Friday 22 September 2017

Quick random hack! Digispark, neo pixels and USB battery




 




A few things collided this week... one being I managed to knacker my back and therefore spent some time trapped in the house! The next thing being the constant stream (as my long suffering postperson will attest) of small cheap random components from the far east creates little pools of tech that lie await for such times (you can tell I've not spoken to many people this week with my waffle?!). So I came across this small Digispark clone which I hadn't played with and I couldn't quite remember what I'd ordered it for! Essentially its a Attiny85 on a board with a PCB USB connector and after some trials and tribulations I managed to get an Arduino IDE to talk to it on a windows 7 machine (my linux box is poorly atm but that's another story!)

Also in the tech flotsam I have a few of those excellent poundland USB batteries and a small plan emerged! So with the addition  of a piece of white heatshrink glued to the battery pack into which I inserted a 8 pixel adafruit neo pixel strip (needs to be inside something cos dang they are bright!) and a microswitch glued to the side of the Digispark/Attiny board we have a switchable portable superbright mood light/torch! I've stuck a couple of strong neomydium magnets to the back of the USB battery so I can stick it to metal things! Its handy to stick to my field toolbox and also I've added a short strip of metal to the back of my larger rolling toolbox I use for workshops.. useful for a bit of light but also a be seen be safe addition on these dark winter nights! Code is just a tweaked version of the button cycler sketch from the adafruit neopixel library.

Wednesday 13 September 2017

Level 1 Rocket Certification Achieved!

Panta Rhei on the rail ( and some dodgy geezer) Photo Credit Charles Simpson.

Panta Rhei is away... Photo credit Damian Burrin

Lovely to see the chute deployed! Photo Credit Damian Burrin


Just over a week ago I travelled down to the beautiful BMFA regional centre in Buckminster for the UK rocketry association AGM and launch day with my main purpose being to try and fly my completely scratch  built rocket "Panta Rhei" and achieve my level one certification in high power rocketry.

So I've been building up to this for a while and in a way I have done it in a tricky but rewarding manner.. I scratchbuilt Panta Rhei after creating the design in the opensource rocket design software Openrocket and it was designed to use some cheap cardboard postage tubes I had bought off ebay as opposed to tubes made specifically for rocketry. As postal tubes are slightly random sizes it means you have to make everything (nosecones, centring rings, coupling sections etc) from scratch and so you can't buy anything off the shelf that fits! So the cnc router and the 3d printer saw a lot of use in the construction of Panta Rhei... I went even further in that I didn't even buy a parachute I rather cut and stitched my own and even went as far as buying a length of Nomex to sew a flameproof parachute protector!

The other challenge for me, was that I (until arriving at this event) I had never been to a high power rocket event and had no knowledge/had never seen another high power rocket in real life! I had no real knowledge of launch rails and launch procedures or indeed how (apart from I had read in a book) the delay adjustment tools for rocket motors work or how they are packed etc...

The Saturday morning morning came and everyone started to show up.. I was quite nervous tbh and so pressed on to try and get the flight out of the way in the morning. I tell you what... HPR rocketry people are great... whilst I had to do everything myself in terms of the preparation of the rocket, everyone was there to give me advice if needed but also to leave me alone to work through prepping Panta Rhei. I was assigned a certifying officer Charles Simpson the chair of UKRA and my range safety officer (RSO) was Damian Burrin. Both of whom offered really constructive support and guidance. The other LEGEND of this story is another UKRA council member Andy Mell .. who is one of the most supportive guys you'd wish to meet, he gave lots of advice the night before and also allowed me to test fit Panta Rhei on the launch rail to check clearances etc. Andy had also brokered getting the motors (cesaroni 29mm H133 3 grain bluestreak) to me and also supplied me with some of the correct rail buttons I needed to fit the launch rail... and most importantly he was up for a pint in the local pub the night before!

Motor all prepped!


By around 11.30 am everything was ready and walked out to the launch rail and proceeded to mount Panta Rhei and  connect the ignitor. My nerves got the better of me though and after the obligatory photo I nearly forgot to remove the remove before flight tag that would arm the altimeter! However, the tag was removed, the bleeps confirmed the altimeter was working and I retreated to the launch controller. After the RSO and those present looked around the sky the RSO called that the airspace of interest was clear and gave me the signal to put the key in the launchpad.. once confirmed a countdown was given and I hit the button!

Panta Rhei leapt off the pad in a beautiful (even if I say so myself) vertical flight into lovely blues skies with no wind.. perfect! The motor fired the deployment charge a little after apogee and seperation was followed by a couple of heart stopping seconds before the bright yellow chute unfurled perfectly! I didn't have too long a walk but arrived to find Panta Rhei in great condition in a textbook landing with everything laid out in a straight line! Having launched and recovered with no damage... I'd passed my level 1 high power rocketry certification! The altimeter put the apogee at 460 meters which was around what was simulated.



So finally.. I can heartily recommend trying to get your L1 certification, but I definitely recommend its a good idea to go and check out how launch days work and look at some HPR rockets being prepped in advance if you can.. dates of launch events can be found on the UKRA website.