Hackday London: The Story of Beagle 3, pt 1

So the second Yahoo! Hackday was last weekend, held in conjunction with the BBC Backstage team. Having recieved an invite from the ever bashful Tom Coates early in May, I was looking forward to this in a sort of madcap “good to physically meet up” with the UK Web 2.0 developer crowd. The venue, Alexandra Palace (the ultimate Web 0.2 hack thanks to the early television broadcasts) was perfectly suited, and provided a huge amount of space for planning, tables, flip-charts, beanbags, coffee, projectors, and the 101 other things an event like this needs.

Going to the event, I honestly had no idea what I would end up doing. Probably some podcast interviews, I thought, and maybe some recording to play around with the video capabilities of the new Nokia N95. Even after bumping into Simon and Nat at Kings Cross I was ready to let the whole event roll past me as I tried to capture it. Even the idea of an ‘Automatic LOLCat’ (grab a live feed, say from a presentation, do some speech to text, pick out some words and generate a live LOLCar to liven up a conference) was nice, but wasn’t really up my street (thanks to my lack of current programming skills).

It was at the end of the walk from the station to Ally Pally, and my thought that ‘the green space at the front of the palace is just like where those guys did the Diet Coke / Mentos fountain display…’

And with that hop, a tiny skip towards wondering what would happen to the diet coke bottles if they were upside down, and I was jumping at the idea of building a rocket. But not any old rocket. A three stage, diet coke and mentos powered rocket.

So that pretty much nixed the idea of walking around with a microphone. It was time to start planning

After attacking a whiteboard, the plan was this. A three stage rocket, with a 2 litle bottle first stage, a 1 litre second stage, and a ‘recovery capsule’ made of a 330ml Yahoo! branded water bottle that were circulating around the Palace. The first stage would be a bottle rocket powered by water and air – pressurise the bottle, release it, and the water forced out provides thrust thanks to Newton’s third law. As this stage lifted off the ground, a string would pull out a ker-plunk style pin at the top of the second stage, allowing a bundle of mentoes to drop into a tank of diet coke. This would fizz up over a few seconds, blasting the second and third stage higher. As that ‘burned’ out, the third stage would fall off, do something interesting with its payload, and return to the ground on a parachute.

Time to get some opinions from other hackers, and find out if anyone was interested in helping out with a non-coding hack. Turns out that both Gervase Markham and Greg McCarroll were up for the challenge as well. In Gervase words…

I intended to spend some time building a personal project, but when Ewan wandered over and suggested rocketry, I switched over like a shot :-). Our project was called Beagle 3; the initial plan was a multi-stage rocket using air/water for the first stage and Diet Coke/Mentos for the second stage, with a camera payload.

And with that, the plans were tweaked, the goal was set (the camera payload), a shopping list was drawn up, and it was off to the supermarket to pick up supplies, tanks, fins, tape, fuel and cameras for our rocket. Oh and a six pack of Irn-Bru for me. It was going to be a long weekend.

By this point my body clock is out of sync – I’m convinced we’ve got back to Hackday around lunchtime after the trips to Tescos, B and Q (for some drainpipe), Halfords (valves) and ‘The Best Wine Shop’ for some corks. Rather than a complicated release mechanics, on stage one, we went for a simple ‘pop-valve’ arrangement – once the bottle reached a certain pressure, the cork would be forced out, and we would have ‘ignition!’ In actual fact it was after 6pm. It was time to get to work.

For the next three hours, Gervase, Greg and I went back and forwards from our table (which looked remarkably like the set of Blue Peter during a make, but messier), testing out various bits and pieces. How much thrust did the diet coke deliver? How well does the deployment of mentos work? How much work do we need to do on the coke bottles to prep them for launch? Will the first stage have enough ooomph to launch the second and third stages.

Well we discovered quite a lot. The first was the kerplunk pins had to be replaced, as the holes were letting out too much CO2. So they got replaced by a magnetic catch release. Even then, though, the problem was how to throw the fluid out the bottle with enough speed. We couldn’t drop the mentos through the exhaust hole, so they had to be up top. And while we could use a dremmel to cut through the base of a bottle, and then slap some tape over the hole until the pressure built up, all the work was (a) releasing too much CO2 as the bottle was opened and (b) causing more CO2 to be released at the site where we had cut (thanks to a non-smooth surface).

We tried. We really tried. As all the people watching our ongoing tests suggested ideas we threw them in the mix as well. All to no avail. We did design a system that would allow us to simply unscrew the lid, pop on the ‘motor assembly’ and be ready to launch again, but it would be impossible to fashion before 2pm Sunday. So we called it a night, decided to ponder a bit, and settled down to watch Doctor Who.

Yes, Doctor Who. There’s something about 500 people running away from their laptops and their precious code, to descend on the space in front of the stage. Yes the projection system was about to be hijacked for the return of Captain Jack and the rest of the good ship Tardis. And quite frankly, in a room full of hackers, the Doctor complaing about everyone blogging went down an absolute treat. That hour reminded me so much of Rocky Horror, of watching something cherished with a few friends in your living room, but with the volume and capacity of a cinema. Fantastic.

Overnight, I was hoping for some sleep, but unlike Rag times of old, I just couldn;t get comfy on a roughly hewn beanbag and a too-short sofa, so I sat up with Jim Purbrick and a few others with his latest ‘wacky game’ that is best described as a tabletop version of VGA Planets played with translucent pyramids. Totally engrossing and strategic, and probably something I’ll never play ever again. But cool nonetheless.

So how did Beagle 3 fare on Sunday? Did it take to the skies? Did we get our pictures? What was it like doing the whole presentation with just a smartphone? And where did we end up in the final judging. Keep reading, part two is coming up soonnow available!