I just wanted to share my latest project with you. The University asked me for some small copter for swarm experiments. Since they want to load some additional electronic, I found my Leora frame to be a little too small while Rachel is too big with a span of 35cm.
So I developed a new frame with a 240mm mtm span. It looks pretty much like a streched Leora but is different in some details. 2.5mm was not stiff enough for the longer arms so I took 3.0mm plates which gives rock solid arms. I expect the frame itself to be almost as indestructable as Leora where we only sold one spare arm after more than 300 sold units.
Besides the 30x30mm mounting holes I have added a standard 45x45mm hole pattern which allowed me to mount a simple battery cage which is also good as landing gear. As an add-on I milled a simple top plate which may be useful as a carrying platform for electronics or simply as a protection cage for the M4.
The copters are equipped with M4, Jörg's expansion board, 12A KISS ESCs and Tiger MN1806 motors. The first indoor hover was scary: The copter was only oscillating slightly but after only 15 seconds hovering the motors were hot enough to almost light a cigarette at them.
After some PID tuning now the copters fly smooth and agile and the motor graphs look perfect. Indoor flight time with a 2S 1250mAh lipo (AUW: 312g) is 14-15 minutes. I did choose the PID controller for Quatos because the guys will surely change the payload many times and surely don't want to calculate masses everytime.
I didn't plan to release this frame but if anyone is interested in them for a special project, just let me know.