More prototypes

It's taken a full 20 prototypes, over several weeks, using both FDM (fused deposition modelling (filament)) and SLA (Stereolithography (resin)) 3D printing techniques, to finally get close to a production model of the switch300 UAV.

The major challenge with the early prototypes was to get the FDM print started, to organise the model into printable components and to start getting the wings, tails and propeller to fold. As you can see, various pieces of wood and cardboard shims were needed to fill gaps where parts were misaligned or just not fitting together.

These prototypes started the experiment with SLA (resin) printing - very suitable for the grid base and for solid blocks like the fuselage and the nose, but useless for thin components like the drone's wings and tails. The SLA nylon is an infuriating material - very nice at picking up surface detail, extremely prone to warping and tending to be strong when you don't want it to be, and very brittle when you'd like it to be strong! Also printed separate lenses for the main nose cameras using a neutral (clear) PLA material.

This print features a resin printed fuselage and brown FDM printed wings, tails and prop. The folding prop is printed in one and is quite a delicate component to coax intact from its support material. I did try printing a folding prop in resin, but the light bleed-through on the resin layers meant that it was an epic fail. The rudders also have a version (not very accurate) of the steering mechanism - my main problem being that no images of the steering servos and sender were available at the time.

We're getting there - new and updated steering mechanism still not installed on this one, but everything else is starting to work.

Here we see the folding mechanisms in action - if the model is taken off the base stalk, the wings will fold in under the fuselage, just like the real thing. The switch300 is tube launched, 3 inches in diameter. This model is only rough painted, using acrylics and yes, the more experienced modelmakers amongst you will certainly enjoy filling gaps, smoothing surfaces and generally getting a much more accurate finish!

Though I've attempted to stay pretty accurate to the various originals, it's just not possible to do a fully accurate scale model, because accurate plans aren't in the public domain, because there are so many different versions of the drone and because some of the key information about the switch300 is hidden from the public. Also, some components (especially the rudder steering mechanism) have had to be overscaled in order to make them strong enough to construct.

But this model does present a very nice demonstrator version, clearly showing the folding wings, tail and prop.