84 posts • joined 7 Dec 2011
We believe that it actually blew back in the last test in Spain, but the glass wasn't blackened (well not much - just a tad at the underside) so it wasn't obvious. Igniters can short circuit when the blow, plus the battery supply erred on the "let's make sure this goes" side, resulting in an igniter current about 3 times the fuse rating.
So, for next time, "check the damn fuse" gets added to the check list. Also, the SPEARS firmware has been updated to check the fuse and other items so it will report over the radio if there's an issue, and the receiving end will display a "DON'T LAUNCH" message in such a case.
Not many doing the "live" pix. Only a couple doing it regularly and a few more doing it sometimes.
You have been watching someone else's flight. Our imaging tracker was "RICHARD" and as no doubt noticed the images are from one called "POPEYE".
Re: Oxygen supply?
I'm sure Lester has plans to add an oxygen tank, complete with a stirrer ...
Re: Rubber band problem?
True, but it'll be nice and warm in there what with the Pi etc.
Actually, it was 1605.
Re: The title is too long.
The camera already draws approx 200mA at 3.3V so it heats itself, so if I were worried (which I'm not) I could just leave the camera on all the time.
I've flown these cameras with very little insulation, and sometimes with none. They've never fogged. It's not a problem and doesn't need a solution.
Re: Too late but still
No, Lester got it right. For high altitude work, windows tend to fog up inside. I know of several HAB flights where people have used windows, lenses or Go Pro covers and without exception unless they're heated they fog up for part of the flight.
Re: We assume it has been updated
The problem was actually that the met office didn't launch their normal quota of balloons that day, so the prediction was based on older data than usual. A weather front was predicted to come in during the evening, but actually came in several hours earlier, changing the flight path enormously and thus dooming our heroic playmonaut to an early, salty, wet grave.
Yes, all true. Graphics use the OpenVG C library so no X at all. Total CPU for the whole thing (GPS receiver, video streaming, chase car upload, display update) runs at around 10%; without the h/w acceleration it'd be 100%!
Re: Airframe comparison
> .. idiot(s) ... military grade
Coincidentally, those are the 3 words that came to mind when reading your post. Though not necessarily in the same order.
Re: From the RockBLOCK spec....
SBD was extensively tested in our workshop, which thankfully was large enough for the "messages" to dissipate.
Re: smart phone
A reader suggested a Bond-style trigger box, so the RPi was an obvious choice!
The message can't be sent using SMS, but is sent by POSTing a URL to the RockBLOCK server. So yes it could have been done using a simple program on a smartphone or a PC (in fact I tested it all on a PC before porting the code to the Pi).
We wanted to put the full week's worth of empties in front of the camera, but decided that the weight was far too much, and the camera would have had to be the other side of the street.
Re: What are the various circles on the map?
We had 2 transmitters in each payload (1 main 1 spare) but only 2 receivers on the ground. The backup trackers were ignored during the flight hence appeared to stay at the launch site.
All images are stored on the SD card, which we recovered after the mountain rescue expedition the following day.
That really is a most appalling piece of deduction. They cannot rule out contamination and they appear to have done very little to prevent it.
Re: From the photo showing the battery pack...
Er, yes, that's how I switch it off you see :-)
I contacted them before when I got the "highest images transmitted by an amateur over radio", but they turned me down. So .... stuff 'em.
I know! Sadly I didn't think of that till after I'd done the deed.
It cuts the payloads down from the balloon. I usually wrap the nylon cord around a resistor and heat that up with a few watts. I suspect this time though pyros will be used.
The cut is above the parachute for what I hope are obvious reasons :-)
Hand Operated Remote Release Over Rockblock
Indeed. It was hardly worth having a custom PCB made for a one-off, and it's a lot quicker too.
Re: LOHAN shouldn't suck wet caps!
Yeah, I remember at school accidentally blowing up a 5000uF cap. Which I was holding at the time. Fortunately the top of the cap was facing away from my hand, otherwise A&E would have been required! It took some time for the cloud of white dust to settle.
Re: LOHAN shouldn't suck wet caps!
It's a super-cap. It's there so the device can be run from USB. When transmitting it uses a lot more than the 500mA that USB can manage.
In our case power comes from some Lithium Energizer cells so the supercap isn't needed.
Re: Most importantly...
