Sunday 31 March 2013

Canon Camera Setup

Screen shot of the setting up.
So this morning we woke up and took our camera out of the freezer, as you do. We left it there overnight to test that it can work under freezing conditions. It is a Canon PowerShot A810 and has had the Canon Hack Development Kit (CHDK) installed so we can upload a script to continually take photos on a loop every few seconds. The kit itself runs directly from the SD card of the camera, without actually touching the existing firmware. This only works on Canon cameras and for each camera there is a specific file to download. A full 'how-to' can be found here.

There are a few example scripts around on the Internet but nothing that exactly fitted our needs, so I wrote our own. It's quite simple in that it takes photos on a loop, with the ability to change the time period between the photos on the camera itself.  You can see the script here on our GitHub!

We also thought that this blog was lacking a graph, so here we go:

One of the other great benefits of the CHDK is it has the ability to write log files. This means we can see what the camera got up to while in the air - including making use of the thermometer within the camera! This graph shows how the temperature dropped over time against the amount of photos taken. We managed to take over 2000 photos over the four hour time period. The period between the shots was 12 seconds, but I think we could reduce this, maybe by half. We might try this test again to see how it fares. Another thing to bare in mind is that our home freezer only got to -15C, where as in the Stratosphere it can get to -50C.

As you may have seen in our Payload Part Two post, we will have the camera facing down, the idea being that we get some good ground shots of our fantastic Forest of Dean scenery on the way up in addition to some general 'Earth' shots when we are up at 100,000ft. With the GoPro on the side, hopefully we have all angles covered!

Friday 29 March 2013

Four Day Weekend

Another busy few days at STRATODEAN HQ. We found out last weekend that our CAA application has been accepted with all our requested dates gaining approval. Yey!

We've been trying to make the most of the extra long bank holiday weekend and tick some more jobs off the old to-do list.

We visited our launch site to get a greater idea of how to plan our launch day, just basic things like parking (somewhere where we don't have to drag our helium too far!), where to set up our tarpaulin and equipment etc.

The helium has been purchased! After much umm-ing and ahh-ing he decided to take the hit and order a jumbo-sized canister (BOC cylinder size 'L'). This beast holds 9m³ and weighs 76.5kg. We were hoping the medium-size would be sufficient (BOC size 'T') but our calculations predicted we would require approximately 4m³. Even though this figure was rounded up, the medium's 3.6m³ of helium would have been little too close for comfort. We were hoping to procure the helium from a local company but all those approached required us to have an account with BOC before they would deal with us. In the end we ordered from who seems to be a common HABer's port of call.

Our balloon (plus a spare), parachute and cord have arrived from Random Solutions (thanks Steve!). The latex balloons are tucked away in storage until needed but we took the parachute for a little (highly technical) test run a little earlier...

Still on the to-do list for the weekend ahead:
  • Finish testing Canon camera and CHDK.
  • Make balloon filler.
  • Attach cord to payload and duct tape.
  • Make decision on hand warmers and make necessary payload modifications.
  • Check credit on backup tracker.
  • Check credit on 3G dongle.
  • Write 'night before' list.
  • Write 'on the day' list.
Finally, Happy Easter from the resident STRATODEAN HQ Bunnies.
Summer wishes you a Happy Easter from her cardboard castle.

Thursday 21 March 2013

Payload - Part Two

We've been making some real progress with the payload this week - if you missed our first post detailing how we constructed our polystyrene box you can see it here.

We've made a video which we hope will explain things further.  Be sure to read below for more information and pictures.

The majority of the work has been organising the layout of the components within the payload and making compartments inside the box to offer them extra protection and insulation. Basically we need everything to fit nice and snug! Here come the photos:
Drilling a hole for the camera lens with a hole cutter.
The hole. 
We tested a few options based on recommendations by other HABers for cutting out this aperture, such as using metal cookie cutters or just cutting it freehand. This method however gave us the cleanest finish. The cookie cutter method proved particularly tricky as our polystyrene has a closed cell structure. This is the property that makes it waterproof in case it lands in the world's deepest muddy puddle or the English Channel etc. It is therefore very dense and resilient to cookie cutter pressure!
A spot of hoovering.
Freehand trimming was easiest with a fine hacksaw blade.
Layer 1 - the base of the payload.

The first layer of polystyrene shown left is actually one layer of our 1" polystyrene sitting on top of the base of our payload box. Here we have the GoPro resting on top and facing outwards with a square cut into the side wall. The backup tracker is slightly sunken down into the polystyrene level and a space for the digital camera has been completely cut out so it can face down and the lens can extend out through the circle cut out of our payload base.
A quick weigh of the payload.
It was essential for us to check our payload mass as we added our internal compartments - the polystyrene can add a surprising amount of weight and we didn't want to go overboard and let the weight creep up. It doesn't matter how well organised and pretty it looks - it's got to get off the ground after all! Luckily it was all under control so we set about making Layer 2.
Layer 2 in the making.

Our tracker and battery pack in position.
The space on the right is to secure the GoPro in position.
The hole in the middle is for the aerial.
The tracker's nice and snug.
Layer 2 in situ.
With all of our components housed and layers completed, we decided our payload box had approximately 2" of excess height. When we originally designed the box, we opted for a cube mainly for ease/it seemed pretty logical, and well you have to start somewhere don't you? Now in hindsight this extra polystyrene was an unnecessary weight so we trimmed it off.
Things get a little nervy as we measure
what's about to get the chop.
The moment of truth. With an upturned dust bin lid acting as a polystyrene dust receptacle. Resourceful.

Bye bye extra weight.
Our new low profile design being sanded.

Time to make it a hat.
Our double layer lid being glued together.

Wednesday 13 March 2013

Another step closer..!

We've only just gone and bought a balloon, parachute and some nylon cord!

Cue happy faces..!:

Thursday 7 March 2013

Still on the To Do List...

The CAA Application has been emailed off but still plenty to do!