BabyShark 65mm

By nwbb on Aug 22, 2017

10  1,103  2

A prototype 2.5" (65mm) frame + POD from Falcon Multirotors.

This thing is tiny. Tiny! A 16x16 stack running 1103 motors. Component selection for this build is critical.

Went with Racerstar BR1103b's vs the regular (and cheaper) BR1103s. This is because the regular BR1103s mounting is m1.6 x 8.5mm and the frame is more standard at m2 x 9mm (which matches the 1103b). You can get the BR1103s to fit, but its tight. The 1103b motors came with ridiculously long mounting screws that go straight into the windings. I didn't have any M2 hardware, and rather than buy some, I just used a nylon nut on the bottom as a spacer - which is exactly the right amount needed!

From the get-go, I wanted this thing to be lighter than the hoverbot and support both 1s and 2s. Given the pod, an external camera is needed rather than an AIO, and all of the stand-alone VTXs want 3.3v - 5.5v in. Unfortunately, there is no 16x16 FC or ESC with a 5v regulator and enough current to handle a VTX. This means you either go with a 6v+ VTX (and they're all on expensive AIOs that you'd have to chop apart) or a 3.3v-5.5v VTX. Instead, I found the smallest step-up / step-down regulator I could find and shoehorned it in. Works great! They said it couldn't be done....

Have the 4in1 ESC all turned around and not in the proper order in order to fit well. It's also upside down to give more breathing room to the FC. This gave very little distance between the CF plate and the lipo leads, so I added a bit of liquid electrical tape as insulation (easy to peel off).

I wired the motors to the ESCs so that the joints would be inside the pod. One of the problems with these little 1103s are the shitty wires that become brittle and break easily at the solder joint. A lesson learned from the hoverbot. Wanted to protect them this way. The wires themselves are wrapped around the arms to preserve as much length as possible - thinking ahead for when/if the wire breaks and I need to reconnect it to the 4in1. Also thinking about a smidge of electrical tape on the arms to sturdy up the wires a bit more...

Went with an xt30 connector instead of the standard JST RCY (red) 2-pin or the JST-PH 3-pin. Those latter two have given me many headaches in my brushed micro days and with the hoverbot. Between a potential bottleneck for power after many, many plug/unplug cycles had worn them down (increased resistance) to just outright breaking, I was willing to sacrifice a couple of grams for something beefier. So far, I'm a happy man.

Running these Gemfan 2035 quad props at the moment, as they're super quiet and work really well. I'm also going to try out some Ladybird 65mm props as well as my trusty cut-down HQ T3x3s.... .... but it's just so fast on 2s right now I can't manage to stop myself long enough to try it. It flies like a 5" mini quad flew a year ago. Rough math says a power-to-weight ratio around 8:1!

On 1s, it still wants to move. It needs a prop guard, which Falcon Multirotors has a few prototypes of. A fair bit of throttle control is needed.

If the hoverbot is fun, this thing is ridiculous. It's also sturdy as hell. Between the pod (which is much of the weight) and the 2mm plate, it's not going to break.

Photos

Discussion

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Rookrider   Aug 26, 2017  

where did you get the frame

nwbb   Aug 26, 2017 

Prototype frame I'm testing for Falcon Multirotors. I can't speak for them, but it sounds like it will be on the market soon!

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