I like this :-)
Re: Live piccies!
Well, we already have the option of sending images over the radio link, and even though we won't have so many radio listeners as usual that will probably still be the best option.
A foam box landing by parachute at 10mph is going to have trouble killing anyone. Even an American-sized foam box like that one. In the UK our flights are typically much, much smaller.
In the UK there are around 50 amateur flights per year listed on the UKHAS site, and maybe the same again that don't appear there. The UK met office fly about 2000 per year, and they haven't managed to kill anyone either (worst they managed was breaking a greenhouse window).
Re: accelerometer readings from the 3-axis magnetometer
Those are from the accelerometer. There was also a megnetometer and gyro, but not shown in the article.
Re: Vaguely OT: Dara O'Briains science club ..
No chainsaw yet, however the tree in question proved no match for the muscle-power and a rather effective handsaw.
Re: Are you saying...
Anything dropped from weather balloon *must* descend by parachute.
No gliding, guided or otherwise.
Re: Very stable
Just to confirm my earlier suspicion, the glitchy video is down to a sub-par SD card.
Re: More helium wasted
Yes, it was hydrogen. More lift less money and as a bonus stops Lester from lighting up too often :-)
The plan was to release the glider before burst, with a tethered line to pull a large 'chute out of the back of the fuselage. The small chute was to help make sure that happened. We had to ensure that the glider fell by parachute and didn't actually fly.
In the end the release mechanism didn't release the glider, so the whole lot came down together. 1.3kg of balloon came down with it to, so the tree-landing was a tad faster than we aimed for. Not that we aimed for a tree either :-)
It had to have a chute - CAA won't allow flight from altitude whether the glider is guided or not.
The James May thing had to stay within sight of an operator at all times.
yes, some (not many) GPS units correctly operate this way, but many stop if the velocity OR altitude limit is exceeded. Generally we use ublox modules which are known to work at high ltitudes (up to 50km which is higher than we can get our balloons), provided that we put them into "flight mode" first.
Re: Very stable
Yes the Earth concave/convex thing is down to the lens on the GoPro Hero 3 that took that video, popular for their ability to cram everything into the field of view. The downside of course is the enormous distortion, which is kind of OK in some stills but hideous when recording video of what should be a slightly curved Earth.
As for the Pi, the video part was a late addition. A script took small images during the launch phase, then larger images during flight (from 3km up, then down to 2km), and finally it ran a single 10 minute video for the landing before reverting to the small images again. The video part was the standard current Pi Cam software with no special parameters. Guess #1 is the SD card wasn't fast enough. Guess #2 is the processor was a tad busy (but was generally around 20% on the telemetry etc., which I'm guessing isn't enough to cause a problem). The jumps were visible when playing the video back on a Windows PC, as well as in the converted-to-mp4 version uploaded to Youtube.
Re: I thought you weren't allowed aero mobile?
This is correct.
Which funnily enough is why we aren't :)
All transmitters are using a license-free frequency/power, explicitly allowed for airborne use.
Re: Air traffic safety
A jet engine would spit it out without noticing. The payload is smaller, much lighter, and much much more fragile than the (Harrods) frozen chickens that Rolls Royce fire into their engines for tests.
All aircraft are warned in advance by NOTAM, as part of the process we go through to obtain permission for the flight.
Re: What are they hiding?
If you check the image collection at http://ssdv.habhub.org/ you'll see this suspicious image downloaded from the flight http://ssdv.habhub.org/images/2013-04-13--20-43-44-PIE5-DD.jpeg?u=66 ...
Yes, the flights will head across the North Sea.
Re: No aerial APRS? I did not know that.
As I understand it (and I'm not a Ham) they don't allow airborne amateur radio transmissions *at all*. Hence our use of unlicensed transmitters with a frequency and power rating that is specifically allowed.
Re: Across the English Channel?!
It's a one-way unmanned mission; no Playmonauts will be harmed!
Cheers! http://www.daveakerman.com/?p=873 will do nicely :-)
Thanks for including 2 of my photos.
Thanks for not including my project that they came from.
Strange combination that don't you think?
Dave (Pi In The Sky bloke)
Re: I would just like to say that....................
You might want to stay away from your local BOC depot then, because that's exactly how they do it.
You don't need a trolley to shift a cylinder 5 metres,
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