BananaSplit: An Experiment in Frame Design

As much as I love drones, all drones, there is still a part of me that wants to see machines that are as slick and aggressive looking as the drones we see in sci-fi or the work, so I set about designing something with “interesting” aesthetics as one of the key design elements.

Unfortunately for me, the reason that most FPV drones look so similar is that flat plates of carbon fiber assembled at right angles is really quite close to the optimum solution, especially when performance, durability and manufacturability are driving factors.

I wasn’t willing to sacrifice much in performance or durability, so instead decided to explore more expensive, but more flexible, manufacturing methods (like milled aluminium and 3D printing). I also decided to standardise on a set of electronics that I like (Primarily the Vista and NBD Infinity AIOv2) so that I could have a compact, tightly integrated, frame design.

One of the earliest design choices were to use vertical arms, and then to split those into a triangulated shape, providing a rigid arm which is resistant to twisting. The “droop” of the arms allow the motors to be dropped downwards, resulting in a CoG very close to the prop line.

Early design, with high potassium levels

This particularly bananary version was the first “complete” CAD, taken to the point of 3D printing, CNC cutting and flight. It surprised me, but had definite room for improvement.

Banana Pod

This pod was optimized for FDM printing and has large side holes for Vista cooling and access, but isn’t pretty.

Motor Mount Brackets

Milled from Aluminium these brackets will support NBD 2004 to 2306.5 motors

"Final" CAD

Representative of the full assembly as shown in the video, with Aluminium parts and SLS printed nylon pod

Section View

The layout of the Vista and the NBD AIO are visible here

Caddx Peanut Mounts

A weird, and a less weird, mount for the Caddx Peanut, in order to get 3rd person footage

Now, although I said I was willing for the manufacturing to be more complicated, I still didn’t want it to be ludicrous, so I made an effort to keep the part count down. There are only 3 carbon shapes (2 center plates and 1x8 arm halves) and 2 Aluminium pieces (4x motor mounts and 8x arm mounts), which makes it very easy to keep spares. The camera pod itself is a challenge, it is integral to the unique look of the drone, but is also a large printed part, which is not ideal for mass manufacturing, I’ll no doubt be rethinking this part.

Banana in Flight

The first flying prototype, spinning 5” bi-blades on 2004 motors. Oodles of 3D printing.

SLS Nylon Pod

Glass-Filled PA12 Nylon printed on an SLS 3D printer results in a beautiful object that is reasonably strong.

Early Build

Here an FDM-printed ABS pod is mounted on the final design for testing.

Beauty Shot - with flaws

I’m thrilled with how this drone looks in flight. Those carbon tips need protection though!

Weeeeeeee!

whoooooooo flip flop flip zwish!

Assembly

The internal mounting brackets are all visible here, that’s part of the secret to the rigidity.

There are a lot of things I like about how my design turned out, but as with any first (or second) draft, there are also a number of issues that I would like to improve upon. I will be adding further blog posts to dive into some of those details, but for now if this has piqued your interest, and might be interested in a release in the future, please follow along here on NewBeeLabs or: