × 52.3°) must be clear — no propellers, ducts or frame parts may enter the image at any point, or the detector sees them instead of the pad. Verify with a live preview, not by eye.
  • Rigid mounting. A vibrating camera blurs exactly the low-light indoor frames the detector needs.
  • Ribbon cable care. The CSI cable to the Pi Zero is fragile: keep the run short, avoid sharp bends, and clamp it at both ends.

Drop mechanism and payload bay

  • Pocket for a standard 9 g micro servo, held rigidly enough that the release torque cannot flex the mount (positions: 1100 µs closed, 1900 µs open — see the servo mechanism).
  • Payload centred under the CG so the drone trims the same loaded and empty, and so the release does not shift the balance mid-flight.
  • Release path clear of the sensors: the falling payload must not pass under the MTF-01P or through the camera's field of view.
  • Wiring: signal from Pi GPIO18; servo power comes from its separate 5 V BEC, never the Pi's 5 V pin — the bay needs routing space for both leads.

Pi Zero 2 case (top platform)

  • Sits on the M3 standoff platform (M3x9 / M3x12 screws).
  • Accessible without disassembly: the USB gadget port (the Pi is administered over USB), the microSD slot, the CSI connector and the GPIO header pin for the servo signal must all stay reachable.
  • Ventilation openings — the Pi runs the state machine and mavlink-router continuously.
  • Short cable runs to FC SERIAL4 and to the camera.

Planned Tinkercad workflow

  1. Measure the real part with calipers (footprint, hole spacing, connector positions). Never model from datasheet drawings alone.
  2. Model in Tinkercad in millimetres; give holes ~0.1–0.2 mm extra clearance for printing tolerance (to be calibrated with a test print).
  3. Export STL and slice in Cura with the settings in the Print Guide.
  4. Test print and fit-check against the real hardware before mounting anything on the drone; iterate on clearances.
  5. Weigh the final part and log the mass.

Validation checklist before flight

Every mount must pass this on the assembled aircraft before the first armed test:

  • Sensor level: with the drone on a flat surface, the MTF-01P face is parallel to the ground and the FC reports level attitude.
  • Unobstructed rangefinder: Mission Planner shows a plausible rangefinder distance on the bench and while lifting the drone by hand.
  • Unobstructed flow: optical flow quality is nonzero over a textured floor.
  • Clear camera view: a live camera preview shows no propeller, duct or frame part anywhere in the image.
  • Nothing under the MTF-01P: with payload loaded and servo cycled, nothing can reach the ~2 cm zone under the sensor.
  • Servo travel: full 1100–1900 µs sweep without fouling the frame or wiring.
  • Strain relief: every cable is clamped; tugging any wire does not move a connector.
  • Screws torqued and standoffs tight; nothing rattles when shaken.
  • Mass and CG: total takeoff weight recorded; the drone balances at the frame centre with the payload installed.