Blogs

After experimenting with Sorbothane grommets, moongel, O-rings, etc. I have had very good success with anti-vibration bobbins supporting an electronics deck on the quad.  The graph from a recent flight is shown below.

Flight log graph of AccX, AccY, and AccZ from a recent flight.

The quad, pictured below, is a wood frame 13mm square alder with 3mm Baltic birch ply decks, 420mm prop to prop, 28-26 1200kv motors w/ 8 x 4.5 props, and a 2.5 APM with the upgraded GPS.  The flight graphed above was with a 3300 mah 3 cell battery and no camera or telemetry gear attached.

The bobbins were purchased from Kronos Robotics (here)  but they are used with a simple ply platform.  One of the key elements is having a bit more weight on the platform than just the APM.  The dampening remains about the same with a camera attached…just a cheap point and shoot non HD video…but it weighs about the same as a GoPro.

Flight facts:  hovers at about 55% with 3300 mah battery, flight time with no camera about 13 minutes.  Very stable loiter, RTL works well (400 meters is max I’ve tried).  No experience with planned missions yet since most of my available open flight space is covered with 8 foot tall blackberry bushes (and I’m not going in there to recover anything…the coyotes can have it!)

Frame is a 420 mm quad. The design criteria was to have “easy replace” everything (legs, motor mounts, etc) including an electronics flight deck which can easily be switched between different quads by only switching the ESC leads.  Camera, telemetry etc. will go on electronics deck.  The wood frame is two 13mm square x 630mm wood members notched in the middle and glued to a 120mm square 3mm Baltic ply.  Weight as shown with 300 mah battery, no camera, is 1.32 kg.  The "bones" of the quad can be cut, assembled, glued, and clamped in about 60 minutes.  I built 3 basic frames and haven't broken any arms or basic frame components in multiple crashes as I continue to learn to fly.

View of the bobbins mounted.  I have the upper deck about 5.5 cm above the power deck as I am experimenting with compassmot results, currently at <20%.  The spacers are nylon threaded and have no metal except the small mounting screws.  The clear top deck (which is actually straight, the macro lens distorts it) is for protection of the electronics since I’m a novice pilot!  Note the CG marked on the deck for quick CG balance of each new battery.

Props are cheap HK 8 x 4.5 but balanced very carefully.

Top view of electronics deck, camera can mount on top or bottom of the nose.  I may make a bigger (extend the back) deck when telemetry is installed to allow for separation of RX and TX.

Close view of rear of electronics platform.  Note nylon screws wherever possible.  Once I install an APM 2.6 or PX4 with separate compass I will lower the deck spacing and raise the GPS/compass itself to help compassmot.