HAPS-1, UMSFB1 redux Options

[djellison]

Next weekend, if everything goes well, a 15x30cm carbon deck will fly onboard HAPS-1 -http://www.pegasushabproject.org.uk/wiki/doku.php/missions:haps:haps-1

One end of the deck will be the flight radio, the other is my responsibility, a single camera (Powershot A560 ), stand alone GPS logger (to 18km), and a small wide angle mirror so the camera can see the payload, the chute and the envelope above.

Still working on a hacked firmware for the A560 - but the intention is every minute will include 15s of video, and then 5-10 stills in fairly quick succession - with the hope that the rotation of the balloon will give us some mosaics out of each section.

More details, some photos etc, later in the week.

[Stu]

Congratulations! That sounds very exciting, can't wait to see the pics that - hopefully - come back.

But tell me, is it true you've had to brief Downing Street on the anticipated results of this test flight..?

[djellison]

What, brief the worlds second dullest scotsman ( after Andy Murray ). I'd rather pull my own teeth

Having issues with the expanding foam I use to insulate the camera - might take some work. We'll get there.

Doug

[djellison]

Possibly - and it's only possibly - we'll have uStream from the launch site, and live tracking, if we can, during some/all/none of the flight. More details as and when I have them.

Camera and GPS have their own housing now - reasonably pleased with it - need to tidy it up a bit - but the camera is rigid inside, the gps sits on top - but the battery pack is tucked away.

I'm fairly sure that I'll go with the wide-angle lens to stick on the front of the camera - I'll regret it after the flight if I don't. I'll do back to back tests on image quality, however, to make sure it isn't screwing everything.

We'll be using the chute I bought some time ago with the intention of doing my own project...so it wasn't wasted

Doug

[djellison]

Following on from the high altitude balloon thread, I thought it made sense to make a new thread for (hopefully) next weekends launch of HAPS 1 ( http://www.pegasushabproject.org.uk/wiki/d...ons:haps:haps-1 )

[nprev]

So, what's it like to not require sleep, anyhow?

(Never mind...ramblings from an old dude.) Good luck & godspeed; looking forward to seeing the results!

[djellison]

Just for testing, I did a walk-around with the GPS logger on 10s intervals yesterday

Should drop straight into Google Earth. It starts ratty and all over the place - but once it's had a few mins to get a proper log once we left the house, it's an accurate trace of a walk around the block - no point more than about 2m out.

It'll work till about 40kft - and then hopefully log back on again on the way down. in case of a failure of the flight computer - we can extrapolate the ascent, extrapolate the descent, and where they cross is a rough estimate of apogee

Doug

[djellison]

The 'flight' SD card ( and a flight spare ) have arrived - the Sandisk Extremem III 4gb SDHC card.

From Sandisk.com

# Ideal for demanding photo shoots under severe weather conditions—heat, cold, wind, rain, snow, etc.
# Built to perform in the most extreme environments and temperatures—from
-13º F to 185º F
-25º C to 85º C
# Min 20MB/second** sequential read and write
# Durable, reliable and thoroughly tested—temperature tested (heat and cold); shock and vibration tested

OK - not the -50 we may see on flight - and sadly we wont get values for the flight min/max temp (next time maybe) - but it's the sensible option just to get the most robust card I can reasonably find.

After the joy of 200hz Phoenix EDL data - I desperately want to log Acceleration for the next flight. The motherboard doing the work on the avionics side has an accelerometer, but it's very much KISS this flight, and no data volume to save such a a large data set either - but I'm going to push to try and achieve that next time around.

Foam enclosure is finished, deck has foam underneath as a stand-off on which the 1/4 wavelength antenna will go.

[mps]

OK - not the -50 we may see on flight - and sadly we wont get values for the flight min/max temp (next time maybe) - but it's the sensible option just to get the most robust card I can reasonably find.

The memory card can handle -25 C - that's fine, but what about the camera? A560's nominal operating temperature is only 0 to 40 deg C

[djellison]

Essentially there's not a lot we can do about that... what we CAN do, we do do...

