New Rocketry CAD tools: FreeCAD Rocket Workbench

In my never ending quest to get more opensource stuff around rocketry going I posted over at the FreeCAD forum about a concept for a Rocketry themed workbench. It seemed like it would be a good fit and that it might be an interesting area for developers to work on. I explained how I'd often used Openrocket to design and simulate a rocket design and then, quite often, I found myself copying dimensions into FreeCAD or sometimes OpenSCAD to create 3D objects of nosecones, centring rings, fins and more. I suggested that automating some of this would be a good starting point, but that also the sky was the limit, ultimately it is *possible* to recreate something like Openrocket or Rocksim in FreeCAD, with the benefit then of any design is auto-magically in a CAD format for other techniques to be applied. FreeCAD already has a wealth of tools that can be leveraged at rocket parts, from 3D printing mesh tools, to CNC toolpath work, through snazzy computational fluid dynamics tools,  FEA and more. Hell, there'ss even a glider workbench for designing gliding parachutes within the community so the end really is limitless!

What happened next was utterly brilliant and testimony to opensource culture! People got interested and one chap, Dave,  (AKA DavesRocketShop ) got stuck in. Within a couple of weeks we now have a rocketry workbench released with some useful tools already up and running. Also there is a tantalising roadmap of exciting features to come. 

The first release when installed as a workbench gives you some parametric tools to create rocket air-frame components. Nosecones in all the common geometries are all there, Haack, VK, Ogive, Parabolic series, Power series etc. Transitions are similar in choices and there are tools to create body tubes, centring rings and bulkheads. It's really straight forward to begin to assemble great parts that can be adorned and edited using the entire suite of tools FreeCAD has to offer. Fins, in the first release, are limited to trapezoidal designs but there are a wealth of parameters to play with and it's trivial to auto generate aerofoil geometries etc.  The rocket workbench is already available via the addon manager which makes installation and updating a breeze and on the forum thread the mighty Dave is occasionally releasing manual install versions for those of us keen to try experimental features. 

Dave is currently working on importing parts from the openrocket databases. This is really interesting as all the common manufacturers parts are in there, so if you want a particular Estes replacement nosecone, or to upscale one for some crazy project this will be but a click away! I'm most excited about that there is a plan to allow the workbench to import Openrocket, Rocksim and RASAero files, whilst that may be some way off it really opens up some astonishing opportunities for rocket designers. Also having got to grips with the technical drawing workbench in FreeCAD I am looking forward to being able to document my designs well, important if one day I go for L3 HPR certification. 

Finally if you are new to FreeCAD but want to try FreeCAD I'm writing a reccurring series for Hackspace Magazine on FreeCAD and it started back in issue 37 here. 

Cheap Small FPV Quadcopter Conversion

I've been getting back into a few long stalled projects including building up a Robocat 270 quadcopter kit I've had for ages on the build pile (will post on that soon). the reignited interest in quads has made me want to try and learn to fly First Person View (FPV). The Robocat needs a few line of sight flights before I commit to rigging it with FPV and so I wanted to learn on something smaller and cheaper. My very first quadcopter was this Syma X11 a small brushed drone that is a brilliant little stable flyer to learn on. There was a version sold with a camera (non FPV, 0.3 megapixel and micro SD) but all the Syma X11 bodies are the same and on mine there was a blanked off lens area and a void where the camera would be. I'd picked up a set of cheap Eachine goggles off eBay and so I bought a tiny Eachine TX06 split FPV camera and video transmitter (VTX).  As the X11 is a little airframe I am used to, and , as I felt I could get the TX06 rig in it, it felt a good option for a cheap small learner FPV setup.

Flipping the X11 over you can see the lens cover which was the target area for the camera. Undoing the 4 screws allows the lower body and the battery cage to be removed. 

The battery cage (the white piece) can then be removed with 4 small screws. I realised that the VTX would sit happily underneath the battery cage and that the small antenna could be pushed through the rectangular hole you can see at the back of the body shell on the left. On the white battery cage above I needed to snip of the square moulding seen at the front in the picture above. After removing the small fake lens in the body I snipped some plastic to widen out the hole for the camera. 

You can just make out in the image above that I've places a small piece of double sided pad between the camera and the battery frame and you can see the amount I have trimmed off the battery cage and the body on the right of the image. 

Powering the camera and VTX I simply trimmed the connector off the TX06 and soldered the wires onto the pads where the LiPo connects to to the board. I've managed to fold the wires out of the way and the battery slides into the battery cage as it did before. You can tell there's a little extra weight in flight, but it really isn't an issue as in stock form the X11 had a reasonable flight time. Now to get used to the wibbly wobbly world of FPV!