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03 - Mechanical

The Airframe V2 in cad/airframe_v2/ is the current mechanical design. The previous V1 frame and cradle files have been removed from main; they remain recoverable through Git history.

Frame geometry

• 123 mm diagonal Quad-X motor-center wheelbase
• motor centers at ±43.49 mm X/Y
• adjacent motor spacing about 87 mm
• 8520 brushed motors, nominal 8.5 mm body diameter
• 75/76 mm propellers
• shared 30 × 30 mm M2 stack
• battery mounted underneath for longitudinal CG adjustment

Printable stack

1. battery_sled_650_v2.stl
2. frame_v2.stl
3. four 5 mm M2 spacers
4. electronics_deck_v2.stl
5. flight_cage_v2.stl or canopy_v2.stl

The XIAO camera mount faces forward. Keep the GY-91 close to the geometric center and aligned with the frame axes.

Part files

All current OpenSCAD sources and STL exports are in cad/airframe_v2/. Each printable part has a preview image in cad/airframe_v2/renders/ and is documented in the Airframe V2 README.

The shared parametric geometry is in cad/airframe_v2/scad/icedrone_v2_lib.scad; the small wrapper SCAD files render one selected part each.

8520 motor-cup calibration

Print motor_cup_test_v2.stl before the full frame. It contains 8.55 / 8.60 / 8.65 / 8.70 / 8.75 mm cup IDs. Use the smallest size that accepts the actual motor with a firm press fit without deforming the motor can or cracking the cup. Then adjust motor_id in icedrone_v2_lib.scad if required.

Battery and center of gravity

The default sled targets a 1S pack around 550–650 mAh and an envelope up to roughly 62 × 20 × 8 mm. Measure the delivered battery before the final print and slide it longitudinally until the assembled aircraft balances at the geometric center.

Kobra S1 print settings

Part	Material	Layer	Walls	Infill	Support
Main frame	PETG	0.16–0.20 mm	4	100%	none
Electronics deck	PETG	0.16–0.20 mm	3–4	60–100%	none
Battery sled	PETG/TPU	0.16–0.20 mm	3	50–100%	none
XIAO mount	PETG/TPU 95A	0.16–0.20 mm	3	50–100% / 25–40%	normally none
IMU saddle	TPU 95A preferred	0.20 mm	3	20–35%	none
Flight cage	PETG	0.16 mm	3	100%	tree/build-plate support for top bridges only
Canopy	PETG	0.16–0.20 mm	3	60–100%	print roof-down; support as required

Propeller CAD

Replacement/test propeller models are in cad/propellers/: standard 75 mm two-blade CW/CCW, experimental toroidal/low-noise CW/CCW, and a 1 mm shaft-fit coupon. The purchased molded propellers remain the preferred starting point.

Safety

Perform electrical, motor-order, motor-direction, IMU-orientation and failsafe tests without propellers installed. Fit propellers only after all prop-off checks pass. Use eye protection and restrain the aircraft for initial powered propeller tests.

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