Monday, 13 November 2017
Just in case it's useful I decided I'd chuck a few bits of openSCAD code I use to generate 3d models of transitions and nosecones and couplers for rockets onto github. I am no amazing coder but it's nice to opensource what little I can! Its pretty well commented so you just stick in the dimensions you need and render!
Saturday, 4 November 2017
(Obligatory lathe shot above!)
In high power rocketry often a rail is used to launch the rocket rather than a simple rod as the aluminium tee slotted extrusion ( the same types that many 3d printer or hobbiest cnc router frames are made from) is more stable and rigid. This means that instead of a launch tube/lug being mounted to the rocket airframe a pair of rail buttons that slide into the slotted extrusion are added instead.
I struggled when I was building Panta Rhei for my level one certification to find out which rail buttons I needed or indeed the dimensions of the ones I needed as I hadn't ever been to a high power event. However I eventually discovered there are 2 types of rails commonly used, the 2020 rail with a 6mm slot or the 3030 rail with an 8mm slot.. Eventually a very kind UKRA member (driven mad by my constant questions) took pity on me and sent me a set of rail buttons that would fit a rail that would be used at the launch event I was aiming for.
They worked brilliantly and I've been doing a few experiments to make further rail buttons to try and shave the weight and also to be able to use a metric fit as the commercial ones use a 3/16 machine screw to fit them. People who know will know have a bit of a thing about using SI units... but also I think that the 3/16 screws with quite a course pitch thread when usually being fitted into 2 -4mm wall thickness they don't really offer an optimal thread type/contact area. So above is a picture of the commercial ones aimed to be used in a 6mm slotted 2020 rail.
Above is the first set I turned up, here I used Delrin which has a higher Young's modulus than nylon (which I believe the commercial ones are) and is very free to machine and also has a self lubricating quality as you can see about fitted with M3 12mm bolts (with a large head) offers almost a 2 gram saving over the originals.
So I also had a go at turning some out of Nylon and again they represent a weight saving over the originals even though the actual Nylon piece is slightly heavier than the original the M3 bolt weight saving makes a saving overall.
So I think the future is Delrin.. stronger and lighter!
Sunday, 29 October 2017
So travelled down to Derby yesterday to see the Mini Maker Faire... mainly becasue it is an ace proper maker faire and also the venue is closing for a couple of years for a large refurbishment project so its the last one for a while! Had a fabulous time and saw loads of amazing people and things!
So many cool robots in the place!
Me and the fabulous KonichiwaKitty... :)
Spencer... Mr RC2014, maker of extraordinary retro computing kits!
Fascinating bit of machining this... a WWII bomb made by Qualcast ... yep thats right Qualcast the lawnmower company, this is one of the many objects being digitised into an archive of models at Derby Silk Mill museum.
Bristol Hackspace had this brilliant manual machine for drawing great images!
Sunday, 15 October 2017
Hole cutting drills.. I always tread carefully with these as they seem to want to fling the drill about as they engage!
Couldn't be simpler way to mount the table... and yes ... my shed needs tidying!
Friday, 13 October 2017
Heres a few shots from last night!
Not a bad turnout with a couple of people also not in this shot!
Didn't take many shots of the different spaces but here's one!
Some very nice 3d printers including a sweet Ultimaker extended (good for BIG nosecones!)
Do we get the pun?! A cheesey rocket pizza.... Top work and great pizza was consumed!
So, went over to Noordwijk in the Netherlands last weekend to attend the Open ESTEC day with thousands of other people! ESTEC is the technical heart of ESA and they open a massive amount of it and a load of the staff volunteer to come back in to talk about the work that they do. It was a fabulous day and met some wonderful people. I took far to many photographs to upload them all so for now I though I'd chuck some of the tweets I did in the storify below. It was great to see all the science and technology but additionally brilliant to meet up with a few people again or for the first time! Most notable was to meet Montasser who works at Innovative Solutions In Space who I have talked to for 4 years and even been on a Hackaday Prize team with but had never met irl. I also got to see the DARE rocketry team (blog from when I visited them earlier this year here) and also got to see Jasper from the Delfispace program who does a lot of work on Pocketqubes. A fabulous event.. if you get the chance to go... GO!
Friday, 22 September 2017
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
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
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...
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.