Original URL: http://www.theregister.co.uk/2014/03/10/lohan_avionics/
Heroic Playmonaut wowed by LOHAN's bulging package
LOHAN team wraps Vulture 2 spaceplane avionics install
Pics Following the recent successful fitting and testing of our Vulture 2 spaceplane's Raspberry Pi and Picam rig, the Low Orbit Helium Assisted Navigator (LOHAN) team is relieved to announce that we've wrapped the permanent installation of the rest of the aircraft's avionics.
What's more, our heroic Playmonaut now has the proper seat we promised him, but more on that later.
Here's the view last week, with the Pi temporarily removed to give us a bit of wrangling space. We'd already fitted the digital airspeed sensor and probe, and mounted the external LED and safety switch:
Starting at the rear, first up on the agenda was to position the power supply module (top left) and provide a fetching pink plastic straw to accommodate one of the antennas of LOHAN team member Anthony Stirk's back-up PAVA tracker:
The PAVA - destined to sit right at the rear of the front fuselage/nose assembly - has three antennas, which are actually guitar strings.
While two will protrude from the fuselage, one has to run straight up it, hence the straw to prevent the antenna snagging on something during installation. LOHAN regulars will know that the straw colour choice is in deference to Anthony's penchant for pink gaffer tape.
With a free passage for the PAVA antenna assured, we could stick in a Velcro-covered battery mount board, and place the Pixhawk radio transmitter beside that. To the left you can see the styrofoam cradle for the PAVA...
...and here is the tracker held in place with our quite sensational "elastogrip" system: a couple of cable tie mounts, some metal clips and a rubber band:
It's worth noting that anything which needed gluing down, like the cable tie mounts in this case, was fixed with Scotch-Weld 2216 Epoxy ("certified for aircraft and aerospace applications" and "excellent for cryogenic bonding applications").
It's the same stuff we used to fix the Vulture 2's outer wings to the rear fuselage/inner wing (for photos of the aircraft's components, see here):
Taming the Pixhawk
So, onwards towards the spaceplane's nose. Next up on the list was how to tame the Pixhawk and its GPS/compass unit...
...which first required the placing of a new Futaba S.BUS R/C receiver. Unlike the previous ArduPilot Mega (APM) 2.6, with its eight separate inputs, the Pixhawk has a single S.BUS in, hence the new kit. Note the Pixhawk's I2C extender to the left:
A block of wood on either side of the receiver, with some bolts and rubber washers provided support...
...for the removable autopilot platform:
The autopilot is separated from the platform by self-adhesive foam mounts, and more securely held using rubber bands. Behind it, we lovingly crafted a platform for the GPS/compass...
...and with that last component Velcroed down, it was pretty much a wrap:
And now, ladies and gentlemen, we present a view of the whole thing shipshape and Bristol fashion, with the Raspberry Pi reinstalled:
For clarity, feast you eyes on this astounding annotated version of the above:
A few notes:
- The Raspberry Pi is still lacking its breakout board, with accelerometer, GPS and Radiometrix transmitter. The board will sit atop the Pi and connect via the GPIO.
- The USB to TTL gizmo is to connect the Pi to the Pixhawk via the latter's second telemetry socket. Try this fetching close-up:
- The Velcro battery platform has space for two racks of AAs - four for the Pixhawk and R/C systems, and four for the Pi.
- For operational purposes, the batteries are connected by cables soldered directly to the terminals. The battery holder shown here is for testing.
Finally, for absolute clarity and those of you who haven't been paying attention at the back, here are all the components of the Pixhawk rig for your viewing pleasure:
Oh, hold on, we nearly forgot. Our impressed Playmonaut took a moment to try out his new seat, courtesy of some Playmobil aircraft breaker's yard down on eBay. The USB to TTL acts as a handy table aboard what is a right-hand-drive spaceplane, which is only right and proper:
More from the lovely LOHAN:
- You can find full LOHAN coverage right here.
- If you're new to LOHAN, seek out our mission summary for enlightenment.
- There are photos our our magnificent Vulture 2 spaceplane here, and detailed structural plans here.
- For your further viewing pleasure, we have all our photographic material stored on Flickr.
- Our LOHAN and Paper Aircraft Released Into Space (PARIS) videos live on YouTube.
- We sometimes indulge in light consensual tweeting, as you can see here.