A 3D printer camera shroud for the Mobius Mini was ordered from Additive Aerospace. However upon closer inspection I noticed the design could be optimized a bit for the GIGA rocket being:
- The Additive Aerospace camera shroud used four screws positioned in a square to secure the shroud to the airframe. This is particularly hard to accurately drill in an aluminium tube as the holes are not radial / perpendicular to the centerline. A skewed camera shroud could induce undesired roll to the rocket. Slender rockets, like the GIGA with an L/D of 34:1, are highly susceptible to Inertia Roll coupling. Taking the roll out of the equation – as much as practically possible – is one of the mitigating actions which can help to reduce the possibility of this phenomena.
- Improvement: Removed all mounting holes and added only two holes on the centerline of the part. These holes accept M3 socket cap screws. The bolt head tightly fits into the 3D printed part thereby centering the camera shroud and absorbing the loads from the 3D print into the airframe.
- We / I approach the rocket for activating the camera and arming from the same side. This is where the pull pins are also conveniently located. However the status indicator LED of the Mobius Mini is at the exact opposite when it is mounted in its normal orientation. Not a big problem for a single stage rocket where you can walk around the rocket but when it is used as a sustainer and it’s 5m in the air it would preferable be on the same side as the ladder and pull pin. Hence the camera needs to be mounted inverted in the shroud and due to recess for the protruding push buttons this is currently not possible.
- Improvement: the recess for the push buttons inside the camera shroud was mirrored vertically to accept an upside down Mobius Mini. Furthermore the camera was programmed to record the image inverted.
Results: the camera is now accurately aligned to the airframe by means of two M3 bolts and the status LED is now facing the operator arming the electronics.