Use Lithium AA cells which dont drop off at cold temps (http://data.energizer.com/PDFs/l91.pdf - OK to -40deg - very expensive at £1 each roughly, but worth every penny)
Give the camera quite a lot of work to do (hence the 4gb card, I intend to fill it on a schedule of 3hrs) thusdumping the 9 whrs of energy from the two cells about as rapidly as possible into the camera which will render itself as heat.
Insulated as well as I can in foam (although the fact that the lens 'opens' means it's not even slightly sealed around the front)
And a 'get up and get down' flight plan to avoid lingering at altitude.

The first, third and last of those has been enough for similar flights in the past.

I feel sorry for the GPS logger on top of the foam -it's only going to have a layer of duct tape between it and the hell outside BUT - thermally speaking, the camera will be a warm glow underneath.

Doing something as simple as a pair of 9v cells dumping to a thin film heating element is just too much complexity and mass. If we mature the project to go for high altitudes or lingering, then I will be aiming to disable the camera's motor-driver lens deployment, keep it stuck out, and match foam around the lens to better insulate.

Of all the things that could go wrong - the camera getting too chilly isn't top of the list by a long long way. DOing it this way has worked for lots of other projects, so I'm happy to go that way. Next time around maybe we log temps internally on the camera, externally on the foam and then in free air under the balloon - using a Picaxe kit or similar.

It's worth mentioning though, that for perhaps 10 minutes, maybe half an hour, this whole schbang will be at 10mbars or less, at -50 degrees, with lots of UV radiation.

Remind you of anywhere

Doug

[hendric]

Doug,
What about the chemical hand-warmers used for camping/hunting? I believe those last several hours. Might not be worth the bother unless there are some definite temperature issues.

[nprev]

Aren't those based on some sort of magnesium compound, or something else rather volatile? I don't know how they'd behave @ peak altitude (or if they'd work at all.)

All I'm directly familiar with is the US military's Meals-Ready-To Eat (MREs)...and those heaters get HOT really fast upon addition of water, plus they emit some fairly nasty gasses if you catch a plume; it'll bring tears to your eyes, and not just because you ended up with "spaghetti" instead of something sort of edible...

Dunno. Packaged chemical heat sources seem to peak out rather quickly & require an external trigger to activate. Sounds complex & risky to me.

[ElkGroveDan]

It's worth mentioning though, that for perhaps 10 minutes, maybe half an hour, this whole schbang will be at 10mbars or less, at -50 degrees, with lots of UV radiation.

At least there will be no perchlorates to deal with.

But seriously, I feel a bit like Rip Van Winkle here. Can you share with us some of the history of this version of your project? Last I heard there were too many restrictions in the UK and you dropped the entire balloon idea. Now it seems like 20 years have past and everything is different. What did I miss???

[djellison]

I simply 'got a ride' with people who know what they're doing - namely James Coxon and friends ( http://www.pegasushabproject.org.uk/wiki/doku.php )

I emailed them and just went over to watch them do some cool things ( drop a parafoil type vehicle from under a balloon, then two normal launches ) - and on the two normal launches, the camera was hung under the gondola, which was under the radio payload. I commented that I'd tried to have a go myself but found it too damn complicated, and then commented that perhaps the camera payload wasn't the best way of doing it - so James basically said 'think you can do better...go on then!'. And so here we are

I promise - some pictures before it goes up - it's not pretty, but it should work

I've looked at the hand-warmer thing - but actually too hot - and they can expand as well - they're a small bag, and taking a bag to 10mbar could burst it, dumping hot chemical gooo all over the camera etc. You have to be careful to use open-cell foam or it can pop-corn all over the place. Bubble wrap can burst as well.

[ElkGroveDan]

I might add that I recall someone giving me socks that were powered by AA batteries several years ago when I was a hiker. They are meant more for an emergency when your feet are getting cold in a bad way. Lemme see if I can find them online somehwere. For the next flight anyway.

EDIT: http://www.rei.com/product/703131?cm_mmc=p...CFSQdagodWVVYrg